The Influence Of Enhanced UV-B Radiation And Salt Stress On Trichome Mutants Of Arabidopsis Thaliana

Trichome is a kind of unicellular structure that develops on the surface of most shoot-derived organs,which is differentiated from epidermal cell.Arabidopsis trichomes are widely spread on the surface of the cauline Ieaves,rosette leaves,stem,carpel,petal and so on.The presence of trichome can increase the boundary layer thickness between the epidermal tissue and the environment,and reduce heat and water loss,trichomes also help protect the plant against insect and pathogen attack by physically limiting insect access to or mobility on vegetative tissues,thus,trichome plays an positive role on the mechanisms of plant against biotic stress and abiotic stress.To better understand the effect of enhanced UV-B radiation and salt stress on plant's growth and development,as well as the relationship between trichome and the sensitivity of Arabidopsis to UV-B radiation and salt stess,we performed studies by providing supplementary UV-B radiation on Arabidopsis thaliana ecotypes and several trichome mutants such as gis,zfp8,gis2,gll,ttgl,sti,try82,gl3,gl2,35S:GIS, 35S:GIS2,and irrigating these plants with NaCl solution respectively.The major results are as follows:1.The effect of UV-B radiation on Arabidopsis morphology. Under the enhanced UV-B radiation,the growth and morphology of the two Arabidopsis ecotypes and other trichome mutants are remarkably suppressed.Compared with the control group,all the height,maximum rosette diameter and rosette leaf area of the plants are decreased to some extent.Meanwhile,trichome-increased mutants such as try82,35S:GIS,35S:GIS2, cpc are less sensitive to UV-B radiation than ecotypes,and trichome-decreased mutants such as zfp8, gis, gis2, ttg1 are more sensitive to UV-B radiation than ecotypes.2.The effect of UV-B radiation on Arabidopsis development. Under the enhanced UV-B radiation,the flowering time of Arabidopsis is delayed,suggests that the UV-B radiation has restrained the development of Arabidopsis. Trichome-increased mutants such as try82,35S:GIS,35S:GIS2, cpc show lower sensibility to UV-B radiation than ecotypes,while trichome-decreased mutants such as gl1, gis2, sti, ttgl show higher sensibility to UV-B radiation than ecotypes.3.The effect of UV-B radiation on Arabidopsis trichome density of rosette leaves. Under the enhanced UV-B radiation,the trichome number of the 9th rosette leaf was significantly increased, and the increased proportion of trichome number on zfp8 and gis rosette leaf is higher than ecotypes,while the proportion on trichome-increased mutants such as 35S:GIS,35S:GIS2 and cpc is lower than ecotypes.The results suggest a different sensitivity to the UV-B radiation between the two groups.4.The Real-time Quantitative PCR experiments show that the the increase of trichome density on rosette leaf of zfp8,gis and 35S:GIS is consistent with the GL3 gene expression level,suggesting a possible mechanism that UV-B radiation induces trichome formation by up-regulating trichome regulatory genes.We believe that Arabidopsis trichome has play an important role in the defense system of Arabidopsis to UV-B radiation.5.The effect of salt stress on Arabidopsis morphology and development.Under the salt stress,the height,maximum rosette diameter and rosette leaf area of the Arabidopsis ecotypes and mutants are significantly decreased,suggest that the salt stress has suppressed the growth of Arabidopsis.6. After irrigating with NaCl solution,the flowering time of Arabidopsis was shorten in some degree,indicating that salt stress can quicken the developmental process of Arabidopsis.7.Under the salt stress, no significant change of trichome density on Arabidopsis leaf was found,suggest that the NaCl solution treatment may not influence the formation of Arabidopsis leaf trichome.