Effects Of Shaded On Morphology Structure And Gene Expression Of Trichomes Of Flue-Cured Tobacco

In order to analyze the effects of light intensities on trichome, taking the flue-cured tobacco K326 potted as experiment materials, we studied the morphology structure, secretion content, gene expression and so on under shade and natural light in developmental process of tobacco leaf. The main results as follows:1.Effect of shade on trichome densityAs the development of tobacco leaves, the trichome density in natural light treatment and shade treatment showed downtrend. However, the trichome density in shade treatment showed fewer than that of natural light, and the difference of trichome density between natural light and shade was very significant in every growth stage.The results indicated light intensities played important role on occurrence of trichome, and shade treatment didn’t helpful to the occurrence of trichome.2. Effect of shade on the trichomes development and chlorophyllUnder shaded conditions, the cell inclusion of trichomes is less than which under natural condition, indicating that the weak light influenced the development of trichomes.By fluorescence microscope observation, the Chlorophyll fluorescence in trichomes’ head cells changes regularly. In the growth and development period the, chlorophyll fluorescence in trichomes head cells under shaded is brighter than which under natural light. In secretory period, the chlorophyll fluorescent light of trichomes cell were gradually disappear in natural light, but were still evident under shade conditions. These results showed that weak light was helpful to synthesis and accumulation of chlorophyll in early period, but inhibited the degradation of chlorophyll in latter period.3.Effect of shade on ultrastructure of trichomeUnder natural light conditions, the thylakoid membrane of chloroplast disappeared and osmiophilic globules accumulated in secretory period.Under shade, the cytoplasm was more rarefied, the structural of chloroplast was integrated, the membrane structure of thylakoid was clearly visible, the black osmiophilic particles was less and smaller. It could be speculated that the shade affected thylakoid membrane of chloroplast degradation, as well as the accumulation of osmiophilic matter; the content of trichomes secretions was less than under normal light conditions.4.Effect of shade on the secretion content of trichomeDuring the leaves mature, the content of the duvatriene diol in the trichomes secretions presented inverted V-shaped trend in different light conditions and were significantly lower in shaded conditions than that in natural light conditions, and the differences reached extremely significant level by significant analysis. It could be speculated that the shade might lead to disruption of the trichomes development and reduced ability of secrete.5.Effect of shade on gene expression of trichomeShade had some influence on gene expression in trichomes.There were 1204 genes detected by the gene chip.There were 268 differentially expressed trichomes genes found by gene chip under shade. There were 119 higher expressed trichomes genes under shade which mainly concentrated in the chloroplast development, photosynthesis-related genes, and the corresponding stress and defense-related genes. There were 149 lower expressed genes which were mainly concentrated in terpenoid metabolism and carbon metabolism. There were 57 genes were unknown functions, and the different expression of these genes was closely related to light intensities.