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Title: Characterization of glucosaminidase from developing cantaloupe fruit

Author
item BILES, C.L. - EAST CENTRAL UNIV. ADA,OK
item Bruton, Benny
item CLUCK, T.W. - EAST CENTRAL UNIV. ADA,OK
item JUDKINS, M. - EAST CENTRAL UNIV. ADA,OK
item SWENSON, R. - EAST CENTRAL UNIV. ADA,OK
item PARDUE, T. - EAST CENTRAL UNIV. ADA,OK
item WATSON, M.L. - EAST CENTRAL UNIV. ADA,OK

Submitted to: Southern Association of Agricultural Scientists Bulletin of Biochemistry and Biotechnology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 4/3/2001
Publication Date: 11/5/2001
Citation: Biles, C., Bruton, B.D., Cluck, T., Judkins, M., Swenson, R., Pardue, T., Watson, M. 2001. Characterization of glucosaminidase from developing cantaloupe fruit. Southern Association of Agricultural Scientists Bulletin of Biochemistry and Biotechnology. 14:11-19.

Interpretive Summary: Chitinase and N-acetyl-B-glucosaminidase are found in several species of plants. These compounds have been demonstrated to exhibit antifungal activity. The true fungi contain chitin as a major cell wall constituent. Consequently, chitinases may function as a plant defense mechanism against chitin-containing fungal pathogens. Continious and intensive cultivation of cucurbit crops has resulted in an increase in both the number and severity of fruit rot diseases. This study was designed to establish the presence of chitinase and N-acetyl- -glucosaminidase in cantaloupe fruit and determine the relationship between concentration and site within the fruit. Glucosaminidase activity was observed in mesocarp and exocarp tissue with the highest activity in fruit exocarp 5 to 10 days after pollination. Isolation and genetic manipulation of the genes for chitinase and glucosaminidase may provide greater protection against postharvest fungal pathogens of cantaloupe fruit.

Technical Abstract: Chitinase and N-acetyl-B-glucosaminidase have been found in several plant and fungal species and are implicated as having antifungal activity. Glucosaminidase activity was observed in mesocarp and exocarp tissue with the highest activity in fruit exocarp tissue 5 and 10 days after pollination. Experiments indicated two peaks of glucosaminidase activity when crude samples were separated using an HPLC anion exchange column. Later day samples (fruit harvested 15 to 50 days after pollination) showed only one peak of glucosaminidase activity. The predominant peak sample from the anion-exchange column was applied to a size-exclusion column (SEC) which indicated one peak of glucosaminidase activity. SDS-PAGE of the glucosaminidase fractions from the SEC showed one protein band at 64 kD. Salt and acetone protein extractions were used in these experiments. Acetone precipitated glucosaminidase was the preferred method in regard to purification. Isolation and genetic manipulation of the genes for chitinase and glucosaminidase may provide greater protection against postharvest fungal pathogens.