Performance Story: A Comparative Genomics Approach to Improve Doubled Haploid Breeding for Common and Durum
In order to support a demand for increasing wheat yields, improvement of existing breeding tools is necessary. Isolated microspore culture (IMC) is one such tool that has the potential to rapidly accelerate breeding efforts. The goal of this project has been to increase productivity of the IMC-mediated doubled haploid (DH) production pipeline in wheat. Trichostatin A (TSA), an inhibitor of repressive epigenetic marks, has a demonstrated role in promoting embryogenesis and green plant production in wheat through IMC. Addition of TSA to our culture media, significantly improves the IMC method and the current project builds on this success by utilizing comparative genomics to identify genes important for the success of IMC and plant regeneration using TSA. Cells at different stages of regeneration after treating with or without TSA in common wheat, triticale and barley have been compared for a common transcriptional response. A comparative genomics approach to analyzing the transcriptome has allowed us to see a universal response and key pathways involved in inducing embryogenesis. Our results show that a cold treatment of isolated tillers is important for priming microspores to respond to TSA application post-isolation. As microspores adjust to cold pre-treatment, their chromatin changes to an apparently more open state allowing more genes to be expressed once isolated. Several thousand genes are activated and help push microspores to a nuclear state that is more conducive to embryogenesis following cold and TSA treatment. This work has identified the genes involved in priming microspores for improved DH production. Prior to this work, very little was know about how cold and TSA application improve wheat androgenesis. The list of genes identified in this study provide a foundation for further studies aimed at targeted modulation of gene expression and improvements to the IMC method of DH production.