The Teosinte-branched 1/Cycloidea/Proliferating (TCP) plant-specific transcription factors (TFs) have been demonstrated to play a fundamental role in plant development and organ patterning. However, it remains unknown whether or not the TCP gene family plays a role in conferring a tolerance to drought stress in maize, which is a major constraint to maize production. In this study, we identified 46 ZmTCP genes in the maize genome and systematically analyzed their phylogenetic relationships and synteny with rice, sorghum, and Arabidopsis TCP genes. Expression analysis of the 46 ZmTCP genes in different tissues and under drought conditions, suggests their involvement in maize response to drought stress. Importantly, genetic variations in ZmTCP32 and ZmTCP42 are significantly associated with drought tolerance at the seedling stage. RT-qPCR results suggest that ZmTCP32 and ZmTCP42 RNA levels are both induced by ABA, drought, and polyethylene glycol treatments. Based on the significant association between the genetic variation of ZmTCP42 and drought tolerance, and the inducible expression of ZmTCP42 by drought stress, we selected ZmTCP42, to investigate its function in drought response. We found that overexpression of ZmTCP42 in Arabidopsis led to a hypersensitivity to ABA in seed germination and enhanced drought tolerance, validating its function in drought tolerance. These results suggested that ZmTCP42 functions as an important TCP TF in maize, which plays a positive role in drought tolerance.

Rice is one of the major staple cereals in the world, but heat stress is increasingly threatening its yield. Analyzing the thermotolerance mechanism from new thermotolerant germplasms is very important for rice improvement. Here, physiological and transcriptome analyses were used to characterize the difference between two germplasms, heat-sensitive MH101 and heat-tolerant SDWG005. Two genotypes exhibited diverse heat responses in pollen viability, pollination characteristics, and antioxidant enzymatic activity in leaves and spikelets. Through cluster analysis, the global transcriptomic changes indicated that the ability of SDWG005 to maintain a steady-state balance of metabolic processes played an important role in thermotolerance. After analyses of gene ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway enrichment, we found that the thermotolerance mechanism in SDWG00 was associated with reprogramming the cellular activities, such as response to abiotic stress and metabolic reorganization. In contrast, the down-regulated genes in MH101 that appeared to be involved in DNA replication and DNA repair proofreading, could cause serious injury to reproductive development when exposed to high temperature during meiosis. Furthermore, we identified 77 and 11 differentially expressed genes (DEGs) involved in lignin and flavonoids biosynthetic pathways, respectively. Moreover, we found that more lignin deposition and flavonoids accumulation happened in SDWG005 than in MH101 under heat stress. The results indicated that lignin and flavonoid biosynthetic pathways might play important roles in rice heat resistance during meiosis.

Global maize cultivation is often adversely affected by drought stress. The CC-type glutaredoxin (GRX) genes form a plant-specific subfamily that regulate plant growth and respond to environmental stresses. However, how maize CC-type GRX (ZmGRXCC) genes respond to drought stress remains unclear. We performed a TBLASTN search to identify ZmGRXCCs in the maize genome and verified the identified sequences using the NCBI conservative domain database (CDD). We further established a phylogenetic tree using Mega7 and surveyed known cis-elements in the promoters of ZmGRXCCs using the PlantCARE database. We found twenty-one ZmGRXCCs in the maize genome by a genome-wide investigation and compared their phylogenetic relationships with rice, maize, and Arabidopsis. The analysis of their redox active sites showed that most of the 21 ZmGRXCCs share similar structures with their homologs. We assessed their expression at young seedlings and adult leaves under drought stress and their expression profiles in 15 tissues, and found that they were differentially expressed, indicating that different ZmGRXCC genes have different functions. Notably, ZmGRXCC14 is up-regulated at seedling, V12, V14, V16, and R1 stages. Importantly, significant associations between genetic variation in ZmGRXCC14 and drought tolerance are found at the seedling stage. These results will help to advance the study of the function of ZmGRXCCs genes under drought stress and understand the mechanism of drought resistance in maize.

Heat stress (HT) exerts significant negative impacts on plant growth, development, and productivity. In this study, we identified OsLAC12, a heat-induced laccase-encoding gene, as a key regulator of heat tolerance in rice. Functional validation confirmed that OsLAC12 encodes an active laccase, with supporting evidence showing that roots of OsLAC12 overexpression lines exhibited ~1.5-fold higher laccase activity and nearly three times the lignin content compared to the wild type (WT). Under HT, oslac12 mutants showed significantly lower seedling survival rates (~13–22%) than WT (~43%), whereas OE lines displayed higher survival rates (~68–74%). At the heading stage, OsLAC12 overexpression lines activated the antioxidant enzyme system in spikelets, regulated reactive oxygen species (ROS) levels in anthers, and mitigated HT-induced damage to pollen viability. In contrast, oslac12 mutants showed an average 10.8% reduction in pollen viability compared to WT, accompanied by significantly lower seed-setting rates. Collectively, our findings demonstrate that the laccase OsLAC12 positively regulates rice resistance to HT stress, providing critical insights for improving plant thermotolerance through genetic improvement of cell wall-associated pathways.

RING-type E3 ligases are critical regulators of diverse plant processes, yet their roles in maize remain poorly defined, particularly in drought responses. To address this knowledge gap, we conducted an integrative analysis of maize RING genes, combining evolutionary profiling, and candidate-gene association studies to identify drought-associated candidates. Key genes were further characterized via quantitative expression profiling, subcellular localization, in vitro ubiquitination assay, and functional validation in transgenic Arabidopsis. This study aimed to provide new insights into the maize RING gene family’s role in drought stress adaptation. We employed three distinct methods and identified a total of 590 proteins. Phylogenetic analysis revealed that these proteins could be grouped into 11 separate clusters. Our findings suggested that the expansion of the RING family in maize was likely due to gene duplication events. Notably, genetic variations in ZmRING-93 were significantly associated with drought tolerance, and its expression was up-regulated under various abiotic stress conditions and hormone treatments. We further discovered that ZmRING-93 was a functional ubiquitin E3 ligase that localized to the nucleus, cytoplasm, and parts of the endoplasmic reticulum. Transgenic Arabidopsis plants overexpressing ZmRING-93 exhibited enhanced drought tolerance, with a lower water loss rate, further supporting the importance of ZmRING-93 in drought tolerance. These findings revealed that ZmRING-93 contributed to drought tolerance in maize and provided a basis for further investigation of the role of RING domain-containing proteins.