Department of Biochemistry and Molecular Biology, University of Nevada, Reno, NV, 89557, USA.
Present address: College of Agriculture and Environmental Sciences, Bahir Dar University, Bahir Dar, Ethiopia.
BMC Plant Biol. 2020 Feb 4;20(1):55. doi: 10.1186/s12870-019-2012-7.
Grapevine is an economically important crop for which yield and berry quality is strongly affected by climate change. Large variations in drought tolerance exist across Vitis species. Some of these species are used as rootstock to enhance abiotic and biotic stress tolerance. In this study, we investigated the physiological and transcriptomic responses to water deficit of four different genotypes that differ in drought tolerance: Ramsey (Vitis champinii), Riparia Gloire (Vitis riparia), Cabernet Sauvignon (Vitis vinifera), and SC2 (Vitis vinifera x Vitis girdiana).
Ramsey was particularly more drought tolerant than the other three genotypes. Ramsey maintained a higher stomatal conductance and photosynthesis at equivalent levels of moderate water deficit. We identified specific and common transcriptomic responses shared among the four different Vitis species using RNA sequencing analysis. A weighted gene co-expression analysis identified a water deficit core gene set with the ABA biosynthesis and signaling genes, NCED3, RD29B and ABI1 as potential hub genes. The transcript abundance of many abscisic acid metabolism and signaling genes was strongly increased by water deficit along with genes associated with lipid metabolism, galactinol synthases and MIP family proteins. This response occurred at smaller water deficits in Ramsey and with higher transcript abundance than the other genotypes. A number of aquaporin genes displayed differential and unique responses to water deficit in Ramsey leaves. Genes involved in cysteine biosynthesis and metabolism were constitutively higher in the roots of Ramsey; thus, linking the gene expression of a known factor that influences ABA biosynthesis to this genotype's increased NCED3 transcript abundance.
The drought tolerant Ramsey maintained higher photosynthesis at equivalent water deficit than the three other grapevine genotypes. Ramsey was more responsive to water deficit; its transcriptome responded at smaller water deficits, whereas the other genotypes did not respond until more severe water deficits were reached. There was a common core gene network responding to water deficit for all genotypes that included ABA metabolism and signaling. The gene clusters and sub-networks identified in this work represent interesting gene lists to explore and to better understand drought tolerance molecular mechanisms.
葡萄是一种经济上重要的作物，其产量和浆果品质受气候变化的影响很大。不同的葡萄品种对干旱的耐受能力有很大的差异。其中一些品种被用作砧木，以增强对非生物和生物胁迫的耐受能力。在这项研究中，我们调查了四个不同基因型（Ramsey、Riparia Gloire、Cabernet Sauvignon 和 SC2）对水分亏缺的生理和转录组响应，这些基因型在耐旱性上存在差异。
Ramsey 比其他三个基因型更耐旱。在适度水分亏缺下，Ramsey 维持较高的气孔导度和光合作用。我们使用 RNA 测序分析鉴定了四个不同的葡萄物种之间共享的特定和共同的转录组响应。加权基因共表达分析确定了一个水分亏缺核心基因集，其中包括 ABA 生物合成和信号基因 NCED3、RD29B 和 ABI1，它们是潜在的枢纽基因。许多脱落酸代谢和信号基因的转录丰度随着水分亏缺的增加而强烈增加，同时还与脂质代谢、半乳糖苷合成酶和 MIP 家族蛋白相关的基因有关。这种响应发生在 Ramsey 的水分亏缺较小的情况下，并且转录丰度高于其他基因型。一些水通道蛋白基因在 Ramsey 叶片中对水分亏缺表现出不同的和独特的响应。半胱氨酸生物合成和代谢相关基因在 Ramsey 根中持续较高；因此，将影响 ABA 生物合成的已知因素的基因表达与该基因型 NCED3 转录丰度的增加联系起来。
耐旱的 Ramsey 在相当于其他三个葡萄基因型的水分亏缺下维持较高的光合作用。Ramsey 对水分亏缺的响应更为敏感；其转录组在较小的水分亏缺下响应，而其他基因型则在达到更严重的水分亏缺时才响应。所有基因型对水分亏缺都有一个共同的核心基因网络响应，其中包括 ABA 代谢和信号。本工作中鉴定的基因簇和子网络代表了探索和更好地理解耐旱性分子机制的有趣基因列表。
