Effects of viral infection on physiological and biochemical characteristics and the yield and quality of Polygonatum kingianum

Abstract

[Objective] The study aims to clarify the influence of virus infection on the growth and rhizome yield and quality of Polygonatum kingianum , as well as provide basis for further study on the pathogenic mechanism of virus. [Methods] The 4-year-old disease-resistant and naturally infected plants planted in Qujing and Yuxi, the main producing areas of P . kingianum , were taken as the research objects. We determined the changes of chloroplast ultrastructure, photosynthetic gas exchange parameter, total chlorophyll content, superoxide dismutase (SOD), peroxidase (POD), polyphenol oxidase (PPO), phenylalanine ammonia lyase (PAL), biological characteristics of tuber, and content of medicinal effective chemical components after virus infection. [Results] (1) After P . kingianum was infected by virus, linear virus particles and a large number of inclusions were scattered in the cytoplasm of leaves, and the chloroplast structure was seriously damaged, some were disintegrated. (2) The chlorophyll of susceptible P . kingianum was degraded, and the contents of chlorophyll a and chlorophyll b were reduced by 22.97% and 35.38%, respectively. The net photosynthetic rate, stomatal conductance, and intercellular CO2 concentration of leaves were reduced by 49.75%, 11.25%, and 5.79%, respectively, and the photosynthetic efficiency was weakened. (3) There was a strong lipid peroxidation reaction in the leaf cell membrane of susceptible P . kingianum , and the content of MDA was increased by 117.17%. Meanwhile, the activities of defense enzymes, including SOD, POD, PPO, and PAL, were increased, in which PPO was increased by 61.81% on average. (4) The swelling and bud growth of infected rhizome were inhibited, and the fresh mass per plant was decreased by 49.47%. The relative content of polysaccharides in rhizome was decreased by 6.97%, while the contents of saponin, flavonoid and total phenol were decreased by 23.31%, 15.32%, and 11.07%, respectively. [Conclusion] After virus infection, cell membranes are damaged and photosynthesis is undermined, which led to a decrease in rhizome yield and medicinal quality of P . kingianum , although the defense reaction of the antioxidant enzymes is activated.

Keywords

• polygonatum kingianum coll. et hemsl
• virus disease;
• physiological and biochemical characteristics;
• rhizome yield
• medicinal quality