|Artlip, Timothy - Tim|
|DROBY, SAMIR - Agricultural Research Organization Of Israel|
Submitted to: Meeting Abstract
Publication Type: Abstract Only
Publication Acceptance Date: 9/28/2013
Publication Date: 11/15/2013
Citation: Wisniewski, M.E., Norelli, J.L., Artlip, T.S., Droby, S. 2013. Using biotechnology and genomics to improve biotic and abiotic stress in apple [abstract]. Plant and Animal Genome Conference. p. 60.
Technical Abstract: Genomic sequencing, molecular biology, and transformation technologies are providing valuable tools to better understand the complexity of how plants develop, function, and respond to biotic and abiotic stress. These approaches should complement but not replace a solid understanding of whole plant biology, if this genetic information is to truly lead to improved new cultivars. Two examples will be presented of how genetic transformation and genomic tools are being used to address critical problems facing the apple industry. The first example will demonstrate how overexpression of a CBF transcription factor in apple can be used to improve cold hardiness and alter dormancy. The results of lab studies and three years of field evaluation will be presented. The role of CBF genes in cold response and acclimation has been well documented in both herbaceous and woody plants. Our initial research demonstrated that overexpression of a peach CBF gene in ‘M.26’ apple increases freezing tolerance of non-acclimated plants and unexpectedly also results in short-day induced dormancy (Wisniewski, et al. 2010. Planta 233:971-983). Field performance of transgenic ‘M.26’ apple overexpressing a peach CBF gene (T166) and transgenic ‘M.26’ apple in which the expression of a native CBF gene was silenced (T186) has also been conducted. Results indicate that the T166 line has improved cold hardiness, reduced growth, earlier leaf senescence, and later budbreak. The reduced growth would be advantageous as ‘M.26’ is a rootstock and the delayed budbreak would help trees avoid late spring frosts, a problem that is expected to become more significant due to climate change. Preliminary data on reciprocal grafting experiments under field conditions will also be presented. In summary, it appears that overexpression of a peach CBF gene in apple has significant, long-term effects on apple physiology, development, and response to environmental cues. The second example will discuss efforts to utilize the apple progenitor species, Malus sieversii, as a novel source for biotic and abiotic stress resistance, as well as new fruit quality traits. Blue mold (Penicillium expansum) is a major postharvest disease of apple and causes significant postharvest losses in all apple-producing countries. One of the most effective and safest means to control plant diseases is the use of resistant cultivars. Blue mold resistance, however, is not a high priority in apple breeding programs due to the time required for seedlings to produce enough fruit to phenotype the trait and the absence of sources of resistance. Therefore, identification of resistance would represent a significant accomplishment. Malus sieversii PI613981, collected from the wild in Kazakhstan, is resistant to blue mold. Fruit collected from a ‘Royal Gala’ X PI613981 mapping population (GMAL4593) in 2011 and 2012 were inoculated with P. expansum and evaluated for decay at seven days post inoculation (dpi). There was a clear segregation of resistance with the mean radius of decay ranging from 0-11 mm among individual progeny. Lesion diameters observed on 101 genotypes evaluated for resistance in both years were significantly correlated (r equals 0.44, P is less than 0.001). Kruskal-Wallis analysis (MapQTL 6.0, Kyazma) indicated a significant association between blue mold resistance and DNA markers on linkage group four. Transcriptomic analysis of individual and pooled susceptible and resistant genotypes utilizing RNA-Seq is being used to identify candidate resistance genes that could be used for marker-assisted selection (MAS) and to better understand the host-pathogen interaction. Transgenic early-flowering apple plants are being used to validate the markers and to transfer resistance to economically important cultivars. These two examples demonstrate how genetic transformation and sequencing