Background

Salinity is one of the most widespread abiotic stresses affecting rice productivity worldwide. The purpose of this study was to establish the relative importance of different traits associated with salinity tolerance in rice and to identify new quantitative trait loci (QTL) conferring tolerance to salinity at seedling stage. A total of 231 F_2:3 plants derived from a cross between a sensitive variety BRRI dhan29 (BR29 hereafter) and Capsule, a salt tolerant Bangladeshi indica landrace, were evaluated under salt stress in a phytotron.

Results

Out of the 231 F₂ plants, 47 highly tolerant and 47 most sensitive lines were selected, representing the two extreme tails of the phenotypic distribution. These 94 plants were genotyped for 105 simple sequence repeat (SSR) and insertion/deletion (InDel) markers. A genetic linkage map spanning approximately 1442.9 cM of the 12 linkage groups with an average marker distance of 13.7 cM was constructed. QTL were identified on the long arm of chromosome 1 for Na⁺ concentration, K⁺ concentration, Na⁺-K⁺ ratio and survival; chromosome 3 for Na⁺ concentration, survival and overall phenotypic evaluation using the Standard Evaluation system (SES); and chromosome 5 for SES. A total of 6 pairwise epistatic interactions were also detected between QTL-linked and QTL-unlinked regions. Graphical genotyping indicated an association between the phenotypes of the extreme families and their QTL genotypes. Path coefficient analysis revealed that Na⁺ concentration, survival, Na⁺-K⁺ ratio and the overall phenotypic performance (SES score) are the major traits associated with salinity tolerance of Capsule.

Conclusions

Capsule provides an alternative source of salinity tolerance aside from Pokkali and Nona Bokra, the two Indian salt tolerant landraces traditionally used for breeding salt tolerant rice varieties. Pyramiding the new QTL identified in this study with previously discovered loci, such as Saltol, will facilitate breeding varieties that are highly tolerant of salt stress.

中文翻译：

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使用孟加拉国水稻地方品种胶囊，评估性状贡献并绘制新的QTL耐盐性。

背景

盐度是影响全球水稻生产力的最普遍的非生物胁迫之一。这项研究的目的是确定与水稻耐盐性有关的不同性状的相对重要性，并确定赋予幼苗耐盐性的新的数量性状位点（QTL）。共有231˚F _2：3种从横一个敏感品种BRRI dhan29（BR29下文）和胶囊，其盐之间衍生的植物耐受孟加拉籼稻地方品种，在人工气候室盐胁迫条件下进行了评价。

结果

在231株F ₂植物中，选择了47株高耐受性品系和47株最敏感的品系，它们代表了表型分布的两个极端。对这94株植物进行了105型简单序列重复（SSR）和插入/缺失（InDel）标记的基因分型。构建了一个遗传连锁图谱，该图谱涵盖了12个连锁组中大约1442.9 cM，平均标记距离为13.7 cM。在1号染色体的长臂上确定了QTL的Na ⁺浓度，K ⁺浓度，Na ⁺ -K ⁺比例和存活率；Na ^+的3号染色体使用标准评估系统（SES）进行浓度，存活率和总体表型评估；和5号染色体用于SES。在QTL连接的区域和QTL未连接的区域之间还检测到总共6个成对的上位相互作用。图形基因分型表明极端家族的表型与其QTL基因型之间存在关联。路径系数分析表明，Na ⁺浓度，存活率，Na ⁺ -K ⁺比值和总体表型表现（SES评分）是与胶囊耐盐度有关的主要特征。

结论

除了Pokkali和Nona Bokra（这两个印度传统的耐盐水稻品种）常用于育种耐盐水稻品种外，胶囊还提供了另一种耐盐碱性来源。用先前发现的基因座（如Saltol）对本研究中鉴定的新QTL进行金字塔聚合，将有助于培育高度耐盐胁迫的品种。