DNAJ protein gene expansion mechanism in Panicoideae and PgDNAJ functional identification in pearl millet

Analyze the evolutionary pattern of DNAJ protein genes in the Panicoideae, including pearl millet, to identify and characterize the biological function of PgDNAJ genes in pearl millet. Global warming has become a major factor threatening food security and human development. It is urgent to analyze the heat-tolerant mechanism of plants and cultivate crops that are adapted to high temperature conditions. The Panicoideae are the second largest subfamily of the Poaceae, widely distributed in warm temperate and tropical regions. Many of these species have been reported to have strong adaptability to high temperature stress, such as pearl millet, foxtail millet and sorghum. The evolutionary differences in DNAJ protein genes among 12 Panicoideae species and 10 other species were identified and analyzed. Among them, 79% of Panicoideae DNAJ protein genes were associated with retrotransposon insertion. Analysis of the DNAJ protein pan-gene family in six pearl millet accessions revealed that the non-core genes contained significantly more TEs than the core genes. By identifying and analyzing the distribution and types of TEs near the DNAJ protein genes, it was found that the insertion of Copia and Gypsy retrotransposons provided the source of expansion for the DNAJ protein genes in the Panicoideae. Based on the analysis of the evolutionary pattern of DNAJ protein genes in Panicoideae, the PgDNAJ was obtained from pearl millet through identification. PgDNAJ reduces the accumulation of reactive oxygen species caused by high temperature by activating ascorbate peroxidase (APX), thereby improving the heat resistance of plants. In summary, these data provide new ideas for mining potential heat-tolerant genes in Panicoideae, and help to improve the heat tolerance of other crops.