QTL detection for internode diameter and its association with yield-related traits in wheat

Optimal stem structure affects stem strength and significantly contributes to wheat yield, for which internode diameter (ID) characteristics are considered important. To specify the genetic basis of wheat internode characteristics, quantitative trait loci (QTL) mapping for the ID trait was performed using a recombinant inbred line (RIL) mapping population derived from a cross between Kenong 9204 (KN9204) and Jing 411 (J411), denoted as KJ-RIL. IDs of the 187 KJ-RILs were evaluated in five different environments, and all five IDs were found to be positively associated with thousand kernel weight (TKW) and negatively associated with spike number per plant (SNPP). A total of 47 putative additive QTLs associated with ID were detected, distributed across all 21 wheat chromosomes. Individually, these QTLs explained 3.7-12.3% of the phenotypic variance, and the LOD values ranged from 2.0 to 5.7. Of these 47 QTLs, 36.2% (17) were co-localized with QTLs for kernel number per spike (KNPS), 29.8% (14) for TKW and 25.5% (12) for yield per plant (YPP), respectively, indicating ID traits can influence yield-related traits (YRTs) to some extent. Moreover, three stable QTLs of qID-3-KJ-3D, qID-4-KJ-7A and qID-5-KJ-6B were identified in this study. The present study provides new insights into understanding the genetic relationships between ID and yield potential.