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10 March 2023, Volume 37 Issue 2 Previous Issue    Next Issue
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Identification and Gene Mapping of a Zebra Leaf Mutant zl7 in Rice LIAN Yuanxun, WEI Ziyun, ZHANG Qiang, LI Qing, REN Deyong, HU Jiang, ZHU Li, GAO Zhenyu, ZHANG Guangheng, GUO Longbiao, ZENG Dali, QIAN Qian, SHEN Lan 2023, 37(2): 113-124.  DOI: 10.16819/j.1001-7216.2023.220314 Abstract ( )   HTML ( )   PDF (1223KB) ( )   【Objective】 Zebra leaf mutants, as important germplasm resources of rice leaf color mutants, are ideal materials for studying the mechanism of plant photosynthesis and high photosynthetic efficiency breeding, and play an important role in analyzing the mechanism of photosynthesis and improving rice yield. 【Method】 A zebra leaf mutant, designated as zebra leaf 7(zl7), was isolated from an ethyl methanesulfonate (EMS)-mutagenized population of Chunjiang 06 (CJ06). Under conventional paddy field management, the differences in leaf color phenotype and yield characters between the mutant and its wild type at seedling stage, heading stage and maturity stage were compared respectively. The development of leaf chloroplast were analyzed with a transmission electron microscope. Candidate genes were cloned by map-based cloning method, and the expression levels of genes involved in chlorophyll synthesis and chloroplast development were analyzed by fluorescence quantitative PCR. 【Result】From seedling stage, the mutant zl7 showed typical zebra leaves with decreased chlorophyll contents. During the heading stage, the zebra leaf phenotype disappeared and the leaves gradually turned green, and there was no significant difference in chlorophyll contents. The measurement of photosynthetic rate and the observation with an electron microscope showed that the photosynthetic rate, stomatal conductance and chloroplast development of the mutant zl7 were abnormal. Compared with the wild type, the plant height, the number of tillers, panicle length, primary rachis branch number, secondary rachis branch number and grains per panicle of the mutant decreased significantly, while the grain length, grain width and 1000-grain weight increased slightly. The results of fluorescence quantitative PCR showed that the expression levels of genes involved in chlorophyll degradation increased significantly, while the expression levels of genes involved in chlorophyll synthesis and chloroplast development decreased significantly. Genetic analysis showed that the mutant was regulated by a pair of recessive nuclear genes. The gene was mapped on chromosome 7 by map-based cloning, and the sequencing results showed that the coding region of ZL7 in zl7 has a single-base substitution mutation, causing an amino acid change from serine to asparagine. 【Conclusion】ZL7 mutation leads to abnormal chloroplast development, consequently resulting in zebra leaf phenotype, which plays an important role in rice chlorophyll synthesis and chloroplast development.

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Improvement of the Resistance of Nanjing 9108 to Blast and Sheath Blight by Pyramiding Resistance Gene Pigm and Quantitative Trait Genes qSB-9TQ and qSB-11HJX WANG Yu, SUN Quanyi, DU Haibo, XU Zhiwen, WU Keting, YIN Li, FENG Zhiming, HU Keming, CHEN Zongxiang, ZUO Shimin 2023, 37(2): 125-132.  DOI: 10.16819/j.1001-7216.2023.220413 Abstract ( )   HTML ( )   PDF (1015KB) ( )   【Objective】 Blast and sheath blight are two major diseases in rice, causing huge yield and quality losses. Breeding resistant varieties is the most economical and effective approach to control the two diseases. 【Method】 Using molecular marker assisted selection, we introduced the broad-spectrum blast resistant gene Pigm and quantitative resistance genes qSB-9TQ, qSB-11HJX to sheath blight into Nanjing 9108, a japonica rice cultivar with good grain quality. Plant lines with different gene/gene combinations were obtained and the resistance phenotypes were identified as well as the main agronomic and quality traits. 【Result】 The inoculation results showed that Pigm introduction could increase rice resistance to seedling blast and panicle blast significantly. Both qSB-9TQ and qSB-11HJX could improve rice sheath blight resistance significantly. Moreover, pyramiding of the two quantitative resistance genes had an additive effect on sheath blight resistance. As for the main agronomic and quality traits, the lines with Pigm showed increased panicle length, number of grains per panicle and the lines with qSB-11HJX showed significantly increased grain weight. Incorporating these genes exerted no significant effect on other agronomic and quality traits. 【Conclusion】 Pyramiding the three genes could improve blast and sheath blight resistance without apparently negative effect on agronomic and quality traits, and the pyramided rice line can be used as a new germplasm for breeding disease-resistant japonica rice varieties.

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QTL-Seq Analysis for Identification of Resistance Locus to Bacterial Leaf Streak in Rice WEI Minyi, MA Zengfeng, HUANG Dahui, QIN Yuanyuan, LIU Chi, LU Yingping, LUO Tongping, LI Zhenjing, ZHANG Yuexiong, QIN Gang 2023, 37(2): 133-141.  DOI: 10.16819/j.1001-7216.2023.220607 Abstract ( )   HTML ( )   PDF (1889KB) ( )   【Objective】 The aim is to identify new resistance genes to bacterial leaf streak(BLS) and enrich the disease-resistance gene resources in rice, so as to lay a foundation for resistance gene cloning and molecular breeding in rice. 【Method】 A population of 278 recombinant inbred lines (RILs) was developed by crossing WP1 and 9311. WP1 was derived from Guangxi common wild rice(Oryza rufipogon Griff.), which was resistant to BLS, while 9311 was highly susceptible to BLS. QTL-Seq was used to analyze the high resistant and susceptible pools and their parents for quickly locating the genomic regions harboring QTLs resistance to BLS. Subsequently the resistant locus was further verified by QTL mapping using Ici Mapping 4.1 and narrowed down by substitution mapping.【Result】 Three genomic regions harboring resistance QTLs to BLS were identified on chromosomes 4, 8 and 10, respectively. A major resistance locus was verified by ICIM on chromosome 4, designated as qBLS4.1 accounting for 10.65% of the phenotypic variation with a LOD score of 5.03. Finally, the qBLS4.1 locus was delimited in the region of 521 kb from 5.27 to 5.79 Mb by substitution mapping, and there were 41 predicted protein-encoding genes with a total of 252 non-synonymous mutations between the resistant and susceptible parents.【Conclusion】 QTL-Seq combined with ICIM method can locate QTLs in rice more quickly and efficiently. The QTL qBLS4.1, a new locus against BLS will lay a basis and provide a reference for locating and cloning new genes for BLS resistance.

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Mechanism of Interaction Between Calcium Ion and Hydrogen Sulfide Alleviating the Inhibitory Effect of Aluminum on Root Elongation in Rice WEI Qianqian, XU Qingshan, PAN Lin, KONG Yali, ZHU Lianfeng, CAO Xiaochuang, TIAN Wenhao, LIU Jia, JIN Qianyu, XIANG Xingjia, ZHANG Junhua, ZHU Chunquan 2023, 37(2): 142-152.  DOI: 10.16819/j.1001-7216.2023.220603 Abstract ( )   HTML ( )   PDF (1708KB) ( )   【Objective】 The objective of this study is to elucidate the molecular and physiological mechanisms of the interaction between calcium ion (Ca2+) and hydrogen sulfide (H2S) alleviating aluminum (Al) toxicity in rice.【Method】 The rice cultivar kasalath was selected as test material, and treated with 0 μmol/L and 30 μmol/L AlCl3, 0.1 mmol/L and 0.5 mmol/L CaCl2, 0.2 μmol/L NaHS and 100 μmol/L H2S scavenger hypotaurine (HP). The seeds were incubated at 30℃ in the dark for 24 h, then the root elongation, total Al content, Al content in cell sap, Al content in apoplast, Al content in cell wall, pectin content, pectin methylesterase activity and the relative expression of OsSTAR2, OsNRAT1 and OsFRDL4 were measured to explore the molecular and physiological mechanism of the interaction between Ca2+ and H2S alleviating Al toxicity in rice. 【Result】 Under Al stress, compared with 0.1 mmol/L CaCl2 treatment, 0.5 mmol/L CaCl2 treatment significantly increased root elongation, H2S content, total calcium (Ca) content and cytoplasm Ca content, and significantly decreased total Al content in root, cell sap Al content, apoplastic Al content and cell wall Al content in rice. The pretreatment of NaHS significantly increased the elongation of rice roots at the two calcium concentrations, accompanied with the significant increase of root tip Al content, root total Al content, cell sap Al content, apoplastic Al content and cell wall Al content. The relative expression levels of OsSTAR2 and OsFRDL4 were significantly increased and the relative expression of OsNRAT1 was significantly decreased at the two Ca2+ concentrations after pretreated with NaHS. However, the application of HP produced an opposite result. 【Conclusion】 Under Al stress, Ca2+ reduced the accumulation of Al in rice root cell wall and the absorption of Al by rice roots through increasing the production of H2S in rice root, and finally alleviated the inhibition of Al on rice root elongation.

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Responses of Rice Varieties Differing in Salt Tolerance to Salt Stress and Their Physiological Mechanisms ZHOU Zhenling, LIN Bing, ZHOU Qun, YANG Bo, LIU Yan, ZHOU Tianyang, WANG Baoxiang, GU Junfei, XU Dayong, YANG Jianchang 2023, 37(2): 153-165.  DOI: 10.16819/j.1001-7216.2023.221005 Abstract ( )   HTML ( )   PDF (1261KB) ( )   【Objective】 The purpose of this study is to clarify the response of salt-tolerant and salt-susceptible rice varieties to salt stress and their agronomic and physiological characteristics. 【Method】 Tow salt tolerant rice varieties Lianjian 5 and Yandao 16Z38 and two salt sensitive rice varieties Huajing 5 and Lianjing 17 were grown in pots at salt concentrations of 0 g/kg (control) and 3 g/kg (salt stress) in the soil. 【Result】 Compared with the control, salt stress decreased grain yield of both salt tolerant varieties and salt sensitive varieties, with more reduction in the latter. A higher grain yield for salt tolerant varieties than that for salt sensitive varieties under salt stress was mainly attributed to more total spikelet number and higher seed setting rate. Compared with salt sensitive varieties, salt tolerant rice varieties had higher activities of antioxidant enzymes, such as superoxide dismutase, in leaves at the stages of mid tillering, jointing heading, and mid grain filling, higher contents of organic osmotic regulators such as proline and proline synthase activities in roots, and higher K+/Na+ values at jointing and heading stages. Salt tolerant rice varieties also showed higher crop growth rates from tillering to jointing and from heading to maturity, higher leaf area index and leaf SPAD value at heading stage, and higher root oxidation activity from heading to mid grain filling stage. 【Conclusion】 More total spikelet number, stronger antioxidant and osmoregulation ability, higher root oxidation activity, and higher K+/Na+ values contributed to a higher grain yield for the salt tolerant varieties under salt stress. Higher superoxide dismutase activity and root oxidation activity could be used as important physiological indexes in breeding and selecting salt tolerant rice varieties.

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Effect of Free-air Temperature Increasing on Activities of Enzymes Involved in Starch Synthesis and Accumulation of Double-cropping indica Rice CHEN Liming, YANG Taotao, XIONG Ruoyu, TAN Xueming, HUANG Shang, ZENG Yongjun, PAN Xiaohua, SHI Qinghua, ZHANG Jun, ZENG Yanhua 2023, 37(2): 166-177.  DOI: 10.16819/j.1001-7216.2023.220414 Abstract ( )   HTML ( )   PDF (1887KB) ( )   【Objective】 To elucidate the response and mechanism of starch accumulation and its component contents of double-cropping indica rice cultivars to the future warming conditions. 【Method】 With Xiangzaoxian 45 (Inbred indica rice) and Qiliangyou 2012 (Hybrid indica rice) as early rice, and Jiuxiangnian (Inbred indica rice) and Taiyou 398 (Hybrid indica rice) as late rice, a free-air temperature increasing facility (FATI) (1.4－1.5 ℃ increase in early rice, 2.0－2.3 ℃ increase in late rice) was used to study the effects of warming throughout the growth period on activities of enzymes involved in starch synthesis and accumulation of double-cropping indica rice. 【Result】 There was no significant change in the starch contents and amylopectin contents in rice, but the amylose content and the proportion of amylose content were reduced under warming conditions. Among them, the amylose content of Qiliangyou 2012 and Jiuxiangnian decressed by 4.2% and 3.4%, respectively. Compared with the ambient treatment, warming increased the total starch and amylose accumulation in grains at the early growth stage of grain filling (7-14 d after heading), but the effect on the amylose accumulation in late rice was longer than that in early rice. This was mainly related to the varying degrees of increased activity of key enzymes in starch synthesis. Under warming conditions, the activity of adenosine glucose diphosphate pyrophosphorylase (ADGPase) in grains at grain filling stage of early rice increased first and then decreased, while that of late rice increased gradually. Warming decreased the activity of bound starch synthase (GBSS) in grains of early rice 14 d after heading and 7 d after heading of late rice, but significantly increased GBSS activity in grains of late rice during late heading stage(21, 28 d after heading). The soluble starch synthase (SSS) activity in Qiliangyou 2012 and Jiuxiangnian 7 and 14 days after heading was significantly increased by warming. The activity of starch branching enzyme (SBE) in late rice grains followed an increasing trend under the warming treatment. In general, the effects of warming on ADGPase and GBSS activities in late rice grains were significantly greater than those in early rice. 【Conclusion】 FATI significantly increased the activities of ADGPase, GBSS and SSS enzymes in the grains of double-cropping indica rice at the early stage of grain filling (7-14 d after heading), thereby improving the synthesis and accumulation of total starch and its components in grains of double-cropping indica rice at the early stage of grain filling. The effect of warming on the key enzymes of starch synthesis varied with seasons and varieties.

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Nutritional Quality and Cooking and Eating Quality Characteristics of Low Glutelin Semi-glutinous japonica Rice YAO Shu, ZHAO Chunfang, CHEN Tao, LU Kai, ZHOU Lihui, ZHAO Ling, ZHU Zhen, ZHAO Qingyong, LIANG Wenhua, HE Lei, WANG Cailin, ZHANG Yadong 2023, 37(2): 178-188.  DOI: 10.16819/j.1001-7216.2023.220511 Abstract ( )   HTML ( )   PDF (1924KB) ( )   【Objective】 The objective of this study was to clarify the relationship of nutritional quality with eating and cooking quality and their difference of low glutelin semi-glutinous japonica rice varieties(lines) and other types of japonica rice, so as to lay a scientific basis for breeding nutritional and high quality japonica rice.【Method】 The low glutelin semi-glutinous japonica rice lines were used as materials, and the semi-glutinous japonica rice and common japonica rice varieties were used as control. A total of 16 japonica rice varieties including the three types were planted under the same environment and cultivation conditions. The differences in contents of total protein and its components and physicochemical characteristics of amylose content, gelatinization temperature and gel consistency were analyzed, as well as the correlation of rice nutrition with eating and cooking quality. 【Result】 The glutelin content of low glutelin semi-glutinous japonica rice was significantly lower than that of semi-glutinous japonica rice and common japonica rice, and the gliadin and albumin contents were significantly higher than those of semi-glutinous japonica rice and common japonica rice. The breakdown value of low glutelin semi-glutinous japonica rice was significantly lower than that of semi-glutinous japonica rice and common japonica rice, and the gel consistency and peak viscosity of semi-glutinous japonica rice were significantly higher than those of common japonica rice and low glutelin semi-glutinous japonica rice. In terms of rice taste index, there was no significant difference in appearance, viscosity, balance degree, taste value between low glutelin semi-glutinous japonica rice and common japonica rice, but they were significantly lower than those of semi-glutinous japonica rice. The results of correlation analysis showed that the contents of total protein and gliadin were significantly negatively correlated with peak viscosity, breakdown value, appearance, stickiness, balance degree and taste value, and significantly positively correlated with setback viscosity and hardness. The correlation of glutelin was quite the contrary.【Conclusion】 There were significant differences in glutelin content, amylose content and breakdown value among the three different types of japonica rice varieties, among which the low glutelin semi-glutinous rice varieties has low glutelin content and higher gliadin content. Semi-glutinous japonica rice varieties have lower protein content, amylose content, setback value and consistency value, higher gel consistency and breakdown value. Among the four protein components, gliadin content has the greatest negative impacts on the taste value of rice, and was significantly negatively correlated with the appearance, stickiness and balance degree of rice.

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Spatio-temporal Evolution of Rice Production Outsourcing Process in Zhejiang Province: A Follow-up Survey from 2010 to 2019 GUAN Yaqi, E Zhiguo, WANG Lei, SHEN Hongfang 2023, 37(2): 189-199.  DOI: 10.16819/j.1001-7216.2023.220610 Abstract ( )   HTML ( )   PDF (2704KB) ( )   【Objective】 Zhejiang Province has been at the forefront of China in the moderate-scale operation of agriculture, and its experience has great reference significance in the path selection and policy formulation of outsourcing of rice production and moderate-scale agricultural management in the country.【Method】 Based on the follow-up survey in Zhejiang Province from 2010 to 2019, the empirical research and comparative research methods are used to analyze the temporal and spatial changes and influencing factors of production outsourcing in Zhejiang Province.【Result】 From the temparal perspective, the overall development process of rice production outsourcing in Zhejiang Province is on the rise; from the spatial perspective, the production outsourcing in Zhejiang Province started early and developed rapidly. In recent years, the gap between agricultural production outsourcing in other provinces and Zhejiang Province has gradually narrowed, the first-mover advantage of Zhejiang Province has weakened, and the later-mover advantage of economically underdeveloped areas has increased. Among the factors that affect outsourcing, the effect of individual factors such as farmer age, education standard, and rice planting time in labor-intensive link outsourcing in Zhejiang Province is less than that of technology-intensive link outsourcing. The increasing age and working time of rice farmers have a negative impact and the rice planting scale and family relative income have a significant positive impact on the outsourcing of rice technology-intensive links in Zhejiang Province.【Conclusion】 Affected by the development trend of simplified rice farming technology, the outsourcing mix of technology-intensive links has changed; farmland transfer and production link outsourcing are two ways to achieve moderate-scale land management, and the two influence each other and coexist for a long time; The influence of decision-making in agricultural production outsourcing has gradually shrinked, and the role of the group effect has been highlighted.

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Streptomyces zaomyceticus Sz-11, a Potential Biocontrol Agent with the Functions of Preventing Plant Diseases and Promoting Plant Growth WANG Xuandong, YU Junjie, GAO Runjie, LAN Heting, JIANG Yingzi, QI Wenjie, SONG Zhen, JIANG Donghua 2023, 37(2): 200-212.  DOI: 10.16819/j.1001-7216.2023.220802 Abstract ( )   HTML ( )   PDF (2037KB) ( )   【Objective】 The aim is to evaluate the growth promoting ability of Streptomyces zaomyceticus Sz-11 and its biocontrol potential against rice bacterial leaf streak disease, and to explore its preliminary bacteriostatic mechanism. 【Methods】 The antibacterial spectra of Sz-11 against seven plant pathogenic bacteria and 11 plant pathogenic fungi were determined by Oxford cup method. The growth promoting potential of Sz-11 was evaluated in a seed soaking experiment and irrigation experiment. SDS-polyacrylamide gel electrophoresis (SDS-PAGE), agarose gel electrophoresis (AGE), confocal laser scanning microscope (CLSM), scanning electron microscope (SEM) and fourier transform infrared spectroscopy (FTIR) were used to analyze the effects of the active products in fermentation liquor on Xooc protein expression, genomic DNA synthesis, cell membrane permeability, cell morphology, cell membrane surface material structure and composition. The biocontrol potential of Sz-11 against rice bacterial leaf streak (BLS) disease was studied in a potted experiment.【Results】 Sz-11 showed good antagonistic activity against Pseudomonas syringae pv. tomato, Fusarium oxysporum f. sp. momordicae, Colletotrichum orbiculare, Alternaria alternata and other plant pathogens, and had outstanding antagonistic activity against Xanthomonas oryzae (Xoo and Xooc). Sz-11 can promote the germination and growth of rice seeds, shorten the germination cycle, which can also accelerate the accumulation of organic matter and root differentiation in the vegetative growth stage of rice. Sz-11 can affect Xooc protein expression, change cell membrane permeability and membrane surface material composition, resulting in cell swelling, deformation and death, but does not affect Xooc genome DNA synthesis. The relative control effect of Sz-11 on BLS of four rice varieties ranged from 65.63% to 84.38%, and the prevention effect in advance was better than the post-infection treatment as revealed in a pot experiment. 【Conclusion】 Sz-11, with a broad antibacterial spectrum, is a beneficial plant growth promoting rhizobacteria. By functions on the cell membrane and hampering protein synthesis of Xooc, it inhibits the growth and reproduction of pathogenic bacteria, thereby effectively preventing the occurrence of rice bacterial leaf streak disease. Thus, the information listed in this article shows that Sz-11 has utilization potential in biological control.

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Analysis of Agrobacterium-Mediated Genetic Transformation System of indica Rice 9311 and Huazhan ZHANG Jia, WANG Huijie, HE Zhengquan, LIU Wenzhen 2023, 37(2): 213-224.  DOI: 10.16819/j.1001-7216.2023.220305 Abstract ( )   HTML ( )   PDF (2866KB) ( )   【Objective】 The rice transgenic technology is an important tool to promote rice molecular biology research and precision breeding. Agrobacterium-mediated transgenic technology has become the mainstream method for rice genetic transformation. Nevertheless, due to its genotype, the genetic transformation efficiency of typical indica rice is still quite low. It is urgent to improve its transformation efficiency. 【Method】 The effects of medium composition and photoperiod on genetic transformation efficiency of recalcitrated indica rice varieties 9311 and Huazhan were investigated. 【Result】 The results showed that MS macro element, B5 micro element, N6 organic matter and maltose were the best combination for 9311 tissue culture. MS macro element, MS micro element, MS organic matter and maltose were the best combination for Huazhan tissue culture. Adding 0.5 mg/L BAP or 1.5 mg/L KT into the induction medium could significantly improve the regeneration rate of 9311 and Huazhan tissue culture, up to more than 70.0%. The transformation efficiency with 100 μmol/L AS in the infection solution was higher than that with 200 μmol/L AS. Photoperiod experiments suggested that different photoperiod strategies should be adopted for 9311 and Huazhan transformation. 9311 transformation efficiency peaked, 6.0%?6.4%, under continuous darkness at the induction and selection stages and continuous light at the differentiation stage. Huazhan transformation efficiency reached the highest, 5.0%?7.5%, under 12 h photoperiod at all stages. 【Conclusion】 Collectively, the present study optimized tissue culture and genetic transformation system of recalcitrant indica rice varieties 9311 and Huazhan. Our methods could also be applied to the genetic transformation of other related indica rice genotypes.