Identification of Quantitative Trait Loci for Yield and Yield Components in Guar ( Cyamopsis tetragonoloba L. Taub.)

Abstract

ABSTRACT Guar ( Cyamopsis tetragonoloba L. Taub.), a resilient legume valued for its galactomannan‐rich seeds used in industrial applications, exhibits limited productivity due to limited genetic diversity and insufficient breeding efforts. This study aimed to dissect the genetic architecture of yield‐related traits using quantitative trait loci (QTL) mapping in a recombinant inbred line (RIL) population comprising 128 F 2:8 lines derived from high (TAMG149) and low (TAMG343) seed‐yielding parents. Field experiments were conducted in Vernon, Texas, across two seasons (2023 and 2024) using a randomized complete block design with three blocks to evaluate seed yield, pod number per plant, pod harvest index (PHI) and pod length. Phenotypic analyses revealed significant genotypic variation, with seed yield ranging from 145.73 to 3628.68 kg ha −1 (mean 1409.42 kg ha −1 , CV 38.96%), and strong positive correlations between yield and pod number ( r = 0.65, p < 0.0001) as well as PHI ( r = 0.37, p < 0.0001). A total of 381 filtered single nucleotide polymorphisms (SNPs) obtained from genotyping‐by‐sequencing (GBS) were used to generate the genetic maps spanning 1197.7 cM (average inter‐marker distance, 3.05 cM). Composite interval mapping (CIM) identified 40 QTLs across traits and environments, including stable loci for seed yield on Chromosomes 2 ( Ct_yd_2 , R 2 = 9.19%) and 6 ( Ct_yd_6 , R 2 = 0.95%), pod number on Chromosomes 2 and 5, PHI on Chromosomes 1, 5 and 6, and pod length on Chromosomes 3, 5, 6 and 7. These findings highlight pod number as the primary yield driver, with stable QTLs offering robust targets for marker‐assisted selection to enhance guar productivity. This is the first study on linkage map construction and QTL mapping for yield and yield components in guar.