Alternaria mycotoxins in black rot lesion of tomato fruit: conditions and regulation of their production.

Abstract

Alternaria represents the most colon decay organism of the post-harvest tomato fruit. The prevalent type of decay, black rot lesion, is caused by Alternaria alternata which may invade tomato tissue damaged by sun scald. The mainly natural mycotoxins produced in rotted tomato are alternariol (AOH), alternariol monomethyl ether (AME), and tenuazonic acid (TA). Whereas, altertoxin-I and -II (AT-I and -II), in addition to AOH, AME and TA were produced by local A. alternata in a synthetic medium. The optimum temperature for toxin production by A. alternata IMI 89344 was 28 degrees C for AOH and AME, 21 degrees C for TA and 14 degrees C for AT-I and -II. The growth and toxin were produced in a noticeable amount at 7 degrees C but drop at 35 degrees C. Significant inhibition in these toxins was attained at 500 ppm cinnamon oil in YES-Czapek's medium and in homogenate of tomato.