A major vernalization-independent QTL for tiller angle on chromosome arm 2BL in bread wheat

Tiller angle (TA) strongly influences plant architecture and grain yield in cereals. However, the genetic basis of TA in wheat is largely unknown. We identified three TA-related quantitative trait loci (QTL). One of them was QTa.sau-2B-769, a major QTL localized on chromosome arm 2BL. QTa.sau-2B-769 was detected in seven environments, explaining 18.1%–51.1% of phenotypic variance. We developed a linked Kompetitive Allele-Specific Polymerase chain reaction (KASP) marker, KASP-AX-108792274, to further validate this locus in three additional populations in multiple environments. QTa.sau-2B-769 increased TA by up to 24.9% in these populations. There were significant and positive correlations between TA and flag leaf angle (FLANG). However, TA was not correlated with plant height or anthesis date, suggesting that expression of QTa.sau-2B-769 is independent of vernalization. TraesCS2B01G583800, a gene known to be involved in leaf angle regulation, was identified as the most likely candidate gene for QTa.sau-2B-769. These results enrich our understanding of the mechanisms regulating wheat TA at maturity and may support precise mapping and cloning of gene(s) underlying QTa.sau-2B-769.