关键词: 臭柏(Sabina vulgaris Ant.), 光抑制, 热耗散, 叶黄素循环, 毛乌素沙地

Abstract: Photoinhibition is common in plants which grow under natural conditions.For the duration of species,plants have developed a variety of photoinhibition defense mechanisms during their long-term adaptation and evolution,such as the exercise to avoid light by leaves and chloroplasts,photorespiration,active oxygen scavenging system,conversion of light harvesting pigment,protection by phenolic compounds (anthocyanin,for example),increasing non-photochemical dissipation,depending on the xanthophyll cycle thermal dissipation,and accelerating the turnover of D1 protein.Sabina vulgaris Ant.is the only natural evergreen coniferous shrub in the Mu Us Sandland,it has a strong vitality,a wide range of adaptability,good ecological function and high medical value.The photoinhibition defense mechanisms,such as the heat dissipation mechanism,play an important role during the natural regeneration of S.vulgaris in the desert with strong light environment.In this paper,the photoinhibition of plants and the main photoinhibition defense mechanisms in plants under strong light were reviewed.Light energy is the power source and the basic driving force of photosynthesis,energy shortage restricts photosynthesis,and photoinhibition of photosynthesis caused by light energy exceeds the photosynthesis need.Under strong light stress,photosynthetic pigment antenna absorbing the excessive solar light causes photoinhibition,and then affects the photosynthetic metabolism.Although the light is the direct reason of plant photoinhibition,drought and low or high temperature stress caused by saline and seasonal change lead indirectly to plant photoinhibition.There are two situations for photoinhibition: One is that plant can recover after suffering from photoinhibition,strong light provides more photochemical effect than the leaf photosynthesis,and photosynthesis process overload could cause lower photonutilization and lower photosynthetic quantum yield,this situation occurs often in the sun plants,which depends on the energy dissipation mechanism occurring mainly in photosystem Ⅱ (PSⅡ) reversible inactivation and relating to the light harvesting complex LHCⅡ (Light-harvesting complex Ⅱ) reversible detachment.The other is that plant cannot recover after suffering from photoinhibition called photodamage,extremely high radiation damages the photosynthetic pigment and thylakoid structure,this case occurs often in ombrophytes,which causes a photosynthetic organ damage dominated by the PSⅡ’s irreversible damage.The present research and prospect of the photoinhibition defense mechanisms of S.vulgaris were briefly summarized.In recent years,although there are many research reports about S.vulgaris, the research on photoinhibition defense mechanism of S.vulgaris is less.In general,the research about photoinhibition defense mechanisms of Sabina vulgaris still remains at the preliminary exploration stage,and how S.vulgaris defenses the photoinhibition by photosynthetic physiological and molecular mechanisms is not clear.

Key words: Sabina vulgaris Ant., photoinhibition, heat dissipation mechanism, xanthophyll cycle, Mu Us Sandland