Effects Of Environment On Photosynthesis And Secondary Metabolitesr Of Korean Pine

Korean pine (Pinus koraiensis), also known as fruit pine, belongs to evergreen trees of Pinaceae. Korean pine had a high medicinal value, such as anti-oxidation activity, anti-aging activity and anti-tumor activity. This article take Korean pine as material, did the research and analysis of photosynthesis and secondary metabolites on environmental stress (drought-rehydration and high temperature), and reveals the difference response to physiological and biochemical basis of neddles and bark chlorenchyma, provides a theoretical basis of optimization of cultivation conditions and cultivating high-quality raw materials. The following conclusions were found:(1) The total chlorophyll content and chlorophyll a/b of needles and bark chlorenchyma decreased significantly under drought stress, which reducing the PSII antenna to capture light energy and reduced the risk of photoinhibition. The main reason for restricting Net photosynthetic rate (Pn) of Korean pine had stomatal and non-stomatal limitation. Pn of needles and bark chlorenchyma recovered to the control level after rehydration. PSII maximum fluorescence efficiency (Fv/Fm), actual photochemical efficiency of PSII (φPSⅡ), photochemical quenching (qP) of Korean pine were exhibited varying degrees of reduced, non-photochemical quenching (NPQ) significantly increased under drought stress, indicating that photoprotection was effective and both are basically the same performance. Malondialdehyde (MDA) of needles and barkchlorenchyma were significantly increased under drought stress and resulting in oxidative stress, the activities of superoxide dismutase (SOD), catalase (CAT), ascorbate peroxidase (APX), and glutathione reductase (GR) were significantly increased. These increased antioxidant enzyme activity of pine on drought stress defense played an active role. The activities of phosphoenolpyruvate carboxylase (PEPC), NADP-malate dehydrogenase (NADP-MDH) of bark chlorenchyma were significantly increased under drought stress, showing that both C4 photosynthetic enzymes were beneficial to bark chlorenchyma against drought stress. C4 photosynthetic enzyme activity of needles had shown varying degrees of reduced. The Korean pine of needles and bark chlorenchyma in response to drought stress were showing partial match reactions and there had some differences, bark chlorenchyma in resisting drought stress also plays an important role.(2) Flavonoids, tanninand procyanidin content of bark chlorenchyma decreased significantly under drought stress, flavonoids and tannin content continue to decrease after rehydration and three kinds of content were not returned to control levels. Flavonoids and procyanidin content of needles decreased and tannin content significantly increased, after rehydration they were not returned to control levels. DPPH free radical scavenging activity of needles and bark chlorenchyma was significantly decreased, after rehydration DPPH free radical scavenging activity of neddle and bark chlorenchyma were returned to control levels. There were some different responses to drought stress between needles and bark chlorenchyma. In addition, the related analysis between secondary metabolites and photosynthesis of Korean pine, Pn and flavonoids, tannins, procyanidin were not significantly (P>0.05).(3) The total chlorophyll content of bark chlorenchyma decreased by increasing the temperature and chlorophyll a/b was highest by increasing the temperature up to 28℃.The chlorophyll a/b of neddles decreased by increasing the temperature, but the total chlorophyll content of neddles was not affected. Pn of neddles and bark chlorenchyma was inhibited and Ci and Gs increased by increasing the temperature up to 33℃. Simultaneously Fv/Fm and φPSII of neddles and bark chlorenchyma decreased, showing that the main reason for restricting photosynthesis of Korean pine had mesophyll, also non-stomatal limitation. POD、APX and SOD activities of neddles and bark chlorenchyma increased can reduced the damage of high temperature stress on needles and bark chlorenchyma. NADP-ME of bark chlorenchyma increased by increasing the temperature and the others decreased, showing that NADP-ME plays an active role in resist high temperature stress. PEPC and NADP-MDH increased by increasing the temperature up to 33℃, the other parameters effect was not significantly.(4) Flavonoids and proanthocyanidins content of bark chlorenchyma decreased significantly by increasing the temperature, tannic content was the highest by increasing the temperature up to 33℃. The main reason for restricting flavonoids and proanthocyanidins had high temperature. Tannic content of neddles decreased was related to different organs. DPPH free radical scavenging activity of needles and bark chlorenchyma was significantly decreased by by increasing the temperature, showing that the antioxidant activity of needles and bark chlorenchyma will increased by temperature is too low or too high. In addition, the related analysis between secondary metabolites and photosynthesis of Korean pine. Pn and tannin, procyanidin of neddles were significantly correlation (P<0.05), Pn and flavonoids. procyanidin of bark chlorenchyma were significantly correlation (P<0.05).(5) Comparative study of needles and bark chlorenchyma to stress response was found that more than half of the indices show that the value of bark chlorenchyma are lower than neddles in 26 physiological indices under re-water after drought stress and rising temperatures. Simultaneously, Ci、qP、Chla/b、APX、SOD、NADP-ME、Rubisco、NADP-MDH、 flavonoids. tannin and procyanidin of Korean pine were significantly changes to re-water after drought stress and rising temperatures (p<0.05), and had inconsistently trends (p<0.05).