Radicinols and radicinin phytotoxins produced by Alternaria radicina on carrots.

The phytotoxin epi-radicinol, a diastereomer of radicinol, was isolated from large cultures of Alternaria radicina grown on carrot slices and identified by GC-MS, LC-MS, 1H NMR, and 13C NMR. Four strains of A. radicina isolated from rotted carrot produced epi-radicinol as the major metabolite (up to 39414 .mu.g/g) together with radicinol (up to 2423 .mu.g/g), and, to a lesser extent, radicinin when cultured on carrot slices, whereas on rice they mainly produced radicinin (2486-53800 .mu.g/g). Radicinin and epi-radicinol reduced root elongation of germinating carrot seeds at concns. of 10-20 .mu.g/mL. Carrot samples naturally infected by A. radicina contained detectable quantities of epi-radicinol also in combination with lower levels of radicinin or radicinol. Accumulation of radicinols and radicinin in stored carrots, either naturally contaminated or artificially inoculated with A. radicina, was stimulated by successive temp. rises from 1 to 10 and from 10 to 20, reaching max. levels of 60 .mu.g/g epi-radicinol and 26 .mu.g/g radicinin. This is the first report on the prodn. of radicinols by A. radicina and its natural occurrence in carrots in assocn. with radicinin.