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10 March 2022, Volume 36 Issue 2 Previous Issue    Next Issue
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Reviews and Special Topics

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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 2022, 36(2): 105-117.  DOI: 10.16819/j.1001-7216.2022.210609 Abstract ( )   HTML ( )   PDF (28738KB) ( )   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.

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Effects of Low Temperature on the Growth and Development of Rice Plants and the Advance of Regulation Pathways: A Review XU Qingshan, HUANG Jing, SUN Aijun, HONG Xiaozhi, ZHU Lianfeng, CAO Xiaochuang, KONG Yali, JIN Qianyu, ZHU Chunquan, ZHANG Junhua 2022, 36(2): 118-130.  DOI: 10.16819/j.1001-7216.2022.210602 Abstract ( )   HTML ( )   PDF (4554KB) ( )   Early rice often suffers from low temperature during rice seedling raising, which seriously affects the quality of rice seedlings, and the growth and development of rice in paddy field, and reduces rice yield. It is of great significance to study the effect of low temperature on rice growth and development and the appropriate exogenous regulation pathways to ensure the production of early rice in China. In this work, the effects of low temperature on early rice seedlings, vegetative growth and reproductive growth were reviewed, and the physiological, biochemical and molecular mechanisms of rice responding to low temperature stress were summarized, including antioxidant system and the expression of low temperature induced genes. Finally, we put forward the measurements to improve the tolerance of rice to low temperature stress, such as screening of rice varieties with low temperature tolerance, application of exogenous hormones and reasonable fertilization. The research prospects of improving the tolerance of rice to low temperature and expanding the area of early rice in China were also put forward, such as screening of excellent rice varieties with low temperature tolerance and integrated agronomic cultivation technology.

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Research Progress in Biosynthesis and Influencing Factors of 2-acetyl-1-pyrroline in Fragrant Rice WEI Xiaodong, ZHANG Yadong, ZHAO Ling, LU Kai, SONG Xuemei, WANG Cailin 2022, 36(2): 131-138.  DOI: 10.16819/j.1001-7216.2022.201214 Abstract ( )   HTML ( )   PDF (3456KB) ( )   The formation of rice fragrance is a complex and changeable physiological process, and affected by genetic and environmental changes. The fragrance is mainly controlled by the fragrance gene BADH2. Climate, soil and cultivation conditions also directly affect the synthesis of fragrance compounds in rice. In order to further accelerate the breeding process and improve the quality of fragrant rice. We reviewed recent research progresses in the genetic and physiological mechanisms of the formation of fragrance compounds in rice and the effects of environmental factors on its formation in this manuscript. The effects of light, water, temperature, fertilizer and mineral elements on rice fragrance synthesis were particularly summarized. Meanwhile, the future research directions were pointed out to provide a reference for improving the cultivation techniques and quality of fragrant rice in China.

Research Papers

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Effects of OsESV1 on Starch Synthesis in Rice WANG Yongxiang, YAN Hangang, XU Hancong, FU Yushuang, SHAN Zhuangzhuang, HU Xiaoqing, ZHANG Wenwei, JIANG Ling 2022, 36(2): 139-149.  DOI: 10.16819/j.1001-7216.2022.210308 Abstract ( )   HTML ( )   PDF (329907KB) ( )   【Objective】 It is important to reveal the role of EARLY STARVATION1 (OsESV1) in starch metabolism of rice.【Method】 The osesv1 mutants were obtained by using the CRISPR-Cas9 system. The phenotype and the physicochemical properties of endosperm starch of osesv1 were investigated. The expression pattern and function of OsESV1 were analyzed. 【Result】 The OsESV1 protein was conserved in plants. Compared with the wild type, the osesv1 mutants exhibited lower plant height, panicle length, and grain number per panicle, but higher tiller number. Though the starch contents in osesv1 leaves significantly decreased, the total starch contents of osesv1 grains did not obviously altered and the amylose contents increased. The expression of OsESV1 was constitutive and rhythmic. OsESV1 was located in chloroplasts with a dot-like distribution. Yeast two-hybrid and bimolecular fluorescence complementation(BiFC) assays showed that OsESV1 could interact with ADP glucose pyrophosphorylase small subunit (OsAGPS) 2a and OsAGPS1.【Conclusion】 OsESV1 significantly affects the starch synthesis pathway in rice leaves, while not in endosperm.

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Identification and Gene Cloning of DSP2 in Rice (Oryza sativa L.) QIU Linlin, LIU Qiao, FU Yaping, LIU Wenzhen, HU Guocheng, ZHAI Yufeng, PANG Bo, WANG Dekai 2022, 36(2): 150-158.  DOI: 10.16819/j.1001-7216.2022.210606 Abstract ( )   HTML ( )   PDF (12517KB) ( )   【Objective】 Plant height and panicle length play important roles in rice production. Identifying and cloning genes related to rice plant height and panicle architecture will enrich the molecular mechanism of the regulation of rice plant height and panicle development, and will provide a theoretical foundation and genetic resources for molecular design breeding. 【Method】 A dwarf and small panicle mutant dsp2-D(dwarf and small panicle2-Dominant) was obtained from T-DNA insertion population of Nipponbare. The main agronomic traits of dsp2-D and the wild-type were characterized under conventional planting conditions in field. An F2 mapping population was generated by crossing the dsp2-D mutant with Longtefu B (an indica rice variety) and DSP2 was identified by map-based cloning and T-DNA tag method. The candidate gene was determined by the relative expression analysis of three genes located upstream and downstream of the T-DNA insertion site, respectively, which was carried out by real-time RT-PCR. The function of DSP2 was confirmed by overexpressing DSP2 (DSP2-OE) in wild-type Nipponbare.【Result】 The plant height, panicle length, the length of primary and secondary inflorescence branches of dsp2-D was dramatically reduced compared with the wild type. Genetic analysis indicated that the phenotypes of dsp2-D were regulated by an incomplete dominant gene. The DSP2 gene was mapped to a region between RM208 and RM7337 on chromosome 2, and co-segregated with RM3850. Subsequently, T-DNA insertion site was found to be co-segregated with dsp2-D phenotype, and T-DNA insertion sequence was separated by TAIL-PCR, which showed that T-DNA was inserted into the two genes between RM208 and RM7337. Real-time PCR analysis indicated that the expression level of LOC_Os02g57490, which located down-stream of T-DNA site, was dramatically up-regulated. While the expression levels of the rest five detected genes were not significantly changed in dsp2-D. DSP2 (DSP2-OE) overexpressing transgenic plants showed semi-dwarf and small panicle,which were similar with the phenotypes in dsp2-D. The results confirmed that DSP2 gene was the target gene controlling dsp2-D.【Conclusion】 The overexpression of DSP2 caused the mutant phenotypes of dsp2-D. And we found that DSP2 encodes a LOB family transcript factor and negatively regulates plant height and panicle length in rice. Our findings will open new perspectives on DSP2-based improvement of plant height and panicle type of rice.

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Mapping and Analysis of QTLs for Rice Grain Weight and Grain Shape Using Chromosome Segment Substitution Line Population HUANG Tao, WANG Yanning, ZHONG Qi, CHENG Qin, YANG Mengmeng, WANG Peng, WU Guangliang, HUANG Shiying, LI Caijing, YU Jianfeng, HE Haohua, BIAN Jianmin 2022, 36(2): 159-170.  DOI: 10.16819/j.1001-7216.2021.210204 Abstract ( )   HTML ( )   PDF (20467KB) ( )   【Objective】 Mining quantitative trait loci (QTL) for grain weight and grain shape related traits in rice plays an important role in the genetic mechanism of rice grain.【Method】 QTLs associated with grain weight and grain shape of grain and brown rice were analyzed using the population of chromosome segment substitution lines (CSSLs) with indica rice 9311 as recipient and japonica Nipponbare as donor in four different environments.【Result】 A total of 77 QTLs for grain weight and grain shape of paddy and brown rice were detected, and the phenotypic variation explained by each QTL ranged from 4.62% to 51.01%. Among these QTLs, 19 have additive alleles from Nipponbare and 58 have additive alleles from 9311. These QTLs distributed in 46 regions of 10 chromosomes in rice, and 16 regions are pleiotropic loci. There are 14 QTLs that can be repeatedly detected in two or more environments, qGW5.1 and qLW5 could be repeatedly detected in four environments and were located in the same chromosome region; qBRL3.2 and qGL4.1 were newly identified QTLs affecting grain weight and grain shape in rice.【Conclusion】 The results laid a foundation for cloning these QTLs and analyzing the genetic mechanism of grain shape and grain weight in rice.

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Analyses on Agronomic Traits and Genetic Characteristics of Two New Plant-architecture Lines in Rice LIANG Cheng, XIANG Xunchao, ZHANG Ouling, YOU Hui, XU Liang, CHEN Yongjun 2022, 36(2): 171-180.  DOI: 10.16819/j.1001-7216.2022.210208 Abstract ( )   HTML ( )   PDF (17251KB) ( )   【Objective】 Ideal plant-architecture (IPA) can increase photosynthetic efficiency, economic yield and resistance to disease of rice. The objective is to develop excellent germplasms with IPA for high-yield and resistance breeding by exploring variation in traits and genetic characteristics of two rice germplasm with new plant-architectures. 【Method】 The two germplasms ‘08yi’ and ‘RIL60’ with new plant-architecture from two recombinant inbred lines (RIL) by natural recombination, and their corresponding conventional germplasm ‘08yc’ and ‘RILc’ from the same RIL were used as materials. The constitute factors of plant architecture, yield traits in different developmental periods, as well as sequencing of IPA1 gene and waxy identification in four germplasm were comparatively analyzed. 【Result】 The functional leaf traits, dry matter accumulation at different developmental stages as well as panicle and yield traits of the two new lines were significantly different from those of conventional germplasms. Compared to the corresponding conventional germplasm, ‘08yi’ and ‘RIL60’ were featured with favorable variations including reduced angles of functional leaf, proper leaf length, compact plant architecture, an increase of 1-2 panicle in the effective panicles per plant and increased seed setting rate by 7.37% and 5.09%, respectively. In addition, the chlorophyll contents of the new germplasm ‘08yi’ significantly increased, and the stem of ‘RIL60’ was thicker than that of ‘RILc’. The panicle traits of the two new germplasm under stress condition were better because they had smaller reduction of economic yield and stronger stress resistance compared to their corresponding conventional germplasm. However, their unfavorable variations include decreased panicle weight, shorter panicle length, decreased number of grains per panicle, seeds, branch length and branch number. The results of IPA1 gene sequencing showed that there were no mutations at 874 site of IPA1(C→A) in the two new germplasm compared with the Shaoniejing ipa1, and the variation of plant architecture was attributed to other factors. The result of waxy identification showed that ‘RIL60’ had waxy variation. 【Conclusion】 Thanks for preferred variation in agronomic traits, the two new lines can be used as excellent germplasms for IPA breeding and research. As a glutinous rice variety with IPA and economic yield equal to non-glutinous rice, RIL60 has enormous potential for extension.

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Effects of Trinexapac-ethyl on Lodging Resistance, Yield and Rice Quality of Northern Rice with Good Quality ZHANG Xiaopeng, GONG Yanlong, YAN Bingchun, LI Li, LI Kunyi, WANG Yiwei, JU Xiaotang, CHEN Xiaoyi, XU Hai 2022, 36(2): 181-194.  DOI: 10.16819/j.1001-7216.2022.210809 Abstract ( )   HTML ( )   PDF (11525KB) ( )   【Objective】 The present study aims to evaluate the effect of trinexapac-ethyl spraying on rice lodging resistance,yield and quality performance of good quality rice.【Method】 Good quality rice varieties Toyonishiki and Shennong 09001 were used as test materials to investigate the effects of trinexapac-ethyl at different concentrations(CK, 0 mg/L; C1, 90 mg/L; C2, 180 mg/L; C3, 360 mg/L) during different growth stages(T1, late tillering stage; T2, early jointing stage; T3, booting stage) on lodging resistance, yield and quality of good-quality rice based on lodging index, bending resistance and thrust resistance.【Result】 The morphological and anatomical structure of stem, and the lodging resistance of rice plants were improved by trinexapac-ethyl application. With the increasing application concentration, the plant height decreased, the center of gravity moved down, the length of the first, second and third internodes at the base shortened, the stem diameter and stem wall thickness increased, the number of large and small vascular bundles and the area of large vascular bundles first increased and then decreased, the bending resistance and plant thrust resistance increased, the lodging index decreased and the lodging resistance increased. There were significant differences in lodging resistance among different application periods. Application during booting stage was the most effective to improve lodging resistance. With the increasing application concentration, the number of effective panicles, seed setting rate, grain number per panicle, the panicle length, and the yield significantly decreased, but the 1000-grain weight significantly increased. The grain yield was on a downward slide as the application of trinexapac-ethyl was postponed. The protein content increased with the increase of application concentration, the protein content significantly increased, the taste value of rice, the brown rice rate, and milled rice rate significantly decreased, which had no significant effect on other rice quality traits. Trinexapac-ethyl spraying exerted a declining influence on rice quality and nutritional quality for delayed application, and the rice quality was relatively good.【Conclusion】 With the increasing concentration, the lodging resistance of good quality rice increases. Although the yield, processing quality and nutritional quality decline, they can make up for the loss caused by lodging to a certain extent. Therefore, lodging resistance can be used as a plant growth regulator to improve lodging resistance in the production of good quality rice. The best combination of application concentration and application period was 180 mg/L (1200 L/hm2) during early jointing stage(T2C2).

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Effects of Nano-magnesium on Rice Yield Formation and Nitrogen Utilization CHEN Zhiqing, LIU Mengzhu, WANG Rui, CUI Peiyuan, LU Hao, WEI Haiyan, ZHANG Hongcheng, ZHANG Haipeng 2022, 36(2): 195-206.  DOI: 10.16819/j.1001-7216.2022.210608 Abstract ( )   HTML ( )   PDF (1176KB) ( )   【Objective】 To investigate the effects of nano- and ion-magnesium on rice grain yield, yield formation and nitrogen uptake and utilization.【Method】 A pot experiment was conducted to study the effects of nano-magnesium and ion-magnesium on rice yield formation and nitrogen accumulation and utilization under nitrogen application rates of 0 kg/hm2, 180 kg/hm2and 270 kg/hm2, respectively.【Result】 Application of nano-magnesium and ion-magnesium can effectively increase rice yield at the same N application level. The yield of rice treated with nano-magnesium were significantly higher than that treated with sodium magnesium. Moreover, the same trend was also observed in LAI and the accumulation of dry matter in the late stage of rice growth. The application of nano-magnesium could improve the dry matter formation in the late stage of rice growth, increased the SPAD value, photosynthetic potential and net photosynthetic rate of the flag leaf after heading, promoted the synthesis of rice dry matter and the accumulation in grains, and finally achieved the goal of increasing rice production. At the same level of nitrogen fertilizer application, the application of nano-magnesium and ionic-magnesium increased the nitrogen concentration and nitrogen accumulation in rice stems, leaves, and grains, and promoted the partial productivity of nitrogen fertilizer, nitrogen agronomic utilization rate, nitrogen physiological utilization rate and nitrogen absorption and utilization. These promotion effects of nano-magnesium were better than that of ionic-magnesium in this study.【Conclusion】 In summary, nano-magnesium can be used as a fertilization measure for green and high-efficiency rice cultivation.

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Deposition and Distribution of Droplets Sprayed by Different Plant Protection Machinery in Rice Canopy and Comparison of Control Effects on Diseases and Pests CHEN Yixuan, QIN Guiliang, ZHOU Xiaoxin, HUANG Junjun, MENG Quan, WU Junhui, YAN Xiaojing, YUAN Huizhu 2022, 36(2): 207-214.  DOI: 10.16819/j.1001-7216.2022.210704 Abstract ( )   HTML ( )   PDF (16291KB) ( )   【Objective】 To clarify the deposition and distribution characteristics of droplets sprayed by unmanned aircrafts and ground plant protection machinery in rice canopy, compare their control effects on diseases and pests in different canopy, and scientifically popularize and use plant protection machinery. 【Methods】 The distribution and utilization of droplets on the canopy of six kinds of plant protection machinery were studied by means of droplet deposition distribution detection, utilization rate measurement and field investigation, and their control effects on sheath blight and Cnaphalocrocis medinalis were also studied. 【Results】 The results showed that the deposition density and coverage of droplets sprayed by the three UAVs in rice canopy were significantly different. The deposition in the upper part of the rice canopy was higher than that of the other three ground plant protection machines, but the deposition in the lower part was lower and the difference was significant. The deposition density, coverage and deposition of different plant protection machinery on the upper, middle and lower layers of rice canopy showed a decreasing trend. Fourteen days after application, the control effect of the three kinds of unmanned aircraft on rice leaf rollers was higher than that of the other three kinds of ground plant protection machinery, up to 73.2%–84.7%. The electric sprayer and stretcher sprayer are more effective against the sheath blight than the 3 UAVs, up to79.6%–85.2%. 【Conclusion】 It is better to use unmanned aircraft to control rice leaf rollers in the upper layer of rice canopy, while it is better to use ground plant protection machinery with large amount of pesticide solution for sheath blight in the lower layer of canopy.