MaCDSP32 From Mulberry Enhances Resilience Post-drought by Regulating Antioxidant Activity and the Osmotic Content in Transgenic Tobacco

Abstract

Desiccation tolerance is a complex phenomenon that depends on the regulated expression of numerous genes during dehydration and subsequent rehydration. Our previous study identified a chloroplast drought-induced stress protein (MaCDSP32) in mulberry, a thioredoxin (Trx) that is upregulated under drought conditions and is likely to confer drought tolerance to transgenic plants. Mulberry (Morus spp.) is an ecologically and economically important perennial woody plant that is widely used in forest management to combat desertification. However, its stress tolerance physiology is not well understood. In this study, the functions of MaCDSP32 gene were investigated. The expression of MaCDSP32 exhibited a circadian rhythm and was induced by mild and severe water deficits. Under abiotic stress, MaCDSP32-overexpressing plants exhibited increased stress sensitivity with lower water retention capacity and more severe lipid peroxidation than the wild-type (WT) plants. Furthermore, the activity of superoxide dismutase (SOD), the contents of proline and soluble sugars and the expression of stress-related transcription factors were lower in the MaCDSP32-overexpressing plants than in the WT plants. However, the MaCDSP32-overexpressing lines exhibited stronger recovery capability after rewatering post-drought. Moreover, the SOD enzyme activity, proline content, and soluble sugar content were higher in the transgenic plants after rewatering than in the WT plants. The production of the reactive oxygen species (ROS) H 2 O 2 and O 2 − was significantly lower in the transgenic plants than in the WT plants. In addition, under abiotic stress, the MaCDSP32-overexpressing lines exhibited improved seed germination and seedling growth, these effects were regulated by a positive redox reaction involving MaCDSP32 and one of its targets. In summary, this study indicated that MaCDSP32 from mulberry regulates plant drought tolerance and ROS homeostasis mainly by controlling SOD enzyme activity and proline and soluble sugar concentrations and that this control might trigger the stress response during seed germination and plant growth. Overall, MaCDSP32 exerts pleiotropic effects on the stress response and stress recovery in plants.

Genes and pathways associated with drought tolerance in Populus wutunensis under drought stress

“…They gradually acquire growth, morphological, physiological, and biochemical characteristics that are adapted to their local soil moisture conditions, including the "drying-wetting" cycle [9]. Plants can cope with changing external moisture conditions by changing external morphology, physiology, biochemistry, and gene expression [10,11,12]. Previous studies have shown that when water supply is restored after drought stress, plants can return to a growth state close to normal irrigation conditions through compensation mechanisms [13].Drought intensity differences can lead to different compensation effects.…”

“…The rehydration recovery of Populus trichocarpa is related to the activity of AQP [18]. In addition, overexpression of mulberry macdsp32 gene in tobacco could regulate antioxidant activity and carbohydrate substances, improving the drought resistance of transgenic tobacco, and enhance its recovery ability [12]. Therefore, understanding the recovery mechanisms of different plant species after rewatering is of great signi cance in elucidating their drought resistance mechanisms.…”

Molecular mechanism of mulberry response to drought stress revealed by complementary transcriptomic and iTRAQ analyses

“…For example, mulberry glutamate dehydrogenase ( GDH ) can improve the protein solubility and chlorophyll content in transgenic tobacco to increase the drought tolerance of transgenic plants [ 19 ]. A chloroplast drop-induced stress protein ( MaCDSP32 ) can increase the drought tolerance of plants by regulating the activity of SOD and the concentration of proline and soluble sugar [ 20 ]. Overexpression of receptor for activated C kinase 1 (Rack1) protein in Arabidopsis decreased the drought tolerance of transgenic plants, which may play a role as a negative regulator of drought stress [ 21 ].…”

Characterization of the gene expression profile response to drought stress in Haloxylon using PacBio single-molecule real-time and Illumina sequencing

“…Molecular mechanisms to drought stress have been extensively studied in broad-leaved species such as Populus nigra ( Yildirim and Kaya, 2017 ), Betula platyphylla ( Li H. Y. et al, 2020 ), and Morus spp. ( Sun et al, 2020 ), but only a few studies have focused on Haloxylon ammodendron ( Long et al, 2014 ; Fan et al, 2018 ) and Haloxylon persicum ( Thayale Purayil et al, 2020 ). Therefore, it is important to understand the drought tolerance of H. ammodendron and H. persicum .…”