1693:
Abscisic Acid, Ethylene, and Polygalacturonase Are Involved In Young Fruit Abscission Induced by NAA and Shading In ‘Golden Delicious' Apples

Tuesday, July 28, 2009: 3:45 PM
Chouteau (Millennium Hotel St. Louis)
Hong Zhu , Alson H. Smith, Jr. Agricultural Research and Extension Center, Virginia Polytechnic Institute and State University, Winchester, VA
Rongcai Yuan , Alson H. Smith, Jr. Agricultural Research and Extension Center, Virginia Polytechnic Institute and State University, Winchester, VA
Expression of genes for abscisic acid (ABA) biosynthesis, ethylene biosynthesis, ethylene perception and cell wall degradation in fruit and fruit abscission zones was studied in relation to young fruit abscission after treatment with Naphthaleneacetic acid (NAA) at 15 mg·L-1 and shading in ‘Golden Delicious’ apples (Malus x domestica). Both NAA and shading enhanced fruit ethylene production and young fruit abscission. NAA enhanced the expression of 1-aminocyclopropane-1-carboxylate (ACC) synthase genes (MdACS5A and MdACS5B), whereas shading increased MdACS5A and MdACS5B expression in fruit abscission zones but not in fruit cortex. Both NAA and shading increased the expression of ACC oxidase gene (MdACO1) in fruit cortex and fruit abscission zones. Ethylene receptor genes (MdETR1a, MdETR1b, and MdERS1) were up-regulated by shading in fruit cortex and fruit abscission zones. NAA increased the expression of MdETR1a, MdETR1b, and MdERS1 in fruit cortex but had a little or no effect on their expression in fruit abscission zones. The expression of genes related to cell wall degradation (MdPG2) and ABA biosynthesis (MdNECD1) in fruit abscission zones was increased by NAA and shading. Our results suggested that ABA and ethylene biosynthesis is involved in young fruit abscission caused by NAA and shading in ‘Golden Delicious’ apples.
See more of: Crop Physiology/Physiology: Fruit Crops
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