Abstract: Thirty japonica rice germplasm resources were used as experimental materials and planted in normal paddy soil（control，CK）and soils with different alkalization degrees［alkalized saline soil（T1，alkalization degree of 39.7%）and alkaline soil（T2，alkalization degree of 57.3%）］.The full⁃length sequence of the GS3 gene was obtained by Sanger sequencing.Combined with panicle and grain phenotypic traits such as 1 000⁃grain weight，grain length and panicle length，as well as the change rates of panicle and grain traits under different treatments，haplotype analysis was carried out to explore the regulatory effects of different haplotypes of the GS3 gene on panicle and grain traits of japonica rice under alkaline stress condition.Comparative analysis of the full⁃length GS3 gene in 30 japonica rice germplasm resources was studied，and a total of 27 effective variation sites，including 13 missense mutation sites and 14 Indel sites，were detected.A correlation analysis between these sites and the change rate of 1 000⁃grain weight revealed that two Indel sites，SDP（significant differences are present in all）and SOA（significant differences are only under higher alkaline stress），which were located at positions 16730526 and 16732228 on chromosome 3，respectively，were significantly correlated with the change rate of 1 000⁃grain weight，and together formed four main haplotypes，SDP1，SDP2，SOA1 and SOA2.A frameshift mutation in the coding region of SDP2 haplotype led to the premature termination of the protein domain，which weakened the sensitivity of GS3 to changes of alkalinity，mainly reflecting in the non⁃significant difference in 1 000⁃grain weight，grain length，panicle length and their change rates between T1 and T2 treatments.The SOA2 haplotype had a 2 bp insertion mutation in the intron region，which reduced the response ability of GS3 to alkaline stress and weakened its functional effect，mainly manifesting in that the 1 000⁃grain weight under T2 treatment was extremely significantly higher than that of SOA1，and the change rate of 1 000⁃grain weight under T2 treatment was extremely significantly different from SOA1，but there were no significant difference in grain length，panicle length and their change rates compared with SOA1.In summary，this study is the first to reveal the functional trade⁃off mechanism of the GS3 gene between alkali tolerance and grain weight trait regulation，and clarify the specific regulatory effects of the SDP2 and SOA2 haplotypes on panicle and grain traits under alkaline environments.

Key words: Rice, GS3 gene, Alkaline environment, Panicle and grain traits, Thousand?grain weight change rate, Haplotype

摘要： 以30份粳稻种质资源为试验材料，分别在正常稻田土（对照，CK）及不同碱化程度的土壤［碱化盐土（T1，碱化度39.7%）和碱土（T2，碱化度57.3%）］种植，通过Sanger测序获得GS3基因的全长序列并结合千粒质量、粒长和穗长等穗粒表型性状和在不同处理下的穗粒性状变化率，开展单倍型分析，旨在探讨GS3基因不同单倍型在碱胁迫条件下对粳稻穗粒性状的调控效应。结果表明，对30份粳稻种质资源GS3基因全长进行对比分析，共检测到27个有效变异位点，包含13个错义突变位点和14个Indel位点，将其与千粒质量变化率进行相关性分析发现，2个Indel位点SDP（Significant differences are present in all）、SOA（Significant differences are only under higher alkaline stress）与千粒质量变化率显著相关，分别位于第3染色体的16730526和16732228位置，共形成4种主要单倍型SDP1、SDP2、SOA1、SOA2。SDP2单倍型由于编码区发生移码突变，导致蛋白质结构域提前终止，削弱了GS3对碱度变化的敏感能力，主要表现在千粒质量、粒长、穗长及其变化率在T1与T2处理间差异均不显著。SOA2单倍型则因内含子区域发生2 bp插入突变，导致GS3对碱性胁迫的响应能力下降，功能效应减弱，主要表现在T2处理下千粒质量极显著高于SOA1，且千粒质量变化率与SOA1差异也极显著，粒长、穗长及其变化率与SOA1无显著差异。综上，首次揭示了GS3基因在耐碱性与粒质量性状调控之间的功能权衡机制，明确了SDP2和SOA2单倍型在碱性环境下对穗粒性状的特异性调控效应。

关键词: 水稻, GS3 基因, 碱环境, 穗粒性状, 千粒质量变化率, 单倍型