10 January 2023, Volume 37 Issue 1 Previous Issue   

Review and Special Topic
Research Papers
For Selected: Toggle Thumbnails

Review and Special Topic
Research Progress in Alleviating Effects of Exogenous Substances on Salt Stress in Rice
LIU Shuli, ZHANG Rui, Shahid HUSSAIN, WANG Yang, CHEN Yinglong, WEI Huanhe, HOU Hongyan, DAI Qigen
2023, 37(1): 1-15.  DOI: 10.16819/j.1001-7216.2023.220404
Abstract ( )   HTML ( )   PDF (424KB) ( )  

Salt stress is one of the main abiotic factors hindering rice growth, development and grain yield. By the use of exogenous substances, adverse effects can be alleviated and its growth and yield traits can be improved. This work reviews the regulation mechanism and mitigation effect of different exogenous substances (auxin, gibberellin, cytokinin, abscisic acid, ethylene, melatonin, salicylic acid, polyamine, brassinosteroid and jasmonic acid as well as calcium and silicon ionic exogenous substances) on rice salt stress. Finally, the utilization and research work of exogenous substances on salt tolerance of rice is prospected in order to lay a theoretical basis for improving rice growth, yield and quality in saline soil.

Research Papers
Evaluation of New japonica Rice Lines with Low Cadmium Accumulation and Good Quality Generated by Knocking Out OsNramp5
PEI Feng, WANG Guangda, GAO Peng, FENG Zhiming, HU Keming, CHEN Zongxiang, CHEN Hongqi, CUI Ao, ZUO Shimin
2023, 37(1): 16-28.  DOI: 10.16819/j.1001-7216.2023.220503
Abstract ( )   HTML ( )   PDF (1649KB) ( )  

【Objective】 It is crucial to elucidate the effects of OsNramp5 gene knockout on cadmium and other metal elements accumulation, yield and quality in japonica rice, which can provide new materials and theoretical references for scientific and efficient production of high-quality and green japonica rice.【Methods】 Using CRISPR/Cas9 technology, the OsNramp5 was knocked out under the background of Nanjing 46 (NJ46), a japonica rice variety with good taste and high yield. Combined with molecular marker-assisted selection, some OsNramp5 knockout lines without exogenous genes were obtained. The changes in yield and quality traits and seven metal elements contents such as cadmium, manganese and selenium in grains after spraying zinc fertilizer or selenium fertilizer and cultivated in soils with different cadmium content were investigated. 【Results】 Five transgenic plants with different mutations of OsNramp5 were obtained in the T0 generation, and specific molecular markers of three of them were designed. Then, combined with marker-assisted selection, homozygous knockout lines without hygromycin selective marker gene and CAS9 protein gene were obtained in the T2 generation of each plant. Compared with the wild type, the cadmium content in the whole plant including the grain of the knockout lines and the manganese content in shoots were significantly lower than those of the wild type in both high and low concentrations of cadmium soil. The plant height and grain number per panicle of the knockout lines decreased slightly, and the yield per plant decreased significantly in the knockout lines at high and medium tillering fertilizer levels while no changes were observed at the low tillering fertilizer level. The appearance of the knockout lines was better than that of the control, and the contents of protein and amylose were significantly higher than those of the control. The contents of copper, manganese and selenium in grains of knockout lines were significantly lower than those of the control NJ46, but zinc and selenium fertilizer could significantly increase the contents of zinc and selenium, and further reduce the content of cadmium in grains. Application of selenium was beneficial to rice appearance quality, but application of zinc was contrary. Spraying both fertilizers reduced the edible value of rice, worsening taste quality. The change of seed setting rate of the knockout lines under extreme high and low temperature conditions was the same as that of the control, but the resistance level to rice sheath blight was significantly reduced.【Conclusion】 We obtained marker-free OsNramp5 knockout lines under the background of japonica variety with high quality and yield, and proved that OsNramp5 was of great value in the production of low-cadmium, Se- and zinc-rich, though their yield and eating quality were decreased to different extents.

Generating Guangdong Simiao Rice Germplasms by Applying CRISPR/Cas9 Gene Editing and Marker-assisted Selection Technology
WANG Shiguang, LU Zhanhua, LIU Wei, LU Dongbai, WANG Xiaofei, FANG Zhiqiang, WU Haoxiang, HE Xiuying
2023, 37(1): 29-36.  DOI: 10.16819/j.1001-7216.2023.220705
Abstract ( )   HTML ( )   PDF (1140KB) ( )  

【Objective】 To generate new germplasms of high-quality and fragrant Simiao rice, explore new ways of rice breeding and improvement, and build the Guangdong Simiao Rice brand. 【Method】 Using the leading variety Yuenongsimiao (YNSM) and high-quality rice variety Yuewangsimiao (YWSM) as materials, the fragrance gene Badh2 of these varieties was knocked out by CRISPR/Cas9 gene editing technology to generate new fragrant rice lines. Subsequently, the excellent GW7/GL7 was introduced into these new fragrant rice lines by marker-assisted selection (MAS). 【Result】 Two new fragrant rice lines, yn-kobadh2 and yw-kobadh2, were successfully generated by CRISPR/Cas9 gene editing technology. 2-AP contents of these lines were significantly increased, ranging from 239.39 to 440.79 μg/kg, other main agronomic traits, including effective panicle number, grain number per panicle, appearance quality of brown rice, 1000-grain weight, and grain yield, were not significantly affected. Two novel fragrant Simiao rice lines, NWbadh2GW7-1 and NWbadh2GW7-2, with high grain yield and slender grain size of length to width ratio more than 4.3, were selected by MAS combined with pedigree breeding, which met the identification standards of Guangdong Simiao rice varieties on aroma and appearance grain size. 【Conclusion】 Combination of CRISPR/Cas9 gene editing and MAS technology contribute to accurate and efficient breeding of new excellent rice germplasms. The new germplasms developed can provide important germplasms and genetic resources for breeding of new high-quality fragrant Simiao Rice varieties in Guangdong Province.

Fine-mapping of SegD8 Loci for Rice Hybrid Segregation Distortion
YUAN Yang, AO Hejun, ZHOU Zhonghua, YING Jiezheng, ZHANG Jian, NI Shen
2023, 37(1): 37-44.  DOI: 10.16819/j.1001-7216.2023.220203
Abstract ( )   HTML ( )   PDF (684KB) ( )  

【Objective】 This study aims to fine-map and clone genes related to segregation distortion(SD) by using a rice introgressive line population, and thus to explore the molecular mechanism underlying the segregation distortion in rice. 【Method】 A set of introgressive line population was constructed by using an indica/japonica combination Huazhan/Koliya. The gene loci were mapped with different genotype separation ratios of offspring as phenotypes. 【Result】 We identified a segment on chromosome 8 that displayed obvious deviated segregation ratio from Mendelian's separation law. Further analysis revealed that the SD was controlled by two loci on chromosome 8, which were termed as SegD8A and SegD8B, respectively. SegD8A was a segregation locus, but its segregation was regulated by SegD8B. When both SegD8A and SegD8B were heterozygous, the ratio of SegD8AHH and SegD8AKK in progeny was close to 1:4. When SegD8B was homozygous Huazhan genotype, the ratio of SegD8AHH and SegD8AKK in progenies was close to 1:1. When SegD8B was homozygous Koliya genotype, SegD8AHH almost did not appear in its progeny. The SegD8A gene was mapped to a 46.5 kb region and the SegD8B gene was mapped to an 1160.2 kb region using the separation ratio of the progeny. 【Conclusion】 The results lay a foundation for further cloning of these two genes and elucidating the partial separation phenomenon.

Identification and Gene Mapping of a New Photo-thermo-sensitive Male Sterile Mutant tms3650 in Rice
TANG Jie, LONG Tuan, WU Chunyu, LI Xinpeng, ZENG Xiang, WU Yongzhong, HUANG Peijin
2023, 37(1): 45-54.  DOI: 10.16819/j.1001-7216.2023.220109
Abstract ( )   HTML ( )   PDF (1021KB) ( )  

【Objective】 Male sterility is the basis of rice heterosis utilization. To further analyze the regulation mechanism, a male sterility mutant was identified.【Method】 The tms3650 mutant was isolated from the mutant library of 60Co-γ-treated indica cultivar 93-11. The indica rice Minghui 63 was crossed with the mutant tms3650 as the male parent to construct F2 and F3 populations, and the target gene was fine-mapped by map-based cloning. 【Result】 The other agronomic traits of tms3650 were the same as those of the wild type, but the anthers of the mutant were white-green and thin, the pollen could not be stained blue-black by 1% iodine-potassium iodide solution with panicle-enclosure and delayed heading stage. Genetic analysis indicated that the mutant phenotype was controlled by a pair of recessive nuclear genes. The results of fine mapping showed that the gene was located within a distance of 135.25 kb between the SSR markers RM15927 and RM15934 on the long arm of chromosome 3, and co-segregated with the RM15931 marker. The identification of southern breeding in Lingshui in winter revealed that the fertility of mutant was affected by light and temperature, indicating that the tms3650 was a photo-thermo-sensitive male sterile mutant. 【Conclusion】 By comparing with the reported male sterility genes, the tms3650 was controlled by a new gene locus, TMS3650.

Development of New Low Glutelin Content japonica Rice Lines with Good Eating Quality and Fragrance by Molecular Marker-Assisted Selection
CHEN Tao, ZHAO Qingyong, ZHU Zhen, ZHAO Ling, YAO Shu, ZHOU Lihui, ZHAO Chunfang, ZHANG Yadong, WANG Cailin
2023, 37(1): 55-65.  DOI: 10.16819/j.1001-7216.2023.220302
Abstract ( )   HTML ( )   PDF (3616KB) ( )  

【Objective】 Developing new low glutelin content varieties is an important direction of functional rice breeding. It is necessary to strengthen the synchronized improvement of rice functionality and eating quality in breeding to meet the needs of nephropathic patients for rice quality and physical health. 【Method】 The good eating quality japonica rice variety Nanjing 46 with the low amylose content gene Wxmp and fragrance gene fgr was used as the parent to cross and backcross with the variety LGC-1 from Japan containing the Lgc1 gene. The molecular markers co-isolated with target genes were utilized for genotypic detection in combination with field selection and five new lines were obtained in BC2F6 generation. Taking parents Nanjing 46 and LGC-1 as control, the agronomic, yield and quality traits of these lines were analyzed. 【Result】 Compared with LGC-1, these lines has similar glutelin content and absorbable protein content, improved eating quality, excellent comprehensive characters and high yield potential. They are suitable to grow in different regions of Jiangsu Province. 【Conclusion】 As a rapid, accurate and effective method, the molecular marker-assisted selection, in combination with conventional breeding technology, can significantly improve the breeding efficiency of the low gluten rice varieties with good quality and high yield.

Effect of Free Air Temperature Increase on Grain Quality of Double-cropping Rice in South China
YANG Taotao, ZOU Jixiang, WU Longmei, BAO Xiaozhe, JIANG Yu, ZHANG Nan, ZHANG Bin
2023, 37(1): 66-77.  DOI: 10.16819/j.1001-7216.2023.220402
Abstract ( )   HTML ( )   PDF (5498KB) ( )  

【Objective】 The double cropping rice growing area in South China is one of the main producing areas of high-quality indica rice. However, the impact of global warming on rice quality of double-cropping rice in South China remains unclear. 【Method】 A field experiment was designed with ambient temperature treatment (CK) and whole growth period warming treatment (W). The warming treatments were generated with free air temperature increase (FATI) facilities. The milling, appearance, nutritional and eating quality of early rice (i.e., Hefengsimiao in 2020 and Yuehesimiao in 2021) and late rice (i.e., Yuehesimiao in 2020 and 2021) were compared and analyzed between CK and warming treatments. 【Result】 Compared to the CK, the warming treatment (early rice, 1.5-1.8 ℃; late rice, 1.9-2.0 ℃) had no significant effect on the brown rice rate of early and late rice. The milled rice rate and head rice rate of early rice decreased significantly, while the milled rice rate and head rice rate of late rice did not change under warming conditions. The warming effects on the chalky grain rate and chalkiness fallowed opposite trends between the early and late rice. Warming significantly increased the chalky grain rate and chalkiness of early rice, but decreased the chalky grain rate of late rice. The amylose contents of early and late rice decreased, while the protein contents increased under warming conditions. In addition, warming increased the peak viscosity and stickiness of early and late rice, while decreased their setback, pasting temperature and hardness of late rice. Correlation analysis showed that the changes in rice flour pasting property and cooked rice texture of early and late rice were mainly related to the reduction in amylose content under warming conditions. 【Conclusion】 Warming worsens the milling and appearance qualities of early rice, but it is beneficial to improving its nutritional and eating quality. The appearance, nutritional and eating quality of late rice are improved under warming conditions.

Effects of Nitrogen-reducing and Oxygen-increasing Irrigation on Rice Yield and Nitrogen Use Efficiency
ZHANG Lu, LIANG Qingduo, WU Longlong, HUANG Jing, TIAN Cang, ZHANG Junhua, CAO Xiaochuang, ZHU Chunquan, KONG Yali, JIN Qianyu, ZHU Lianfeng
2023, 37(1): 78-88.  DOI: 10.16819/j.1001-7216.2023.220307
Abstract ( )   HTML ( )   PDF (1049KB) ( )  

【Objective】 To clarify the effects of nitrogen reduction and oxygen-increasing irrigation on growth, yield and nitrogen utilization of rice.【Method】 Three rice varieties Zhonghan 221 (upland rice), Zhongzheyou 8 (rice) and IR45765-3B (deep water rice) were used as materials, and two nitrogen levels of conventional nitrogen application level(195.0 kg/hm2), reduced nitrogen application level (157.5 kg/hm2) and two irrigation modes of conventional flooding irrigation (WL) and micro-nano bubble water oxygen enhancement irrigation (MBWI) were designed. The tiller dynamics, leaf chlorophyll content, leaf area, dry matter quality, yield and nitrogen absorption and utilization characteristics of the three rice varieties were compared and analyzed. 【Result】 The results showed that MBWI treatment significantly increased rice yield, and the 2-year average yield in MBWI treatment was 12.4%, 7.5% and 6.7% higher than that of WL treatment, respectively, which may be attributed to the number of effective panicles and grains per panicle. The amount of micro-nano bubble water oxygenated irrigation and nitrogen fertilizer significantly increased the chlorophyll contents and leaf area of rice leaves, and increased the dry matter accumulation of rice. Both nitrogen fertilizer and aerobic irrigation affected the nitrogen use efficiency of rice. Compared with flooded irrigation, micro / nano bubble water aerobic irrigation could significantly increase the nitrogen harvest index, nitrogen partial productivity and nitrogen grain production efficiency of the three rice varieties, reduced nitrogen transport efficiency and nitrogen transport contribution rate of rice. Nitrogen reduction treatment significantly increased nitrogen transport efficiency, nitrogen transport contribution rate, nitrogen grain production efficiency and nitrogen partial productivity, but decreased nitrogen harvest index.【Conclusion】 Aerobic irrigation can increase the chlorophyll contents and leaf area of rice leaves, thus increase the number of tillers and dry matter accumulation of rice, and then significantly increase rice yield and affect the characteristics of nitrogen utilization. Under the conditions of reduced nitrogen application in paddy field, oxygen-increasing irrigation can help build a high-yield population and maintain a higher yield.

Effects of Nitrogen Rate on Photosynthesis, Yield and Grain Quality of Superior Quality Rice “Fuxiangzhan”
WANG Yingheng, CHEN Lijuan, CUI Lili, ZHAN Shengwei, SONG Yu, CHEN Shian, XIE Zhenxing, JIANG Zhaowei, WU Fangxi, ZHUO Chuanying, CAI Qiuhua, XIE Huaan, ZHANG Jianfu
2023, 37(1): 89-101.  DOI: 10.16819/j.1001-7216.2023.220606
Abstract ( )   HTML ( )   PDF (1634KB) ( )  

【Objcetive】 Tobacco-rice rotation can effectively improve soil ecology, promote agricultural efficiency and increase farmers' income. Nitrogen fertilizer is a key factor affecting the growth and development of rice. In order to determine the optimal nitrogen application rate and to give full play to the high quality and high yield potential of the superior quality rice “Fuxiangzhan” in the tobacco-rice rotation areas of Fujian Province, 【Method】 Five nitrogen rates, (CK: 0, N1: 51.75, N2: 103.5, N3: 155.25, and N4: 207 kg/ hm2 by nitrogen) were set to analyze effects on photosynthetic characteristics, grain yield and its components, grain quality and aroma of brown rice under the field environment. 【Result】 The results showed with the increase of nitrogen application rate, the growth duration of “Fuxiangzhan” was gradually prolonged, chlorophyll SPAD value, net photosynthetic rate, chloroplast size, sucrose and starch contents in flag leaves were increased, and all the parameters mentioned above reached the highest value in N3 or N4 treatment. The grain number per panicle and grain yield maximized in N2 treatment, but the seed setting rate and 1000-grain weight decreased with the increase of nitrogen application rate. For the processing quality of grain, it performed best in N2 treatment. The appearance quality and eating quality were not significantly affected by nitrogen rates. The total protein contents increased with the increase of nitrogen rates. For RVA profile, the peak viscosity, hot viscosity, final paste viscosity and breakdown value decreased, while the setback viscosity value increased. The content of 2-acetyl-1-pyrroline (2-AP) in brown rice under N2 treatment was the highest. 【Conclusion】 The results showed nitrogen treatment promoted the photosynthesis of “Fuxiangzan”, but excessive nitrogen made plants late-ripening, reduced seed setting rate and yielding. At the nitrogen application rate of N2 (103.5 kg / hm2), we struck a balance between high yield and good quality with the most aroma substances accumulated. This study laid a foundation for the further popularization and application of “Fuxiangzhan” in production and the development of high-quality rice industry in the tobacco-rice rotation areas of Fujian Province.

Demand Elasticity Estimation and Market Potential of Middle and High-end Rice in China: A Case Study of the Yangtze River Delta Market
CHEN Pin, LIU Jiacheng, ZHAO Xiaosong
2023, 37(1): 102-112.  DOI: 10.16819/j.1001-7216.2023.220312
Abstract ( )   HTML ( )   PDF (1785KB) ( )  

【Objective】 With the rising income level of residents and the change of consumption concept, we are facing an increasing demand for the upgrading of staple grain mix. The Yangtze River Delta region, the most developed area and an important grain consumer in China, epitomizes the change of staple grain consumption mix in the future. 【Method】 Here, taking rice as an example, we estimated the demand elasticity of different grades of rice by econometric model using the sales data of large chain supermarkets, and predicted the market consumption potential of high-end rice in the Yangtze River Delta region in the next 20 years. 【Result】 The rice consumption market in the Yangtze River Delta region has become stable, and the consumption mix has gradually changed from ordinary rice to middle and high-end rice. It is expected that the demand for middle and high-end rice will reach 1231×104-2463×104t, and the market value will reach 108.5-230.2 billion Yuan by 2040. 【Conclusion】 Taking into consideration the trend of middle and high-end demand for rice, we should do a good job in top-level design, scientifically figure out the regional layout, development direction and industrial scale on the basis of the existing market and future market, optimize the mixes of product, variety and upgrade operation practices, constantly increase the proportion of high-quality green rice, and intensify the protection of high-end rice industry development.