Alternaria brassicae

B Cyanobacteria (yanucamides A, B) [37] marine bacteria3, marine sediments3 [38]. PR Dinoflagellata (dehydro-/ -Ala, palytoxin) [36]. Fa Ascomycota Alternaria brassicae, Metarhizium anisopliae (destruxin B) [32] Hapsidospora irregularis (leualacin) [39] ... 

As pointed out above, bioassay choice is extremely important since different sensitivities and different responses are observed that are dependent on the bioassay specimen. For example, comparison of four bioassay methods for detection of destruxin B, a host-specific toxin produced by Alternaria brassicae, indicated a lack of rapid electrolyte leakage and insensitivity of host protoplasts. However, leaf and pollen bioassays were sensitive to low toxin levels. Pollen germination was the most rapid, sensitive and quantitative bioassay for the toxin. Significant inhibition of Brassica campestris pollen germination and pollen tube growth occurred only 30 min after incubation with 2.5 pg mL 1, and 7.5 pg mL 1 caused total inhibition.3... 

Bains, P. S. 1990. Purification, chemical characterization, host-specificity, bioassay, mode of action, and herbicidal use of the toxin produced by Alternaria brassicae. Dissertation Abst. Internat. 50, 2708-B... 

Doughty, K.J., Porter, A.J.R., Morton, A.M., Kiddle, G. and Bock, C.H. (1991) Variation in the glucosinolate content of oilseed rape Brassica napus L.) leaves. II. Response to infection by Alternaria brassicae (Berk.) Sacc. Ann. Appl. Biol, 118, 469-78. 

The fungicidal activity of the compounds v/as screened in vitro by employing Food Poison Technique [7] against the plant pathogens viz. Alternaria brassicae, Aspergillus niger, and Fusarium oxysporum. 

The Alternaria black spot fungi A. brassicae and A. brassicicola produce host-selective toxins as well. While A. brassicicola produces brassicicolin A (11) as the major host-selective phytotoxin [28], A. brassicae produces destruxin B (12) (Fig. 9.4) [29]. Consistent with the virulence of these phytopathogens, both brassicicolin A (11) and destruxin B (12) appeared to be more phytotoxic to the susceptible cruciferous species B.juncea than to the tolerant B. napus. 

Fig. 9.4 Chemical structures of the selective phytotojdns 11 and 12 produced by mustard virulent isolates of Alternaria brassicicola and A. brassicae, respectively. Phytotoxins 11 and 12 are produced in a chemically defined medium...

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