Effects Of Gradually Drought On Physiological Indeces Of Seeding In Tree Peony And Cloning With Sequence Analysis Of Ga20-ox Synthesis Of Tree Peony

Seedings in Paeonia ostii'Feng Dan'were used as material to study the changes of physiological indeces, such as chlorophyll content, photosynthesis, CAT activity. Meanwhile, taking Paeonia suffruticosa'Luoyanghong'as experiment materials, the study cloned partial fragments of GA20-oxidase gene, which is helpful for obtaining the whole cDNA and understanding the role of GA in tree peony growth and development. The main results are as follows:1. Chlorophyll content increased then decreased with the intensification of draught. In contrast to non-drought, chlorophyll content maximized under mile drought increasing by 18.6% and minimized under severe drought decreasing by 51.2%. Pn, Ci and Gs were all declining and at the lowest volume under severe drought, seperately going down by 88%, 78.6%, 89.4% compared to non-drought. Tr increaced then decreaced. After peak volume under moderate drought Tr droped by 50% under severe drought conpared to non-drought. The changes showed that photosynthesis of seedings was restrained to some degree. CAT activiity changes deffirently in roots and leaves. In leaves, it rised then droped with the intensitification of draught but increased on the whole under drought stress compared to non-drought. In roots, CAT activity brought do gradually and the study needs to be more further.2 . Designing specific primers PSGA20-1 and PSGA20-2 according to the nucleotide sequence of GA20-oxidase of Paeonia suffruticosa'Luhehong'( the accession number in GenBank is EF607139), a partial fragment of GA20-oxidase were amplificated from Paeonia suffruticosa'Luoyanghong'named PSGA20-ox. The length of the nucleotide was 186bp which encoded 61 amino acids.3.The partial amino acid fragment of PSGA20-ox being blasted with the GA20-ox amino acid fragments of tree peony (EF607139.1), poplar (XM₀02307005.1), grape (DQ508817.1) and pea (X91658), bean (PVU70530), cotton (AY895169), it was found that the homologies all aimed to 70%. Then GA20-ox phylogenetic trees were constructed according to homologous analytic results, and it indicated the tree peony had the closer genetic relationship with populus etc. and farer with grape etc.4,Undertaking conservative domain-search in the amino acid sequence of PSGA20-ox of NCBI, the paper found that the sequence greatly homologized with 2OG-Fe(II) oxygenase superfamily, and the E-value was 2e-23, which contained 86 amino acids from the 77th to the 162nd of the cloned amino acid sequences.