Phenotypic Diversity in Moricandia nitens (Brassicaceae): An Integrative Study of Sympatric Flower-Color Morphs in Coastal Egypt

Abstract

Moricandia DC. (Brassicaceae) is a Mediterranean genus of agronomic importance as a co-cenospecies of Brassica L., comprising eight recognized species. During spring 2022, white- and pink-flowered morphs were collected from five sympatric populations at Ras El-Hikma, Mersa-Matruh coastal plain, Egypt (31°15′17.20″ N, 27°21′1.99″ E). Twenty flowering specimens were evaluated using macro- and micromorphology, scanning electron microscopy (SEM) of leaf epidermis and seed coats, and inter-simple sequence repeat (ISSR) markers. The morphs differed mainly in petal color, leaf size, and siliqua length. White-flowered plants had leaves up to 4 cm and siliquae 4–5 cm, whereas pink-flowered plants had leaves ≤2.5 cm and siliquae up to 6 cm. SEM showed broadly similar epidermal and seed-coat structures, with minor differences in epicuticular wax, epidermal channel depth, and seed-coat sculpture. Eleven ISSR primers produced 116 reproducible bands, including 18 polymorphic bands (15.52%), with Dice similarities of 76.19–100%. Multivariate analysis of 35 morphological and geographical characters across eight species indicated contributions of morphology, geography, and soil characteristics to species clustering. The two morphs exhibited marked phenotypic but limited molecular differentiation and were therefore best treated as intraspecific variants, highlighting the value of integrative taxonomy and the conservation of wild Moricandia germplasm for Brassica breeding.