Abstract
Maize is an important cereal crop but is sensitive to heat stress, which significantly restricts its grain yield. To explore the molecular mechanism of maize heat tolerance, a heat-tolerant hybrid ZD309 and its parental lines (H39_1 and M189) were subjected to heat stress, followed by transcriptomic and metabolomic analyses. After six-day-heat treatment, the growth of ZD309 and its parental lines were suppressed, showing dwarf stature and rolled leaf compared with the control plants. ZD309 exhibited vigorous growth; however, M189 displayed superior heat tolerance. By transcriptomic and metabolomic analysis, hundreds to thousands of differentially expressed genes (DEGs) and metabolites (DEMs) were identified. Notably, the female parent H39 shares more DEGs and DEMs with the hybrid ZD309, indicating more genetic gain derived from the female instead of the male. A total of 299 heat shock genes detected among three genotypes were greatly aggregated in sugar transmembrane transporter activity, plasma membrane, photosynthesis, protein processing in the endoplasmic reticulum, cysteine, and methionine metabolism. A total of 150 heat-responsive metabolites detected among three genotypes were highly accumulated, including jasmonic acid, amino acids, sugar, flavonoids, coumarin, and organic acids. Integrating transcriptomic and metabolomic assays revealed that plant hormone signal transduction, cysteine, and methionine metabolism, and α-linolenic acid metabolism play crucial roles in heat tolerance in maize. Our research will be facilitated to identify essential heat tolerance genes in maize, thereby contributing to breeding heat resistance maize varieties.
Highlights
High temperature as a consequence of global warming has become a common concern worldwide that threatens to crop production [1–3]
Kernel development was repressed in other hybrids, with almost no apparent impact on the ZD309
Excessive reactive oxygen species (ROS) alters a series of physiological responses, including photosynthesis, respiration, transpiration, membrane thermostability, and osmotic regulation [3]
Summary
High temperature as a consequence of global warming has become a common concern worldwide that threatens to crop production [1–3]. Maize (Zea mays L.) is a well-known important crop for food, fuel, and feed [4] but is sensitive to heat stress, decreasing grain yield [2,5]. The network of heat stress response involves heat shock transcription factor (HSF), heat shock protein (HSP), reactive oxygen species (ROS), and phytohormones pathways [2,3,10,11]. HSPs, HSFs, and protein kinases play essential roles in the heat-response signaling, protecting cellular compartments from over-heating temperature [10]. The signal cascade initiates terminal, calmodulin, or protein kinase regulates HSFs, followed by HSFs-guided transcriptional regulation, and modulates downstream heat stress response genes [13]. Current results found that jasmonic acid is involved in the protective response against heat stress [14,15]. The molecular mechanism underlying heat stress response has been largely uncovered, and the gene regulatory network is still less addressed
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