APPLE SUMO E3 LIGASE MDSIZ1 NEGATIVELY REGULATES DROUGHT TOLERANCE

doi:10.15302/j-fase-2021388

Abstract

<List><ListItem><ItemContent> •MdSIZ1 RNAi transgenic apple trees are drought tolerance than wild type—GL-3. </ItemContent></ListItem><ListItem><ItemContent> •MdSIZ1 RNAi plants get enhanced ability to keep water and scavenge ROS under drought conditions. </ItemContent></ListItem><ListItem><ItemContent> •MdSIZ1 may participate in apple drought tolerance by affecting ABA biosynthesis. </ItemContent></ListItem></List> Drought stress typically causes heavy losses in apple production and uncovering the mechanisms by which apple tolerates drought stress is important in apple breeding. MdSIZ1 is a SUMO (small ubiquitin-like modifier) E3 ligase that promotes SUMO binding to substrate proteins. Here, we demonstrate that MdSIZ1 in apple has a negative relationship with drought tolerance. MdSIZ1 RNAi transgenic apple trees had a higher survival rate after drought stress. During drought stress they had higher leaf water potential, reduced ion leakage, lower H2O2 and malondialdehyde contents, and higher catalase activity. In addition, MdSIZ1 RNAi transgenic plants had a higher net photosynthetic rate during the latter period of drought stress. Finally, the transgenic apple trees also altered expression levels of some microRNAs in response to drought stress. Taken together, these results indicate that apple MdSIZ1 negatively regulates drought stress by enhancing leaf water-holding capacity and antioxidant enzyme activity.

Highlights

Water has a range of functions in plant physiological and metabolic processes including seed germination, seedling growth, flower bud differentiation, root growth, leaf transpiration, plant respiration, stomatal opening and antioxidant enzyme activity[1]
We designated MD11G1131700 and MD03G1112700 MdSIZ1, and MD01G1111200 and MD07G1177400 MdSIZ1-like. Both MdSIZ1 and MdSIZ1-like contained conserved domains similar to those of AtSIZ1, including an SAP domain, a PHD domain and an Sp-RING finger domain (Fig. 1)
Drought stress upregulated MdSIZ1 expression 2.2-fold (Fig. 2(b)). These results suggest that MdSIZ1 was involved in the apple drought stress response

Summary

Introduction

Water has a range of functions in plant physiological and metabolic processes including seed germination, seedling growth, flower bud differentiation, root growth, leaf transpiration, plant respiration, stomatal opening and antioxidant enzyme activity[1]. Water deficiency is an important global agricultural challenge inhibiting the yield and quality of crops and fruit trees[2]. Elucidating the mechanisms by which plants respond to drought stress is a useful approach in breeding stress-resistant crops, thereby contributing to worldwide food security[3,4]. It is important to understand the function of key drought-responsive genes and investigate the physiological mechanisms by which apple trees respond to drought[5,6]. Plants may respond to drought stress by controlling stomatal movement[7], hormone biosynthesis[8], the ability to scavenge reactive oxygen species[9], accumulation of metabolic products[10], root development[3], transcriptional regulation[10] and microRNA biogenesis[11]

Methods

Results

Discussion

Conclusion