Transcriptome analysis reveals genes associated with kernel size in apricots cultivated for kernel consumption (Prunus armeniaca × Prunus sibirica)

Abstract

Seed size is an important component of overall seed yield trait, and apricots cultivated for consumable kernels produce kernels that are large and sweet. However, the molecular mechanism of kernel development in kernel consumption apricots remains unclear. We measured kernel weight, length, width, and thickness and investigated the transcriptome profiles of kernel consumption apricots (Prunus armeniaca × Prunus sibirica) at six different developmental stages. The phenotypic analysis results showed that rapid kernel size development occurred from 15 to 45 days after flowering (DAF), and that the kernel coat size almost reached its the maximum at 45 DAF, suggesting that the early kernel development was important factor that determine overall kernel size. A total of 8,108 differentially expressed genes (DEGs) were identified, and a weighted gene co-expression network analysis revealed that turquoise module was strongly correlated with the kernel size. Six hub genes were identified as potential regulators of the kernel size. Furthermore, we analyzed the DEGs related to kernel size in the phytohormones metabolic pathways, ubiquitin-proteasome pathway, G-protein signaling, mitogen-activated protein kinase signaling, and HAIKU pathway, which were considered to be important regulators of kernel size. Our findings provide new insights into the molecular mechanisms underlying the regulation of kernel size in kernel consumption apricots.