Water-use efficiency (WUE) is the ratio of biomass produced per unit of water consumed; thus, it can be altered by genetic factors that affect either side of the ratio. In the present study, we exploited natural variation for WUE to discover loci affecting either biomass accumulation or water use as factors affecting WUE. Genome-wide association studies (GWAS) using integrated WUE measured through carbon isotope discrimination (δ 13 C) of Arabidopsis thaliana accessions identified genomic regions associated with WUE. Reverse genetic analysis of 70 candidate genes selected based on the GWAS results and transcriptome data identified 25 genes affecting WUE as measured by gravimetric and δ 13 C analyses. Mutants of four genes had higher WUE than wild type, while mutants of the other 21 genes had lower WUE. The differences in WUE were caused by either altered biomass or water consumption (or both). Stomatal density (SD) was not a primary cause of altered WUE in these mutants. Leaf surface temperatures indicated that transpiration differed for mutants of 16 genes, but generally biomass accumulation had a greater effect on WUE. The genes we identified are involved in diverse cellular processes, including hormone and calcium signaling, meristematic activity, photosynthesis, flowering time, leaf/vasculature development, and cell wall composition; however, none of them had been previously linked to WUE. Thus, our study successfully identified effectors of WUE that can be used to understand the genetic basis of WUE and improve crop productivity.

中文翻译：

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自然变异确定了拟南芥水分利用效率的新效应

用水效率 (WUE) 是单位用水量所产生的生物量之比；因此，它可以通过影响比率任一侧的遗传因素来改变。在本研究中，我们利用 WUE 的自然变异来发现影响生物量积累或水利用的位点作为影响 WUE 的因素。全基因组关联研究 (GWAS)，使用通过碳同位素鉴别 (δ13C）的拟南芥种质确定了与 WUE 相关的基因组区域。根据 GWAS 结果和转录组数据选择的 70 个候选基因的反向遗传分析确定了 25 个影响 WUE 的基因，通过重量和 δ 测量13C 分析。4个基因突变体的WUE高于野生型，而其他21个基因突变体的WUE较低。WUE 的差异是由生物量或耗水量（或两者）的改变引起的。气孔密度 (SD) 不是这些突变体中 WUE 改变的主要原因。叶面温度表明 16 个基因的突变体的蒸腾作用不同，但通常生物量积累对 WUE 的影响更大。我们发现的基因参与多种细胞过程，包括激素和钙信号、分生组织活动、光合作用、开花时间、叶/脉管系统发育和细胞壁组成；然而，他们之前都没有与 WUE 相关联。因此，