Isolation of genes specifically involved in hyponastic growth in Rumex palustris during ethylene treatment.

Due to physical entrapment, Rumex palustris accumulates ethylene in response to complete submergence. Recently, our research has shown that this gaseous plant hormone plays a critical role in the induction of hyponastic (upward) growth and petiole elongation in submerged R. palustris. These adaptive responses allow survival of the plant by bringing the leaf tips above the water surface and thus re-establishing gas exchange. The full response to submergence can be mimicked by treating plants with 5 ppm ethylene. Hyponastic growth starts one hour after the onset of ethylene treatment and is completed after 6 hours. The kinetics of hyponastic growth depends on the initial angle of the petiole at the time of the start of the ethylene treatment. Manipulation of petiole angles revealed that petioles with an initial angle of 70 degrees and above do not show hyponastic growth as a response to ethylene anymore. However, plants are still capable of petiole elongation. To identify genes specifically involved in the hyponastic response we employed a DNA subtraction method. For this purpose we prepared cDNA from mRNA isolated from non-manipulated (initial angle 30 degrees) petioles (hereafter called the 30 pool) and manipulated petioles (70 degrees, no more hyponastic growth, hereafter called the 70 pool) after 2 h of ethylene treatment. Two-way subtraction of these pools identified five genes in the 30 pool that were not expressed in the 70 pool, and three genes in the 70 pool that were not expressed in the 30 pool. The genes were cloned, sequenced and are now under further investigation.

کلیدواژه ها:

Rumex palustris Sm. ، Ethylene ، hyponastic growth ، subtraction