The Functional Verification Of GIS Family Genes In Tobacco

Trichome is a specialized structure developed from epidermal cell which located on the surface of aerial parts of many higher plant species. Development of root hair and epidermal cell of Arabidopsis is the model system to study cell development in plants. The GIS (GLABROUS INFLORESCENCE STEMS) gene controls inflorescence trichome initiation through gibberellin signaling whereas GIS2played partially redundant and essential roles in inflorescence trichome initiation and mainly regulates trichome initiation on flower by integrating GA and cytokinin signallings. Overexpression of ZFP6resulted in more trichomes on carpels and other inflorescence organs. ZFP6loss-of-function mutants exhibit a reduced number of trichomes on sepals and lateral branch, in comparison to wild-type plants. Moreover, loss of ZFP6function results in short and less root hairs. Tobacco leaf and stem are covered by epidermal hair which can be cataloged into two types:glandular trichome and non-glandular trichome. Aroma of tobacco is from the fragrant compounds produced by glandular trichomes. The high density of trichomes is considered as the potential for the high content of the fragrant compounds. Diterpenoids are the main components of tobacco leaf extracts, including labdanoids and cembranoids.By using overexpression constructors of GIS, GIS2, ZFP6constructor and promoter-GUS fusion constructor, we obtained the species of tobacco with high density of trichomes with the overexpressions of GIS, GIS2, ZFP6genes. After analyzing these transgenic tobacco lines, we have found the following results:1. Over-expressioned GIS and its homologous gene GIS2, ZFP6can increase the formation of glandular trichomes in tobacco leaf.2. With the construct of promoter:GUS fusions, the results show GIS, GIS2, ZFP6are mainly expressed in glandular cells of Tobacco.3. The contents of L-Nicotine and Cembratrien-diol which is a precursor essential for aroma in the overexpressions of GIS and ZFP6transgenic tobacco lines are significantly higher than in the control plants. However, the contents of long chain menthanes such as Hexacosane and3,4-Dihydro-2H-1,4-ethanoquinoline are not significantly different between the overexpressor and the control. Thus, we could conclude that the overexpressors of GIS, GIS2and ZFP6transgenic lines could have a sharper and richer taste than the control.