Effects of carrageenan as elicitor to stimulate defense responses of basil against Cuscuta campestris Yunck

Abstract

AbstractCuscuta campestrisis a holostemparasitic plant that obtains its resources from its hosts. Sweet basil is an important commercial plant, widely cultivated in many countries. It is a common host forC. campestris. Generally,C. campestrishas negative effect on the growth of infected plants and its infestation is difficult to control. Therefore, environmental friendly control ofC. campestrisseems to be useful. In this work, the relationship betweenC. campestrisand its host, sweet basil, and effects of κ-carrageenan on protection againstC. campestrisand suppression of its invasion were studied. Basil was sprayed with a solution of carrageenan at a final concentration of 1 g L−1, once a week, 3 times in total. Infection of basil withC. campestriswas performed 2 days after the last carrageenan treatment and the plants were collected two weeks afterC. campestrisattachment. In this study, phenylalanine ammonia-lyase activity (PAL), phenolic, flavonoids and antioxidant content increased remarkably in the basil plants parasitized withC. campestris, and therefore it seems that the parasitic plant induced a defense response in the host plants. Treatment with carrageenan significantly increased shoot length and leaf area of basil and decreasedC. campestrisinfestation by about 26%. Carrageenan treatment caused a significant increase in PAL activity, phenols, antioxidant and lignin content in basil. Thus, the present observation suggested the phenylpropanoid pathway was activated and defense responses were stimulated. Our results showed that carrageenan spraying induced beneficial effects in plants, corresponding to growth stimulation and defense compound synthesis. Thus carrageenan treatment is recommended as a natural biostimulator for the protection of plants againstC. campestris.