Drought Resistant Physiological Research And Transcriptome Analysis In Flue-cured Tobacco Line LY1306

In order to cultivate the flue-cured tobacco lines with good resistance to drought and to research the drought resistant mechanisms of flue-cured tobacco,the drought resistance of a new flue-cured tobacco line LY1306 was assessed with varieties of Zhongyan100 and Hongda as the control.The physiological mechanisms and transcriptome profiles response to drought in LY1306 line under different drought treatments were analyzed.The main results are as follows:1.Compared with the control varieties,the flue-cured tobacco line LY1306 could keep good leaf status,higher SOD activity and stronger ability of osmoregulation under different PEG-6000 concentrations treatment which could simulate the drought conditions.2.The LY1306 line showed higher drought resistance under water shortage stress.The CAT activity in LY1306 leaf samples increased more than that in the control varieties under mild water shortage drought condition.Under severe drought stress,LY1306 lines also had a significant increasing of CAT activity and the content of proline.3.The LY1306 line also showed good drought resistance under repeatedly stressed by water shortage.Under the treatment the LY1306 tobacco line could also keep higher CAT activity,less accumulation of MDA,higher water use efficiency and lower transpiration rate to reduce the water lose through leaf.After repeated drought stress,the LY1306 line cloud also keep the normal morphology of chloroplasts and no obvious decreasing of the number of chloroplasts in the leaf compare with the control varieties.4.Transcriptome results showed that compared with the control varieties,after 15%PEG-6000 stressed for 16 hours,LY1306 tobacco leaf had a higher gene expression level in tobacco aroma substances and aroma precursors synthesis pathway.Genes related to resistance,biosynthetic pathways and key enzymes involved in those pathways were significantly up-regulated in the leaf of LY1306.Also the genes related to chloroplast,chloroplast thylakoid,chloroplast,amyloplast and cortical microtubules were significantly up-regulated compare with both two control varieties.The results showed that the LY1306 line could keep good leaf status,had good osmotic adjustment capacity,water holding capacity and the capacity of holding the number of chloroplasts and the normal morphology of chloroplasts under different drought conditions.The genes expression in LY1306 leaf after PEG treatment was significant up-regulated in the pathway of aroma components and the high resistance.The results showed that LY1306 flue-cured tobacco line is a very good candidate variety which has a strong drought resistance.