Switchgrass (Panicum virgatum L.) is a promising candidate species for sustainable biofuel feedstock production on marginal land. Soil salinity is one of the significant factors that limits sustainable agricultural production worldwide including a substantial reduction in biomass yield of switchgrass. This study was designed to assess genetic variation in lowland switchgrass and identify genomic regions contributing to an increased level of salinity tolerance using a subset (550 pseudo F₂) of a nested association mapping (NAM) population. Salinity tolerance was evaluated based on salt injury score (SIS) using a 1 to 9 scale (1 = the most tolerant, 9 = the most sensitive) and stress tolerance index (STI) calculated from plant height measurements. Substantial variation among NAM families and genotypes within families was observed (p < .05) for SIS. However, no variation was evident among NAM families and genotypes within families for STI. The switchgrass plant accessions EG 1104–1, and EG 1104–2 displayed a high level of salinity tolerance based on SIS which can be used as source material for cultivar development. A total of five quantitative trait loci (QTL) associated with SIS were detected by composite interval mapping on four chromosomes 2B, 6B, 7B, and 9B. The phenotypic variation explained by an individual QTL ranged from 1.4 to 6.5%. The additive genetic effects of individual QTL ranged from −0.07 to 0.63. Homologs of five candidate genes were identified, which were reported to be associated with salinity tolerance.

中文翻译：

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与低地柳枝稷耐盐性相关的基因组区域

柳枝稷（Panicum virgatum L.）是边缘土地上可持续生物燃料原料生产的有前途的候选物种。土壤盐分是限制全球可持续农业生产的重要因素之一，包括柳枝稷生物量产量的大幅下降。本研究旨在评估低地柳枝稷的遗传变异，并使用子集（550 伪 F ₂) 的嵌套关联映射 (NAM) 群体。基于盐害评分 (SIS) 使用 1 到 9 级（1 = 最耐受，9 = 最敏感）和从植物高度测量计算的胁迫耐受指数 (STI) 评估耐盐性。观察到 NAM 家族之间和家族内基因型之间的显着差异（p < .05) 对于 SIS。然而，NAM 家族之间和 STI 家族内的基因型之间没有明显差异。柳枝稷植物种质 EG 1104-1 和 EG 1104-2 显示出基于 SIS 的高水平耐盐性，可用作栽培品种开发的源材料。通过对4条染色体2B、6B、7B和9B的复合区间作图，共检测到5个与SIS相关的数量性状基因座（QTL）。由单个 QTL 解释的表型变异范围为 1.4% 至 6.5%。个体QTL的加性遗传效应范围为-0.07至0.63。鉴定了五个候选基因的同源物，据报道它们与耐盐性有关。