School of Agriculture Food and Wine, The University of Adelaide, Waite Campus, Urrbrae, Glen Osmond, SA, 5064, Australia.
SARDI, Waite Precinct, Urrbrae, SA, Australia.
Planta. 2021 Jan 2;253(1):5. doi: 10.1007/s00425-020-03518-8.
Dormancy in white-grained wheat is conditioned by the cumulative effects of several QTL that delay the onset of the capacity to germinate during ripening and after-ripening. Grain dormancy at harvest-ripeness is a major component of resistance to preharvest sprouting in wheat (Triticum aestivum L.) and an important trait in regions where rain is common during the harvest period. Breeding lines developed in Australia maintained their dormancy phenotype over multiple seasons and during grain ripening, the time between anthesis and the acquisition of the capacity to germinate, dormancy release, increased in line with the strength of dormancy. Genetic dissection of two dormant lines indicated that dormancy was due to the cumulative action of between one and three major genetic loci and several minor loci. This presents a significant challenge for breeders targeting environments with a high risk of sprouting where strong dormancy is desirable. Only around half of the difference in dormancy between the dormant lines and a non-dormant variety could be attributed to the major genetic loci on chromosomes 4A and 3A. A QTL that was mapped on chromosome 5A may be an orthologue of a minor QTL for dormancy in barley. At each locus, the dormancy allele increased the time to dormancy release during ripening. In combination, these alleles had cumulative effects. Embryo sensitivity to abscisic acid was related to the dormancy phenotype of the whole caryopsis, however, changes in concentrations of abscisic acid and gibberellins in embryo sections and de-embryonated grains during ripening and after-ripening could not be linked to the timing of dormancy release.
休眠性是白粒小麦的一个重要特征，受多个 QTL 的综合影响，这些 QTL 会延迟成熟和后熟期间发芽能力的出现。收获成熟时的谷物休眠是小麦（Triticum aestivum L.）防止穗发芽的主要组成部分，也是在收获期降雨较多的地区的一个重要特性。在澳大利亚开发的育成系在多个季节和谷物成熟过程中保持其休眠表型，从开花到获得发芽能力的时间（休眠释放）随着休眠强度的增加而增加。对两个休眠系的遗传剖析表明，休眠是由于一个到三个主要遗传基因座和几个次要基因座的累积作用。这对那些针对发芽风险高的环境进行选育的育种者来说是一个重大挑战，因为在这些环境中，强烈的休眠是理想的。在休眠系和非休眠品种之间，只有大约一半的休眠差异可以归因于 4A 和 3A 染色体上的主要遗传基因座。在 5A 染色体上定位的一个 QTL 可能是大麦休眠的一个次要 QTL 的同源物。在每个基因座上，休眠等位基因都会增加成熟过程中休眠释放的时间。这些等位基因的组合具有累积效应。胚胎对脱落酸的敏感性与整个颖果的休眠表型有关，然而，在成熟和后熟过程中，胚胎切片和去胚的谷物中脱落酸和赤霉素的浓度变化与休眠释放的时间无关。
