Study Of Accumulate Mechanism And Drought Resistance Of Phenolic Acids Under Drought In Salvia Miltiorrhiza Bunge

Accumulate mechanism and drought resistance of phenolic acids in Salvia miltiorrhiza Bunge under drought were studied by pot culture experiments simulating different water content of soil. Three different levels of soil water treatments with 75%θf, 55%θf and 40%θf field water capacity were set by artificial controlling the soil moisture. The Salvia miltiorrhiza Bunge seedlings were obtained from Shangluo in Shaanxi. In this paper, physiological characteristics, key enzymes of phenylpropanoid metabolism, total phenolic acids content and content of water-soluble active components were studied, then the changing trends of the above-mentioned indices with the time and space were discussed under different soil water treatments. Meanwhile, from the view of the metabolic pathway, the accumulate mechanism of phenolic acids in leaves and the content of water-soluble active components in roots of Salvia miltiorrhiza Bunge under drought were revealed respectively. Additionally, both the effect of protocatechuic aldehyde on physiological characteristics in maize leaves under water stress and the resistance of protocatechuic aldehyde were elucidated. The main conclusions were as follows:1. The relative water content(RWC) in leaves of Salvia miltiorrhiza Bunge decreased and severe water stress(WSD) increased with the soil drought increased. The activity of protective enzymes, such as SOD,POD,CAT and APX have significant differences. SOD activity at 55%θf had the same trend as 75%θf and they firstly ascended and then declined, while SOD activity at 40%θf firstly decreased and then increased. POD activity firstly increased and then decreased, CAT activity ascended and then decreased and gradually increased at three different soil water contents. APX activity and CAT activity had an opposite trend, and APX activity showed 55%θf>75%θf>40%θf. The MDA centent had the same trend as POD activity and the MDA content increased with the soil drought increased. The soluble protein content declined and then a small rebounding was showed with the extending of water stress. The contents of proline and soluble sugar had similar changing trend and they firstly increased and then decreased, furthermore, the contents of proline and soluble sugar in leaves of Salvia miltiorrhiza Bunge increased with the soil drought increased.2. The TAT activity in leaves of Salvia miltiorrhiza Bunge were increased at 40%θf-55%θf of soil water content. The content of total phenolic acids in leaves of Salvia miltiorrhiza Bunge had significant improvement at 55%θf of soil water content. The beginning period of total phenolic acids accumulate largely was August. After October, total phenolic acids had a higher level. A positive correlation between activity of PAL or C4H and the accumulation of total phenolic acids content were found at three different soil water contents. There was a certain association between the controlling of PAL or C4H and soil moisture environment, the controlling capacity was highest at 40%θf, followed by that at 75%θf and 55%θf. The accumulation mechanism of phenolic acids under drought in Salvia miltiorrhiza Bunge was found. The key enzymes system of phenylpropanoid metabolism was started in Salvia miltiorrhiza Bunge at the soil drought and regulated the PAL and C4H activities and then the total phenolic acids contents increased. PAL and C4H activity had synergistic effect but PAL played a leading role under stress.3. The crucial period for accumulation of water-soluble active components in roots of Salvia miltiorrhiza Bunge was Late June and another smaller peak was September. Soil drought accelerated accumulation of Sodium Danshensu and Caffeic acid, moist soil environment accelerated accumulation of Rosmarinci acid and Salvianolic acid B. The moderate drought (55%θf) was benificial to accumulation of Caffeic acid and soil water content at 75%θf was good for accumulation of Rosmarinci acid during the growth period. The soil water content at 55%θf and 75%θf were benificial to accumulation of Sodium Danshensu and Salvianolic acid B respectively before September, while 40%θf was better after September. Soil water demand of water-soluble active components indicated that Rosmarinci acid was highest, followed by Salvianolic acid B and Caffeic acid, Sodium Danshensu was lowest.4. Protocatechuic aldehyde could improve the antioxidative ability of maize seedlings and thus are advantageous to the resistance of plants to water stress. The mitigate degree of water stress was positively correlated with the concentration at 0.5μg·ml^-1-25μg·ml^-1 of the concentration of protocatechuic aldehyde. The 25μg·ml^-1 of the concentration was stronger relatively than the others .