Hybrid necrosis as a problem in handling hexaploid × tetraploid wheat crosses

Abstract

SummaryA tetraploid wheat breeding programme was initiated at the Plant Breeding Institute in 1970. Hexaploid × tetraploid wheat crosses were expected to contribute to the improvement of the tetraploid wheats but severe hybrid necrosis caused the death of the pentaploid Fxhybrid plants in most crosses. The genotypes of tetraploid wheat selections derived from crosses involving Rampton Rivet, a non-carrier of Neu were determined by test crossing to hexaploid wheat varieties which were known to carry the Neim allele. Similarly, hexaploid wheat selections which did not carry Ne2 were identified from crosses involving Maris Ranger by test crossing to durum selections which carried the Nef allele. By the careful choice of one parent, hexaploid x tetraploid wheat crosses were then made which avoided the hybrid necrosis problem. Segregation of the Ne% gene was as expected but selection for agronomic characters appeared to favour the retention of the dominant allele of the Ne1gene. Nevertheless, test crossing on a relatively small scale still identified many non-carriers.

Hybrid necrosis as a barrier to gene transfer in hexaploid winter wheat × triticale crosses

“…This phenomenon was reported as a serious problem in interspecific crosses of hexaploid wheats with tetraploid wheats (Gregory 1974(Gregory , 1980, because Ne genes are widespread in wheat cultivars and breeder lines. A few authors have also mentioned that hybrid necrosis could be a severe barrier in crossing hexaploid triticales with octoploid triticale and hexaploid wheat (Gupta and Priyadarshan 1982;Vishwakarma et al 1983;Singh et al 1987).…”

Ne2, a typical CC–NBS–LRR‐type gene, is responsible for hybrid necrosis in wheat

“…As both Ne1 and Ne2 are widespread among wheat varieties in the world, the F 1 hybrids from the interspecific or intraspecific cross frequently exhibit necrotic phenotypes (Galaiev, 2016; Pukhalskiy et al ., 2019; Si et al ., 2021). Therefore, hybrid necrosis is a serious barrier for combining desirable traits from different genotypes (Gregory, 1980; Mizuno et al ., 2010; Vikas et al ., 2013).…”