Morphology, Ultra Structure And Gene Expression Profiles Studies Of Tobacco Leaf Trichome

In order to understand the potential mechanism of tobacco trichome contributing to the tobacco aroma, taking the flue-cured tobacco K326 as experiment materials, this paper studied on the morphology, structure and the result of gene expression of flue-cured tobacco trichome in different development stages and different soil moisture stress, which were planted in experiment field and pot of Henan Agricultural University during 2006 and 2007, the primary results was the following:1. The sudies of different stages on the morphology, structure of tobacco leaf trichomeChloroplast structure and chlorophyll content of the tobacco glangular trichome during development were investigated through electron microscopic observation and autof1uorescence microscopic observation. At the beginning of the development, weak autof1uorescence was appeared in the head cells of trichome with dense cytoplasm, and the chloroplast grana lamellae could be seen clearly. With the elongation of the leaves, the growth and proliferation of the trichome head cell , autof1uorescence became stronger. The number of chloroplasts increased, and the osmiophilic materia formed. When the morphological development was accomplished, the head cell maintained its number stable, and the autof1uorescence became weaker and weaker. In the chloroplast, thylakoid structure disappeared, and osmiophilic materia increased. Afterwards ,in the active secretion stage, the chloroplasts gradually disappeared, and lipophilic materials were dispersed in the vacuole, and were processed and transferred to the plasmalemma.2. Effects of water stress on leaf trichome morphology and structure of trichomesSoil moisture lack or abundance had great influence on chlorophyll fluorescence of trichomes and ultrastructure of trichome head cells. At maturity stage, because of the soil continuous drought stress, the morphology and structure development of trichomes were inhibited by water stress (soil moisture content in the field 40%±5%) compared with adequate water (moisture content of soil in the field 80%±5%, CK) ,and chlorophyll fluorescence was weaker than CK. During the same period, the trichome head cells by water stress secreted earlier than CK.3. Effects of water stress on gene expression of trichomesThere were 75 differently expressed genes under different drought stress condition, in which 47 appeared to be up-regulated and other 28 appeared to be down-regulated. In up-regulated genes(drought stress treatment trichomes), the significant differences mainly focused on the defense system, secondary metabolism, signal transduction protein genes and protein kinase genes. In down-regulated genes (water sufficient treatment trichomes), the significant differences mainly focused on protein genes which were related to the growth process. In addition, 19 novel genes were also detected, their different expression might also be associated with water stress-induced.