|Norelli, John (jay) - Jay|
|Farrell, Jr, Robert|
Submitted to: Biomed Central (BMC) Plant Biology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 5/6/2014
Publication Date: 6/24/2014
Citation: Bassett, C.L., Baldo, A.M., Moore, J.T., Jenkins, R.M., Soffe, D., Wisniewski, M.E., Norelli, J.L., Farrell, Jr, R.E. 2014. Genes responding to water deficit in apple (Malus × domestica Borkh.) roots. Biomed Central (BMC) Plant Biology. 14:182. Interpretive Summary: Crop damage due to drought episodes can result in the loss of millions of dollars to American agriculture. Fruit trees subjected to prolonged drought periods in orchards without irrigation can suffer decreased production due to flower or fruit loss, and can also experience long term consequences due to greater susceptibility to disease and insect damage. The current study was designed to identify genes responding to a simulated drought in young apple trees. Some genes common to other crops were identified, and a few genes uniquely affected in apple were characterized in more detail in different organs and during recovery from drought treatment. A gene encoding a protein for nitrate uptake was elevated in roots and may be a consequence of low nitrate availability during drought. A gene encoding a protein involved in defense against pathogens was suppressed in leaves, but significantly elevated in drought-treated roots. This is the first report of the expression of these genes in roots under water deficit. Such information can be exploited to develop varieties with superior resistance to drought and disease.
Technical Abstract: Individual plants adapt to their immediate environment using a combination of biochemical, morphological and life cycle strategies. As long-lived perennials, this is especially true for woody plants which cannot rely on annual life cycle strategies alone to survive abiotic stresses. In this study, we followed the expression of genes in the roots of ‘Royal Gala’ apple responding to a simulated drought and subsequent recovery. Suppression subtractive hybridization (SSH) was used as an approach for identifying and isolating genes both up- and down-regulated during water deficit treatment and recovery. In agreement with studies from both herbaceous and woody plants, a number of common drought-responsive genes were identified, as well as a few not previously reported. Three genes were selected for more in depth analysis: a high affinity nitrate transporter (MdNRT2.4), a mitochondrial outer membrane translocase (MdTOM7.1), and a gene encoding an NPR1 homolog (MpNPR1-2). Quantitative expression of these genes in apple roots, bark and leaves was consistent with their roles in nutrition and defense.