*Email: msehar@live.harper.ac.uk

Drought is severely affecting the yield of numerous food crops worldwide, especially wheat. The application of antitranspirants, substances that minimise water loss from plants, has demonstrated the ability to enhance crop yield in wheat, associated with pollen viability under water stress conditions when applied before meiosis. To understand the mechanisms through which antitranspirants promote pollen viability, transcriptomic responses were investigated in wheat anthers obtained from polytunnel-grown plants sprayed with antitranspirants and compared with droughted unsprayed and well-watered plants.

Film-forming (Vapor Gard – VG) and metabolic (S-Abscisic Acid – ABA) antitranspirants were sprayed at the flag leaf stage, and anthers were collected during the early meiosis stage (leptotene-zygotene). Gene expression of hormonal responses and the processes related to carbohydrate/sugar metabolism were significantly affected in the anthers of treated plants, with a notable downregulation of genes involved in these processes compared to well-watered. The application of antitranspirants significantly altered the expression patterns of genes in the early meiotic anthers under drought stress.

The majority of differentially expressed genes (DEGs) in the anthers of droughted, antitranspirant-treated plants (ABA and VG) exhibited transcriptional downregulation (over 3,900 genes) compared to unsprayed droughted plants. In contrast, the number of upregulated genes was lower (around 800 genes). Additionally, the number of downregulated genes was higher in VG-treated plant anthers (3,325 genes) compared to ABA-treated plant anthers (634 genes).

Thus, under drought stress antitranspirants suppress transcriptional responses of genes involved in various biological processes. However, despite these major transcriptomic changes, antitranspirants did not show any improvement in crop yield, and no significant differences were observed for improved pollen viability between plants treated with antitranspirants and unsprayed ones.

This suggests that male reproductive parts are more sensitive at the transcriptional level than subsequent physiological processes determining yield.