Study On Pigment Accumulation And Photosynthesis Of Different Phenotype Suaeda Salsa L. Under Natural Conditions

Suaeda salsa plants grown in the intertidal zone (phenotype: red-violet) andthose in high salinity soils at elevation and land far from the seaside (phenotype:green) of the Yellow River Delta were used to study the relations of leaf succulence toionic contents in cell sap and in saline soils, and to study the category and content ofpigments and characteristic of photosynthesis, which was available for discoveringthe mechanisms of pigment accumulation regulated by environmental factors and theroles of pigments in phenotype formation and in stress resistance. The main resultswere shown as follows.1. Analysis of growth conditions of Suaeda salsaThe water content of soil, the contents of Na+ and Cl-of the high salinity soilswere lower than those in the intertidal zone soils. However, the temperature on thesurface of soil and in the depth of 10 cm from the surface, the content of K+ and Ca2+of the high salinity soils were significantly higher than those in the intertidal zonesoils. These results suggest that Suaeda salsa grown in the high salinity soils wasmainly suffering from salt stress, while Suaeda salsa grown in the intertidal zonesoils was suffering from waterlogging stress and low temperature and salt stresstogether.2. Effects of different environmental conditions on the growth of Suaeda salsaThe growth of whole plant, the fresh weight, organic dry weight, inorganic dryweight of both mature leaves and expending leaves per plant, the height of plant, thenumber of branches and the length of branches in the high salinity soils weresignificantly superior to those in the intertidal zone soils. These results indicat that thegrowth of the Suaeda salsa in the high salinity soils was significantly stronger thanthat in the intertidal zone soils.3. The analysis of the factors affecting leaf succulence of Suaeda salsaThe sequence of the degree of leaf succulence was as following: mature leaf inthe high salinity soils > mature leaf in the intertidal zone soils > expending leaf in thehigh salinity soils > expending leaf in the intertidal zone soils. Correlative analysisshowed that the degree of leaf succulence was positively correlated to soil watercontent, Na+ and Cl-content in soil and in the leaves. The correlative order: leaf Na+and Cl-content > Na+ and Cl-content in soil > soil water content;Na+> Cl-. Theseresults suggest that leaf Na+ and Cl-accumulation are the main factors affecting leafsucculence and leaf Na+ plays a critical role. Compared with Suaeda salsa plantsgrown in the intertidal zone, higher air temperature of soil surface and soil and lowerwater content of the high salinity soils were possibly important reasons for higher leafsucculence of Suaeda salsa plants grown in the high salinity soils at elevation andland far from the seaside of the Yellow River Delta. Additionally, the water content ofmature leaf per plant was significantly higher than that of expending leaf both in highsalinity soils and the intertidal zone soils.4. Effects of different environmental conditions on the pigment accumulation ofSuaeda salsaThe chlorophyll a content and chlorophyll b content were not significantlydifferent between in mature leaf and in expending leaf under the same environmentalcondition, but chlorophyll a content and chlorophyll b content of both mature leaf andexpending leaf of Suaeda salsa grown in the intertidal zone soils were significantlylower than those grown in the high salinity soils, respectively. However, betacyanincontent and carotenoid content of the same type leaf of Suaeda salsa grown in theintertidal zone soils were significantly higher than those grown in the high salinitysoils. Under the same environmental condition, the betacyanin content and carotenoidcontent in expending leaf of Suaeda salsa were significantly higher than those inmature leaf in the intertidal zone soils. However, there was no significant difference inthe betacyanin content and carotenoid content between mature leaf and expending leafin the high salinity soils. These results suggest that integrative stress (salt stres,flooding and low temperature), especially low temperature and waterlogging stress,stimulates the accumulation of betacyanin and carotenoid, at the same time reducesthe content of chlorophyll a and chlorophyll b, which leads to the red-violetphenotype of Suaeda salsa grown in the intertidal zone soils.5. Effects of different environmental conditions on the photosyntheticparameters of Suaeda salsa leavesThe Ci of mature leaf of Suaeda salsa grown in the intertidal zone soils wassignificantly higher than that in the high salinity soils. However, the Gs wassignificantly lower than that in the high salinity soils. Fv/Fm, ФPSⅡ and netphotosynthetic rate of mature leaves of Suaeda salsa grown in the high salinity soilswere significantly higher than those in the intertidal zone soils.In conclusion, different environmental conditions significantly affected leafsucculence, pigment accumulation and characteristics of photosynthesis of Suaedasalsa, and Suaeda salsa adapted to the integrative stresses such as salt stress,waterlogging stress, low temperature stress and so on. Accumulation of Na+ and Cl-inthe leaves is the main factor affecting leaf succulence and leaf Na+ plays a critical role.The decrease of chlorophyll a content and chlorophyll b content and the increase inbetacyanin content and carotenoid content, on the one hand, contributed to thered-viole phenotype;on the other hand, reduced the generation of ROS, andbetacyanin and carotenoid played a critical role in scanvaging ROS, which ensuredthe growth, development and fulfilling life cycle of Suaeda salsa grown in theintegrative stresses of the intertidal zone of Yellow River Delta. These results are thenew interpretations on the biological roles of betacyanin and also lay foundations offurther study on the molecular mechanisms of betacyanin metabolism in Suaedasalsa.