The Resistance Functional Studies Of The Xanthophyll Cycle Gene VDE In Cerasus Humilis

Cerasus humilis belongs to Rosaceae cherry fruit trees,which is known as calcium fruit because of its high calcium content in fruits.The C.humilis fruits were edible,and kernels can be used as medicine,while stems as animals feed and woven goods.Specially,C.humilis showed a strong drought resistance.Cerasus humilis can avoid stress damage during drought or rainy season,showing a promising plants to be developed and utilized further.However,it is susceptible to stresses in seeding stage of C.humilis.The xanthophyll cycle exists in higher plants and green algae,which is considered to function as protecting plant photosynthetic apparatus from the damage of excessive light.At present,the researches of violaxanthin deepoxidase(VDE),which is a key enzyme in xanthophyll cycle,mainly concentrate on the pattern of model plants.The reports of VDE in trees are very rare.The functions of VDE may vary in different plants.Therefore,we first constructed the plant expression vector of ChVDE,and then transformed into Arabidopsis thaliana,so that to further explore the role of ChVDE.The main results are as follows:1.The full-length of ChVDE gene(KM504154)in C.humilis contained 1803 base pairs.The open reading frame(ORF)contained 1446 base pairs,coding 481 amino acids.It’s calculated molecular mass and theoretical pI was 54.4kD and 5.57,respectively.The comparison of amino acid sequence and phylogenetic tree indicated that it had high homology with species such as Pyrus x bretschneideri,Malus x domestica,Prunus persica and Prunus mume,etc.Phylogenetic analysis also indicated that ChVDE showed the highest similarity with Camellia sinensis and Citrus sinensis.2.We constructed the vector of 35S: ChVDE-GFP by Gateway,and then transformed into wild-type(WT)and VDE mutant(npq1-2)Arabidopsis plants,respectively,with the floral dip method.We successfully gained 3 ChVDE overexpression(OE)lines and 4 ChVDE complement expression(CE)lines.Subcellular localization analysis showed that ChVDE was located at the chloroplast and also been observed around the stomatal guard cell edge,speculating that VDE involved in photosynthesis in the stomatal opening and closing.ChVDE OE-1 line showed more vigorous root growth and higher levels of free proline content than wild type(WT)and npq1-2 plants.3.The results showed that the epoxidation rate of OE-1 was significantly higher than other lines,and the net photosynthetic rate,epoxidation rate and total respiration rate also showed the strongest drought-resistant ability totally,while the mutant showed more susceptible to abiotic stress,based on the analysis of WT,npq1-2,ChVDE OE-1,and ChVDE CE-3 lines under drought and salt stresses.In conclusion,the results indicate that ChVDE plays a positive role in the response to drought and salt stresses in plants,which can provide some guidance for genetic improvement of woody plants to stress telerance.