D. K. Chakrabarti

Parasitism of Imperata cylindrica on Pancratium biflorum and the concomitant chemical changes in the host species

Abstract A rare incidence of phanerogamic parasitism of Imperata cylindrica on Pancratium biflorum and the concomitant changes in the chemical constituents, from the hypersensitive responses in the host species, are reported.

The occurrence of 12, 13-epoxytrichothecenes in seeds of safflower infected with Fusarium oxysporum f. sp. carthami.

From the seeds of safflower (Carthamus tinctorius Linn.), infected with Fusarium oxysporum f. sp. carthami, 3 toxic compounds have been isolated in quatities sufficient to cause mycotoxicosis on prolonged ingestion. 2 of these have been identified as diacetoxyscirpenol and T-2 toxin, while the third one has also been partially characterized as a 12, 13-epoxytrichothecene. Additionally, the incidence of secondary fusarial infection of healthy seeds due to contamination with the infected ones has been reported for the first time.

Toxic substances produced byFusarium. X. Concerning the malformation disease of mango

Accumulation of mangiferin and degraded carotenoids, in response toFusarium moniliforme infection, has been suggested to be responsible for the malformation disease ofMangifera indica L. (Anacardiaceae).

Differences in phenolic and steroidal constituents between healthy and infected florets of Mangifera indica

Abstract Differences in the low- and medium M r phenolic and steroidal compounds in healthy and malformed florets of Mangifera indica , the latter infested with Fusarium moniliforme var. subglutinans (IMI 225231), and in those intentionally infected with this fungus are reported. The biochemical significance of the changes in these constituents, resulting from the hypersensitive responses in the host species, is appraised in respect to the etiology of the malformation disease of mango.

Toxic substances produced byFusarium. III. Production and screening of phytotoxic substances ofF. oxysporum f. sp.carthami responsible for the wilt disease of safflowerCarthamus tinctorius Linn.

Fusarium oxysporum f. sp.carthami, a causative agent for the wilt disease of safflower (Carthamus tinctorius Linn.), has been shown to produce diacetoxyscirpenol, T-2 toxin, fusaric acid and lycomarasmin in artificial media. These substances produced disease syndromes, similar to those seen after the natural infection, when administered in healthy plants. Diacetoxyscirpenol and T-2 toxin have been detected in diseased safflower plants after inoculating with the wilt pathogen. This study is the first demonstration of vivotoxicity of diacetoxyscirpenol.

Mycotoxins produced by Fusarium oxysporum in the seeds of Brassica campestris during storage.

Three recognized mycotoxins, viz. diaxetoxyscirpenol, T-2 toxin and zearalenone, along with the fatty esters of these toxins were isolated from the flask culture extractives of Fusarium oxysporum Schlecht (IMI 273220) as also from seeds of Brassica campestris var. sarson (mustard) infected with this fungus in storage. Evaluation of biological activity and toxicity of the extractives and the effects of prolonged ingestion of the mouldy seeds by animals suggest that the infected seeds may present high toxin-risk to humans.

Toxic substances produced byFusarium VI. Anti-F. oxysporum f. sp.carthami effect of 2,2′,4-trihydroxybenzophenone

Anti-Fusarium oxysporum f. sp.carthami activity of 2,2′,4-tri-hydroxybenzophenone was evaluated. Pretreatment with the benzophenone offered complete protection to safflower seeds and seedlings, and recovery of the latter from the fungal infection.

Effect of 3 polyphenolic compounds against ear-rot of corn incited byFusarium moniliforme Sheld

Anti-F. moniliforme activity of 3 non-toxic polyphenolic compounds, viz. mangiferin, 1,3,6,7-tetrahydroxyxanthone, and 2,2′,4-trihydroxybenzophenone, was evaluated. The mycotoxin-producing fungus incited ear-rot in sweet corn in fields and during storage. The test compounds provided different degrees of protection to sweet corn from the ingress of the fungus. Additionally, noteworthy postinfectional curative action was observed in the case of the trihydroxybenzophenone.

Toxic substances produced byFusarium. VII. Control of fusarial wilt of safflower by root exudates and extractives ofRuellia tuberosa

Exudates and extractives of roots ofRuellia tuberosa, containing 2,6-dimethoxyquinone, acacetin and a C16-quinone, have been shown to produce significant protective and curative actions againstFusarium oxysporum-incited wilt of safflower. The potentiality of the root extractives as a foliar fungicide is appraised.