DnaJ proteins, also known as HSP40s, play a key role in plant growth and development, and response to environmental stress. However, little comprehensive research has been conducted on the DnaJ gene family in maize. Here, we identify 91 ZmDnaJ genes from maize, which are likely distributed in the chloroplast, nucleus, and cytoplasm. Our analysis revealed that ZmDnaJs were classified into three types, with conserved protein motifs and gene structures within the same type, particularly among members of the same subfamily. Gene duplication events have likely contributed to the expansion of the ZmDnaJ family in maize. Analysis of cis-regulatory elements in ZmDnaJ promoters suggested involvement in stress responses, growth and development, and phytohormone sensitivity in maize. Specifically, four cis-acting regulatory elements associated with stress responses and phytohormone regulation indicated a role in adaptation. RNA-seq analysis showed constitutive expression of most ZmDnaJ genes, some specifically in pollen and endosperm. More importantly, certain genes also responded to salt, heat, and cold stresses, indicating potential interaction between stress regulatory networks. Furthermore, early responses to heat stress varied among five inbred lines, with upregulation of almost tested ZmDnaJ genes in B73 and B104 after 6 h, and fewer genes upregulated in QB1314, MD108, and Zheng58. After 72 h, most ZmDnaJ genes in the heat-sensitive inbred lines (B73 and B104) returned to normal levels, while many genes, including ZmDnaJ55, 79, 88, 90, and 91, remained upregulated in the heat-tolerant inbred lines (QB1314, MD108, and Zheng58) suggesting a synergistic function for prolonged protection against heat stress. In conclusion, our study provides a comprehensive analysis of the ZmDnaJ family in maize and demonstrates a correlation between heat stress tolerance and the regulation of gene expression within this family. These offer a theoretical basis for future functional validation of these genes.

Plant promoters play a vital role in the initiation and regulation of gene transcription. In this study, a rice protein/gene of unknown expression, named Os8GSX7, was gained from a rice T-DNA capture line. The semi-quantitative RT-PCR analysis showed that the gene was only expressed in root, glume, and flower, but not in stem, leaf, embryo, and endosperm of japonica rice. The GUS activity analysis of the GSX7R promoter showed that it was a reverse green tissue expression promoter, except in endosperm. The forward promoter of GSX7 cannot normally drive the expression of the foreign GUS gene, while the reverse promoter of GSX7 is a green tissue-specific expression promoter, which can drive the expression of the foreign GUS gene. The region from −2097 to −1543 bp was the key region for controlling the green tissue-specific expression. The regulatory sequences with different lengths from the 2097 bp reverse sequence from the upstream region of the Os8GSX7 were fused with the GUS reporter gene and stably expressed in rice. Furthermore, transgenic rice plants carrying Cry1Ab encoding Bacillus thuringiensis endotoxin, regulated by GSX7R, were resistant to yellow stem borer. The analysis suggested that 10 light responsive elements of tissue-specific expression were found, including ACE, Box4, CAT-box, G-Box, G-box, GATA motif, GC motif, I-box, Sp1, and chs-unit1 M1. In addition, the results of 5′ and 3′ deletions further speculated that ACE and I-box may be the key elements for determining the green tissue-specific expression of GSX7R promoter.

Bacterial blight is a destructive disease in rice caused by Xanthomonas oryzae pv. oryzae (Xoo). Single resistance genes often have limitations in providing broad-spectrum resistance, as pathogens continuously evolve and vary. Breeding rice varieties with multiple disease resistance genes has proven to be an effective strategy for controlling bacterial blight. In this study, a single Cas9/gRNA construct was used to target the homologous sequences of Xa13 and Xa25 genes through destroying the target gene function, creating bacterial blight resistance in five rice varieties. These materials provide promising germplasm resources for the development of rice varieties with durable resistance to bacterial blight.

Fusarium graminearum is a devastating plant pathogenic fungus that is the predominant causal agent of Fusarium head blight. Our previous study showed that the polarisome core component FgPea2 regulates polarized growth, deoxynivalenol (DON) production and virulence of F. graminearum . To further investigate the regulatory network of FgPea2, FgPea2-GFP pull down was performed and the anillin-related protein FgBoi2 was identified. FgBoi2 interacts with FgPea2 and exhibits partial co-localization at the hyphal tips of F. graminearum . Interestingly, FgPea2 regulates the polarized localization of FgBoi2-GFP, suggesting that FgPea2 functions upstream of FgBoi2. Furthermore, deletion of FgBOI2 resulted in a significant reduction in vegetative growth, conidiation, DON production and pathogenicity, as well as increased hyphal branching in F. graminearum . Structural analysis revealed that FgBoi2 contains SH3, SAM and PH domains. Further domain deletion experiments showed that the PH domain is crucial for vegetative growth, hyphae branching and polarized localization of FgBoi2. In addition, FgBoi2 negatively regulates the cell wall integrity and oxidative stress response pathways. FgPea2 and FgBoi2 modulate susceptibility to the fungicides tebuconazole, carbendazim, phenamacril and difenoconazole. In conclusion, this study shows that FgPea2 interacts with FgBoi2 and regulates FgBoi2-mediated polarized growth, stress tolerance, pathogenicity and fungicide resistance in F. graminearum .