"Deviating from the beaten path: barley microspores as a system to study embryogenesis, DNA damage and recombination"

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In some plants, it is possible to alter the fate of an immature microspore, a cell normally destined to become a pollen grain, such that it starts to divide and develops into an embryo and, eventually, a normal plant. Initially, such plants are haploid, i.e. they have only half the normal number of chromosomes and are sterile at flowering. In barley, however, more than 2/3 of such haploid plants undergo a spontaneous chromosome doubling that restores their ability to produce seed. Such doubled haploid (DH) lines are used in breeding programs to accelerate the speed with which new varieties can be developed. Despite being in use for over 30 years in barley, we have very little understanding of androgenesis, the process by which a microspore can be reprogrammed to develop into a plant. One can certainly hypothesize that this change must occur through a comprehensive genetic reprogramming that switches off the genes that would lead to pollen formation and to reinitiate the program that allows a single cell to undergo an orderly succession of cell divisions and differentiation leading to an embryo and eventually a new plant. The aim of this program is to investigate androgenesis in barley by using the most powerful technologies to describe epigenetic changes in the barley genome as well as changes in the set of mRNAs or small RNAs that occur in response to treatments known to induce androgenesis in immature barley microspores. In addition, we wish to investigate two other phenomena observed during androgenesis in barley: 1) the occurrence of albino plants and 2) the occurrence of unusually strong segregation distortion in doubled haploid progeny. The proposed work aims to exploit a range of extremely powerful technologies that are becoming accessible in barley thanks to the imminent completion of a draft genome sequence for the barley genome. The knowledge acquired through this research will allow further improvements to the production of DH lines for breeding purposes and allow Canadian breeders to accelerate the pace of innovation in developing new and improved varieties for Canadian farmers.