Comparative Biology Research on the Reproductive Organs Between Physalis pubescens L. and Solanum lycopersicum var. cerasiforme

The post-anthesis sepal inflation forming a Chinese lantern in Physalis pubescens represents a striking morphological novelty, whereas in the related genus Solanum lycopersicum var. cerasiforme, the sepals remain non-enclosing, providing an ideal comparative system to study reproductive organ divergence. This study aimed to systematically compare the reproductive development between Physalis pubescens L. and Solanum lycopersicum var. cerasiforme. We integrated phylogenetic analysis, light and scanning electron microscopy, semi-thin sectioning, and quantitative RT-qPCR analysis of six MADS-box genes. Phylogenetic analysis placed P. pubescens in a clade with P. alkekengi (L.) and P. ixocarpa (Brot. ex Hornem.), distinct from tomato. Floral organs differed markedly in petal color, anther morphology, and dehiscence type. Microspore development was delayed before the tetrad stage but accelerated thereafter in P. pubescens; S. lycopersicum anthers exhibited pronounced connective tissue proliferation absent in P. pubescens. P. pubescens sepals expanded 6.92-fold by 17 days post anthesis and enclosed the fruit, while S. lycopersicum sepals grew minimally. Sepal expansion was driven by inner epidermal cell enlargement and intercellular space formation, producing a hollow structure with a trichome-free inner epidermis. Expression of six MADS-box genes exhibited diversity: PfMPF2 and PfAGL1 were upregulated during sepal growth, PfMPF3, PfSEP1 and PfSEP3 exhibited a high–low–high pattern with minima at peak growth, and PfAGL6 declined. These findings reveal that coordinated epidermal cell expansion, parenchyma cavity formation, and a dynamic MADS-box gene network govern the inflated sepal syndrome, and highlight key divergences in anther morphogenesis, providing a cellular and molecular framework for reproductive evolution in Solanaceae.