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

在某些植物中，有可能改变未成熟小孢子的命运，这种细胞通常注定要成为花粉粒，这样它就开始分裂并发育成胚胎，最终发育成正常的植物。最初，这样的植物是单倍体，即它们只有正常染色体数目的一半，并且在开花时不育。然而，在大麦中，超过2/3的这样的单倍体植物经历了自发的染色体加倍，恢复了它们产生种子的能力。此类双单倍体（DH）系用于育种计划，以加快新品种的开发速度。 尽管在大麦中使用了30多年，但我们对雄核发育的了解很少，雄核发育是小孢子重新编程发育成植物的过程。我们当然可以假设，这种变化必须通过全面的遗传重编程发生，这种重编程关闭了导致花粉形成的基因，并重新启动了允许单个细胞进行有序的细胞分裂和分化的程序，从而导致胚胎并最终形成新植物。该计划的目的是通过使用最强大的技术来描述大麦基因组中的表观遗传变化以及在已知诱导未成熟大麦小孢子雄核发育的治疗中发生的一组mRNA或小RNA的变化来研究大麦雄核发育。此外，我们希望研究在大麦雄核发育过程中观察到的另外两个现象：1）白化病植株的发生和2）加倍单倍体后代中异常强烈的分离畸变的发生。拟议的工作旨在利用一系列非常强大的技术，由于即将完成大麦基因组的基因组序列草案，这些技术在大麦中变得可用。通过这项研究获得的知识将进一步改进用于育种目的的DH系的生产，并使加拿大育种者能够加快为加拿大农民开发新品种和改良品种的创新步伐。

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.