The shape of fruits is a critical trait affecting the commercial value and consumer acceptance of horticultural crops. Genetic regulation of fruit shape involves complex interactions among multiple genes and environmental factors. This review summarizes recent advances in understanding the genetic mechanisms controlling fruit shape in several key horticultural crops, including tomato, pepper, cucumber, peach, and grape. We present the identification and characterization of genes and quantitative trait loci (QTLs) that influence fruit shape, focusing on the roles of genes such as OVATE, SUN, FAS, LC, ENO, GLOBE, CsSUN, CsFUL1, CsCRC, PpCAD1, PpOFP1, and VvSUN. This review highlights the importance of hormonal pathways, particularly those involving synthesis and concentration of cytokinins and brassinosteroids in shaping fruit morphology, and explores how these genes interact and form regulatory networks that collectively determine the final fruit shape. This knowledge provides a foundation for developing strategies to improve fruit quality and yield through genetic modification and breeding programs.

Luffa is a genus of tropical and subtropical vines in the Cucurbitaceae family, recognized as an important cultivated commercial vegetable. However, the seeds of the luffa species are considered hard-seeded, and the processes governing seed germination remain understudied. The 9-cis-epoxycarotenoid dioxygenase (NCED) genes, which are critical for seed germination, have not been well characterized in Luffa. In this study, we identified four LaNCED genes in Luffa acutangula and four LcNCED genes in Luffa cylindrica, distributed across four chromosomes in each species. Phylogenetic analysis classified these genes into two subgroups. Gene structure and motif composition analyses revealed both similarities and differences among the NCEDs. Cis-element analysis further revealed that these NCEDs may be involved in growth regulation by modulating the phytohormonal network and responding to stress stimuli. Expression profiling of LcNCED genes during seed germination showed a decrease in LcNCED2 levels, coinciding with an increase in α-amylase activity throughout the germination process. Subcellular localization assays demonstrated that LcNCED2 is localized in the chloroplast. Furthermore, transient overexpression of LcNCED2 in tobacco leaves led to a significant increase in ABA content. Our findings provide a comprehensive genomic characterization of the NCED family in Luffa cylindrica and Luffa acutangula and reveal the functional role of LcNCED2 in regulating ABA levels, which may play a critical role in seed germination.

Pepper (Capsicum annuum L.) fruits at immature stage (IS) display colors that range from dark green to light green and white. Due to the influence of genetic factors and consumption habits, white-fruited pepper germplasms are rare in nature and depend on artificial creation. However, the unclear complex genetic basis, coupled with the absence of developed functional markers cosegregation with white fruit trait, has impeded the efficiency of breeding white-fruited peppers. Herein, an F₂ segregation population consisting of 3,000 individuals is derived from a cross between B1-2 with white fruit and D50 with dark green fruit at IS. Using bulked segregant analysis, a previously reported gene CaGLK (Capana10g000333) is identified as a candidate that is responsible for white/green fruit color. A single nucleotide polymorphism (SNP) (G/A) at the position of the last base of the second intron of CaGLK, resulting in alternative splicing at the junction of the second intron and the third exon, causing the exclusion of 31 bp in cDNA sequence of B1-2, is associated with white fruit trait. A KASP marker is developed and shown to distinguish white-fruited pepper from the F₂ population. The distinguishing efficiency of this marker reached up to 78.3% when tested in a natural population. This first report of a new allele CaGLK^A that controlled white color provided a new handle to develop pepper cultivars with white color fruit.