The Comparison of Sugar Components in the Developing Grains of Sweet Corn and Normal Corn

The sugar components and their dynamic variation in the developing grains of sweet corn(Zea mays L. seccharata Sturt)and normal corn (Zea mays L. indentata Sturt) were compared. There are WSP (water-soluble polysaccharides), sucrose, fructose, glucose, mannitol and sorbitol in both sweet corn and normal corn, but no maltose. Two components with different degrees of polymerization (D. P. N) were detected in the sweet corn; only one of them was detected in the normal corn 20 days after pollination. With the development of grains, the total soluble sugar content(TSS)in sweet corn increased, but in normal corn it decreased. The dynamic variation of WSP, sucrose, glucose, fructose, mannitol and sorbitol in sweet and normal corn grains are different. The contents of sugar components in the sweet corn grains are higher than that in the normal corn. Sweet corn accumulates less starch than normal corn.

Grafting Onto Artemisia annua Improves Drought Tolerance in Chrysanthemum by Enhancing Photosynthetic Capacity

Drought stress drastically influences the yield and quality of chrysanthemums,and thus grafting has been widely used to improve tolerance to biotic and abiotic stresses.To explore the mechanisms underlying improvements in drought resistance afforded by grafting,we investigated the changes in growth,gas exchange,ribulose-1,5-bisphosphate carboxylase/oxygenase(Rubisco)expression and activity,sugar components,and the relative expression of photosynthesis-related genes of chrysanthemum(Chrysanthemum morifolium Ramat.‘Hangbaiju')plants grafted onto Artemisia annua rootstocks under drought stress by withholding water for 6 d.The results revealed that the growth declines in the grafted chrysanthemums were relatively lower than those of the non-grafted plants under drought stress,and net photosynthetic rate,stomatal conductance,water use efficiency,and transpiration rate in the non-grafted chrysanthemums were significantly decreased.Moreover,the intercellular CO_2 concentrations were significantly increased compared with the grafted plants at 5 and 6 d following drought stress.The grafted plants exhibited higher relative expression of the Cmrbc L,Cmrbc S,Cmpsa B,and Cmcab genes,as well as higher Rubisco activity and chlorophyll content under the drought treatment.Sugar accumulation also increased under drought stress,particularly in the non-grafted plants.This result suggested that non-grafted chrysanthemums were less able to resist dehydration,and repressed the genes encoding the expression of photosynthetic components.In conclusion,using A.annua rootstock could alleviate drought stress in chrysanthemums by improving gas exchange capacity and maintaining Cmrbc L,Cmrbc S,Cmcab,and Cmpsa B gene expression,thereby increasing Rubisco activity and improving photosynthetic performance.