Mapping of a thermo-sensitive earliness per se gene on Triticum monococcum chromosome 1Am

Abstract

An earliness per se gene, designated Eps-A m 1, was mapped in diploid wheat in F 2 and single-seed descent mapping populations from the cross between cultivated (DV92) and wild (G3116) Triticum monococcum accessions. A QTL with a peak on RFLP loci Xcdo393 and Xwg241, the most distal markers on the long arm of chromosome 1A m , explained 47% of the variation in heading date (LOD score 8.3). Progeny tests for the two F 2:3 families with critical recombination events between Xcdo393 and Xwg241 showed that the gene was distal to Xcdo393 and linked to Xwg241. Progeny tests and replicated experiments with line #3 suggested that Eps-A m 1 was distal to Xwg241. This gene showed a large effect on heading date in the controlled environment experiments, and a smaller, but significant, effect under natural conditions. Eps-A m 1 showed significant epistatic interactions with photoperiod and vernalization treatments, suggesting that the different classes of genes affecting heading date interact as part of a complex network that controls the timing of flowering induction. Besides its interactions with other genes affecting heading date, Eps-A m 1 showed a significant interaction with temperature. The effect of temperature was larger in plants carrying the DV92 allele for late flowering than in those carrying the G3116 allele for early flowering. Average differences in heading date between the experiments performed at 16°C and 23°C were approximately 11 days (P < 0.001) for the lines carrying the Eps-A m 1 allele for early flowering but approximately 50 days (P < 0.0001) for the lines carrying the allele for late flowering. The large differences in heading time (average 80 days) observed between plants carrying the G3116 and DV92 alleles when grown at 16°C, suggest that it would be possible to produce very detailed maps for this gene to facilitate its future positional cloning.

Mapping chromosomal regions affecting flowering time in a spring wheat RIL population

“…By comparing the NW map and the International Triticeae Mapping Initiative (ITMI) map, we noted that both intervals have loci detected by markers gbxG259, KsuE11 and KsuI27 (Xue et al 2008), suggesting that QFlt.nau-1B and QFlt.nau-1D are homoeologous. Even though no flowering time QTL has been reported in the corresponding interval on chromosome 1A of common wheat, an earliness per se gene, designated as Eps-A m 1 in diploid wheat, was located between Xcdo393 and Xwg241 on the distal region of chromosome 1A m and was also closely linked to XgbxG259 (Bullrich et al 2002). Therefore, QFlt.nau-1B and QFlt.nau-1D are very likely orthologues of Eps-A m 1.…”

“…Chromosomes that carry Eps genes include 2BL (Scarth and Law 1983), 3A, 4B, 4D, 6B (Hoogendoorn 1985), and7B (Flood andHalloran 1983). Chromosome 1A m of T. monococcum and all barley chromosomes, except 1H, carry Eps genes (Laurie et al 1995;Bullrich et al 2002).…”

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

“…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].…”

Past, Present and Future Molecular Approaches to Improve Yield in Wheat

“…Börner et al [51] mapped 211 QTLs distributed over 20 chromosomes, of which they detected 64 major QTLs with a LOD score of >3.0 conferring glume color, leaf erectness, peduncle length, ear emergence time, lowering time, plant height, ear length, winter hardiness, grain-illing, grain number, thousand-grain-weight, fusarium resistance, powdery mildew resistance, and leaf rust resistance. The mapping of an earliness per se gene in wheat was carried out by Bullrich et al [52]. This gene was located between the RFLP Xcdo393 and Xwg241 on the log arm of chromosome 1A, which showed a large efect on heading date with a phenotypic variance of 0.47.…”