| Dendrobium officinale is a Orchid perennial herbaceous plant and an traditionalvaluable herbal medicine of Chinese. Dendrobium officinale is facultative CAM plants[1],Its growth is very strict on the ecological environment, and relatively sensitive on lightintensity changes. The effects of sodium hydrosulfide on the chlorophyll fluorescence andantioxidant system of Dendrobium officinale under high light stress were studied,investigated physiological regulation function of sodium hydrosulfide on the CAM plants inthis paper. And used the methylation sensitive amplification polymorphism technologyresearch the change of methylation level and state in before and after the stress. Discussingcorrespond physiology mechanism of Dendrobium officinale under high light stress, aswell as the molecular mechanism of H2S regulate Dendrobium officinale in response tolight and relieve adversity stress.The results were as follows:（1）200μmol L-1NaHS could significantly promote the enzyme activity of SOD, CAT andPOD, reduce the content of MDA and relieve oxidative damage caused by strong lightstress on Dendrobium officinale, While high concentration NaHS (600μmol L-1)increased the oxidative damage.（2）200μmol L-1hydrogen sulfide treatment remission Fv/Fm drop degree on Dendrobiumofficinale under high light; High concentration (600μmol L-1) hydrogen sulfidetreatment aggravate the Fv/Fm drop degree, increasing photoinhibition phenomenon.（3） In the PCR amplification experiment,66-primer combinations were used, averageamplificated1193.5bands, each pair of primers average amplificated18.1fragments.The total methylated and full methylation ratios are differently in different treatment.The totality level of DNA methylation in different treatment is28.9%-35.4%. Amongthem, the total methylation level is19.9%-19.9%.（4） The analysis of methylation sensitive amplified polymorphism showed that, Under highlight the different concentration of NaHS (0,200and600μmol L-1), demethylation andmethylation points were75ã€93ã€78and106ã€99ã€107, respectively. So demethylationand methylation of DNA were6.4%,7.7%,6.7%and9.0%,8.1%,9.2%, respectively.T3and T5, DNA methylation levels respectively go up8.1%and8.8%, compared withthe control. Proportion of type D less than1%of the total testing locus.（5） Using66pairs of primer combination totality obtain37Polymorphism fragments which have200-500bp. Sequencing of11fragments which change is stable, found1band happened hypermethylation,3bands happened methylation, and then7bandshappened demethylation. Several variable MSAP profiles were isolated and sequenced.By Blast analysis, the relevant photosynthetic enzymes and transcription factor werefound. Sequence analysis showed that Seq2is a kind of MYB transcription factors,they broad participated in plant secondary metabolism regulation and response tohormones and environmental factors, involved in cell cycle regulation, control andregulate cell differentiation, thus plays an important regulatory role in the process ofplant being forced. Seq9is an AP2transcription factors, may be controlled variety ofgene expression which adjust the molecular responses of plants under high light stress,can effectively improve crop tolerance to adversity stress. Seq5, Seq8is ATPsynthetase gene and ATP binding protein, respectively. Their’s demethylation mayinduced gene expression, participated in oxidative phosphorylation and photosyntheticphosphorylation, relieve damage caused by strong light stress. Speculated that H2S mayby regulating methylation status on this transcription factors and functional gene, thatcaused the changes of gene expression and produced adaptive mechanism to high lightstress which relieved oxidative damage caused by strong light stress on Dendrobiumofficinale. |
