Genetic analysis of some flowering time and adaptive traits in wheat

Abstract

SUMMARYThe present understanding of the genetic control of flowering m wheat is reviewed. Although this information will continue to be of value in breeding and in recognizing the role such genes have had in adapting the wheat crop to global agriculture, its use in defining the processes responsible for flowering will be limited. Progress here will depend on developments in model plant systems such as Arabidopsis, where methods for isolating genes are much more advanced than in wheat. These developments, which have already started, will probably be used to establish homologies between the genes for flowering within the cereals, as well as more widely. An understanding of the flowering process in wheat is likely to emerge from this approach. In the meantime, there are some unknowns in the genetics of flowering in wheat which need to be resolved. These include the identification of a gene(s) on the group 4 chromosomes of wheat which is homoeoallelic with the gene Sh in barley. Also, the proposed gene(s) delaying flowering and located on the group 6 chromosomes needs to be recognized and mapped. Similar needs occur for the group 1 chromosomes as well as the resolution of whether or not Vrn5 is correctly positioned on chromosome 7BS.

Segregation analysis of heading traits in hexaploid wheat utilizing recombinant inbred lines

“…The existence of a homoeologous gene on 5B to Vrn-A1 and Vrn-D1 for vernalization requirement has been suggested by Hoogendoorn (1985a). Law and Worland (1997) concluded that Vrn-B1 should be located on 5B at a homoeologous position to Vrn-A1 and Vrn-D1 by utilizing the substitution lines of CS with 5B from the Italian variety Mara. However, there were conflicting reports as to whether the Vrn gene on chromosome 5B corresponded to Vrn2 or Vrn4, which had been identified by segregation tests with the marker lines (Hoogendoorn, 1985b;Maystrenko, 1980).…”

The Edaphic Factor in the Origin of Plant Species

“…In fact, the genetic basis for many of the traits discussed above-salt tolerance (Hurkman, 1992;Taeb et al, 1992;Quesada et al, 2002), drought tolerance (Teulat et al, 1997;Haake et al, 2002;Hsieh et al, 2002), copper tolerance (Macnair, 1983;Fogel et al, 1988), and flowering-time differences (Law and Worland, 1997;McKay et al, 2003)-have already been investigated in wild or model plant species such as Arabidopsis thaliana and cereal crops or in yeast, and it will only be a matter of time before investigators apply this knowledge to their research species. Further, the genetic architecture of serpentinite tolerance is now being investigated by several groups (Bradshaw, Schemske, and colleagues;Bratteler et al, 2002) and will no doubt soon provide a much persuasive picture of the role of the edaphic factor in the diversification of plant lineages.…”

The wheat and barley vernalization gene VRN3 is an orthologue of FT

“…VRN-H3 was tentatively assigned to chromosome 1H based on its loose linkage with the morphological marker BLP (24), whereas VRN-B4 was mapped on the short arm of wheat chromosome 7B (25)(26)(27)(28). We show here that the VRN-H3 gene actually is located on barley chromosome arm 7HS and is orthologous to the wheat vernalization gene VRN-B4, which is referred hereafter as VRN-B3.…”