Heat stress induces severe meiotic defects in plants, leading to significant male sterility and substantial yield losses in crops. However, few genes involved in meiotic thermotolerance have been characterized. In this study, we demonstrate that HSP101, a conserved heat shock protein, plays a critical role in protecting pollen mother cells from heat-induced meiotic defects in both rice and Arabidopsis. HSP101 is highly expressed during early pollen development, and its loss of function leads to meiotic instability under heat stress. Transcriptomic analysis revealed that HSP101 deficiency disrupts the transcriptional network essential for cellular homeostasis during heat stress. Importantly, overexpression of HSP101 enhanced thermotolerance during microsporogenesis without obvious adverse effects on plant growth. Our findings establish HSP101 as a positive regulator of meiotic thermotolerance during microsporogenesis using rice and Arabidopsis as model systems, providing critical insights for improving adaptation of male meiocytes to high temperatures in crops.

Grain protein content (GPC) is an indicator of cereal nutritional quality. Identification of genes involved in the regulation of GPC provides targets for molecular breeding for crop protein quality. We characterized a maize gene encoding the putative amino acid transporter ZmAAP6, a gene expressed mainly in immature seeds, especially in the basal endosperm transfer layer. Total protein and zein contents were decreased in ZmAAP6 null mutants and increased in ZmAAP6 overexpression (OE) lines, consistent with their changed in the size of protein bodies. Metabolic and transcriptomic analysis supported the regulatory role of ZmAAP6 in amino acid transportation. These results suggest that ZmAAP6 functions as a positive regulator of GPC in maize, shedding new light on the genetic basis of GPC regulation.

In the subtribe Maydeae, Tripsacum and Zea are closely related genera. Tripsacum is a horticultural crop widely used as pasture forage. Previous studies suggested that Tripsacum might play an important role in maize origin and evolution. However, our understanding of the genomics and the evolution of Tripsacum remains limited. In this study, two diploids, T. dactyloides var. meridionale (2n=36, MR) and T. dactyloides (2n=36, DD), and one tetraploid, T. dactyloides (2n=72, DL) were sequenced by low-coverage genome sequencing followed by graph-based cluster analysis. The results showed that 63.23%, 59.20%, and 61.57% of the respective genome of MR, DD, and DL were repetitive DNA sequence. The proportions of different repetitive sequences varied greatly among the three species. Fluorescence in situ hybridization (FISH) analysis of mitotic metaphase chromosomes with satellite repeats as the probes showed that the FISH signal patterns of DL were more similar to that of DD than to that of MR. Comparative analysis of the repeats also showed that DL shared more common repeat families with DD than with MR. Phylogenetic analysis of internal transcribed spacer region sequences further supported the evolutionary relationship among the three species. Repetitive sequences comparison showed that Tripsacum shared more repeat families with Zea than with Coix and Sorghum. Our study sheds new light on the genomics of Tripsacum and differential speciation in the Poaceae family.