Premature tapetum degradation of Cakile maritima under drought and low or moderate salinity does not reduce its reproductive fitness

Salinity and drought are major environmental stresses that constrain plant growth and reproductive success. Cakile maritima , a facultative halophyte of the Brassicaceae family, represents a promising model for studying plant salt tolerance. In this study, established plants were subjected to eight weeks of increasing salt treatments (100, 200, and 400 mM NaCl) and drought stress to evaluate their physiological and reproductive responses. Mild and moderate salinity had minimal effects on vegetative growth and reproductive output, whereas severe salinity significantly reduced shoot length as well as flower and fruit production. Ion profiling revealed dose-dependent accumulation of Na⁺ and Cl⁻ in roots and leaves, while proline, an osmoprotective compound, accumulated only under extreme salinity. Histological and cytological analyses demonstrated that both stresses induced premature tapetum degeneration and accelerated pollen development. Notably, pollen germination was strongly inhibited under 400 mM NaCl, consistent with the observed reduction in fruit set. This study provides the first comprehensive characterisation of C. maritima reproductive performance under salt and drought stress conditions, highlighting its high resilience and adaptability to low and moderate salinity. These findings advance our understanding of halophyte reproductive plasticity and underscore the potential of C. maritima as a model for investigating mechanisms of stress tolerance.