Allelic variations in phenology genes of eastern U.S. soft winter and Korean winter wheat and their associations with heading date

Authors: MA, FENGYUN - The Ohio State University; Brown-Guedira, Gina; KANG, MOONSEOK - Rural Development Administration - Korea; Baik, Byung-Kee

Submitted to: Plants
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 11/7/2022
Publication Date: 11/15/2022
Citation: Ma, F., Brown Guedira, G.L., Kang, M., Baik, B.V. 2022. Allelic variations in phenology genes of eastern U.S. soft winter and Korean winter wheat and their associations with heading date. Plants. 11(22). Article #3116. https://doi.org/10.3390/plants11223116.
DOI: https://doi.org/10.3390/plants11223116

Interpretive Summary: Short heading (emergence of ear) time of wheat is one of the most important traits necessary for the wheat-soybean double cropping system. It leads to early maturation and harvesting of wheat, which allows for early planting of the second crop (soybean) and ensures a sufficiently long growth time for maximum yield of the second crop. Soybean yield in the double-cropping system is reported to be lower by 10-40% compared to soybean planted on time with no prior crop in the field. Late planting is the major cause of the reduced yield of double-crop soybean. The development of early-maturing wheat varieties is, therefore, crucial to shorten the delay in soybean planting and to minimize yield loss, and therefore to improve the profitability of the double-cropping system. The heading time of wheat depends heavily on climatic conditions including temperature and day-length, and is also controlled by phenology genes, which govern the cold temperature requirement at the seedling stage (vernalization) and day-length requirement (photoperiod) for flowering, and heading and flowing times. Korean wheat varieties have been bred to express early heading and maturing traits suitable for use in the wheat-rice double-cropping system, and are expected to be bountiful genetic resources for early maturity. Knowledge on the variation in phenology genes of eastern U.S. soft wheats and their effects on heading date in comparison to those of Korean wheat varieties would provide a valuable tool for wheat breeders in the development of early-maturing eastern U.S. wheat varieties suitable for the double-cropping system. We determined the variation in heading time-related genes (phenology genes) of 149 eastern U.S. and 32 Korean wheat varieties and assessed their effects on heading date under eastern U.S. environments to identify the genes and gene profiles that provide the early heading trait. Eastern U.S. wheat varieties headed on average 14 days later than Korean wheat varieties in two crop years. Ninety-four percent of eastern U.S. wheat varieties carried three or more copies of the vernalization gene associated with late heading, whereas 81.3% of Korean wheat varieties carried one copy of the vernalization gene associated with early heading, indicating that the presence of a single copy of the vernalization gene could be helpful for early heading. Genetic influences on the heading date of eastern U.S. wheat varieties were largely contributed by the photoperiod and vernalization genes. The following phenology gene profiles were identified to deliver early-heading and early-maturing traits: a single copy of the vernalization gene, the vernalization gene type vrn-D3a, and photoperiod insensitive types of genes. The obtained results will provide eastern U.S. wheat breeding programs with guidance on the genetic resources necessary for the development of wheat varieties carrying early-heading and early-maturing traits that would be suitable for use in the wheat-soybean double-cropping system.

Technical Abstract: Wheat heading time is genetically controlled by phenology genes including vernalization (Vrn), photoperiod (Ppd) and earliness per se (Eps) genes. Characterization of the existing genetic variation in the phenology genes of wheat would provide breeding programs with valuable genetic resources necessary for the development of wheat varieties well-adapted to the local environment and early-maturing traits suitable for double-cropping system. One hundred forty-nine eastern U.S. soft winter (ESW) and 32 Korean winter (KW) wheat genotypes were characterized using molecular markers for Vrn, Ppd, Eps and reduced-height (Rht) genes, and phenotyped for heading date (HD) in eastern U.S. region. The Ppd-D1 and Rht-D1 genes exhibited the highest genetic diversity in ESW and KW wheat, respectively. The genetic variations for HD of ESW wheat were largely contributed by Ppd-B1, Ppd-D1 and Vrn-D3 genes. The Rht-D1 gene largely contributed to the genetic variation for HD of KW wheat. KW wheat headed on average 14 days earlier than ESW wheat in each crop year, largely due to the presence of the one-copy vrn-A1 allele in the former. The development of early-maturing ESW wheat varieties could be achieved by selecting for the one-copy vrn-A1 and vrn-D3a alleles in combination with Ppd-B1a and Ppd-D1a photoperiod insensitive alleles.