Abstract
Earliness per se (Eps) genes are reported to be important in fine-tuning flowering time in wheat independently of photoperiod (Ppd) and vernalisation (Vrn). Unlike Ppd and Vrn genes, Eps have relatively small effects and their physiological effect along with chromosomal position are not well defined. We evaluated eight lines derived from crossing two vernalisation insensitive lines, Paragon and Baj (late and early flowering respectively), to study the detailed effects of two newly identified QTLs, Eps-7D and Eps-2B and their interactions under field conditions. The effect of both QTLs was minor and was affected by the allelic status of the other. While the magnitude of effect of these QTLs on anthesis was similar, they are associated with very different profiles of pre-anthesis development which also depends on their interaction. Eps-7D affected both duration before and after terminal spikelet while not affecting final leaf number (FLN) so Eps-7D-early had a faster rate of leaf appearance. Eps-2B acted more specifically in the early reproductive phase and slightly altered FLN without affecting the leaf appearance rate. Both QTLs affected the spike fertility by altering the rate of floret development and mortality. The effect of Eps-2B was very small but consistent in that -late allele tended to produce more fertile florets.
Highlights
Earliness per se (Eps)-7D effect Eps-2B-lateEps-2B-early Eps-2B effect Eps-7D-late Eps allele CS1 RLA-I RLA-II R2 RLA-IEps-7D-late Eps-7D-early Eps-7D-late Eps-7D-early0.99 ± 0.01 [100.4] 1.12 ± 0.02 [89.3] 0.99 ± 0.02 [100.4] 0.95 ± 0.01 [105.6]0.81 ± 0.03 [123.6] 0.89 ± 0.04 [112.4] 0.69 ± 0.04 [142.9] 0.88 ± 0.03 [114.2]1.03 ± 0.01 [96.8] 1.13 ± 0.02 [88.2] 1.02 ± 0.03 [98.0] 1.08 ± 0.04 [91.9]
We evaluated the effect of Eps-7D on contrasting Eps-2B backgrounds and vice–versa on (1) phenology, determining time to anthesis and quantifying whether they mainly affect development before or after terminal spikelet (TS); (2) rate of leaf appearance; (3) dynamics of leaf, spikelet and floret primordia development; and (4) spike fertility
Specific tests of the genotypic differences in time to heading under saturating long days were not made, we assumed in principle that these genetic factors identified in chromosomes 2B and 7D are “earliness per se” (Eps) QTLs, based on the fact that they are definitively not Ppd genes and still produced significant differences in time to heading in a spring wheat background
Summary
In the present study we aimed to analyse for the first time different developmental traits as affected by two newly identified Eps QTLs on chromosomes 7D and 2B and their interactions
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