QTL Detection for Internode Component Index in Wheat Using a RIL Mapping Population

Plant height (PH) is one of the most important traits related to plant architecture in wheat. Together, the lengths of individual internodes determine plant height and have a great influence on lodging resistance. To specify the genetic basis of wheat internode characteristics, we identified quantitative trait loci (QTLs) for each internode component index (ICI) and plant height component index (PHCI) using a recombinant inbred line (RIL) mapping population derived from ‘Kenong 9204’ (‘KN9204’) × ‘Jing 411’ (‘J411’). Up to 57 putative additive QTLs for the four ICIs and PHCI were detected, which together covered 20 of the 21 wheat chromosomes, with the exception of chromosome 1B. Among them, eight QTLs were major, stable QTLs with a logarithm-of-odds (LOD) score of ≥ 3.0 and a phenotypic variance explained (PVE) of ≥ 7.0%. In the epistatic analysis, only one pair of epistatic QTLs was identified for the first internode component index (FIITCI) and three pairs of epistatic QTLs for the third internode component index (TITCI). A total of 20 of the 57 detected QTLs (35.1%) were co-localized QTLs for PH, spike length, and internode lengths, indicating that those traits have their own individual genetic basis in most cases. Moreover, 12 QTL clusters for PHCI/ICIs and yield-related traits were identified, indicating that plant architecture plays a potential role in the formation of yield in wheat. The plant architecture with gradually bottom-up shortened internode lengths tends to be high-yielding potential, especially for the uppermost internode. This study may provide useful information for understanding the genetic basis of plant height components and to accelerate the genetic improvement of plant ideotypes designed to increase yield.