Impact Of Inhibitors On Physiological Parameters Under Drought Stress And The Preliminary Study On VDE Gene In Cerasus Humilis

Xanthophyll cycle plays an important role in protecting plants against stress. Under drought and highlight, plants can dissipate energy through xanthophyll cycle, which protect the photosynthetic organ from damage. Violaxanthin de-epoxidase(VDE) and zeaxanthin epoxidase (ZEP) are two important enzymes in xanthophyll cycle, and their specific inhibitors are dithiothreitol (DTT) and glucosamine (Gla), respectively. We studied the impact of these two inhibitors on Cerasus humilis (Bge.) Sok seedlings, by assaying some physiological parameters such as photosynthesis, chlorophyll fluorescence parameters, chlorophyll content and the de-epoxidation state (Z+0.5A)/V+A+Z under drought stress. Then we cloned the cDNA of VDE and constructed an efficient plant expression vector, pGWB17-VDE by using the techniques of molecular biology. Furthermore, we obtained over-expression plants of VDE by using agrobacterium-mediated transformation. The main results are as follows:1. Xanthophyll cycle was blocked and (Z+0.5A)/V+A+Z was decreased by applying DTT and Gla on C. humilis seedings. Also, photosynthesis and stomatal conductance were decreased and dissipation energy was abnormal. Eventually it resulted in the damage of photosynthetic organ. The non photochemical quenching coefficient (NPQ) and maximum photochemical efficiency (Fv/Fm) were decreased on time under treatments. But inhibitors increased the contents of chlorophyll.2.We cloned the VDE gene. The total length of VDE is 1803bp and the open reading frame is 1446bp which encodes 481 amino acids. We found that the amino acids sequence of VDE shared a similarity (about 82%) with Fragaria x ananassa by translating the full-length sequence into amino acids and carried on the multiple sequence alignment. We constructed an efficient plant expression vector, pGWB17-VDE, by using agrobacterium-mediated transformation, then we obtained over expression plants of VDE. We observed that the transgenic plants grew better compared with wild plant. Through PCR detection, we found that the expression of VDE gene in transgenic plants were higher than that in wild-type (Columbia) and VDE deletion mutant of Arabidopsis. The results may provide the platform for studying the function of VDE by using the method of reverse genetics in further.