A combination of high potential productivity and ecological stability is essential for current cultivars, which is achievable by breeding. Interspecific/intergeneric hybridization remains a key approach to producing new high-yielding and resistant cultivars. Interspecific reproductive barriers (IRBs) appear in the interaction between the pollen and pistil of interspecific/intergeneric hybrids. The mechanisms underlying these hybridization barriers are to a considerable degree unknown. The pollen–pistil interaction is decisive because the pollen of distantly related plant species either is not recognized by stigma cells or is recognized as foreign, preventing pollen tube (PT) germination and/or penetration into the stigma/style/ovary. This review mainly focuses on (1) the pollen–pistil system; (2) IRB classification; (3) similarity and differences in the function of self-incompatibility (SI) barriers and IRBs; and (4) physiological and biochemical control of IRBs and their overcoming. The main goal is to illuminate the physiological, biochemical, and molecular mechanisms underlying the growth arrest of incompatible PTs and their death. In general, this review consolidates the current understanding of the interaction of the male gametophyte with the sporophyte tissues of the pistil and outlines future research directions in the area of plant reproductive biology.

Distant hybridization in plants is a powerful tool for broadening genetic diversity and developing new varieties with improved traits. However, crosses between genetically distant species are accompanied by reproductive barriers that prevent successful fertilization. This work investigated pollen–pistil interactions during the progamic phase of fertilization in distant crosses involving four members of the Solanaceae family, using several cross combinations. In all cross combinations, pollen of all species germinated on the stigma, grew through the transmitting tissues of the style and ceased growth at a specific distance from the stigma surface. Our studies have revealed that the arrest of pollen tube growth during distant hybridization exhibits a striking similarity to that observed in the gametophytic S-RNase-based self-incompatibility mechanism of Solanaceae plants. Elucidating the mechanisms of pollen tube growth arrest during distant hybridization in Solanaceae will provide deeper insight into the nature of reproductive barriers and aid in the development of strategies to overcome them, thereby expanding the possibilities for successful hybridization between distant species and enabling the creation of valuable new varieties.