Ovary Locule Number Functions as a Key Driver in Shaping the Fruit Architecture of Lycium barbarum L

The external traits of Lycium barbarum L. fruits are primary determinants of their commercial value. Ovary locule number is a fundamental developmental structure hypothesized to be a key intrinsic factor influencing these traits. However, systematic investigation into its specific role remains limited. This study systematically investigated the correlation between locule number and key fruit traits, and compared differences between wild and cultivated accessions from the Ningxia region. Multivariate statistical analyses, including correlation analysis and principal component analysis, were employed. The results revealed an unbalanced distribution of locule number, with bilocular ovaries predominating. Furthermore, locule number showed significant positive correlations with size-related traits (single fruit weight, fruit area) but negative correlations with shape indices (fruit shape index, length-to-width ratio). Interestingly, the average locule number in cultivated L. barbarum was significantly higher than in wild accessions. Cultivated accessions exhibited distinct domestication characteristics, including greater single-fruit weight, altered fruit shape index, and color. Single fruit weight and fruit roundness are identified as key indicators for predicting locule number. We conclude that ovary locule number is a key intrinsic factor determining fruit size and shape, with a trade-off: increased locule number promotes enlargement but leads to a rounder shape. Domestication has preferentially selected for genotypes with more locules and larger fruit size. Therefore, locule number can serve as an effective early phenotypic marker for quality breeding programs in L. barbarum.