Exploration and Genome-wide Profiling of the Arabinogalactan Protein Gene Family Across the Chickpea Genome (Cicer arietinum)

Chickpea (Cicer arietinum) is agriculturally vital due to its nutrition and economic value. Grasping its growth mechanisms is key to better yields. Chimeric Arabinogalactan Proteins (AGPs), glycoproteins in plant cells' matrix, have a protein core wrapped in carbohydrates. These distinct AGPs are crucial for plant physiology, affecting cellular processes like division, differentiation, and expansion, and aiding pollen tube growth. Beyond their core role, AGPs have biotech and agriculture potential, improving yields and stress resistance by affecting cellular functions. Understanding AGPs' plant role could revolutionize productivity and sustainability amid changing environments. Using bioinformatics tools, we successfully identified 69 chickpea genes, encompassing 27 CaXYLP, 19 CaFLA, and 23 CaELA genes. Each gene exhibited distinct conserved domains characteristic of its respective gene family. To ensure naming consistency, we re-designated the CaXYLP, CaFLA, and CaELA genes based on their genuine orthologs in rice and Arabidopsis. Interestingly, most of these genes shared common cis-regulatory elements, responding to factors such as abscisic acid, auxin, salicylic acid, jasmonic acid, drought, and light. Our gene duplication analysis uncovered that all identified paralogous genes originated from segmental duplications (SD). Conversely, Phytocyanin-like AGPs exhibited maximum expression during seed, embryo, and various flower development stages. Lastly, Fasciclin-like AGPs reached their zenith expression in seeds and root hairs. These analyses collectively emphasize the pivotal role of chimeric AGPs in augmenting crop productivity and bolstering stress resilience, while also revealing novel regulatory mechanisms in plant growth and development.