National Key Laboratory of Crop Genetics and Germplasm Enhancement, College of Life Sciences, Nanjing Agricultural University, Nanjing 210095, China.
Int J Mol Sci. 2019 Jan 1;20(1):133. doi: 10.3390/ijms20010133.
In plants, abscisic acid-, stress-, and ripening-induced (ASR) proteins have been shown to impart tolerance to multiple abiotic stresses such as drought and salinity. However, their roles in metal stress tolerance are poorly understood. To screen plant Cd-tolerance genes, the yeast-based gene hunting method which aimed to screen Cd-tolerance colonies from maize leaf cDNA library hosted in yeast was carried out. Here, maize was identified to be putative Cd-tolerant through this survival screening strategy. In silico analysis of the functional domain organization, phylogenetic classification and tissue-specific expression patterns revealed that maize to are typical with considerable expression in leaves. Further, four of them were cloned for testifying Cd tolerance using yeast complementation assay. The results indicated that they all confer Cd tolerance in Cd-sensitive yeast. Then they were transiently expressed in tobacco leaves for subcellular localization analysis and for Cd-challenged lesion assay, continuously. The results demonstrated that all 4 maize ASRs tested are localized to the cell nucleus and cytoplasm in tobacco leaves. Moreover, they were confirmed to be Cd-tolerance genes through lesion analysis in Cd-infiltrated leaves transiently expressing them. Taken together, our results demonstrate that maize play important roles in Cd tolerance, and they could be used as promising candidate genes for further functional studies toward improving the Cd tolerance in plants.
在植物中，已证实脱落酸、胁迫和成熟诱导（ASR）蛋白赋予植物对多种非生物胁迫的耐受性，如干旱和盐胁迫。然而，它们在金属胁迫耐受性中的作用还知之甚少。为了筛选植物 Cd 耐受性基因，我们采用了基于酵母的基因猎捕方法，旨在从玉米叶片 cDNA 文库中筛选出对 Cd 有耐受性的酵母克隆。通过这种生存筛选策略，我们鉴定出玉米是一种潜在的 Cd 耐受型。通过对功能域组织、系统发生分类和组织特异性表达模式的计算机分析，发现玉米到是典型的 ASR，在叶片中有相当高的表达。此外，我们克隆了其中的 4 个，通过酵母互补测定来验证它们对 Cd 的耐受性。结果表明，它们在 Cd 敏感酵母中均能赋予 Cd 耐受性。然后，我们将它们瞬时表达在烟草叶片中，进行亚细胞定位分析和 Cd 胁迫损伤分析。结果表明，在烟草叶片中，所有 4 个被测试的玉米 ASR 均定位于细胞核和细胞质。此外，通过瞬时表达它们并在 Cd 浸润叶片中进行损伤分析，证实它们是 Cd 耐受性基因。总之，我们的结果表明，玉米在 Cd 耐受性中发挥重要作用，它们可以作为进一步研究提高植物 Cd 耐受性的有前途的候选基因。
