Melton R E, Flegg L M, Brown J K, Oliver R P, Daniels M J, Osbourn A E
Sainsbury Laboratory, Norwich, UK.
Mol Plant Microbe Interact. 1998 Mar;11(3):228-36. doi: 10.1094/MPMI.1998.11.3.228.
The anti-fungal, steroidal, glycoalkaloid saponin, alpha-tomatine, is present in uninfected tomato plants in substantial concentrations, and may contribute to the protection of tomato plants against attack by phytopathogenic fungi. In general, successful fungal pathogens of tomato are more resistant to alpha-tomatine in vitro than fungi that do not infect this plant. For a number of tomato pathogens, this resistance has been associated with the ability to detoxify alpha-tomatine through the action of enzymes known as tomatinases. In contrast, the biotrophic tomato pathogen Cladosporium fulvum is sensitive to alpha-tomatine and is unable to detoxify this saponin. This paper describes the effects of heterologous expression of the cDNA encoding tomatinase from the necrotroph Septoria lycopersici in two different physiological races of C. fulvum. Tomatinase-producing C. fulvum transformants showed increased sporulation on cotyledons of susceptible tomato lines. They also caused more extensive infection of seedlings of resistant tomato lines. Thus, alpha-tomatine may contribute to the ability of tomato to restrict the growth of C. fulvum in both compatible and incompatible interactions.
抗真菌甾体糖生物碱皂苷α-番茄碱，在未感染的番茄植株中大量存在，可能有助于保护番茄植株抵御植物病原真菌的侵袭。一般来说，番茄的成功致病真菌在体外比不感染这种植物的真菌对α-番茄碱更具抗性。对于许多番茄病原菌来说，这种抗性与通过一种名为番茄碱酶的酶的作用使α-番茄碱解毒的能力有关。相比之下，活体营养型番茄病原菌番茄叶霉对α-番茄碱敏感，且无法使这种皂苷解毒。本文描述了来自坏死营养型番茄壳针孢的编码番茄碱酶的cDNA在番茄叶霉的两个不同生理小种中的异源表达效果。产生番茄碱酶的番茄叶霉转化体在易感番茄品系的子叶上表现出孢子形成增加。它们还导致抗性番茄品系的幼苗感染更广泛。因此，α-番茄碱可能有助于番茄在亲和与非亲和互作中限制番茄叶霉生长的能力。
