Morphological, pathogenic and genetic variability in castor wilt isolates

Authors

  • M. SANTHA LAKSHMI PRASAD*, M. SUJATHA and MA RAOOF

Abstract

Castor wilt caused by Fusarium oxysporum t.sp. ricini is an economically important and major disease of castor. Variation in resistance to wilt was observed among castor hybrids! varieties in different cultivated areas because of pathotypes. Isolates of fungus were collected from different castor growing areas of India and morphological, cultural characters were studied. The effect of culture filtrates of these isolates was tested on germination of castor seeds and wilt incidence with a view to study differences in the toxin production among the isolates. The isolates showed variation in mycelial growth, pigmentation, sporulation, size of conidia and production of micro and macroconidia. Culture filtrate of the isolates reduced the germination of castor seeds. The germination was directly correlated with the concentration of the culture filtrate in comparison to check. Maximum inhibition in germination was observed with undiluted culture filtrate followed by 100 and 75 ppm concentration. The isolates also differed in the degree of inhibiting the root growth. All the seedlings wilted in undiluted culture filtrate of all isolates whereas, no wilting was observed in seedlings kept at 25 ppm conc. Isolates varied in production of toxin and thereby wilt incidence. The reaction of the 29 isolates on castor cultivars indicated the existence of different virulence of isolates in different castor growing areas of country and five pathotypes of the pathogen were characterized. Isolates 2,14 and 15 were virulent and attacked DCS 9 and Kranthi cultivars. The genetic variation of isolates of F. oxysporum t.sp. ricini was studied by random amplified polymorphic DNA analysis. Tho isolates were grouped into five clusters based on molecular polymorphism generated by RAPD primers. The grouping of isolates based on pathogenic variation has no correlation with grouping based on RAPD analysis with most of the test isolates.

Downloads

Issue

Vol. 61 No. 1 (2008): Indian Phytopathology

Section

Research Articles

License

For Authors

As soon as an article is accepted for publication, authors are requested to assign copyright of the article (or to grant exclusive publication and dissemination rights) to the publisher (Indian Phytopathlogical Society). This will ensure the widest possible protection and dissemination of information.

For Readers

While the advice and information in this journal is believed to be true and accurate at the date of its publication, the authors, the editors, nor the publisher can accept any legal responsibility for any errors or omissions that may have been made. The publisher makes no warranty, express or implied, with respect to the material contained herein.

All articles published in this journal are protected by copyright, which covers the exclusive rights to reproduce and distribute the article (e.g., as offprints), as well as all translation rights. No material published in this journal may be reproduced photographically or stored on microfilm, in electronic data bases, on video disks, etc., without first obtaining written permission from the publisher. The use of general descriptive names, trade names, trademarks, etc. in this publication, even if not specifically identified, implies that these names are protected by the relevant laws and regulations.

How to Cite

M. SUJATHA and MA RAOOF, M. S. L. P. (2008). Morphological, pathogenic and genetic variability in castor wilt isolates. Indian Phytopathology, 61(1), 18-27. http://epubs.icar.org.in/ejournal/index.php/IPPJ/article/view/12690