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10 May 2018, Volume 32 Issue 3 Previous Issue    Next Issue
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Research Papers

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Construction of Genetic Map andMapping andVerification of Grain TraitsQTLs Using Recombinant Inbred LinesDerived from a Cross BetweenindicaC84 andjaponicaCJ16B Mengyu ZHOU, Xinwei SONG, Jing XU, Xue FU, Ting LI, Yuchen ZHU, Xingyun XIAO, Yijian MAO, Dali ZENG, Jiang HU, Li ZHU, Deyong REN, Zhenyu GAO, Longbiao GUO, Qian QIAN, Mingguo WU, Jianrong LIN, Guangheng ZHANG 2018, 32(3): 207-218.  DOI: 10.16819/j.1001-7216.2018.7120 Abstract ( )   HTML ( )   PDF (886KB) ( )   【Objective】The objective of thestudy was to layafoundation for further excavating new genes related to grain traits,analyzing the molecular mechanism and exploring the genetic regulation network of rice grain development,andprovidingtheoretical support for the molecular breeding of super rice.【Method】With the mapping population of 188-line recombinant inbred lines(RILs)derived from the cross between latejaponicarice Chunjiang16B(CJ16B) and wide-compatiblemid-indica restorationlines C84 which were relatively different in plant and grain morphology,a rice linkage genetic map was constructed on the basis of 158 polymorphic molecular markers,covering a total length of 1428.40cM and an average interval of 9.04cM.Five traits such as grain length(GL),grain width(GW),grain thickness(GT), length-to-width ratio(LWR) and thousand grain weight(TGW)were investigated in Lingshui, Hainan Province and Hangzhou, Zhejiang Province, China, and quantitative trait loci(QTLs) were analyzed.【Result】A total of 30 QTLs including 18 new QTLs were detectedand their contribution rates ranged from 3.51% to 17.25%. The number of QTLs related to GL, GW,GT, LWR and TGW were 9,5,5, 6and 5, respectively; Gene locus alignment showed that five cloned genesofgrainshape were found in the QTL marker interval, which were identified with sequencing of parental target genes and dCAPs molecular marker. 【Conclusion】The results showed that the RIL population and its genetic map could be used for the localization and cloning of the main QTLs/genes of important agronomic traits in rice.The new 18 grainQTLs are supplementto the regulation network of rice grain development.

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Targeted Editing of Rice SD1 Gene UsingCRISPR/Cas9 System Xuejiao HU, Jia YANG, Can CHENG, Jihua ZHOU, Fuan NIU, Xinqi WANG, Meiliang ZHANG, Liming CAO, Huangwei CHU 2018, 32(3): 219-225.  DOI: 10.16819/j.1001-7216.2018.7106 Abstract ( )   HTML ( )   PDF (758KB) ( )   【Objective】In the last century, the usage of semi-dwarfrice varieties brought about significant improvements and great achievements inrice breeding.Most of the semi-dwarfrice varieties have loss-of-function mutations in the Semi-Dwarf1 (SD1) gene.In order to obtain sd1 mutant, targeted editing of SD1 gene was performed. 【Method】SD1 gene editing vector CRISPR-SD1 was constructed by using CRISPR/Cas9 system, and transformed into two rice restore linesShenfan17 and Shenfan24 by the Agrobacterium-mediated method.【Result】 Homozygous sd1 mutants were obtained in T0 generation in both varieties, and vector-free sd1 mutant lines were segregated from the T1 population. The plant heights of the two sd1 mutants were decreased by 25% as compared with those of their wild types. 【Conclusion】CRISPR/Cas9 is a powerful tool for rice target gene editing, and has enormous potential in rice molecular breeding.

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Effects ofRicePlanting Combined with ChickenRaisingin Winter on Double-cropping Rice Growth and Soil Fertility Lang ZHANG, Linghong ZHOU, Jiabin WEI, Xiaolin CHENG, Huaqin XU, Zhixiang XIAO, Qiyuan TANG, Jianwu TANG 2018, 32(3): 226-236.  DOI: 10.16819/j.1001-7216.2018.7149 Abstract ( )   HTML ( )   PDF (1394KB) ( )   【Objective】The research aims to illuminate the effects of rice planting coupled with chicken grazing in winter on soil fertility and rice grain yield in the middle and lower reaches of the Yangtze River.【Method】Five treatments were designed, including milk vetch+chicken(MC), ryegrass + chicken(RC), milk vetch(M), ryegrass(R), winter fallow(WF).【Result】Yields in MC and RC were significantly higher than those of other treatments.Rice yield in MC was the highest. The content of organic matter, total nitrogen, ammonium nitrogen and nitrate nitrogen in double-cropping rice fields under MC and RC were significantly increased by 17.36%–22.95%, 73.73%–250.48%, 76.36%–85.11% and 67.89%–70.05%, respectively. However, the total phosphorus and available phosphorus contentsunder M were the highest, and every treatment had little effect on the total potassium content. Correlation analysis showed that there were significant correlations between theoretical yield of rice and soil nitrate nitrogen, ammonium nitrogen, total nitrogen or organic matter contents (P < 0.05).【Conclusion】Compared with green manures or winter fallow, chicken manurereturning was more effective in improving the contents of soil organic matter, total nitrogen, ammonium nitrogen and nitrate nitrogen, which helps increase the rice tiller numbers, leaf area coefficient, dry matter and yields, and the changes undermilk vetch + chickenwas the most significant. Under the mode of rice planting combined with chickenraising in winter, soil organic matter, total nitrogen, ammonium nitrogen and nitrate nitrogencontents improved rice grain yield. Therefore, combining rice planting and chicken raising in winter meets the nutrient demand of rice growth in the following season. Thus, rice yield increase based on ecological field conservation plays an important role in sustainable development of rice production in the middle and lower reaches of the Yangtze River.

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Effect of Site-Specific Nitrogen Management on Grain Yield and Quality of japonicaRice Varieties Differed in Response to Nitrogen Chengxin JU, Yaojie CHEN, Buhong ZHAO, Lijun LIU, Zhiqin WANG, Jianchang YANG 2018, 32(3): 237-246.  DOI: 10.16819/j.1001-7216.2018.7102 237 Abstract ( )   HTML ( )   PDF (797KB) ( )   【Objective】The aim is to clarify theeffect of site-specific nitrogen management on grain yield, nitrogen use efficiency and grain quality of japonicarice varieties with different nitrogen responses. 【Method】 Using fourjaponicarice varieties(Huaidao 5, Lianjing 7, Ningjing 1 and Yangjing 4038) as material, three nitrogen managements, zeronitrogen plot(ZN), farmers’common practice(FCP) and site-specific nitrogen management (SSNM), were applied during the growing season.The yield components, nitrogen use efficiency and grain qualitywere investigated.【Result】Compared with FCP,SSNM significantly increased grain yield and nitrogen use efficiency, especiallyforvarieties with A-type nitrogen response(typeA). SSNM significantly improvedhead rice percentage, gel consistency, hot viscosity and breakdown values, and increased the content of albumin and glutelin, reduced chalkiness, amylose content and gelatinization temperature.Compared with varieties fallen in B-type of nitrogen response(type B), A-type varieties had a greater head rice percentage and breakdown values at the same nitrogen management, higher content of albumin and glutelin, lower chalkiness, amylose content and setback value.【Conclusion】SSNM could significantly increase grain yield and nitrogen use efficiency for both A-type andB-typevarieties,andA-type varieties were more sensitive to nitrogen in terms of grain quality of rice.

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Effects of Sowing Densities on Quality and YieldFormation of Hydroponically Grown Long-mat Rice Seedlings Under Mechanical Transplanting Yuxiang LI, Zhizhou HE, Yanfeng DING, Shaohua WANG, Zhenghui LIU, She TANG, Chengqiang DING, Lin CHEN, Ganghua LI 2018, 32(3): 247-256.  DOI: 10.16819/j.1001-7216.2018.7103 Abstract ( )   HTML ( )   PDF (1162KB) ( )   【Objective】The objectiveof the research is to determine the suitable sowing density of hydroponically grown long-mat rice seedlings(HLMS) under mechanical transplanting. 【Method】The effects of sowing densities on seedling quality, mechanical transplanting quality, field growth characteristics and yield of HLMS were analyzed. A widely grown conventional japonica rice cultivar (Wuyunjing24) and an indica hybrid rice cultivar (6Liangyou9368) were used as test materials. 【Result】Dry weight of shoot and root, root-developing ability, root activity, seedling emergence rate, seedling base stem diameter, dry weight per unit of seedling height and photosynthetic rate were significantly increased and the leaf area index was significantly decreased with decreasing sowing density for both cultivars before transplantation. There were advantages of seedling reviving in the paddy field, tillering capacity and spikelet number per panicle for thin sowing treatments, but less basic seedlings and paniclesat too lowsowing density. The grain yield was not decreased significantly when the sowing density reduced to 738.9g/m2 for Wuyunjing 24 and 431.0g/m2 for 6Liangyou9368, respectively. However, the yield was decreased significantly when sowing density reduced continuously for both cultivars. 【Conclusion】 The suitable sowing density of HLMS was 2.03 cm-2for Wuyunjing24 and 1.14 cm-2 for6Liangyou9368, respectively.

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Characteristics of Nitrogen Uptake and Utilization of Mechanically-transplanted Pot-tray-nursed Rice Seedlings Yajie HU, Pei WU, Ming ZHU, Zhipeng XING, Qigen DAI, Zhongyang HUO, Ke XU, Haiyan WEI, Baowei GUO, Hongcheng ZHANG 2018, 32(3): 257-264.  DOI: 10.16819/j.1001-7216.2018.7086 Abstract ( )   HTML ( )   PDF (910KB) ( )   【Objective】The objective is to illuminate the characteristics of nitrogen uptake and utilization of Mechanically-transplanted pot-tray-nursed rice seedlings.【Method】The experiment was conducted in Xinghua test site of Yangzhou University in 2013 and 2014. Three type rice cultivars including large panicle type (LPT, Yongyou 2640 and Yongyou 8), medium panicle type (MPT, Wuyunjing 24 and Ningjing 3) and small panicle type (SPT, Huaidao 5 and Huaidao 10) were field-grown. With mechanically-transplanted carpet-tray-nursed rice seedlings (CS) as control, the nitrogen accumulation, translocation and utilization of nitrogen in pot seedlings mechanically transplanted rice (PS) were measured. 【Result】Compared to thoseof CS, nitrogen content and nitrogen uptake of PS at the mid-tillering, jointing, heading and maturity were higher. Nitrogen accumulation in a given stage and nitrogen uptake rate of PS during transplanting to the mid-tillering and jointing to heading and heading to maturity were greater than those of CS. Compared to CS, PS led tosignificantly higher nitrogen output, apparent nitrogen translocation rate and nitrogen translocation conversion rate in leaf, and lower apparent nitrogen translocation rate and nitrogen translocation conversion rate in stem and sheath for all rice cultivars. Partial factor productivity of applied nitrogen of PS was significantly greater for all rice cultivars than those of CS. Furthermore, PS gave rise to higher nitrogen harvest index than CSwith significant difference in LPT.【Conclusion】Hence, compared to CS, PS was beneficial to nitrogen absorption during the middle and late growth periods, and higher nitrogen output and nitrogen translocation conversion rate in leaf. The total nitrogen accumulation and nitrogen use efficiency under PS increased significantly as compared with those of CS.

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Simulation of Rice Adaptability Adjustmentin Fujian Province Under RCPs Scenarios Tongyu ZHOU, Min JIANG, Wangliang SUN, Bin SUN 2018, 32(3): 265-276.  DOI: 10.16819/j.1001-7216.2018.7104 Abstract ( )   HTML ( )   PDF (1601KB) ( )   【Objective】The impact of climate change on agricultural production has become increasingly obvious, and someadaptive adjustments on cropcultivation cansignificantly reduce the negative effects of future climate change.【Method】Based on the coupling of the BCC_CSM climate model and the crop model CERES-Rice, we selected the most adaptive rice varieties and the best sowing dates for each rice growing region in Fujian Province, China under the two scenarios of RCP4.5 and RCP8.5(named after a possible range of radiative forcing values in2100 relative to pre-industrial values+4.5,and +8.5 W/m2, respectively), and then we assessed their changes in riceyield, yield stability and the overall output of rice.【Result】The simulated yields of early rice with adaptive adjustments in the double cropping rice region in southeastern Fujian under RCP4.5 and RCP8.5 scenarios increase by 1.6% and 1.9%,respectively compared with those without adaptive adjustments; and forlate rice, by 13.5% and 9.8%, respectively.In doublecropping rice region in northwestern Fujian, the simulated yields of early rice with adaptive adjustments increased by 1.4% and 1.0% under the two climate change scenarios compared with those without adaptive adjustments; and for the late rice, by 11.5% and 7.9%. The simulated yields of single rice with adaptive adjustments increased by 14.1% and 13.7% underthe twoclimate change scenarios comparedwith thosewithout adaptive adjustments.With adaptive adjustments, the overall output of ricein Fujianunder the two climatechange scenarios increased by 9.3% and 10.5%. 【Conclusion】Climate change had adverse effects on rice yield in Fujian, and some adaptive adjustments could be taken to alleviate the negative impact.

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Identification of Strain 7-5, Antagonistic to Rice Sheath Blight, and Preliminary Study of Its Biocontrol Mechanism Qingxia ZHANG, Ying ZHANG, Lingling HE, Xijun CHEN, , Zhaolin JI 2018, 32(3): 277-284.  DOI: 10.16819/j.1001-7216.2018.7074 Abstract ( )   HTML ( )   PDF (985KB) ( )   【Objective】The objective is to obtain antagonistic bacteria for biocontrol on rice sheath blight and reveal the biological control mechanism.【Method】The control experiment of rice sheath blight by seven antagonistic bacteria stored in our lab was performed using pot cultures at the seedling stage. The strain 7-5 was identified based on a 16S rDNA BLAST and the strain’s physiological and biochemical characterization. The antifungal compounds produced by bacterial strain 7-5 were detected by PCR amplification and thin layer chromatography (TLC). 【Result】The suppressive effects of bacteria 7-5, 4-74 and 4-78 on the rice sheath blight in a greenhouse were as high as 69.0%, 70.8% and 75.4%, respectively. Strain 7-5 could strongly inhibit the growth of Rhizoctoniasolani, Moniliniafructicola and Botrytis cinerea, whereas both strains 4-74 and 4-78 had narrow inhibitory spectra. Strain 7-5 was identified as Pseudomonas chlororaphis and produced many antifungal factors, including phenazine-1-carboxylicacid, 2,4-diacetylphloroglucinol, pyoluteorin, siderophores, hydrogen cyanide and extracellular proteinase, but not including pyrrolnitrin, chitinase and cellulase.【Conclusion】The production of antibiotics plays a key role for P. chlororaphis7-5 to control the rice disease.

Reviews

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Advances in Traits of Lesion Mimic Mutants and Its Molecular Mechanisms in Rice Ran JIAO, Na XU, Juan HU, Zhoulin SONG, Jiaqing HU, Yuchun RAO, Yuexing WANG 2018, 32(3): 285-295.  DOI: 10.16819/j.1001-7216.2018.7153 Abstract ( )   HTML ( )   PDF (895KB) ( )   Lesion mimic mutants are similar withnaturally-formed scab on rice leaveswithout significant stress or damage and without exposure to pathogens. The cause of lesion mimic traits in rice is often accompanied by increased resistance to disease, which involves the expression of defense-related genes. The related research mainly focuses on the localization and cloning of various mutants, as well as the disease resistance and its mechanism. We reviewed the research progress in lesion mimic mutant gene traits and disease resistance in rice, especially explaining the causes, genetic characteristics and regulatory pathways of lesion mimic mutants in rice,and expecting to improve rice breeding for disease resistance as well. All these will lay a theoretical foundation for further analysis of various mechanisms of lesion mimic mutants and providing some reference for rice breeding.

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Research Advances on Rice Seed Vigor Anpeng ZHANG, Qian QIAN, Zhenyu GAO 2018, 32(3): 296-303.  DOI: 10.16819/j.1001-7216.2018.7140 Abstract ( )   HTML ( )   PDF (442KB) ( )   It has always been one of common concerns to improve grain yield of rice, one of the most important cereal crops. Seed vigor has been an increasingly important agricultural trait as direct-seeded rice technology is widely applied in some Asian countries and regions. The concepts of seed development, germination and seed vigor were introduced. And the influencing factors of seed vigor, physiological and biochemical factors and genetic mechanism were analyzed. The research progress of QTL/gene mapping in rice seed vigor was introduced and the prospect was predicted, which is of great significance to crop breeding aiming to improve the seed vigor.

Short Communication

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Effects of SublethalConcentration of Two Insecticides on Growth and Development of Rice Leaffolders, Cnaohalocrocismedinalis (Guenée) and Activities ofDetoxification Enzymes Yajun YANG, Caiyun WANG, Hongxing XU, Yanhui LU, Zhongxian LÜ 2018, 32(3): 304-310.  DOI: 10.16819/j.1001-7216.2018.7080 Abstract ( )   HTML ( )   PDF (676KB) ( )   【Objective】In order to understand the sublethal effect of chlorpyrifos and chlorantraniliprole on rice leaffoldersCnaphalocrocismedinalis, 【Method】the development was observed and detoxification enzymatic activitieswere measured observed after treatments with sublethal concentration of insecticides (LC10 and LC25) for 72h. 【Results】In the treatments with LC10 and LC25 of chlorpyrifos, the larval duration prolonged and pupal duration shortened, the adult longevity did not differ compared with the control. LC10 and LC25 ofchlorantraniliprole did not affect the larval and pupal duration, while LC10 ofchlorantraniliprole shortened the longevity of female adult. Esterase and glutathione S-transferase (GST) activity of C. medinalistreated with LC10 and LC25 of chlorpyrifos increased compared with the control. Esterase activity of C. medinalistreated with LC10 and LC25 of chlorantraniliprole increased compared with the control;GST activity of C. medinalistreated with LC25 of chlorantraniliprole increased compared with the control. 【Conclusion】These results indicated that sublethal concentration of chlorpyrifos and chlorantraniliprole could inhibit the development ofpartial stages of C. medinalis, and induce the increase of detoxified enzymatic activities. Selective pressure of sublethal concentrations of these two insecticides on C. medinalis could promote the evolution of insect resistance against insecticides.