Flooding stress affects microsporogenesis, anther development, and pollen quality in tomato (Solanum lycopersicum L.)

Abstract Flooding is an increasing threat to crop productivity under climate change, affecting the reproductive development of many crop plants. Although flooding effects on tomato physiology, growth, and yield are well documented, its impact on male reproductive development remains poorly understood. Here, we investigated the effects of flooding on male gametophyte development in tomato ( Solanum lycopersicum L. cv. Ailsa Craig) using cytogenetic, histological, and pollen performance analyses. Compared with controls, flooded plants showed a higher proportion of meiocytes at later stages, particularly during meiosis II. Meiotic asynchrony was the meiotic irregularity with higher frequency, and trinuclear configurations at telophase II increased significantly. Flooding was also associated with a significant increase in triads, indicating altered sporad formation. Histological analyses of anther development revealed alterations at specific floral stages, including degeneration of microspore mother cells and abnormal tapetal morphology. In vitro pollen germination was reduced. Overall, six-days of flooding did not cause total male sterility but were associated with alterations in male reproductive development, from meiosis through pollen maturation. These findings identify male reproductive development as a sensitive target of flooding stress and provide new insights into the vulnerable developmental stages in tomato. Understanding these responses may support the development of management strategies and breeding approaches aimed at improving reproductive resilience under increasingly variable water regimes associated with climate change.