AUTHOR=Ding Xianlong , Guo Qingling , Li Qiang , Gai Junyi , Yang Shouping 

TITLE=Comparative Transcriptomics Analysis and Functional Study Reveal Important Role of High-Temperature Stress Response Gene GmHSFA2 During Flower Bud Development of CMS-Based F1 in Soybean

JOURNAL=Frontiers in Plant Science

VOLUME=11

YEAR=2020

URL=https://www.frontiersin.org/journals/plant-science/articles/10.3389/fpls.2020.600217

DOI=10.3389/fpls.2020.600217

ISSN=1664-462X

ABSTRACT=<p>High-temperature (HT) is one of the most important environmental factors that negatively impact the yield of some soybean cytoplasmic male sterility (CMS)-based hybrid (F<sub>1</sub>) combinations. The response of soybean to HT, especially at the male organ development stage, is poorly understood. To investigate the molecular mechanisms of the response from soybean CMS-based F<sub>1</sub> male organ to HT, a detailed transcriptomics analysis was performed during flower bud development of soybean HT-tolerant and HT-sensitive CMS-based F<sub>1</sub> combinations (NF<sub>1</sub> and YF<sub>1</sub>) under normal-temperature and HT conditions. Obvious HT damage was observed by subjecting YF<sub>1</sub> with HT, such as indehiscent anthers and decreased pollen fertility, whereas the male fertility of NF<sub>1</sub> was normal. In total, 8,784 differentially expressed genes (DEGs) were found to respond to HT stress, which were mainly associated with anther/pollen wall development, carbohydrate metabolism and sugar transport, and auxin signaling. The quantitative real-time PCR (qRT-PCR) analysis and substance content detection also revealed that HT caused male fertility defects in YF<sub>1</sub> by altering pectin metabolism, auxin, and sugar signaling pathways. Most importantly, the sugar signaling-<italic>PIF</italic>-auxin signaling pathway may underlie the instability of male fertility in YF<sub>1</sub> under HT. Furthermore, HT induced the expression of heat shock factor (<italic>HSF</italic>) and heat shock protein (<italic>HSP</italic>) gene families. Overexpression of <italic>GmHSFA2</italic> in <italic>Arabidopsis</italic> can promote the expression of HT protective genes (such as <italic>HSP20</italic>) by binding to the HSE motifs in their promoters, so as to improve the HT tolerance during flowering. Our results indicated that <italic>GmHSFA2</italic> acted as a positive regulator, conferring HT tolerance improvement in soybean CMS-based F<sub>1</sub>. <italic>GmHSFA2</italic> may be directly involved in the activation of male fertility protection mechanism in the soybean CMS-based F<sub>1</sub> under HT stress.</p>