The effects of heat stress on male reproduction and tillering in Sorghum bicolor

Abstract

Due to global climate change, heat stress is increasingly harming the growth, development, overall biomass, and grain yield of numerous crops. Heat stress impairs pollen development and thus reduces seed set in Sorghum bicolor (L.) Moench; however, the effects of heat stress on anther development at specific stages and tiller formation remain incompletely understood. Here we report that exposure to heat stress [42°C/32°C (day/night)] at pollen mother cell (PMC) and booting stages profoundly disrupts tapetum and pollen development, resulting in a significant decrease in grain yield in sorghum. Sorghum plants subjected to 9 days or less of heat stress at the PMC stage exhibited normal pollen viability, but 12 days of heat stress caused almost complete loss of grain yield and the formation of nonviable pollen grains. Similarly, sorghum plants that were heat‐stressed for 3 days at the booting stage produced few seeds. Further analysis revealed that aberrant tapetum and pollen development contributed to the sterility of pollen in these heat‐stressed plants. Notably, in addition to inhibiting plant height, a 12‐day heat stress at the PMC stage promoted the formation of basal tillers, whereas a 3‐day heat stress at the booting stage stimulated the formation of apical tillers, which helped salvage seed yield under heat stress conditions. Moreover, the application of exogenous auxin promoted the formation of apical tillers and leaf numbers per apical tiller. Collectively, our findings suggest that sorghum is susceptible to heat stress during both early and late anther development, and auxin might be involved in governing the formation of apical tillers.

Environmental stress in crops: Effects and responses during reproduction

“…Heat stress causes detrimental effects on the reproductive development of numerous crop species by impairing pollen development and seed set. Smith et al, (2023) provide a wealth of new data concerning the deleterious effects of heat stress on both the early and late anther developmental stages of sorghum (Sorghum bicolor (L.) Moench), resulting in decrease in grain yield. The analysis of the pollen viability reported in this study shows that the booting stage is more susceptible to the duration of heat stress than the stage of pollen mother cell development.…”