Phytoalexins from onion and their role in disease resistance

Cell wall alterations and localized accumulation of feruloyl‐3′‐methoxytyramine in onion epidermis at sites of attempted penetration by Botrytis allii are associated with actin polarisation, peroxidase activity and suppression of flavonoid biosynthesis

“…However, we failed to detect significant antifungal activity against Botrytis in FMT, FT or CT, so their role in resistance in onion is, therefore, not to form a barrier of fungitoxicity. We have not investigated the possibility that the known phytoalexins from onion, the tsibulins ( Dmitriev et al. 1990), are also present in RM.…”

Natural Fungicides Obtained from Plants

“…The ED 50 values were lower than the actual phytoalexin content in bulb scale spots, were B. cinerea lesion formation was restricted (Dmitriev et al, 1990). Only little accumulation of cyclopentane phytoalexins was observed in onion bulb scales during infection by the specialized pathogen B. allii (Dmitriev et al, 1990). B. allii seems to either suppress tsibulin accumulation; analogous to the interaction of B. narcissicola and its host narcissus of actively degrade tsibulins, as discussed for other antifungal compounds above.…”

“…Tsibulins inhibited spore germination and germ tube elongation of B. cinerea in vitro. The ED 50 values were lower than the actual phytoalexin content in bulb scale spots, were B. cinerea lesion formation was restricted (Dmitriev et al, 1990). Only little accumulation of cyclopentane phytoalexins was observed in onion bulb scales during infection by the specialized pathogen B. allii (Dmitriev et al, 1990).…”

“…Some are constitutive inhibitors, such as the phenolic compounds catechol that is present in the outer bulb layers of pigmented Allium cepa (onion) cultivars were it confers resistance to Colletotrichum (Link & Walker, 1933). Onion also produces a class of cyclopentane phytoalexin upon pathogen infection, designated tsibulins (Dmitriev et al, 1990), which accumulate in bulb scales at infection sites during incompatible interactions with B. cinerea. Tsibulins inhibited spore germination and germ tube elongation of B. cinerea in vitro.…”

Garlicin—fact or fiction? the antibiotic substance from garlic (Allium sativum L.)

“…Russian researchers detected in the bulbs of onion a phytoalexin, 'cibullin' (a different spelling is 'tsibullin'), which is formed in the scales following incubation with a diffusate of Botrytis allii. The carbohydrate fraction of this plant pathogenic fungus was identified as the cytoplasmic elicitor (Dmitriev et al, 1988a(Dmitriev et al, ,b, 1989(Dmitriev et al, , 1990. Induction of cibullin formation in the host plant was also achieved with the mycelial lipids of B. allii which contain an appreciable amount of highly unsaturated fatty acids (Perkovskaya et al, 1991).…”