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Research Progress of Photoperiod Regulation in Rice Flowering Yubo WANG, Yue WANG, Xiong LIU, Wenbang TANG Chinese Journal OF Rice Science    2021, 35 (3): 207-224.   DOI: 10.16819/j.1001-7216.2021.0514 Abstract （1845）   HTML （1075380387）    PDF （1690KB）（3297）       Knowledge map    Save As an important agronomic trait, heading date is determined by its own genetic factors and environmental factors, which has a great impact on the ecological adaptation area and yield factors of rice variety. In the past two decades, from the recognition of day length to the activation of flowering in the stem apex meristem, great progress has been made in the molecular regulation mechanism of rice photoperiod-induced flowering. A large number of regulatory genes related to flowering have been isolated and cloned, and integrated into the molecular network of photoperiod regulation. When plants are in favorable conditions, this network activates floral regulatory genes, promotes the expression of florigen gene, and transports florigen to the apical meristem, thus driving the development of meristem cells and forming flowers finally. In this paper, Arabidopsis thaliana is used as a reference to discuss the genetic variation of rice photoperiod regulation network and its extension from low latitude to high latitude so as to provide valuable information for the cultivation of ecological varieties and the molecular mechanism of photoperiod regulation. Table and Figures | Reference | Related Articles | Metrics | Comments（0）

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Research Progress and Prospect of Functional Rice Shikai HU, Peisong HU Chinese Journal OF Rice Science    2021, 35 (4): 311-325.   DOI: 10.16819/j.1001-7216.2021.201106 Abstract （724）   HTML （1476544697）    PDF （1108KB）（1914）       Knowledge map    Save In this review, we introduced the structure and nutrient compositions of brown rice, and the concept and the connotation of times of functional rice in the new historical period. We emphatically described the types and regulatory mechanisms of bioactive ingredients in functional rice, and summarized the advances in functional rice research by conventional breeding, mutation breeding and genetic engineering. Finally, we summarized the existing problems in the research of functional rice, and forecasted the future development trend of functional rice by taking into consideration the challenges in this front, the current research status, and the public demands for functional rice and its products. Table and Figures | Reference | Related Articles | Metrics | Comments（0）

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Rice Response to Salt Stress and Research Progress in Salt Tolerance Mechanism WANG Yang, ZHANG Rui, LIU Yonghao, LI Rongkai, GE Jianfei, DENG Shiwen, ZHANG Xubin, CHEN Yinglong, WEI Huanhe, DAI Qigen Chinese Journal OF Rice Science    2022, 36 (2): 105-117.   DOI: 10.16819/j.1001-7216.2022.210609 Abstract （1732）   HTML （2042185994）    PDF （28738KB）（1506）       Knowledge map    Save The problem of soil salinization is becoming more and more serious in China. The saline-alkali land within the red line of cultivated land is about 9.3×106 hm2. Salt stress is one of the main abiotic stresses that restrict grain production. Rice is a pioneer crop in saline-alkali land improvement. It is of great significance to understand the response of rice to salt stress comprehensively. The effects of salt stress on growth, yield and quality of rice were reviewed. The physiological mechanism of salt stress affecting the growth and development of rice was discussed at the physiological level such as osmotic regulation, ion balance and gene fronts. The regulation measures to reduce salt stress in rice were put forward, as well as the prospects and suggestions for further research on salt stress in rice. Table and Figures | Reference | Related Articles | Metrics | Comments（0）

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Factors Affecting Cadmium Accumulation in Rice and Strategies for Minimization Nan JIANG, Xu YAN, Yanbiao ZHOU, Qunfeng ZHOU, Kai WANG, Yuanzhu YANG Chinese Journal OF Rice Science    2021, 35 (4): 342-351.   DOI: 10.16819/j.1001-7216.2021.200913 Abstract （568）   HTML （1611203513）    PDF （6696KB）（1458）       Knowledge map    Save Cadmium (Cd) is an extremely toxic and widely distributed heavy metal. Cd in farmland has adverse impacts on crop growth and development, and threatens human health via the food chain. Rice, as a staple food crop in China, plays an important role in food security. However, rice tends to absorb and accumulate more Cd compared with other cereal crops. The ‘Cd-polluted rice’ events were frequently reported in recent years, which has made Cd pollution a serious public concern. Reducing the Cd accumulation in rice grains is urgent. In this review, we summarize the advances in screening and breeding for rice varieties with low Cd, water management, adjustment of soil pH and foliar dressing strategies. The article aims to lay a theoretical foundation for technological integration, extension and application, and development of new technologies. Table and Figures | Reference | Related Articles | Metrics | Comments（0）

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Towards Understanding the Genetic Regulations of Endosperm Development in Rice Juan ZHANG, Baixiao NIU, Zhiguo E, Chen CHEN Chinese Journal OF Rice Science    2021, 35 (4): 326-341.   DOI: 10.16819/j.1001-7216.2021.210307 Abstract （837）   HTML （1762691117）    PDF （11529KB）（1425）       Knowledge map    Save Endosperm, a product of double fertilization, is a tissue nourishing the developing embryo. In addition, cereal endosperm is the primary source of calories of humans. Rice endosperm consists more than seventy percent of the seed dry mass, whose development directly determines the yield and quality of rice grains. To date, we have had a profound understanding of the genetic and epigenetic regulations for rice endosperm development. Many of the important genes required for rice endosperm development have been identified. In this review, we summarize the molecular controls of the key events/processes of endosperm development, including the syncytium-cellualrization transition, endosperm cell differentiation and storage compounds accumulation. We mainly focus on the new findings in rice; however, some important findings in Arabidopsis and other cereal crops are also introduced. We also discuss some questions that need to be elucidated in the future for rice endosperm development. Table and Figures | Reference | Related Articles | Metrics | Comments（0）

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Identification and Gene Mapping of a Lesion Mimic Mutant lm8015-2 in Rice Chen WANG, Beifang WANG, Yingxin ZHANG, Yongrun CAO, Yue ZHANG, Min JIANG, Kangji BIAN, Xiaohui ZHANG, Qunen LIU Chinese Journal OF Rice Science    2021, 35 (4): 352-358.   DOI: 10.16819/j.1001-7216.2021.200908 Abstract （367）   HTML （1241645449）    PDF （26434KB）（1421）       Knowledge map    Save 【Objective】 To substantiate the genetic mechanisms behind the disease resistance of rice, we identified a rice lesion mimic mutant lm8015-2. 【Method】 lm8015-2 was obtained from an EMS-induced Zhonghui 8015 (ZH8015) mutant library. The SOD, CAT, POD activities, H2O2, MDA, SP, photosynthetic pigments contents, the expression level of defense genes were analyzed in lm8015-2 and its wild-type leaves. The population derived from 02428/ lm8015-2 was used for genetic analysis and fine mapping. 【Result】 Its red rust-like spots were first observed on the tips of the mutant leaves three weeks after sowing, then spread gradually to the whole leaf and throughout the plant at tillering stage, causing the death of whole leaf at heading stage. The shading assay showed that the lesions on the leaves of lm8015-2 were induced by natural light. Meanwhile, photosynthetic pigment contents of lm8015-2 decreased significantly. The staining experiments of EB and DAB showed the excessive H2O2 deposition and cell death of lm8015-2. Compared with the wild type, the activities of SOD and POD, the MDA content increased, while the content of SP decreased in the mutant lm8015-2. Genetic analysis suggested that the phenotype of lm8015-2 was controlled by a single nuclear recessive gene, which was located in a 104 kb interval between the markers W32-85 and C32-8 on chromosome 5. Sequencing analysis revealed that a single base substitution (T to A) of the initiation codon (ATG) occurred in the DNA sequence of LOC_Os05g48390, resulting in the absence of initiation codon. The qRT-PCR results showed the expression of partial defense genes were up-regulated obviously in lm8015-2. 【Conclusion】 The results reveal the target gene is allelic to LTN1, and the mutation of LM8015-2 likely enhances the expression of partial defense genes. Table and Figures | Reference | Related Articles | Metrics | Comments（0）

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Study on the Characteristics of Soft japonica Rice Varieties with Good Taste and High Yield in Taihu Lake Area Qing ZHANG, Yajie HU, Baowei GUO, Hongcheng ZHANG, Xiaojie XU, Yufeng XU, Banghui ZHU, Jiefen XU, Zhongyi NIU, Rongwen TU Chinese Journal OF Rice Science    2021, 35 (3): 279-290.   DOI: 10.16819/j.1001-7216.2021.0907 Abstract （299）   HTML （1208001535）    PDF （4251KB）（1272）       Knowledge map    Save 【Objective】It is of significance to explore the characteristics of soft japonica rice varieties with good taste and high yield in Taihu Lake area.【Method】 Soft japonica rice varieties suitable for cultivation in Taihu Lake were collected. According to the growth duration, yield and taste quality of the rice varieties, the differences in yield and quality formation of soft japonica rice varieties at different ripening stages were compared. 【Result】Compared with the medium yield type, the number of grains per panicle and the number of spikelets of the high yield type significantly increased in the population. The number of panicle, grain number per panicle and seed setting rate of the good taste type were equal to those of the medium taste type, while the 1000-grain weight was lower. Compared with the medium yield type, the high yield type had higher dry matter accumulation and nitrogen accumulation in the middle and late growth stages, and the final dry matter weight and total nitrogen accumulation were higher. Compared with the medium taste type, brown rice rate, milling rice rate and head milling rice rate of good taste rice increased, chalky rice percentage and chalkiness degree increased significantly, amylose content and protein content reduced, gel consistency were longer, the peak viscosity, hot paste viscosity, breakdown, final viscosity increased, rice and eating value increased significantly. 【Conclusion】 The soft japonica rice varieties with good taste and high yield in Taihu Lake region were featured with large panicle, low grain weight, strong dry matter and nitrogen accumulation ability in middle and late growth stages, good processing quality, poor appearance quality, and excellent cooking and eating quality. Table and Figures | Reference | Related Articles | Metrics | Comments（0）

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QTL Analysis for Grain Weight and Shape and Validation of qTGW1.2/qGL1.2 Chengxing DU, Huali ZHANG, Dongqing DAI, Mingyue WU, Minmin LIANG, Junyu CHEN, Liangyong MA Chinese Journal OF Rice Science    2021, 35 (4): 359-372.   DOI: 10.16819/j.1001-7216.2021.201205 Abstract （324）   HTML （1073743903）    PDF （74206KB）（1238）       Knowledge map    Save 【Objective】 Grain weight and shape have an important impact on the yield and quality of rice. The purpose is to further reveal the genetic mechanism of grain weight and shape in rice by primary mapping of QTLs for grain weight and shape and validating of the newly identified qTGW1.2/qGL1.2 on the long arm of chromosome 1. 【Method】 An F2:3 population consisting of 277 individuals and a recombinant inbred line (RIL) population with 211 individuals were derived from the cross between the large-grain male parent FM9, and the small-grain female parent EFT. The 1000-grain weight (TGW), grain length (GL) and grain width (GW) were measured. QTL mapping was performed by the inclusive composite interval mapping. As for the qTGW1.2/qGL1.2 region, two residual heterozygotes were screened and self-fertilized to produce segregated populations for QTL validation. 【Results】 A total of 35 QTLs for TGW, GL and GW were detected by QTL primary mapping. Among them, 11 QTLs were detected in both populations, 18 QTLs were detected only in the F2:3 population, and six QTLs only in the RIL population. The effects of the newly identified qTGW1.2/qGL1.2 on TGW and GL were validated by using the segregated populations derived from the two residual heterozygotes. Additionally, significant variations in the length of glume cells were observed, and qPCR results demonstrated that the expression levels of genes related to cell cycle, auxin metabolism and grain shape were up- or down-regulated significantly. 【Conclusion】 The primary mapping of 35 QTLs and the validating of qTGW1.2/qGL1.2 will contribute to a deep insight into the genetic basis underlying grain weight and shape of rice, and also lay a foundation for gene cloning and marker assisted selection. Table and Figures | Reference | Related Articles | Metrics | Comments（0）

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Research Progresses on Response Mechanisms and Control Measures of Cadmium Stress in Rice Xiaobo XU, Penghu AN, Tianjiao GUO, Dan HAN, Wei JIA, Wuxing HUANG Chinese Journal OF Rice Science    2021, 35 (5): 415-426.   DOI: 10.16819/j.1001-7216.2021.201209 Abstract （737）   HTML （2018775095）    PDF （3128KB）（1224）       Knowledge map    Save Soil cadmium pollution is one of the increasingly serious environmental problems. Rice is the bulk cereal crop with the highest cadmium uptake capacity. The accumulation of cadmium by rice and its transfer to the food chain pose a threat to human health. In recent years, a series of significant advances have been made in research on the uptake and accumulation processes of cadmium in rice and its influencing factors. In this review, three aspects were reviewed. First, the effects of cadmium on rice seed germination, growth and development, and yield. Second, the physiological and molecular mechanisms behind cadmium activation in soil, xylem loading and transport, and transfer of cadmium from phloem to grains. Third, the prevention and control measures such as variety selection, soil remediation, and agronomic measures. It is expected to provide theoretical references for research related to Cd stress in rice and to lay a basis for developing effective strategies to reduce Cd level in rice. Table and Figures | Reference | Related Articles | Metrics | Comments（0）

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Differences in Response to Low Phosphorus Stress Among indica Rice Varieties and Their Agronomic and Physiological Characteristics Shengfeng QIAO, Yaping DENG, Hanbing QU, Weiyang ZHANG, Junfei GU, Hao ZHANG, Lijun LIU, Zhiqin WANG, Jianchang YANG Chinese Journal OF Rice Science    2021, 35 (4): 396-406.   DOI: 10.16819/j.1001-7216.2021.210304 Abstract （342）   HTML （1140856400）    PDF （22497KB）（1219）       Knowledge map    Save 【Objective】 The purpose of this study is to explore the differences in response to low phosphorus stress among indica rice varieties and their agronomic and physiological characteristics. 【Method】 Twelve medium-maturity indica rice varieties applied in production in Jiangsu Province in the last 80 years were used and two levels of phosphorus concentrations, low phosphorus level (1/20 of the phosphorus concentration of the standard nutrient solution formulation, LP) and the normal phosphorus concentration (International Rice Research Institute standard nutrient solution formulation, control, NP), were designed. 【Result】 The low phosphorus tolerance index was chosen to evaluate the tolerance to low phosphorus (LP) for rice varieties, and the tested cultivars were classified into three categories based on the index: strong tolerance to LP (LP tolerance index ≥0.9), medium resistance to LP (0.5< LP tolerance index <0.9) and weak tolerance to LP (LP tolerance index ≤0.5). Two varieties with strong tolerance to low phosphorus and two with weak tolerance were chosen to investigate the agronomic and physiological characteristics. Plants grown at LP produced significantly lower grain yield than those grown at NP. Compared to NP, LP increased phosphorus translocation efficiency (PTE), internal phosphorus efficiency (IPE) and phosphorus harvest index (PHI). Under the LP condition, PTE and IPE were higher for the varieties with strong tolerance to low phosphorus than for the varieties with weak tolerance to low phosphorus. Compared to the varieties with weak tolerance to low phosphorus, the varieties with strong tolerance to low phosphorus had greater shoot and root biomass, NSC accumulation and remobilization in stem and sheath, less reduction in root oxidation activity, higher increase in acid phosphatase activity in root, more tillers, greater leaf area index and leaf photosynthetic rate at booting stage and grain filling stage. 【Conclusion】 Compared to the varieties with weak tolerance to low phosphorus, larger dry matter accumulation, NSC accumulation and remobilization, root oxidation activity, acid phosphatase activity, leaf photosynthesis rate, and phosphorus utilization efficiency were important agronomic and physiological traits for the varieties with strong tolerance to low phosphorus under LP level. Table and Figures | Reference | Related Articles | Metrics | Comments（0）

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Identification and Fine Mapping of a Grain Width Mutant gw4 in Rice Xuemei DENG, Peng HU, Yueying WANG, Yi WEN, Yiqing TAN, Hao WU, Kaixiong WU, Junge WANG, Linlin HOU, Lixin ZHU, Li ZHU, Guang CHEN, Dali ZENG, Guangheng ZHANG, Longbiao GUO, Zhenyu GAO, Deyong REN, Qian QIAN, Jiang HU Chinese Journal OF Rice Science    2021, 35 (3): 259-268.   DOI: 10.16819/j.1001-7216.2021.01204 Abstract （516）   HTML （1100054567）    PDF （34626KB）（1215）       Knowledge map    Save 【Objective】Grain size is an important agronomic trait that determines yield and appearance quality in rice. Screening and identification of new grain size mutants will lay a foundation for further study of the regulation mechanism of grain development. 【Method】A grain width mutant gw4（grain width on chromosome 4）was obtained from 1% EMS mutagenized population of Zhonghua 11. The scanning electron microscope analysis of the outer and inner surfaces cells of glumes was carried out, and grain size and other agronomic traits were measured at the heading and maturity stages, respectively. With the map-based cloning, the mutant individuals derived from F2 population of gw4 and TN1 were used for fine mapping. The candidate gene was determined by gene sequencing based on bioinformatics analysis, and expression analysis of grain size-related genes was carried out by the RT-PCR. 【Result】Besides narrow grains, gw4 also showed decreased phenotype values in plant height, grain length, thousand grain weight, grain number, number of primary and secondary rachis branches. Scanning electron microscope observation presented that both cell length and width of inner and outer surfaces cells of glumes were smaller than the wild type. Genetic analysis showed that the narrow grain phenotype was regulated by a single recessive nuclear gene, which was fine mapped to a region of 31.74 kb between the two markers BS6 and EX49 on chromosome 4. Sequence analyses revealed a single base substitution of G to A was found in LOC_Os04g01590 which resulted in a substitution of glycine to aspartic acid, and RT-PCR analysis indicated that it was mainly expressed in young panicles with declined expression level in mutant as compared with the wild type. 【Conclusion】GW4 is mainly involved in grain width development, and its candidate gene should be LOC_Os04g01590, which lays a foundation for further perfecting the genetic regulatory network of grain size. Table and Figures | Reference | Related Articles | Metrics | Comments（0）

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Ecological Differences in Yield, Growth Period and the Utilization of Temperature and Light Resources of Double-cropping Late japonica Rice in the Middle and Lower Reaches of the Yangtze River Mengjia WANG, Min YIN, Guang CHU, Yuanhui LIU, Chunmei XU, Xiufu ZHANG, Danying WANG, Song CHENG Chinese Journal OF Rice Science    2021, 35 (5): 475-486.   DOI: 10.16819/j.1001-7216.2021.201109 Abstract （319）   HTML （1610626314）    PDF （28197KB）（1169）       Knowledge map    Save 【Objective】 The aim of this study is to clarify the differences in yield, growth period and the allocation of temperature and light resources of different types of double-cropping late japonica rice in different ecological regions in the middle and lower reaches of the Yangtze River, so as to lay a theoretical basis for application of early indica and late japonica model in the rice growing area of the middle and lower reaches of the Yangtze River.【Method】 The experiment was conducted at Fuyang (30.13°N, 41.7 m above sea level) and Wenzhou (28.52°N, 83 m above sea level ), Zhejiang Province from 2018 to 2019. Rice cultivars were selected based on the large area of application, including inbred japonica (IJR) and indica/japonica hybrid rice (IJHR) with the high-yield indica rice (IR) as a control. The differences in yield, growth period and the allocation of temperature and light resources of IR, IJR and IJHR in the late growing season in different ecological regions were compared.【Result】 1) The dry matter, effective panicle number and sink of japonica rice declined at low latitude as compared to high latitude. As a result, the yield declined by 2.4%–19.1%, while the grain setting and 1000-grain weight remained stable or went up slightly. Meanwhile, the yield of IJHR was 8.8–10.3 t/hm2 in Fuyang and 8.0–10.2 t/hm2 in Wenzhou, being the highest in both sites. 2) The growth period of the tested cultivars at two latitudes differed. Compared with the high latitude, there was no significant difference in the vegetative stage at the low latitude, and the reproductive stage was slightly reduced (4.2%–27.3%), while the grain filling stage was significantly shortened, among which IR, IJR and IJHR shortened by 7.3%–11.9%, 20.8%–41.9%, 23.1%–35%, respectively. 3) The differences in the temperature and light allocation in different growth period mainly reflected in the grain filling stage. The average temperature during the grain filling stage at the low latitude was higher than that at the high latitude (IR, IJR and IJHR increased by 0.4–2.4 ℃, 2.3–3.5 ℃ and 2.5–2.8 ℃, respectively). The effective accumulated temperature at the two latitudes varied with cultivars, and IR had no significance, while IJR and IJHR declined by 24.7–126.4 ℃ and 25.7–107 ℃, respectively. 4) The analysis of PCA showed that latitude was the primary cause for the accumulation differences of temperature and light resources and the yield (PC1 and PC2, contribution of 49%), followed by the cultivars' temperature and light sensitivity (PC5, contribution of 18%) and the panicle and grain structure (PC3, contribution of 14%).【Conclusion】 Compared to the high latitude, the decrease of yield of japonica rice is mainly due to the shortened growth period especially the grain filling stage, decreased effective accumulative temperature and sink. IJHR is characterized by higher yield advantages, which may be due to its grain superiority. Therefore, japonicas with heavy or large panicles may have higher application potential in the middle and lower reaches of the Yangtze River. Table and Figures | Reference | Related Articles | Metrics | Comments（0）

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Differences in Eating and Cooking Quality Traits of Semi-waxy japonica Rice Cultivars in Jiangsu Province Zheng TIAN, Chunfang ZHAO, Yadong ZHANG, Qingyong ZHAO, Zhen ZHU, Ling ZHAO, Tao CHEN, Shu YAO, Lihui ZHOU, Wenhua LIANG, Kai LU, Cailin WANG, Hongsheng ZHANG Chinese Journal OF Rice Science    2021, 35 (3): 249-258.   DOI: 10.16819/j.1001-7216.2021.01103 Abstract （426）   HTML （537051136）    PDF （9354KB）（1146）       Knowledge map    Save 【Objective】 In recent years, a large number of semi-waxy japonica rice varieties were bred in Jiangsu Province. It was found that there were great differences in ECQ (eating and cooking quality) and physicochemical characteristics among these varieties. Exploring the regulation mechanisms behind the ECQ of semi-waxy rice will provide useful information for rice breeding. 【Method】 In this study, 39 semi-waxy japonica rice varieties from Jiangsu Province Excellent Taste Rice Appraisal Conference were used as materials. By analyzing 24 ECQ related traits, such as taste properties, physicochemical characteristics, RVA spectrum parameters and textural properties, the differences and correlation among different taste value groups were found. 【Result】According to the taste value, these semi-waxy japonica rice varieties were divided into three groups, including the high taste value group (>80), the medium taste value group (70-80) and the low taste value group (<70). Compared with the low taste value group, the high taste value group showed lower chalky grain rate, PC (protein content), and hardness, and higher GC(gel consistency), viscosity and transparency, and better cooked rice appearance. However, AC (amylose content), PaT (Pasting temperature) and RVA values exhibited insignificant difference. The correlation analysis showed that the taste value of rice was significantly positively correlated with AC and GC, and significantly negatively correlated with PC, PaT, transparency and chalkiness. However, there was no significant correlation between each trait in the high taste value group. In the medium and low taste value groups, a significantly positive correlation was detected between AC and the taste value. 【Conclusion】The appearance and physicochemical qualities have important influences on the formation of the ECQ of semi-waxy japonica rice. Varieties with higher taste value tend to have better appearance quality and higher AC and GC, lower PC; thus these traits should be paid more attention in the process of semi-waxy rice breeding. Table and Figures | Reference | Related Articles | Metrics | Comments（0）

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Research Progress on Cadmium Uptake and Its Transport and Accumulation Among Organs in Rice Bo FANG, Tengwei XIAO, Nana SU, Yan XIA, Zhenguo SHEN, Jin CUI Chinese Journal OF Rice Science    2021, 35 (3): 225-237.   DOI: 10.16819/j.1001-7216.2021.0719 Abstract （965）   HTML （67657957）    PDF （29799KB）（1140）       Knowledge map    Save With deteriorating heavy metal pollution in soil and atmosphere, heavy metals contents in crops often exceeds the threshold. Heavy metals in soil are difficult to be degraded and are easily absorbed by plant roots and accumulated in crops. Heavy metals in atmosphere fall down on the surface of leaves and could enter into leaves through the stomata eventually, making their way into human body through the food chain and endangering human health. Rice is one of the most important food sources in China, and in some cases, cadmium content in rice exceeds the standard. Cadmium (Cd) is a non-essential element in rice and mainly enters rice root cells through other divalent ion channels. Besides, Cd can enter rice leaves by the adsorption and internalization of leaf cuticle and the permeation of stomatal. The transport of Cd in rice depends on the transporters of other metal ions. The uptake and distribution of Cd organs is a dynamic process, which is driven by transporters in roots, from root to shoot (xylem loading) and from source to sink in phloem (including seed loading). In this review, we elaborated the uptake of Cd from roots and leaves, the allocation of Cd among organs and the accumulation of Cd in rice grains. This review will lay a theoretical basis for reducing the content of Cd in rice grains and solving the problem about Cd pollution in some planting areas in South China. Table and Figures | Reference | Related Articles | Metrics | Comments（0）

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Nitrogen Fertilizer Management for Main Crop Rice and Its Carrying-over Effect on Rhizosphere Function and Yield of Ratoon Rice Jinwen HUANG, Jiayi WU, Hongfei CHEN, Zhixing ZHANG, Changxun FANG, Caihong SHAO, Weiwei LIN, Peiying WENG, Wenxiong LIN Chinese Journal OF Rice Science    2021, 35 (4): 383-395.   DOI: 10.16819/j.1001-7216.2021.200603 Abstract （341）   HTML （1880171268）    PDF （20941KB）（1128）       Knowledge map    Save 【Objective】 Ratoon rice is the continuation of the main crop. We attempt to elucidate the effect of mechanical transplanting of main crop together with nitrogen fertilizer management on the yield of the main crop and ratoon rice from the perspective of rhizosphere microecosystem, which may provide a reference for the high-yielding and efficient cultivation of ratoon rice. 【Method】 The rice genotype of Yongyou 1540 was used as the material. At a total nitrogen application level of 225.00 kg/hm2 in the main crop, different nitrogen fertilizer treatments were designed to analyze the effects of mechanical cultivation on the yield, root bleeding intensity, enzyme activities and microbial diversity in rhizosphere soil in two consecutive years in paddy field. 【Result】 In N1 and N2 treatments, the root system maintained higher vigor, especially in the late growing period of the main season in the N1 treatment (basal fertilizer : primary fertilizer for tillering : secondary fertilizer for tillering : fertilizer for panicle initiation= 3 : 1 : 2 : 4) showed a significant increase in root bleeding intensity as compared with the control N0 and the local conventional treatment of N4. The total yield of the N1 treatment was the highest in the two growing seasons, reaching an average of 17 351.23 kg/hm2, 23.00% higher than that of N4. Soil enzyme activity analysis showed that the activities of sucrase followed the trend of N2>N1>N3>N4>N0 in the full heading stage during the main season, but N1>N2> N3>N3>N4>N0 for ratoon rice; the activities of catalase and nitrate reductase both followed a trend of N1>N2> N3>N4>N0 in the full heading stage during the main season; the activities of urease, N1>N2> N3>N4>N0 from the heading stage of the main crop to the heading stage of ratoon rice. Highly significant positive correlations were observed between soil enzyme activities and root bleeding intensity at all growing stages. Bacterial 16S rDNA sequencing showed that the structural diversity of bacterial communities differed significantly between the fertilized and non-fertilized treatments, and the Chao1 index and Shannon index of N1 treatment were significantly higher than those of other treatments. Function analysis of rhizospheric bacterial community showed that fertilization increased the number of bacteria closely related to soil carbon and nitrogen cycle, soil organic matter content and soil stress resistance, especially the N1 and N2 treatment with higher relative abundance of nitrospira, which were favorable to soil nitrogen cycle. 【Conclusion】 Under mechanical cultivation, the treatment with properly postponed nitrogen fertilizer application in the main crop is beneficial to the improvement of the rhizosphere microecosystem of ratoon rice, thus improving root vigor, promoting rice growth, and obtaining high yield of rice in both growing seasons. Table and Figures | Reference | Related Articles | Metrics | Comments（0）

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Different Reactions of Rice Monogenic Line IRBL9-W Harboring Pi9 Gene to Magnaporthe oryzae Containing AvrPi9 During Seedling and Adult-plant Stages Shufang LIU, Liying DONG, Xundong LI, Wumin ZHOU, Qinzhong YANG Chinese Journal OF Rice Science    2021, 35 (3): 303-310.   DOI: 10.16819/j.1001-7216.2021.0717 Abstract （331）   HTML （1342183424）    PDF （1295KB）（1127）       Knowledge map    Save 【Objective】 The Pi9 gene confers broad-spectrum resistance against Magnaporthe oryzae. Rice monogenic line IRBL9-W carrying single blast resistance gene Pi9 is highly resistant to leaf blast during the seedling stage, but it is susceptible to neck blast at adult-plant stage in blast nursery. It is important to analyze the mechanism behind the reversion of resistance to Magnaporthe oryzae, which will provide important information for effective utilization of Pi9 in disease-resistant rice breeding program.【Method】Eight single spore strains of M. oryzae isolated from neck blast samples of diseased IRBL9-W, and one isolate Y363 were artificially inoculated by spraying at seedling stage to pathotype their pathogenicity on 24 monogenic lines including IRBL9-W. Two out of eight strains and control strain Y363 were further selected and inoculated on IRBL9-W at late-booting stage by injecting to evaluate their pathogenicity. The alleles of M. oryzae AvrPi9 gene cognate to rice blast resistance gene Pi9 were amplified and sequenced with AvrPi9-specific primers in nine strains. Total RNA of the rice monogenic line IRBL9-W in seedling and late-booting stage was extracted from young leaf and panicle, respectively. The expression analysis of Pi9 gene was performed by semi-quantitative RT-PCR and real-time qRT-PCR. 【Result】 The monogenic line IRBL9-W was completely resistant to the nine M. oryzae strains at the seedling stage exposed to the artificial spraying. However, IRBL9-W was susceptible to panicle blast when inoculated with both two randomly selected strains (YX2-7-1 and YX2-15-1) isolated from panicle blast lesions of IRBL9-W, and the control strain Y363 by injecting inoculation at the late-booting stage. Compared with AvrPi9, allelic sequence amplified from Y363 was identical to cloned AvrPi9, and the coding region of the other eight strains isolated from IRBL9-W panicle blast was identical to AvrPi9 gene, except for a 16-bp deletion at -264 bp upstream of the coding starting position in the eight strains. Given high resistance of IRBL9-W to these strains at the seedling stage, we contended that this 16-bp deletion did not affect the function of AvrPi9 gene; qRT-PCR results showed that the relative expression level of Pi9 gene in panicle was only 47.3% as compared to that in seedling leaves. 【Conclusion】Compared with the relative expression level of Pi9 gene at the seedling stage in IRBL9-W, the significant decrease of Pi9 gene expression level in panicle of IRBL9-W could be the cause of susceptibility to M. oryzae at late-booting stage. Table and Figures | Reference | Related Articles | Metrics | Comments（0）

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A New Approach for Fine-mapping and Map-based Cloning of Minor-Effect QTL in Rice Yujun ZHU, Ziwei ZUO, Zhenhua ZHANG, Yeyang FAN Chinese Journal OF Rice Science    2021, 35 (4): 407-414.   DOI: 10.16819/j.1001-7216.2021.201206 Abstract （451）   HTML （8405399）    PDF （418KB）（1082）       Knowledge map    Save Important agronomic traits in rice are generally controlled by a few major-effect QTLs and a large number of minor-effect QTLs. Great progresses have been made in the cloning of major QTLs, while minor QTLs remain difficult to be cloned due to their small genetic effects and the influence of measurement error. A new approach for fine-mapping and map-based cloning of rice minor-effect QTL was introduced in this article. The approach includes two steps: 1) Use the residual heterozygote to construct near isogenic lines for fine-mapping of the target QTL; 2) Use the genome editing to create mutants of candidate genes for gene function identification. Using the strategy, we fine-mapped six minor QTLs for grain weight and grain size on the long arm of chromosome 1, and successfully cloned the first minor QTL for grain weight. We expect that this approach could provide more options for QTL cloning and new germplasm creation. Table and Figures | Reference | Related Articles | Metrics | Comments（0）

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Effect of Location and Sowing Date on Eating Quality of Semi-waxy japonica Rice Cailin WANG, Yadong ZHANG, Tao CHEN, Zhen ZHU, Qingyong ZHAO, Chunfang ZHAO, Shu YAO, Lihui ZHOU, Ling ZHAO, Xiaodong Wei, Kai LU, Wenhua LIANG Chinese Journal OF Rice Science    2021, 35 (4): 373-382.   DOI: 10.16819/j.1001-7216.2021.210207 Abstract （347）   HTML （1216386113）    PDF （466KB）（1078）       Knowledge map    Save 【Objective】 The aim of this study is to make clear the eating and cooking quality (ECQ) characteristics of new semi-waxy japonica rice and the influence of environmental conditions during maturity. 【Method】 The starch physical and chemical indexes, rapid visco analyzer (RVA) profile characteristics and ECQs of the tested lines were analyzed by varietal comparative experiments in two sites on two sowing dates. Good taste quality rice varieties Nanjing 46 and Nanjing 9108, which were widely planted, and 38 semi-glutinous japonica rice lines derived from the progenies of the hybrid between Nanjing 46 and Nanjing 9108 were used as materials. 【Result】 The differences of 12 ECQs among 40 semi-waxy japonica rice varieties (lines) were significant at 1% level. The tested lines showed better appearance quality (AQ) and ECQ, the taste value (TV) of 10 lines was higher than that of Nanjing 9108, and the TV of six lines was higher than that of Nanjing 46. The TV of late japonica lines was higher than that of medium japonica lines. In addition to peak viscosity (PKV), the effects of location on the ECQs were significant at 1% level. The most affected characters were TV, consistency viscosity (CSV) and amylose content (AC), followed by AQ, the peak time (PeT) and cool paste viscosity (CPV), with PKV, gel consistency (GC) and breakdown viscosity (BDV) being the least affected. The interaction between sites and varieties for AC, GC, PeT, BDV, setback viscosity (SBV), CSV, AQ and TV were also significant at 5% or 1% levels. Compared with the varieties planted in Nanjing, the AC of the varieties planted in Sihong increased generally, while GC generally decreased. The RVA profile characteristics followed an upward trend except BDV. AQ in Sihong was generally better than Nanjing, TV in Sihong was generally better, with an average increase of 7.8 points. The effects of sowing date on ECQs were significant at 1% level except GT, BDV and SBV. GC was the most affected character, followed by AC, CSV, TV and PeT, and BDV was the least. The interaction between sowing dates and varieties in GC, PKV, HPV, CPV, BDV, SBV and TV was also significant at 5% or 1% levels. When sowing was delayed, AC, PKV, HPV, CPV, PeT, CSV, AQ and TV generally increased, GC decreased, GT, BDV and SBV changed little. 【Conclusion】 The AQ and ECQ of semi glutinous japonica rice were significantly affected by location, sowing date and their interaction with varieties. In the production of high quality rice, it is necessary to select the type of high quality varieties suitable for the local climate conditions, and ensure them of optimum climate and cultivation conditions for grain filling. Table and Figures | Reference | Related Articles | Metrics | Comments（0）

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Response Characteristics of Rice Cysteine-rich Receptor-like Kinases Family Genes to Rhizoctonia solani and Plant Hormones Zhiming FENG, Guangda WANG, Jianhua ZHAO, Ran JU, Mengchen LI, Peng GAO, Keming HU, Zongxiang CHEN, Shimin ZUO Chinese Journal OF Rice Science    2021, 35 (5): 439-448.   DOI: 10.16819/j.1001-7216.2021.210305 Abstract （328）   HTML （1073742343）    PDF （26917KB）（1051）       Knowledge map    Save 【Objective】 Clarifying the response characteristics of rice cysteine-rich receptor-like kinases (CRKs) family genes to Rhizoctonia solani and plant hormones is important preliminary work to analyze the functions of CRKs in rice resistance to R. solani. 【Method】 A phylogenetic tree of 45 CRKs in rice was constructed by bioinformatics. qPCR was used to analyze their response characteristics to R. solani, plant hormones ethylene (ET), jasmonic acid (JA), salicylic acid (SA) and cytokinin (CK), and their expression patterns in different tissues.【Result】 The rice CRKs family can be divided into four groups. Most of the CRKs clustered or closely distributed on chromosomes from the same group or branch. Forty-one CRKs responded to R. solani infection, and 17 of them responded strongly. Combined with their tissue expression patterns, it was found that 10 of the 17 CRKs, including CRK15, CRK23, CRK24, CRK26, CRK27, CRK28, CRK29, CRK30, CRK31 and CRK33, were expressed strongly in leaf sheathes and leaves, suggesting that these genes may be involved in regulating resistance to sheath blight. Most of CRKs from the same branch had similar response characteristics to R. solani, indicating that these CRKs may have functional redundancy in regulating resistance to R. solani. Forty CRKs responded to three or four kinds of plant hormones, and their responses to different hormones varied, indicating that CRKs might be widely involved in these plant hormones-mediated defense pathways. There were 17 CRKs with opposite responses to JA and SA, 21 with similar responses to JA and SA, 21 with similar responses to ET and JA, and 23 with similar responses to ET and SA, respectively. These genes may be involved in the interactions among ET, JA and SA. The results not only reflected the synergistic and antagonistic effects of ET, JA and SA signaling pathways, but also indicated that these genes may participate in the interactions among ET, JA and SA.【Conclusion】 Some rice CRKs involved in the regulation of rice sheath blight resistance have been identified, and they may play roles in the plant hormones-mediated defense pathways, which provides scientific clues for us to further explore the function of CRKs in regulating rice sheath blight resistance. Table and Figures | Reference | Related Articles | Metrics | Comments（0）

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Rapid Breeding of New Semi-glutinous japonica Rice Varieties with Good Eating Quality by Crossing Between Sister Lines Cailin WANG, Yadong ZHANG, Tao CHEN, Zhen ZHU, Qingyong ZHAO, Shu YAO, Ling ZHAO, Chunfang ZHAO, Lihui ZHOU, Xiaodong Wei, Kai LU, Wenhua LIANG Chinese Journal OF Rice Science    2021, 35 (5): 455-465.   DOI: 10.16819/j.1001-7216.2021.210405 Abstract （279）   HTML （1073750298）    PDF （4465KB）（1036）       Knowledge map    Save 【Objective】 In recent years, semi-glutinous japonica rice with good taste is favored by farmers and consumers in the Yangtze River Delta region due to its good taste quality, and has become the main varieties for high-quality rice brand building in this region. In order to speed up the breeding of new varieties, we tried to breed new varieties of semi- glutinous japonica rice with good taste by crossing between sister lines of semi-glutinous japonica rice with different growth durations. 【Method】 By the reciprocal crossing between the mid-maturing late japonica rice Nanjing 46 (whole growth duration 165-170 d) and the late-maturing medium japonica rice Nanjing 9108 (whole growth duration 150-155 d) derived from the progeny of Wuxiangjing 14 / Kanto 194, 38 new semi-glutinous lines with different growth periods (whole growth period 140-170 d) were obtained in F6 generation through individual plant selection of F2 and superior line selection of F3-F5. Taking parents Nanjing 46 and Nanjing 9108 as control, 38 new lines were compared for several years, and their resistance to rice blast, agronomic traits, yield and their components, starch physicochemical indexes, RVA spectrum characteristic values and eating quality were analyzed. 【Result】 Most of the new lines have better agronomic characters than their parents, and most of them showed good eating quality, stable agronomic traits, excellent comprehensive characters and high yield. Among them, Nanjing 9036, Nanjing 9308 and Nanjing 66 achieved the variety approval in Jiangsu Province, and five new lines are in the middle of the regional trails in Jiangsu Province. 【Conclusion】 New varieties of semi-glutinous japonica rice with good eating quality and comprehensive characters can be rapidly bred by crossing between sister lines of semi-glutinous japonica rice falling into different ecological types. Table and Figures | Reference | Related Articles | Metrics | Comments（0）