ZmNF-YA1 Contributes to Maize Thermotolerance by Regulating Heat Shock Response

Area of Science:

• Plant Biology
• Stress Physiology
• Molecular Genetics

Background:

• Maize (Zea mays) is a crucial crop facing significant yield losses due to heat stress, often compounded by drought.
• Previous research identified the ZmNF-YA1-YB16-YC17 heterotrimer complex, with ZmNF-YA1 and ZmNF-YB16 acting as positive regulators in drought response and root development.

Purpose of the Study:

• To investigate the role of ZmNF-YA1 in conferring heat stress tolerance in maize.

Main Methods:

• Utilized nf-ya1 mutant and overexpression lines of maize to assess thermotolerance.
• Measured physiological indicators including malondialdehyde (MDA), reactive oxygen species (ROS), and chlorophyll content under heat stress.
• Employed RNA-sequencing (RNA-seq) to analyze transcriptome changes in the mutant and wild-type (WT) under heat stress.
• Performed k-means clustering and Gene Ontology (GO) enrichment analysis on differentially expressed genes (DEGs).

Main Results:

• The nf-ya1 mutant exhibited increased temperature sensitivity, while ZmNF-YA1 overexpression lines displayed enhanced thermotolerance compared to WT.
• Heat-stressed mutant lines showed higher MDA and ROS accumulation and lower chlorophyll content than WT and overexpression lines.
• GO enrichment analysis revealed that ZmNF-YA1 loss-of-function impaired the induction of DEGs related to protein refolding, stabilization, and various stress responses.

Conclusions:

• ZmNF-YA1 plays a critical role in maize thermotolerance.
• Overexpression of ZmNF-YA1 enhances heat tolerance, likely through its contribution to protein stabilization, refolding, and the regulation of abscisic acid (ABA), ROS, and heat signaling pathways.
• The nf-ya1 mutant's heat-sensitive phenotype is attributed to the failure in inducing key stress-responsive genes.