State Key Laboratory of Crop Stress Biology for Arid Areas / Shaanxi Key Laboratory of Apple, College of Horticulture, Northwest A & F University, Yangling, Shaanxi, 712100, China.
Department of Horticulture, Michigan State University, East Lansing, Michigan, 48824, USA.
Plant Physiol Biochem. 2019 Jun;139:504-512. doi: 10.1016/j.plaphy.2019.04.011. Epub 2019 Apr 12.
Plant NAC proteins constitute one of the largest transcription factor families. They play pivotal functions during responses to various abiotic stresses. However, knowledge on roles of NAC proteins in abiotic stress tolerance as well as corresponding mechanisms has not been fully studied in perennial woody plants, including domesticated apple (Malus domestica). In the present study, we characterized the role of apple MdNAC1 transcription factor in response to drought stress. Apple plants overexpressing MdNAC1 gene exhibited promoted tolerance to drought stress, as evident by reduced water loss and electrolyte leakage in leaves, and maintenance of photosynthesis and photosynthetic pigments content under drought conditions. In addition, the levels of malondialdehyde (MDA) and reactive oxygen species (ROS) were significantly lower for transgenic apple lines than those for nontransgenic plants under drought conditions. This was accompanied by higher activities of several antioxidant enzymes, such as superoxide dismutase (SOD), peroxidase (POD), and catalase (CAT), as well as increased expression of the associated genes in transgenic lines. Together, our results indicate that overexpression of the apple MdNAC1 gene enhances drought stress tolerance in apple plants by promoting higher photosynthesis and activities of ROS-scavenging enzymes.
植物 NAC 蛋白构成了最大的转录因子家族之一。它们在应对各种非生物胁迫的过程中发挥着关键作用。然而，在包括栽培苹果（Malus domestica）在内的多年生木本植物中，NAC 蛋白在非生物胁迫耐受性中的作用及其相应机制的知识尚未得到充分研究。在本研究中，我们研究了苹果 MdNAC1 转录因子在应对干旱胁迫中的作用。过量表达 MdNAC1 基因的苹果植株对干旱胁迫表现出更高的耐受性，表现在叶片水分损失和电解质渗漏减少，以及在干旱条件下光合作用和光合色素含量得到维持。此外，在干旱条件下，转基因苹果品系的丙二醛（MDA）和活性氧（ROS）水平明显低于非转基因植株。这伴随着几种抗氧化酶，如超氧化物歧化酶（SOD）、过氧化物酶（POD）和过氧化氢酶（CAT）的活性升高，以及转基因品系中相关基因的表达增加。总之，我们的研究结果表明，过量表达苹果 MdNAC1 基因通过促进更高的光合作用和 ROS 清除酶的活性来增强苹果植株的耐旱性。
