Development and validation of diagnostic markers for the reduced height gene Rht8 in wheat

Wheat (Triticum aestivum L.) production is necessary for global food and nutrition security. Reducing plant height is an effective strategy to increase lodging resistance, harvest index, and eventually wheat yield. Rht8 is a gibberellic acid-sensitive reduced height (Rht) gene and has been cloned. Rht8 encodes a ribonuclease H-like (RNHL) superfamily protein that reduces plant height without reduction in coleoptile length. High-throughput diagnostic markers are not available for precise selection of RNHL in wheat breeding. In this study, we found that different cultivars may carry 1-3 copies of RNHLs on chromosome 2D, and only 2D carries the semi-dwarf allele of RNHL although the wild-type RNHL allele is detected in several other chromosomes. We developed two kompetitive allele specific PCR (KASP) markers, Rht8-KASP-V2 and Rht8-KASP-V3, based on the causal variation in RNHL. The two markers co-segregated with plant height in a recombinant inbred population and were validated in a panel of hard winter wheat breeding lines from the 2022 Regional Germplasm Observation Nursery and Regional Performance Nursery. Rht8 has not been extensively deployed in US hard winter wheat and development of the diagnostic KASP markers will facilitate Rht8 transfer to US wheat cultivars.