African Journal of Biotechnology Vol. 5 (22), pp. 2307-2311, 16 November 2006   

ISSN 1684–5315 © 2006 Academic Journals        

Full Length Research Paper

Physiological effect of the toxin from Xanthomonas retroflexus on redroot pigweed (Amaranthus retroflexus)

Zi-Ling Sun1,2, Ming-Zhi Li1, Jie Chen3 and Yong-Quan Li1*

¹Zhejiang University College of Life Science, Hangzhou310058, P. R. China.

²Soochow University, Suzhou 215006, P. R. China.

³Zhejiang Chem-Tech Group Co. Lt.d, Hangzhou310023, P. R. China.

*Corresponding authors E-mail: lyq@zju.edu.cn, yq1962@yahoo.com.

Accepted 3 October, 2006

A new toxin from Xanthomonas retroflexus could cause a series of physiological responses on seedlings of redroot pigweed. The experimental results revealed that respiratory ratio first increased 106% after treatment with the CFS (concentrated centrifugal fermentation supernatants) of X. retroflexus for 2 h, and decreased after treatment for 3 h; peroxidase (POD) activity increased 30% and 50% after treatment with CFS for 1 h and 2 h, respectively; Malon dialdehyde (MDA), soluble protein and mitotic indices appeared not to be affected by the toxin. Ultrastructure observation indicated that the thylakoids of chloroplast and cristae of mitochondria swelled, when the leaves were placed in the toxin for 2 h. After treatment with the phototoxin for 3 h, the cell membrane was disrupted, the chloroplasts disintegrated and the mitochondria vesiculated.

Key words: Xanthomomas retroflexus, toxin, redroot pigweed, weed control.