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

Authors: SMITH, ASHLEY - University Of Wisconsin; GENTILE, BENJAMIN - University Of Wisconsin; Xin, Zhanguo; ZHAO, DAZHONG - University Of Wisconsin

Submitted to: Food and Energy Security
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 9/24/2023
Publication Date: 11/17/2023
Citation: Smith, A., Gentile, B.R., Xin, Z., Zhao, D. 2023. The effects of heat stress on male reproduction and tillering in Sorghum bicolor. Food and Energy Security. e510. https://doi.org/10.1002/fes3.510.
DOI: https://doi.org/10.1002/fes3.510

Interpretive Summary: High temperature damages sorghum plants at various developmental stages. However, it is not clear at which stage sorghum is most susceptible to high temperature stress. In collaboration with scientists from University of Wisconsin at Milwaukee, ARS scientists from Lubbock, Texas demonstrated that high temperature stress at the pollen mother cell (PMC) and booting stages impairs pollen development and reduces the grain yield. The findings may aid genetic improvement of high temperature tolerance in sorghum.

Technical Abstract: In the world facing an ever intensifying climate, heat stress has increasingly detrimental effects on plant growth and development, reducing overall biomass and grain yield in many crops. Although heat stress in Sorghum bicolor (L.) Moench during late developmental stages including anthesis, pollen germination, and grain filling decreases the grain yield, it is unclear whether heat stress affects male fertility and seed production in early male development. Here we showed that heat stress at the pollen mother cell (PMC) and booting stages impairs pollen development and reduces the grain yield in sorghum. Plants heat stressed at the PMC stage for less than 9 days showed normal pollen development and seed set, but 12-day heat stress caused the almost complete loss of grain yield and inviable pollen grains. Similarly, panicles heatstressed for 3 days at the booting stage had few or no seeds. Further analysis revealed reduced pollen viability, failed anther dehiscence, and aborted pollen tube germination in those 3-day heat stressed plants. Interestingly, besides inhibiting plant height 12-day heat stress at the PMC stage promotes basal tiller formation, while 3-day heat stress at the booting stage stimulates the formation of apical tillers, which salvaged seed yield under the heat stress condition. Collectively, our findings demonstrated that heat stress during early male reproductive development severely decreases grain yield via affecting pollen and anther development, which will help elucidate the molecular mechanisms underlying heat stress caused male sterility in cereal crops.