Title: Differentially expressed drought-responsive genes in Malus sieversii roots may contribute to this species' adaptation to arid environments Authors
Submitted to: Meeting Abstract
Publication Type: Abstract Only
Publication Acceptance Date: April 25, 2014
Publication Date: N/A
Technical Abstract: Understanding naturally evolved adaptation to arid climates may be a key factor in developing crops that can thrive during extreme climate fluctuations. Malus sieversii (Ledeb.) M. Roem. is a wild apple species that has adapted to harsh environments in Kazakhstan, including extreme cold and dry regions. It is also believed to have contributed to the origin of our domesticated apple, Malus H domestica (Borkh.), and as such could be a compatible source of unique genes for developing abiotic stress resistance in economically important cultivars. We clonally replicated a water use efficient (WUE) line of M. sieversii (GMAL3975.k), and a cultivar somewhat less WUE (‘Royal Gala’), and subjected them to a simulated drought (40 percent of full pot weight) or a well-watered regime (90 percent equal to full pot weight) for two weeks. Total RNA was extracted from roots and used as a template in quantitative RT-PCR (qPCR) reactions. Six drought-responsive genes in apple roots were analyzed. Four genes (a cell death protein gene, a COR15-like dehydrin, a 70 kD heat shock protein and a clp protease) did not show any changes in expression between well watered plants and drought treatment. In addition, there were essentially no differences in expression between GMAL3975.k and ‘Royal Gala’ roots whether or not they were subjected to drought. In contrast, an aquaporin gene was considerably downregulated (greater than 10-fold) in GMAL3975.k roots in response to drought, but not essentially different in ‘Royal Gala’ drought-treated and well-watered roots. In contrast, a leucine zipper homeobox gene was two-fold upregulated by drought in the M. sieversii line compared with ‘Royal Gala’ where there was little difference between controls and treated plants. Both genes have been associated with drought responses in other plants, but this is the first report of naturally-evolved changes in gene expression contributing to drought adaptation.