Untitled

Abstract

Analysis of genes controlling flowering time (heading date) contributes to our understanding of fundamental principles of plant development and is of practical importance because of the effects of flowering time on plant adaptation and crop yield. This review discusses the extent to which plants may share common genetic mechanisms for the control of flowering time and the implications of such conservation for gene isolation from the major cereal crops. Gene isolation may exploit the small genome of rice in map-based approaches, utilizing the conservation of gene order that is revealed when common DNA markers are mapped in different species. Alternatively, mechanisms may be conserved within plants as a whole, in which case genes cloned from the model dicot Arabidopsis thaliana provide an alternative route.

Segmental chromosomal duplications harbouring group IV CONSTANS-like genes in cereals

“…Wheat and barley carry colinear vernalization response (VRN) loci that promote flowering, predominantly in response to low temperature (Laurie 1997). In barley, VRN-H2 is located on the long arm of chromosome 4H (Laurie et al 1995).…”

Impact of Growth Habit and Architecture Genes on Adaptation and Performance of Bread Wheat

“…Sufficient information is now available on the effect of eps genes in determining flowering time of wheat. Genetic analyses show that these loci have been mapped only as QTL effects rather than major genes because of their relatively small effect [1,6]. This makes it difficult to undertake a comparative analysis of eps effects with confidence.…”

“…A detailed mapping in bread wheat has detected eps loci on chromosomes of homologous group 2 and on the short arm of chromosome 3A [65,66]. A locus on chromosome 2B is orthologous with the eps2 gene in barley (Hordeum vulgare) [6,11,64], whereas the one on chromosome 3A is orthologous with the Eps-3Am gene in einkorn wheat (Triticum monococcum) [67]. The locus on chromosome 3A has been reported to also have significant effects on plant height, thousand kernel weight, and number of grains per plant [66].…”

“…The locus on chromosome 3A has been reported to also have significant effects on plant height, thousand kernel weight, and number of grains per plant [66]. However, no eps genes have been cloned as yet in bread wheat [12,68] as compared to barley [6,61,69] and einkorn wheat [67]. More than 90 QTL for heading date, with most of them believed to play a role in fine-tuning flowering time, have been reported to be spread over almost the entire wheat genome [62,70].…”

“…The duration of the life cycle of bread wheat is controlled by numerous genes, including those associated with seed germination, vegetative growth, flowering time, seed maturation, and seed dispersal [6]. These processes form the foundation of the reproductive strategy of flowering plants.…”