Identification of Heat Responsive Genes in Brassica napus Siliques at the Seed-Filling Stage through Transcriptional Profiling

Abstract

High temperature stress results in yield loss and alterations to seed composition during seed filling in oilseed rape (Brassica napus). However, the mechanism underlying this heat response is poorly understood. In this study, global transcription profiles of 20 d-old siliques of B. napus were analyzed after heat stress using a Brassica 95k EST microarray. The up-regulated genes included many HSF/HSP transcripts and other heat-related marker genes, such as ROF2, DREB2a, MBF1c and Hsa32, reflecting the conservation of key heat resistance factors among plants. Other up-regulated genes were preferentially expressed in heat-stressed silique walls or seeds, including some transcription factors and potential developmental regulators. In contrast, down-regulated genes differed between the silique wall and seeds and were largely tied to the biological functions of each tissue, such as glucosinolate metabolism in the silique wall and flavonoid synthesis in seeds. Additionally, a large proportion (one-third) of these differentially expressed genes had unknown functions. Based on these gene expression profiles, Arabidopsis mutants for eight heat-induced Brassica homologous genes were treated with different heat stress methods, and thermotolerance varied with each mutation, heat stress regimen and plant development stage. At least two of the eight mutants exhibited sensitivity to the heat treatments, suggesting the importance of the respective genes in responding to heat stress. In summary, this study elucidated the molecular bases of the heat responses in siliques during later reproductive stages and provides valuable information and gene resources for the genetic improvement of heat tolerance in oilseed rape breeding.

PECTIN METHYLESTERASE34 Contributes to Heat Tolerance through Its Role in Promoting Stomatal Movement

“…The cell wall modification enzyme has been reported to be involved in the regulation of the heat response in Brassica napus. The expression of B. napus PME35 (EV193389) also was down-regulated nearly 10-fold under HS (Yu et al, 2014). We found a 21% decrease in total PME activity of pme34 compared with Col under normal conditions (Fig.…”

The plastid metalloprotease FtsH6 and small heat shock protein HSP21 jointly regulate thermomemory in Arabidopsis

“…In contrast to other FtsH genes, FtsH6 is rapidly and highly induced by heat stress in Arabidopsis (Fig. 5c) and other species including dicot and monocot crops37383940, indicating evolutionary conservation and ecological relevance of FtsH6 heat inducibility. In accordance with this, our data presented here demonstrate a role of FtsH6 in regulating the stability of HSP21 after a priming heat stress, although the molecular mechanism through which this occurs is not clear at present.…”

Heat stress during seed development affects forage brassica (Brassica napus L.) seed quality

“…Heat stress has previously been reported to affect seed mass in brassica species (Gan et al., ; Yu et al., ). Gan et al.…”