Anatomic And Metabolic Characteristics In 3 Photo Synthetic Types Among Genus Salsola

The woody species of the genus Salsola which is widely distributed in Central Asia,is the dominant species in the desert area of northwestern China,and one of the earliest genus to discover C4 photosynthesis.Since most C4 species are herbaceous,while C4 woody species are not common with C4 herbaceous species that the photosynthetic evolution of C4 is not well understood in woody species.We analyzed the structural anatomy and photosynthetic enzyme metabolism of C3 and C4 woody species of Salsola,and explored the possible pathways of photosynthetic evolution of C3 woody species to C4,revealing the origin of photosynthetic pathways of C4 woody species.The main findings of the paper are as follows:(1)Observing the results of semi-thin and ultra-thin sections of the woody species in the genus Salsola,it is found that there is an evolutionary trend in the anatomical structure that adapts to the environment and improves the photosynthetic efficiency,including the sheath cells and the mesophyll cells.Complementary changes in morphology and size,development of water storage tissue,and changes in organelle distribution in photosynthetic organs.(2)Through the expression and localization analysis of related photo synthetic enzymes,it was found that different photosynthetic enzymes have different dominant roles in each photosynthetic species,and their distributions are also different,while the distribution changes are caused by changes in anatomical structure.Promoted by compartmentalization.At the same time,in order to adapt to metabolic changes,the anatomical structure is also forced to change accordingly.(3)The anatomical structure of the genus Salsola begins with the Sympgmoid-type structure of a typical C3 photosynthetic species,and then evolves into a proto-Kranz type that is still C3;and then forms a Kranz-of the C3-C4 intermediate species,in which C3-C4 intermediate species with type Ⅰ characteristics(lower C4 photosynthetic enzyme activity)are closer to C3 species,and type Ⅱ characteristics(C4 photosynthetic enzyme activity approaches C4).The structural features are closer to the C4 species;the typical Kranz-type structure of the C4 photo synthetic species is finally formed.(4)Based on the transcriptome analysis of the seven woody plants studied,it was found that the photosynthetic evolution in the genus Salsola is different from the gradual evolution of the photosynthetic types of the genus Flaveria,but it appears to be mosaic in the evolution of C4 photo synthetic type.There is a C3-C4 intermediate type,that is,the evolution of C3 to C3-C4 intermediate type or C3 to C4 type.Furthermore,based on the key enzymes and molecular phylogenetic analysis of the C4 subtype,the C3 woody species of the genus Salsola were finally evolved into the NADP-ME subtype of C4 instead of the NAD-ME subtype.Finally,with reference to the C4 evolution model of the genus Flaveria,we constructed the C4 evolutionary route of the woody plants of the genus Salsola.By comparing the photosynthetic structure and enzyme metabolism characteristics of three photosynthetic wood species of the genus Salsola,it is believed that the morphological and anatomical characteristics of C3 photosynthetic species have changed to C4 photo synthetic structure,with the distribution and metabolism of photo synthetic enzymes have also occurred,a change that matches the structure.One possible photosynthetic pathway in the genus Salsola is from C3 photosynthetic to C4 photosynthetic,and specifically evolved into the C4 photosynthetic NADP-ME subtype.