Salma Benaouda, Said Dadshani, Patrice Koua, Jens Léon & Agim Ballvora

Theoretical and Applied Genetics August 2022; vol. 135: 2833–2848

Key message

The genetic response to changing climatic factors selects consistent across the tested environments and location-specific thermo-sensitive and photoperiod susceptible alleles in lower and higher altitudes, respectively, for starting flowering in winter wheat.

Abstract

Wheat breeders select heading date to match the most favorable conditions for their target environments and this is favored by the extensive genetic variation for this trait that has the potential to be further explored. In this study, we used a germplasm with broad geographic distribution and tested it in multi-location field trials across Germany over three years. The genotypic response to the variation in the climatic parameters depending on location and year uncovered the effect of photoperiod and spring temperatures in accelerating heading date in higher and lower latitudes, respectively. Spring temperature dominates other factors in inducing heading, whereas the higher amount of solar radiation delays it. A genome-wide scan of marker-trait associations with heading date detected two QTL: an adapted allele at locus TaHd102 on chromosome 5A that has a consistent effect on HD in German cultivars in multiple environments and a non-adapted allele at locus TaHd044 on chromosome 3A that accelerates flowering by 5.6 days. TaHd102 and TaHd044 explain 13.8% and 33% of the genetic variance, respectively. The interplay of the climatic variables led to the detection of environment specific association responding to temperature in lower latitudes and photoperiod in higher ones. Another locus TaHd098 on chromosome 5A showed epistatic interactions with 15 known regulators of flowering time when non-adapted cultivars from outside Germany were included in the analysis.

See https://link.springer.com/article/10.1007/s00122-022-04152-6

Fig.1: HD scoring based on winter and spring reference dates. a: Schema showing the seasonal control of heading in temperate wheat (winter type). After sowing in autumn, the plant vernalizes and the vegetative apex is growing slowly over winter and short days. Flowering time is delayed to protect the floral organ to be damaged because of cold (frost). When the days lengthen in spring, the vegetative apex transits into the reproductive apex, which indicates the inflorescence initiation as a response to favorite conditions of ambient temperature and long days. b: Reference dates corresponding to the first day from which growing degree day (GDD) kept being positive until the day of reaching the heading stage BBCH58 in each location*year. Abbreviations: Feb: February, Mar: March, Apr: April. c: The cold periods (in days) calculated from 1st January until the first day from which growing degree day (GDD) kept being positive until the day of reaching the heading stage BBCH58 in each location*year