Computational Insights into Lateral Organ Boundary Domain (LBD) Transcription Factors in Chickpea (Cicer arietinum L.) Reveal Their Roles in Defense Under Biotic and Abiotic Stress Responses

Abstract

Chickpea (Cicer arietinum L.) is an important legume crop, cultivated worldwide due to its high nutritional importance and domestic demand. Due to low genetic diversity, its productivity is limited by both biotic and abiotic stresses. Despite its importance, the study of transcription factors underlying different stresses remains unstudied. In this study, whole-genome analysis of LBD transcription factor in C. arietinum revealed 48 putative CaLBDs genes, distributed across all 8 chromosomes. Comparative phylogeny with Oryza sativa and Arabidopsis thaliana classified LBD transcription factors into 5 groups (I-a, I-b, I-c, I-d, and II-a), based on sequence homology and conserved domains. Variation in intron/exon count across CaLBD genes indicated structural diversity, while conserved motifs suggested functional roles in biotic and abiotic stress responses due to their characteristic LBD domain. Synteny analysis uncovered the evolutionary relationships of C. arietinum with A. thaliana and Medicago truncatula. Gene duplication analysis demonstrated both tandem and segmental duplications expressing their roles in LBD gene family expansion. Transcriptomic profiling of CaLBD genes under Phytophthora root rot treatment revealed strong upregulation of CaLBD38 and CaLBD46. Under Fusarium wilt stress, CaLBD46 was highly expressed, followed by CaLBD14 and CaLBD38. Under the salt and drought stress conditions, CaLBD38 and CaLBD46 expressed the strongest upregulation. This genome-wide study provides a foundation and valuable resources for future genetic studies and serves as a base for development of stress-resilient cultivars with enhanced resistance through advanced molecular breeding programs.