Project Number: 8080-21000-022-00-D
Project Type: Appropriated
Start Date: May 22, 2013
End Date: May 21, 2018
1: Improve environmental stress and disease resistance in tree fruit crops. 1.A. Identify and characterize sources of fire blight resistance for use in apple scion breeding programs. 1.B. Characterize expression patterns and sequence differences of select apple drought-responsive genes in Malus sieversii lines exhibiting high and low water use efficiency. 1.C. Utilize transcriptomic and high-throughput genetic screening approaches to identify CBF-regulated and other stress-regulated genes, and characterize their functional role in stress tolerance and dormancy using transgenics and field evaluation. 2: Develop an accelerated breeding system for new tree fruit crops utilizing transgenic early-flowering lines.
Abiotic and biotic stresses play a major role in determining the economic viability of fruit crop production and postharvest quality. A single fire blight epidemic can destroy an entire young orchard and unfavorable environmental conditions, such as freezing temperatures, as well as heat and drought stress can result in significant reductions in yield, quality, and tree longevity. The overall objective of this project is to utilize genomic and molecular approaches to identify genes that convey resistance to abiotic and biotic stress in fruit crops, identify genetic markers for disease and stress resistance that can be utilized by apple breeders in marker-assisted-breeding programs, and to develop a breeding system that will facilitate the incorporation of specific traits, especially from novel genetic resources, such as Malus sieversii, into advanced selections of breeding lines. Quantitative trail loci (QTLs) and molecular markers for fire blight resistance will be developed for resistance derived from Malus sieversii and ‘Splendour’ apple. Targeted genome sequencing of the promoters of select dehydration and water use efficient responsive genes will be applied to lines of xeric-adapted Malus sieversii. Promoter analysis will identify cis-elements known to affect gene expression. Methylation differences between lines during simulated drought will be evaluated to reveal potential targets for gene regulation. The contribution of the CBF (C-repeat binding factor) family members to cold hardiness, dormancy, and growth will be evaluated. An accelerated breeding system for apple will be developed utilizing transgenic early-flowering lines to facilitate rapid integration of important genetic traits from novel apple genotypes into advanced breeding lines. The proposed research will result in the identification of genes, molecular markers, and a breeding system that can be used to efficiently develop apple germplasm with increased resistance to biotic and abiotic stress.