Molecular, genetic and phenotypic analysis of an early-heading mutant in diploid einkorn wheat
Final Report Abstract
Viable circadian clocks help organisms to synchronize their development with daily and seasonal changes, thereby providing both evolutionary fitness and advantage from an agricultural perspective. Fine-mapping approach combined with mutant analysis revealed a cereal ortholog of Arabidopsis thaliana LUX ARRHYTHMO/ PHYTOCLOCK 1 (LUX/ PCL1) as a promising candidate for the earliness per se 3 (Eps-3Am) locus in einkorn wheat (Triticum monococcum L.). Using delayed fluorescence (DF) measurements it was shown that Eps-3Am containing einkorn wheat accession KT3-5 had a distorted circadian clock. The hypothesis was subsequently confirmed by performing a time course study on central and output circadian clock genes, which showed arrhythmic transcript patterns in KT3-5 under constant ambient conditions. It was also demonstrated that variation in spikelet number between WT and mutants is sensitive to temperature, becoming negligible at 25°C. These observations lead us to propose that the distorted clock is causative for both early flowering, and variation in spike size and spikelet number, and that having a dysfunctional LUX could have neutral, or even positive, effects in warmer climates. To test the latter hypothesis we ascertained sequence variation in LUX in a range of wheat germplasm. We observed a higher variation in the LUX sequence among cultivars coming from the warmer climate and a unique in-frame mutation in early-flowering Chinese T. turgidum cultivar ‘Tsing Hua no. 559’. In this study on LUX ARRHYTHMO in einkorn wheat, we have provided further justification for circadian clock research in modern crops and a clear link to environmental adaptation and yield optimization. We have also shown that the most efficient route to follow can be screening for clock mutants by using the DF measurements and subsequently confirming putative mutations with the time course RT-qPCR. Further investigations are required, including those at the protein level, to bring more direct evidence for the existence and molecular function of an EC in cereal crops.
Publications
- (2012) Analysis of the earliness per se 3Am (Eps-3Am) locus in an einkorn wheat mutant (Triticum monococcum L.) revealed a link to the circadian clock. International Plant & Animal Genome (PAG XX), San Diego, CA, USA; January 15, “QTL Cloning Workshop” W601
Gawroński P, Ariyadasa RT, Poursarebani N, Himmelbach A, Steuernagel B, Stein N, Gould PD, Hall A, Schnurbusch T
- (2012) High density-mapping of the earliness per se-3Am (Eps-3Am) locus in diploid einkorn wheat and its relation to the syntenic regions in rice and Brachypodium distachyon L. Mol Breed 30: 1097-1108
Gawroński P and Schnurbusch T
(See online at https://doi.org/10.1007/s11032-011-9697-0)
