Drought‐responsive genes, late embryogenesis abundant group3 (LEA3) and vicinal oxygen chelate, function in lipid accumulation in Brassica napus and Arabidopsis mainly via enhancing photosynthetic efficiency and reducing ROS

Abstract

Summary Drought is an abiotic stress that affects plant growth, and lipids are the main economic factor in the agricultural production of oil crops. However, the molecular mechanisms of drought response function in lipid metabolism remain little known. In this study, overexpression (OE) of different copies of the drought response genes LEA3 and VOC enhanced both drought tolerance and oil content in Brassica napus and Arabidopsis. Meanwhile, seed size, membrane stability and seed weight were also improved in OE lines. In contrast, oil content and drought tolerance were decreased in the AtLEA3 mutant (atlea3) and AtVOC‐RNAi of Arabidopsis and in both BnLEA‐RNAi and BnVOC‐RNAi B. napus RNAi lines. Hybrids between two lines with increased or reduced expression (LEA3‐OE with VOC‐OE, atlea3 with AtVOC‐RNAi) showed corresponding stronger trends in drought tolerance and lipid metabolism. Comparative transcriptomic analysis revealed the mechanisms of drought response gene function in lipid accumulation and drought tolerance. Gene networks involved in fatty acid (FA) synthesis and FA degradation were up‐ and down‐regulated in OE lines, respectively. Key genes in the photosynthetic system and reactive oxygen species (ROS) metabolism were up‐regulated in OE lines and down‐regulated in atlea3 and AtVOC‐RNAi lines, including LACS9, LIPASE1, PSAN, LOX2 and SOD1. Further analysis of photosynthetic and ROS enzymatic activities confirmed that the drought response genes LEA3 and VOC altered lipid accumulation mainly via enhancing photosynthetic efficiency and reducing ROS. The present study provides a novel way to improve lipid accumulation in plants, especially in oil production crops.

QTL Mapping for Seed Germination Response to Drought Stress in Brassica napus

“…However, the use of low marker density genetic linkage map was not able to reveal the comprehensive genetic diversity of drought tolerance in rapeseed ( Li et al, 2014 ). Despite the progress made in the plant’s response to drought stress, many genetic bases of drought tolerance in rapeseed has yet to be clarified ( Li et al, 2014 ; Zhang, 2015 ; Zhao et al, 2016 ; Liang et al, 2019 ). There has been significant progress in understanding the signaling process that controls plant resistance to drought from perception of signals to cellular mechanisms ( Seki et al, 2007 ), and it was revealed that the signal pathways including many common factors, such as abscisic acid, photosynthesis, and reducing ROS contents under drought, were involved in drought resistance ( Jackson et al, 2003 ; Li et al, 2006 ; Dudziak et al, 2019 ; Liang et al, 2019 ).…”

Overexpression of Ptrlea7, a Late Embryogenesis Abundant Family Gene From Poncirus Trifoliata, Confers Enhanced Drought Tolerance by Enhancing Antioxidant Capacity

“…Thus, searching for LEAinteractive proteins is important in future studies. Additionally, LEA proteins can segregate harmful metal ions and ROS to reduce their damaging effects under stress conditions [11,12,15,32] . As shown in this study, ROS accumulation in PtrLEA7 overexpressed plants was significantly reduced (Fig.…”

“…For example, overexpressing OsLEA3-1 in rice can confer enhanced drought tolerance without reducing yield [10] . The LEA3 gene from Brassica napus was identified to be a positive regulator of drought tolerance by reducing reactive oxygen species (ROS) accumulation and enhancing photosynthetic efficiency [11] . ZmLEA3 from maize can confer enhanced low temperature and osmotic stress tolerance by protecting lactate dehydrogenase activity and binding metal ions [12,13] .…”

“…It is expected that LEA proteins might function as protectants of biomolecules and membranes under abiotic stresses [6,14,15] . In addition, some LEA proteins were found to work in stress tolerance by regulating metal ions and ROS levels [11,16] . Furthermore, LEA proteins have a ubiquitous subcellular distribution across Arabidopsis cells which may provide protection extensively for every cellular compartment, revealing that different LEA proteins might work synergistically under abiotic stresses [15] .…”

“…Antioxidant enzymes are crucial ROS scavengers and include superoxide dismutase (SOD), peroxidase (POD) and catalase (CAT). Many studies have revealed that plants under abiotic stresses can enhance the activities of antioxidant enzymes by upregulating antioxidant enzyme-coding genes to improve tolerance to abiotic stresses [1,11] .…”