Genetic Mapping and Transcriptomic Analysis of Sepal-Derived Seed Shape in Spinach

Area of Science:

• Plant genetics
• Crop science
• Molecular biology

Background:

• Spinach (Spinacia oleracea) is a globally important crop.
• Female spinach exhibits two sepal shapes (thorn-shaped and round) influencing seed morphology.
• Seed shape impacts agricultural practices like mechanized sowing and cultivar classification.

Purpose of the Study:

• To genetically map the locus controlling sepal morphology in spinach.
• To identify candidate genes responsible for sepal-derived seed shape variation.
• To understand the molecular mechanisms underlying sepal development in spinach.

Main Methods:

• Developed an F2 population from contrasting spinach parental lines.
• Constructed a high-density genetic linkage map using ~1615 bin markers.
• Performed transcriptome profiling and integrated differential gene expression with weighted gene co-expression network analysis.
• Conducted structural variation analysis to identify polymorphisms in candidate genes.

Main Results:

• A major 4.31 Mb genomic interval on chromosome 4 was significantly associated with sepal morphology.
• Transcriptome analysis revealed enrichment of cell cycle pathways in developing sepals.
• Identified 25 differentially expressed genes (DEGs) within the mapped interval, with 11 co-expressed with hub genes.
• Uncovered promoter and coding sequence variations in candidate genes.

Conclusions:

• Identified 11 promising candidate genes potentially regulating sepal-derived seed morphology in spinach.
• Provides valuable targets for future functional validation studies.
• Offers new insights into the genetic regulation of sepal development and its impact on seed traits in spinach.