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Expression Patterns of OsHKT Genes in Rice Lixin CUI, Yanan HE, Yaping LI, Xianzhi XIE 2017, 31(6): 559-567.  DOI: 10.16819/j.1001-7216.2017.7070 Abstract ( )   HTML ( )   PDF (49899KB) ( )   【Objective】OsHKTs (High Affinity K+ Transporter) encode Na+ or K+ transporter or Na+-K+ co-transporters that play an important role in Na+ recirculation and maintaining the low concentration of Na+ and low Na+ / K+ ratio in above-ground tissues, especially leaves. Therefore, OsHKT family is related to salt stress tolerance in rice. In this study, we analyzed the tissue specificity and diurnal rhythm of OsHKTs gene expression and expression patterns in rice seedlings treated with either salt or ABA. 【Method】qRT-PCR technique was used to analyze OsHKTs expression patterns. 【Result】Individual member of OsHKT family genes had different expression levels in root and leaf. OsHKT1;1, OsHKT1;3, OsHKT2;3, and OsHKT2;4 mainly expressed in leaves, whereas other members had higher transcript levels in roots relative to those in leaves. Salt treatment affected transcript levels of OsHKT family genes both in leaves and roots. OsHKT1;5, OsHKT2;1, and OsHKT2;2 had similar expression patterns in both leaves and roots of seedlings treated with NaCl, whereas other members did not. Transcript levels of OsHKT family genes were regulated by ABA treatment either in leaves or in roots. OsHKT1;3 and OsHKT1;5 had similar expression patterns in both leaves and roots. In addition, expression patterns of OsHKT genes exhibited similar diurnal rhythm. 【Conclusion】Our results suggest that expression of OsHKT family genes has tissue-specificity and similar diurnal rhythm. Exogenous NaCl and ABA treatment have different influences on OsHKT transcripts, depending on individual member of the family. Our findings lay a foundation for further revealing the functional mechanism of OsHKT genes in rice.

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Identification and Gene Mapping-based Clone of Two Chalkiness Mutants in Rice Xichun ZHANG, Feifei LU, Yusong LÜ, Rongjian LUO, Guiai JIAO, Yawen WU, Shaoqing TANG, Peisong HU, Xiangjin WEI 2017, 31(6): 568-579.  DOI: 10.16819/j.1001-7216.2017.7003 Abstract ( )   HTML ( )   PDF (82108KB) ( )   【Objective】Chalkiness affects the appearance, processing, cooking and eating quality of rice. The objective of the study was to uncover the genetic mechanism of two rice chalky endosperm mutants for improving rice quality. 【Method】Two chalkiness mutants, eb6 and eb7 were identified from EMS-treated japonica rice Zhonghua 11. The agronomic traits and starch physicochemical properties of the two mutants were investigated. Genetic analysis and map-based cloning for the gene responsible for the eb6 and eb7 phenotypes were carried out with the F2 population derived from the cross between eb6 and Nanjing 11, eb7 and 93-11. Furthermore, the expression pattern of candidate gene and the transcript levels of genes related to starch synthase in mutants and wild type(WT) were also investigated.【Result】The central parts of them were white and opaque, with loosely and irregularly arranged and smaller compound starch granules(SGs). Whereas, the marginal part of endosperms of WT and mutants and the central part of WT were filled with densely packed, similar sized polyhedral SGs. The amylose content and gel consistency of mutants were dramatically lower than those of WT. Simultaneously, the proportions of chains with degree of polymerization(DP) of amylopectin in the range from 6 to 16 were significantly increased, whereas the proportion of chains with DP in the range from 16 to 23 was noticeably decreased in the eb6. Genetic analysis showed that a single recessive gene controls chalkiness phenotype of mutants. Based on the F2 population derived from the cross between eb6 and Nanjing 11, the gene was finally narrowed down to a 86.6 kb physical region on chromosome 1. Within this region, one open reading frame(LOC_Os01g44220) has been annotated as large subunit of ADP-glucose pyrophosphorylase gene(OsAGPL2). Sequence analysis revealed that there was only one a nucleotide substitution in the 3rd exon of eb6 and the 7th exon of eb7, which resulted in an amino acid replacement in OsAGPL2, respectively. The qRT-PCR and in-situ hybridization assay indicated that OsAGPL2 was mainly expressed in the developing grains. Moreover, the expression patterns of many genes involved starch synthesis were intensively influenced in mutants.【Conclusion】OsAGPL2 indisputably corresponds to endosperm chalkiness of eb6 and eb7. And all results suggest that OsAGPL2 plays an important role in starch synthesis, the formation of compound starch granules and rice quality.

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Identification and Fine Mapping of Small Grain Gene SG101 in Rice (Oryza sativa L.) Yuqiong WANG, Yaolong YANG, Yujia LENG, Lichao HUANG, Long CHEN, Liping DAI, Zhengjun TU, Yihong GAO, Jiang HU, Li ZHU, Guangheng ZHANG, Deyong REN, Zhenyu GAO, Guojun DONG, Guang CHEN, Longbiao GUO, Guoyou YE, Qian QIAN, Dali ZENG 2017, 31(6): 580-589.  DOI: 10.16819/j.1001-7216.2017.6152 Abstract ( )   HTML ( )   PDF (7983KB) ( )   【Objective】Grain size is an important agronomic trait in determining grain yield. The characterization and identification of grain size related genes will be beneficial to expound the genetic regulatory mechanisms behind yield formation in rice. 【Method】Here, we report the characterization of a rice (Oryza sativa L.) mutant, small grain 101 (sg101), gained by EMS mutagenesis for Zhonghua 11. The effects of sg101 on grain size, panicle-related traits, cell number and size of lemma were assessed by morphological and cytological methods. The responses to brassinolide(BR) were detected based on the variation in leaf angle and coleoptile length. The expression level of BR signal and synthesis related genes were tested by RT-PCR. Map-based cloning was executed for fine mapping of SG101.【Result】The grain length, grain width and grain weight were significantly reduced in sg101. Moreover, sg101 showed decreased panicle length, secondary rachis branch number, plant height and seed setting rate. The paraffin section observation under a scanning electron microscope indicated that the cell number in sg101 was significantly decreased, while the cell size was similar to wild type, suggesting that SG101 affected the grain size by regulating the cell division. Quantitative RT-PCR analysis displayed that the expression of cell cycle related genes was reduced in sg101. After treatment with BR, sg101 showed smaller leaf angle and shorter coleoptile than those of the wild type and the expression of BR biosynthetic and signal pathway related genes was down-regulated in sg101. Genetic analysis revealed that sg101 phenotype was controlled by a single recessive nuclear gene.【Conclusion】SG101 was mapped on the long arm of chromosome 1 between two STS markers S5 and S6 with a 265 kb physical distance. It laid a base for the further cloning and functional analysis of SG101.

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Breeding Potential of Rice TAC1 Gene for Tiller Angle Zongxiang CHEN, Zhiming FENG, Longping WANG, Fan FENG, Yafang ZHANG, Yuyin MA, Xuebiao PAN, Shimin ZUO 2017, 31(6): 590-598.  DOI: 10.16819/j.1001-7216.2017.7100 Abstract ( )   HTML ( )   PDF (278KB) ( )   【Objective】Rice tiller angle is an important plant-type trait. The appropriate tiller angle is generally a critical factor in developing ideal-type high-yielding rice variety. 【Methods】Effects of tiller angle controlling gene TAC1 on agronomic traits, sheath blight resistance, grain yield and quality were investigated under conditions of one-plant one-point and multi-plants one-point transplantation by using four pairs of near isogenic lines(NILs) at TAC1 gene.【Results】TAC1 increased rice tiller angle in all the genetic backgrounds tested, which is beneficial for reducing adverse impacts of sheath blight, without affecting other agronomical traits. Under high-yielding cultivation condition of multi-plant one-point transplantation, numbers of effective panicles in all the NILs with TAC1 were apparently higher than those of corresponding NILs with tac1. In the background of indica rice Teqing, the seed-setting rate, 1000-grain weight and plant yield of Teqing-TAC1 line were all higher than those of Teqing-tac1 line; however, the reverse results were obtained in the background of Lemont. In backgrounds of Wulingjing 1 and Zhendao 88, NILs with TAC1 gene displayed slightly grain yield than those with tac1 gene. The grain processing and appearance qualities of Teqing-TAC1 line were slightly improved compared to the corresponding control, while other TAC1-harboring NILs showed just the reverse with statistically insignificant difference. 【Conclusions】The indica rice with long leaf has a narrow range of appropriate tiller angles but for japonica rice with short leaf, the range is wider. Increasing rice tiller angle to an extent is beneficial for reducing sheath blight influence. TAC1 improves the plant type of japonica rice as well as the compact type indica rice.

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Effects of Mechanical-transplanted Modes and Density on Root Growth and Characteristics of Nitrogen Utilization in Hybrid Rice at Different Seedling-ages Yinghong LI, Yongjian SUN, Yue LI, Tengfei LÜ, Mingjin JIANG, Fengjun YAN, Jun MA 2017, 31(6): 599-610.  DOI: 10.16819/j.1001-7216.2017.7019 Abstract ( )   HTML ( )   PDF (346KB) ( )   【Objective】Mechanical transplanting is the main development direction of the rice planting in China, and it has important significance for increasing rice yield, nitrogen (N) use efficiency and accelerating integration of high yield and efficient cultivation techniques of rice mechanization by researching the effects of mechanical-transplanted modes and density on root growth and characteristics of N utilization in hybrid rice at different seedling-ages. 【Method】A split plot design was used with the super hybrid rice F you 498 as material to analyze the effects of six mechanical-transplanted modes and density combined treatments of “bowl mechanical-transplanting with high density, bowl mechanical-transplanting with middle density, bowl mechanical-transplanting with low density, carpet mechanical-transplanting with high density carpet mechanical-transplanting with middle density, and carpet mechanical-transplanting with low density” on characteristics of N utilization, root growth, and to recover the relationship between root growth with N utilization and yield at different seedling-ages. 【Result】The N uptake of main growth period, N accumulation at growth and development stage, N absorption rate, N translocation amount of stem and leaf from full-heading to maturity, N increase in panicle, N partial factor productivity and root dry weight after jointing stage, and yield of 25-day-old seedlings have an obvious advantage over that of 40-day-old seedlings. Compared with carpet mechanical-transplanting, the bowl mechanical-transplanting can improve the root growth at different growth stages, enhance N accumulation and uptake rate, increase the amount of N translocation to various organs during grain filling stage, so as to increase the grain yield. Especially the best treatment, the bowl mechanical-transplanting with a plant spacing of 15.5 and 25-day-old seedlings has obvious advantages than other treatments. And carpet mechanical-transplanting can also help get a higher yield with the plant spacing of 12 cm and 25-day-old seedlings, but the yield will be reduced when density decreased even though it improved the root to shoot ratio, transport rate of leaf and stem, but decreased N accumulation of each period, absorption rate, and the leaf and stem translocation amount during grain filling stage. Correlation analysis showed that grain yield and N uptake and utilization were significantly correlated with root dry weight of main growth period (r=0.47**~0.83**), but significantly negatively correlated with root-shoot-ratio of full-heading and maturity period (r=-0.52**~ -0.79**). 【Conclusion】For root growth and N uptake and utilization characteristics, 25-day-old seedlings were better than 40-day-old seedlings and bowl mechanical-transplanting can optimize the relationship between individuals and population, but seedling density should be moderate, the most suitable spacing is 33 cm × 15.5 cm. It can promote the absorption and utilization of N and grain yield. Furthermore, the findings suggested that attention should be paid to the root growth from jointing stage and maturity stage, because of its significant effect on yield. The result laid a technical and practical basis for the high yield and high efficiency cultivation technology of bowl mechanical-transplanting.

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Dynamic Growth Characteristics of Roots of Mechanically-transplanted Hybrid Rice Under Different Nitrogen Treatments Ke LIU, Chang YE, Shaowen LIU, Jian LU, Mengtao GAO, Bilin LU, Xiaohai TIAN, Yunbo ZHANG 2017, 31(6): 611-618.  DOI: 10.16819/j.1001-7216.2017.7009 611 Abstract ( )   HTML ( )   PDF (1296KB) ( )   【Objective】This experiment is to study the dynamic characteristics of roots grown under different nitrogen levels and their relationship with grain yield in mechanically-transplanted hybrid rice.【Method】Two-line hybrid rice combinations, Quanliangyou 1 and Quanliangyou 681, were grown under different nitrogen treatments, N0(0 kg/hm2), N1(150 kg/hm2) and N2(250 kg/hm2), respectively. The dynamic root morphological traits and distribution(0–30 cm) from 20 days after transplanting(DAT) to flowering were analyzed with minirhizotron technique.【Result】The total number of roots, root length, root volume and root surface area were all significantly affected by nitrogen levels. The total number of roots of the two combinations under N2 treatment was significantly higher than that under N1 treatment. Compared with N1 treatment, the total number of roots of Quanliangyou 1 and Quanliangyou 681 increased by 12.3% and 17.6%, respectively. The total number of roots of the two combinations maximized 65 days after transplanting. With the increasing amount of nitrogen, the number of roots, root length, root volume and root surface area increased in different soil layers, but the layer (10–20 cm) was much more significant compared with others. The correlation coefficients between the total root length (10–20 cm) and grain yield, the number of roots (10–20 cm) and grain yield were 0.80 and 0.87, respectively, reaching the significant level. Both the number of roots and grain yield of Quanliangyou 681 were much higher than those of Quanliangyou 1.【Conclusion】Higher nitrogen level improve the root biomass, while the root distribution in the soil layer(10–20 cm) is closely related to the grain yield. Given this situation, increasing the deep root distribution can make extraordinary contribution to the improvement of the grain yield.

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Nitrogen Absorption and Utilization Characteristics of the Newly Approved Early-Maturity Late japonica Rice Cultivars in Jiangsu Province Yue WU, Jing HU, Chen CHEN, Jiaxing ZHANG, Wanyuan LI, Dongnan TANG, Jun ZHONG, Bin YANG, Zhengkang ZHU, Youli YAO, Yulong WANG, Guichun DONG 2017, 31(6): 619-630.  DOI: 10.16819/j.1001-7216.2017.7014 Abstract ( )   HTML ( )   PDF (927KB) ( )   【Objective】To clarify the characteristics of nitrogen absorption and utilization in early-maturity late japonica rice cultivars, the grain yield components and their relationship with nitrogen uptake and utilization efficiency were investigated in comparison to a control cultivar Ningjing 1.【Method】A field experiment was conducted in the Rice Research Institute of Jiangsu (Wujin) in 2012 and 2013 with eight newly released early-maturity late japonica rice cultivars in Jiangsu Province (namely Wuyunjing 29, Wuyunjing 23, Yangjing 4227, Tongjing 981, Changnongjing 7, Ningjing 3, Zhendao 16 and Nanjing 5055) as materials.【Results】The actual grain yield of the eight new cultivars surpassed the control by 7.87% on average, with four(Wuyunjing 29, Wuyunjing 23, Yang 4227, and Tongjing 981) increased significantly (P<0.01). The total nitrogen uptake and nitrogen utilization efficiency at maturity in the eight new cultivars increased by 4.97% and 2.85%, respectively, compared to the control, which led to the improved grain yield. Further analysis revealed that the nitrogen content showed little variation among the new cultivars, while the dry matter production was significantly higher than that of the control. The nitrogen absorption before heading contributed about 80%-85% of the total in the whole growth duration. The nitrogen uptake at heading stage and heading-maturity period in the eight new cultivars were 1.35% and 25.94%, respectively, higher than that of the control. The panicle number showed limited contribution to the variation of total nitrogen uptake in the new cultivars, whereas the nitrogen uptake per panicle was 3.19% higher than that of the control. New cultivars had less than five days differences in the whole growth duration (life cycle), whereas the nitrogen uptake rate (average daily nitrogen absorption) of the new cultivars was 5.85% higher than that of the control. Correlation and path analysis revealed that larger dry matter production, daily nitrogen absorption rate, nitrogen absorption per panicle and amount of nitrogen uptake after heading contributed significantly to the higher total nitrogen absorption. In the new cultivars, the nitrogen percentage of the whole rice plants was generally higher. The nitrogen assimilated into and translocated to grains was higher in the new cultivars. All these characteristics contributed to higher total nitrogen uptake and nitrogen grain production efficiency. The nitrogen harvest index, nitrogen absorption percentage, nitrogen agronomic efficiency, and nitrogen partial production efficiency were higher in the new cultivars with more grain yield. 【Conclusion】 In short, the eight new cultivars from Southern Jiangsu Province had more nitrogen uptake and higher nitrogen utilization efficiency, and grain yield. Increasing total nitrogen uptake and improving nitrogen utilization efficiency were helpful in further raising the grain yield in rice production.

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Comprehensive Evaluation and Selection of Rice (Oryza sativa japonica) Germplasm for Saline Tolerance at Germination Stage Lei TIAN, Yaping CHEN, Jun LIU, Xiaogang MA, Na WANG, Bing YANG, Ying LI, Haidong GUO, Juan LI, Hui HU, Yinxia ZHANG, Peifu LI 2017, 31(6): 631-642.  DOI: 10.16819/j.1001-7216.2017.6168 Abstract ( )   HTML ( )   PDF (1129KB) ( )   【Objective】Soil salinity is one of the major abiotic stresses affecting rice growth and production. Salt resistance identification at germination stage, indices screening, and cultivar breeding of rice germplasm resources are important for rice production.【Method】Seeds of sixty-four japonica rice germplasm accessions germinated in the 125 mmol L-1 NaCl solution. On the third day after salt stress, germination number of the seeds was measured. After salt stress for five and ten days, germination number, shoot length and root length were measured and then the relative shoot length, relative root length, relative germination potential, relative germination rate, relative salt damage rate, germination index and vigor index were calculated. Multiple statistical methods were used to comprehensively evaluate the salt tolerance of 64 rice japonica germplasm and the germination characteristics of typical salt-tolerant and salt-sensitive rice germplasm under salt stress were analyzed. 【Result】The relative salt damage rate was significantly negatively correlated with relative root length, relative germination potential, relative germination rate, germination index and vigor index. Except for relative shoot length, these six indexes were significantly correlated with each other. Through cluster analysis, 64 japonica rice germplasm were divided into four groups. The group Ⅰ and Ⅳ were typical salt-sensitive and salt-tolerant germplasm, respectively. The group Ⅱ was mainly composed of low salt-resistant rice and the group Ⅲ was moderately salt-tolerant. With the principal component analysis these seven single indexes could be converted to three principal components. An objective comprehensive evaluation value (D value) of salt tolerance was obtained using membership function with index weight method. The five highest and lowest D value germplasm resources were selected to carry on significance analysis. The results showed that except for relative shoot length, all of these seven indexes measured after stress for five and ten days were significantly different from the two types. 【Conclusion】Rice was sensitive to salt stress at germination stage and there were significant differences between different germplasm. Using stepwise regression and principal component analysis, germination index, relative root length and relative salt damage rate were selected as the key indexes for the rapid identification of salt tolerance of rice germplasm. If multivariate statistical method was used, the reliability will be improved.

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Influence of Symbiotic Bacteria Arsenophonus, Rice Variety and Temperature on the Incidence Rate of Nilaparvata lugens to Metarhizium flavoviride Huanhuan ZHU, Yang CHEN, Pinjun WAN, Weixia WANG, Fengxiang LAI, Qiang FU 2017, 31(6): 643-651.  DOI: 10.16819/j.1001-7216.2017.7012 Abstract ( )   HTML ( )   PDF (1066KB) ( )   【Objective】 To reveal the significant factors affecting the incidence rate of the brown planthopper (BPH) to Metarhizium flavoviride, laboratory bioassays were carried out to study the influence of symbiotic bacteria Arsenophonus, rice variety and temperature on the incidence rate of BPHs to M. flavoviride. 【Method】 Through two completely randomized block trial: 1) symbiotic bacteria Arsenophonus (infected and uninfected) versus rice varieties (TN1, IR56 and Mudgo), 2) and Arsenophonus (infected and uninfected) versus temperatures (21°C, 23°C, 25°C, 27°C, 29°C and 31°C), BPHs with symptoms of M. flavoviride infection were observed after exposure to the spore suspensions of M. flavoviride for different periods. 【Result】 For all tested rice varieties, the incidence rates of M. flavoviride-treated BPHs infected with Arsenophonus (BPH++) were lower than that of BPHs uninfected (BPH--). Out of tested temperatures, only under 25°C, 27°C, 29°C, BPH++ has lower incidence rates than BPH-- at 3 d and 5 d after spraying. However, there was no significant difference among others. The results of two-way ANOVA analysis between Arsenophonus and rice varieties also indicated that the incidence rate of BPH++ was lower than that of BPH--. Furthermore, two-way ANOVA results between Arsenophonus and temperatures indicated the incidence rate of BPH++ was lower than that of BPH-- at 3 d and 5 d after spraying. The effect of temperature was significant on the virulence of M. flavoviride to BPHs. BPHs had higher corrected incidence rates and shorter LT50 under 23°C–29°C than that under 21°C or 31°C. Out of these BPHs, the highest corrected incidence rates and shortest LT50 were found at 27°C. It suggested 23°C–29°C was suitable temperature for infection of M. flavoviride, among which 27°C was the best. This suggested that low or high temperatures would negatively affect the virulence of M. flavoviride to BPH. The temperature also affected the LT50 of BPHs. The LT50 of BPH++ was longer than that of BPH-- under 27°C or 29°C. However, the LT50 of BPH++ was equal or even shorter than that of BPH-- under other temperatures.【Conclusion】 Arsenophonus decreased the virulence of M. flavoviride to BPH, which was influenced by temperature. The temperature also affects the incidence rate of BPHs to Metarhizium flavoviride significantly. However, the effects of rice varieties and interactions of Arsenophonus and rice varieties and Arsenophonus and temperatures were not significant on the incidence rate.

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Expression Under Hypertonic Osmotic Stress of Ab-lea from Aphelenchoides besseyi Qiaoli CHEN, Feng WANG, Danlei LI, Yaming LING, Ruizhi ZHANG 2017, 31(6): 652-657.  DOI: 10.16819/j.1001-7216.2017.7004 Abstract ( )   HTML ( )   PDF (625KB) ( )   【Objective】Rice white tip nematodes (Aphelenchoides besseyi) can enter osmobiosis to survive hypertonic osmotic stress in soil and seeds before infecting hosts, making the prevention and control of the nematode rather difficult. Normally, under hypertonic osmotic stress, the gene expression of late embryogenesis abundant protein (LEA) will significantly increase. As an adversity expressive protein, LEA can protect the organism under adversity. In order to study the expression pattern and the function of LEA gene from A. besseyi (Ab-lea) under hypertonic osmotic stress, 【Method】the gene was cloned according to the results of the transcriptome sequencing. A saturated MgSO4·7H2O solution was used as a hypertonic osmotic solution to dehydrate nematodes. The expression of Ab-lea was tested by RT-PCR during Osmobiosis. RNAi was used to investigate the survival of nematodes under hypertonic osmotic stress after silencing of Ablea.【Result】Nematodes will turn into osmobiosis after soaking in a saturated MgSO4·7H2O solution for 240 min. RT-PCR results showed that the expression of Ab-lea was upregulated when nematodes were at the beginning of hypertonic osmotic stress treatment and during the osmobiosis. 【Conclusion】The survival rate of the nematodes dropped significantly under osmobiosis after Ab-lea silence, which showed that Ab-lea may be involved in the regulation of osmobiosis of the nematode. It lays a foundation of further exploration for the physiological mechanism of nematode-resistance to hypertonic osmotic stress and provides new ideas for the prevention and control of the nematode.

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An Quantitative Analysis of High Temperature Effects During Meiosis Stage on Rice Grain Number per Panicle Chunlin SHI, Zongqiang LUO, Min JIANG, Yongle SHI, Yingxue LI, Shouli XUAN, Yang LIU, Shenbin YANG, Gengkang YU 2017, 31(6): 658-664.  DOI: 10.16819/j.1001-7216.2017.7032 Abstract ( )   HTML ( )   PDF (1363KB) ( )   【Objective】Grain number per panicle is one of yield component factors for rice. In order to analyze the effect of high temperature on the grain number per panicle and develop the quantitative model to evaluate it, 【Method】a pot experiment under different high temperatures and durations during meiosis stage was conducted with Liangyoupeijiu and Nanjing 45 as materials in 2014–2015. 【Result】Grain number per panicle decreased with the rising temperature and prolonging duration exposed to high temperature. The relationship between grain number per panicle and temperature could be expressed with a quadratic equation. The terminal time of grain number per panicle sensitive to high temperature was five days before heading date. The validation result showed the model could better simulate the effect of high temperature during meiosis stage on the grain number per panicle with rRMSE 0.094 and 0.085 for Liangyoupeijiu and Nanjing 45, respectively. 【Conclusion】This study would help improve the quantitative effect of high temperature on rice growth duration.

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Progress in Genetic Research of Rice Grain Shape and Breeding Achievements of Long-grain Shape and Good Quality japonica Rice Haixiang HUANG, Qian QIAN 2017, 31(6): 665-672.  DOI: 10.16819/j.1001-7216.2017.7115 Abstract ( )   HTML ( )   PDF (685KB) ( )   The genetic dissection and breeding of rice grain shape has always been an important subject in rice genetics. The long-grain shape has been a new favored quality trait in the breeding of japonica rice in recent years. While summarizing the genetic research progress in grain length-related traits and the corresponding gene function, we also systematically introduced the breeding course and selection strategy of long-grain japonica rice. Meanwhile, the agronomic and quality traits of long grain japonica varieties, represented by Jiahe 218, were compared with those of typical japonica rice varieties. Based on the successful breeding of long-grain japonica rice with high quality and high yield, we put forward the breeding strategy that combines grain shape selection, plant architecture optimization with yield and quality.