| With the global climate change,many environmental factors affect the growth and development of plants,and the water factor is more and more significant to the normal growth and metabolism of plants.Pueraria montana var.Thomsonii,as a medicinal and edible plant,has great development value in functional products.Because Pueraria montana var.Thomsonii can be used as green vegetation,starch in Pueraria montana var.Thomsonii root has become a number of functional products and edible raw materials,so the planting of Pueraria montana var.Thomsonii has been vigorously promoted in various places.As a special'semi-arid'area,the unique karst landscape in southwest China leads to the lack of groundwater.Therefore,the planting of Pueraria montana var.Thomsonii in southwest China has a lot of environmental protection and economic value.In this study,one-year-old Pueraria montana var.Thomsonii was used as the material for potted water control experiment.Through the study on the structural characterization and functional characteristics of starch granules in Pueraria montana var.Thomsonii root cells,the effects of drought stress on starch granules accumulation and starch physicochemical properties in Pueraria montana var.Thomsonii root cells were explored.Secondly,the growth and physiological changes of plants were observed,and the response of Pueraria montana var.Thomsonii to drought stress and its relationship with starch granules synthesis and accumulation were analyzed.Finally,based on transcriptomics,we studied the gene response differences of Pueraria montana var.Thomsonii root cells under drought stress,and preliminarily discussed the gene expression difference analysis of Pueraria montana var.Thomsonii root under drought stress,in order to provide theoretical basis for the physiological mechanism of water-saving and high-quality cultivation of Pueraria montana var.Thomsonii,and lay the foundation for genetic breeding of Pueraria montana var.Thomsonii The main research results are as follows:1.Drought stress slightly changed the morphology of starch granules in Pueraria montana var.Thomsonii The distribution of small and medium starch granules in Pueraria montana var.Thomsonii was more under the aggravation of drought,which reduced the total starch content and water content,increased the dry matter content,and decreased the amylose content.The starch solubility of Pueraria montana var.Thomsonii was the highest under the moderate drought treatment,and the swelling power decreased significantly with the aggravation of drought.Transparency was positively correlated with the aggravation of drought.The morphological changes of starch granules under microscopic observation were further confirmed by particle size analysis.The average particle size of volume,average particle size of surface area and peak particle size of starch granules were the lowest under the increase of drought degree.Through further analysis of the structure of starch granules,it was found in the XRD pattern that drought stress did not significantly change the crystal type of starch.The normal treatment group belonged to C_Btype,and the crystal type of moderate drought treatment group and severe drought treatment group belonged to C_Atype.The relative crystallinity of starch granules gradually decreased under drought stress.Drought stress also affected the short-range order structure of starch grains,and the order degree decreased significantly.The structural changes of starch granules indirectly affect the functional properties of starch.In the determination of thermodynamic properties,the enthalpy value of heavy drought treatment group was the minimum,and the resistant starch content of moderate drought treatment group was the highest in vitro digestion characteristics.2.Drought stress can inhibit the growth of Pueraria montana var.Thomsonii,leaf relative water content and root activity decreased,total chlorophyll content increased significantly.Superoxide dismutase(SOD),peroxidase(POD)and catalase(CAT)have complementary synergy in scavenging oxygen free radicals;The relative conductivity of mesophyll cells increased significantly,and the concentration of osmotic adjustment substances increased.The content of total flavonoids increased significantly.The results showed that drought stress affected the normal growth and metabolism of Pueraria montana var.Thomsonii,resulting in the decrease of starch biosynthesis.The increase of secondary metabolites was consistent with the decrease of starch content in primary products.Correlation analysis showed that single leaf area was negatively correlated with POD,chlorophyll a,chlorophyll b,total chlorophyll content and soluble protein content,and POD and proline were positively correlated with total flavonoids content.Principal component analysis showed that POD,relative water content,SOD,carotenoids,soluble protein,CAT and total flavonoids were sensitive physiological indexes under drought stress.3.Differential expression analysis of DEseq showed that there were 658 genes,including 444 up-regulated genes and 214 down-regulated genes.In NR database,the number of differentially expressed genes labeled in each functional database was the largest,with a total of 513 differentially expressed genes labeled as 48 GO entries.Differentially expressed genes are mainly annotated as metabolic processes and biofilm components.In the enrichment analysis of KEGG pathway,the differentially expressed genes mainly enriched phenylpropanoid biosynthesis,photosynthesis and other metabolic pathways,and the differentially expressed genes mainly involved the transport and metabolism of carbohydrates.Finally,key functional genes in sugar metabolism,secondary metabolites,photosynthetic system and plant hormone signal transduction pathways were screened. |
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