The Relationship Between The Effect Of Light Regulation And Expression Of Melanin Synthesis Genes From Setosphaeria Turcica

Setosphaeria turcica can penetrate the corn tissue through the mechanical pressure of the appressorium that generated from conidia.Except the appressorium pore, melanin accumulates around the appressorium in the final stage of its formation, the melanin layer can serve as an effective selective permeability barrier, which can generate high turgor pressure accumulate in the appressorium.With the help of the strong turgor, the appressorium can generate sufficient mechanical force to drive the infection thread to penetrate the host epidermis.Light influences numerous developmental and biochemical processes in fungi. The fungus could identify its environment by the help of the light, which is different from the light can be a source for the plant.Through this stimulation of light, fungus could change its growth, morphology, reproduction, gene expression and metabolism. The objectives of this research were to characterize the influence of light on growth ,conidiation and pathogenicity and associated gene expression in the plant pathogenic ascomycete, Setosphaeria turcica.In order to understand the developmental mechanism that is regulated by light and how the environmental factors can control the growth and development of the fungus, explore the interaction between the pathogen and the host furtherly, research the new type of fungicide and the new method , new way of plant disease control, this paper study the biological characteristics, the change of spore yield, pathogenicity and the change in fitness by the strain 01-23 treated with different intensities and quality UV irradiation.A comparative analysis of the cultures grown for the different irradiation treatment and dark incubated was performed. Cultures grown under NUV light were significantly changed in color and appearance: lower colony, mycelium dense, aerial mycelium small, colony color dark gray black While other treatments had no obvious differences between wild-type strainThe study of the influence of light on conidiation in maize was carried out with microscope and haemocytometer.Determination of sporulation (Figure 2), Statistical analysis showed that UV irradiation significantly higher than conidiation without the light of the wild-type strain 01-23 whose sporulation of 2 to 3 times,While other treatments had no obvious differences between wild-type strain.The Pathogenicity analysis showed that it has an increased virulence after UV irradiation and the fitness are also higher than the wild type strain without a light..While the other light irradiation treatments and no light infection of wild-type strains formed similar numbers of spot, lesion area .To elucidate the reasons of these phenomenon furtherly, semi-quantitative RT-PCR and Northern Blot technique are used in this study to identified the melanin synthesis-related genes and the conidia formation of regulatory genes in different light intensity, light quality expression under the Action variation.1. Semi-quantitative RT-PCR and Northern Blot techniques are used to identify Corn melanin synthesis genes Stscd, St3hnr, St4hnr and the melanin synthesis-related gene Stmr , these genes are treated with UV irradiation in order to explore the different expression quantities and expression rules.These changes are obvious in genes Stscd and Stmr, the expression quantity of the melanin synthesis gene Stscd which is irradiated with UV light has a significant increase in 45mins and reached the peak in 1 h, then began decrease; besides this change was same in gene Stmr, the expression quantity of Stmr has a significant increase.But when it comes to the gene St3hnr and St4hnr, these changes are not obvious.2. The expression quantity of the melanin synthesis enzyme gene Stscd which is irradiated with different radiation quantity(100 J/m2,250 J/m2,500 J/m2,800 J/m2,1000 J/m2,1200 J/m2,1500 J/m2) but the same time(1 h) is detected by Northern Blot, it is found that the light intensity is proportional to the expression quantity of Stscd .3. The expression quantity of the gene Stuvi which controlled the formation of the conidia is detected by semi-quantitative RT-PCR and Northern Blot after irradiated with UV light.The results show that the expression quantity has a significant increase and this may be the reason why the Sporulation Quantity is increased, this increase can enhance the pathogenicity of the pathogen.4. Quantity One (Bio-Rad) analysis and comparison of Stuvi and Stscd, St3hnr, St4hnr, Stmr, the results show that after UV irradiation treatment turcicum Stuvi expression was higher than any of melanin synthesis genes expression, suggested that this gene was light-sensitive gene in the pathogenesis of light regulation .