Genome-wide identification unravels the role of the arabinogalactan peptide (AGP) gene family in cotton plant architecture.

Key message: In our study, we identified the gene Gohir.A08G240900 as a potential target for regulating cotton plant height, providing a genetic basis for enhancing cotton morphology. Arabinogalactan peptides are a class of hydroxyproline-rich proteins widely distributed in plants that participate in many life processes, including growth and development, cell division and even plant reproductive development. In this study, we identified 122 members of the AGP gene family via genome-wide identification in six cotton species. Through phylogenetic tree analysis, the AGP family was divided into six different subgroups. A core yet variable region composed of proline, hydroxyproline, serine, threonine, and alanine (PAST) was identified among these members. Furthermore, Ka/Ks analysis revealed that the AGP gene family underwent multiple fragment duplication events. Additionally, we analyzed the 1.5 kb upstream cis-acting elements of all upland cotton family members and identified numerous functional elements associated with growth and development, suggesting a close relationship among the family members. The results of RT‒qPCR analysis revealed that the expression level of Gohir.A08G240900 was significantly different among the four upland cotton varieties, with significant differences in plant height. Virus-induced gene silencing (VIGS) experiments revealed that the height of Gohir.A08G240900 gene-silenced plants significantly decreased. The results revealed that Gohir.A08G240900 may affect plant growth and development and may be a potential functional gene regulating cotton plant height.