Abstract

Drought stress is an environmental factor that seriously threatens plant growth, development, and yield. VQ proteins are transcriptional regulators that have been reported to be involved in plant growth, development, and the responses to biotic and abiotic stressors. However, the relationship between VQ proteins and drought stress has not been well documented in plants. In this study, overexpressing the apple VQ motif-containing protein (MdVQ37) gene in apple plants markedly reduced the tolerance to drought. Physiological and biochemical studies further demonstrated lower enzymatic activities and decreased photosynthetic capacity in transgenic lines compared to wild-type (WT) plants under drought stress. Ultrastructural analysis of leaves showed that the leaves and palisade tissues from the transgenic lines were significantly thinner than those from WT plants. Salicylic acid (SA) analysis indicated that overexpression of MdVQ37 increased the accumulation of 2,5-DHBA by up-regulating the expression of the SA catabolic gene, which ultimately resulted to a significant reduction in endogenous SA content and the disruption of the SA-dependent signaling pathway under drought stress. Applying SA partially increased the survival rate of the transgenic lines under drought stress. These results demonstrate that the regulatory function of apple MdVQ37 is implicated in drought stress, through a change in leaf development and SA homeostasis. This study provides novel insight into understanding the multiple functions of VQ proteins.

中文翻译：

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MdVQ37的过表达通过改变转基因苹果的叶片解剖结构和SA稳态来降低耐旱性

摘要

干旱胁迫是严重威胁植物生长、发育和产量的环境因素。VQ 蛋白是转录调节因子，据报道参与植物生长、发育以及对生物和非生物胁迫的反应。然而，VQ 蛋白与干旱胁迫之间的关系尚未在植物中得到充分证明。在本研究中，过表达含有苹果 VQ 基序的蛋白 ( MdVQ37) 基因在苹果植物中显着降低了对干旱的耐受性。生理和生化研究进一步表明，与野生型 (WT) 植物相比，转基因品系在干旱胁迫下的酶活性较低，光合能力降低。叶片的超微结构分析表明，转基因株系的叶片和栅栏组织比野生型植物的叶片和栅栏组织明显更薄。水杨酸 (SA) 分析表明MdVQ37的过表达通过上调 SA 分解代谢基因的表达增加 2,5-DHBA 的积累，最终导致干旱胁迫下内源性 SA 含量显着降低和 SA 依赖性信号通路的破坏。施用 SA 部分提高了转基因品系在干旱胁迫下的存活率。这些结果表明，苹果 MdVQ37 的调节功能通过叶片发育和 SA 稳态的变化与干旱胁迫有关。这项研究为理解 VQ 蛋白的多种功能提供了新的见解。