Drought alters jasmonate-dependent regulation of anther development in yellow lupin (Lupinus luteus L.)

MAIN CONCLUSION: Drought reshapes phytohormone dynamics and gene expression linked to jasmonate-dependent regulation of anther development, leading to delayed anther dehiscence in yellow lupin (Lupinus luteus L.). Drought is a major factor limiting plant sexual reproduction and yield. Post-meiotic, late anther development involves a multistep dehiscence process leading to the opening of pollen chambers, and subsequent to degeneration of anther tissues (senescence). Effective coordination of these developmental phases is crucial for male fertility and depends on phytohormones, including jasmonates (JAs). Our morphological and histological analyses revealed that anthers of yellow lupin (Lupinus luteus L.) exposed to drought stress display a delayed dehiscence phenotype. The concentrations of jasmonic acid (JA) during individual developmental phases of stressed anthers were disrupted: JA levels were lower under drought during phases in which they were normally elevated under well-watered conditions, whereas they were higher during phases in which they typically declined. This imbalance correlated with JA localization in different cell types and was reflected in the expression of genes associated with phytohormone biosynthesis and perception. Transcriptomic analyses of JA-dependent interactions during specific phases of anther development identified differentially expressed genes involved in the metabolism and signaling of various phytohormones, including gibberellins (GAs), salicylic acid (SA), and indole-3-acetic acid (IAA). Moreover, drought stress altered the levels of selected phytohormones during anther dehiscence and senescence. All these findings improve our understanding of the hormonal and molecular regulatory mechanisms underlying late anther development under water deficit, contributing to breeding strategies for drought-resistant crops and the maintenance of high, stable yields.