2009 Annual Report
1a.Objectives (from AD-416)
This project will address in oat, one of our important cereals, the needs for an understanding of the molecular/structural organization of its large complex genome, means to effectively identify and manipulate more durable race non-specific quantitative resistance to its major disease, crown rust, and the development of new biotic and abiotic stress resistance germplasm in elite agronomic backgrounds through the following objectives: Objective 1: Characterize the complex segmental homoeologous structure of allohexaploid cultivated oat through molecular marker analysis of monosomic and nullisomic chromosome-deficient stocks. Objective 2: Identify and map key genes (quantitative trait loci or QTLs) for important traits, particularly race non-specific crown rust resistance, by developing and phenotyping mapping populations and employing new molecular markers (EST-SSR and DArT). Objective 3: Develop cultivated oat germplasm with introduced biotic and abiotic stress resistance and high-value traits through introgressing crown rust resistance from wild oat species, exploring heat stress and disease resistance from genes introduced by crosses with corn, and evaluating high-value trait sources through coordination of regional spring oat nurseries.
1b.Approach (from AD-416)
Monosomic (single chromosome deficient) oat plants needed to complete a full series of 21 lines each deficient for a different oat chromosome will be identified cytologically and with molecular markers among derivatives of oat x corn crosses. Molecular marker linkage groups will be assigned to chromosome using these monosomic lines to develop a comprehensive genomic map for cultivated oat. The QTL identification of race non-specific (partial) crown rust in oat germplasm MN841801-1 will be enhanced with additional field and molecular marker data including the use of new DArT markers, and the effectiveness of marker-assisted selection will be tested for efficiency and effectiveness in transfer of the resistance QTLs into other oat backgrounds. New oat crown rust resistance genes will be introgressed into cultivated oat from wild oat species. Previously produced oat lines containing segments of corn chromosomes will be further developed and evaluated for possible enhanced heat tolerance and disease resistance. Coordination of cooperative regional spring oat performance nurseries will be used to identify optimal current oat genotypes for use as parents in crosses for introgressions and germplasm enhancement.
The third and fourth rounds of crossing of derived lines from a hybrid made between a cultivated oat variety 'Ogle' and a wild oat line Avena strigosa (PI 258731) were made toward transfer of resistance to the fungal pathogen oat crown rust from the wild oat line to cultivated oat. The resistance gene found in this wild oat line is unique in that plants with the gene are susceptible to the rust pathogen as young seedlings but develop resistance to all current races of the pathogen as the plants grow older. This resistance is effective in the Upper Midwest because rust epidemics do not develop until later in the oat-growing season. It is hoped that this novel type of adult plant resistance will be more durable or longer lasting than the normal types of resistance genes. Previous resistance genes used have become ineffective within a few years after cultivars with them are released due to shifts in virulence patterns in the rust population.
Resistance to the oat crown rust pathogen has recently been identified in several lines of another wild oat species Avena barbata. Initial crosses of six of these lines were made to the cultivated oat variety Ogle, and two subsequent backcrosses of the derivatives were completed in attempts to introduce additional new crown rust resistance genes into cultivated oat.
Phillips, R.L., Rines, H.W. 2009. Genetic Analyses with Oat-Maize Addition and Radiation Hybrid Lines. In: Bennetzen, J.L., Hake, S., editors. Handbook of Maize: Genetics and Genomics. Volume II. New York, NY: Springer Science + Business Media, LLC. p. 523-538.