Tomatine, isolation

The function of these tomatinase in formae speciales that do not pathogenise tomato is unknown. One possible explanation could be the presence of tomatine or similar saponins in their host plant species. However, (i) tomatine has not yet been reported in these plants [2, 7, 9] and (ii) although some of these species contain small amount of tomatine and other saponins structurally related to tomatine (e.g. potato contains a- solanine and a-chaconine [2, 4, 9, 90]), these are inactive as inducers of tomatinase and, moreover, tomatinase cannot use any of these glycoalkaloids as substrate [89]. In addition, it is clear that tomatinase is not required for pathogenicity in these isolates, at least in the case of F. oxysporum f. sp. melonis, where some strains that are fully pathogens on muskmelon lack tomatinase activity [89]. 

One of the isolates used by Quidde et al., was unable to metabolize tomatine and was more sensitive to the glycoalkaloid. In addition, this isolate was not able to induce disease symptoms on detached tomato leaves, but could pathogenize bean leaves, indicating that the ability to degrade tomatine may be required for pathogenicity of B. cinerea on tomato [36]. It would be very interesting to transformed this strain with one tomatinase gene to confirm this hypothesis. 

The structural relationship of tomatinase from B. cinerea to other tomatinases is unknown, but its molecular mass (70 kDa) is different from the other two enzymes mentioned before, 50 kDa from F. oxysporum [35, 38] and 110 kDa from S. lycopersici [33]. Moreover, when Quidde et al., attempted cloning of the tomatinase gene from B. cinerea using the tomatinase from S. lycopersici as a probe, they isolated a gene with high sequence homology, whose product had not tomatinase activity but was able to detoxify avenacin A-l [97], the saponin from oats related to some extent to tomatine. 

In conclusion, F. solani isolates appear to be less sensitive to tomatine than F. oxysporum f. sp. lycopersici, although they produce much lower tomatinase activity, indicating that they must possess other inherent mechanisms of resistance. One possibility is that F. solani may have a lower content of sterols in the membrane than F. oxysporum. Thus, although tomatinase activity may help F. solani to grow on green tomato tissue it does not seem to be determinant in the resistance to tomatine. 

Suleman, P., Tohamy, A.M., Saleh, A. A., Madkour, M.A., Straney, D.C. Variation in sensitivity to tomatine and rishitin among isolates of Fusarium oxysporum f. sp. lycopersici, and strains not pathogenic on tomato. Physiol Mol Plant Pathol 1996 48 131-144. 

The biotransformation of alkaloids of the tomatanine type has also been examined by Wolters 42). In a study with a variety of microorganisms he observed the formation of metabolites of tomatidine (183), tomatidenol (209), soladulcidine (196), solasodine (210), tomatine (188), solamargine (211), and solasonine (212). The products were not isolated and thus no... 

The a-tomatine (Fig. 9.11) is the major glycoalkaloid present in the leaves, stems, and immature fruit of tomato plants. It is reported to be potentially toxic and also is reported to exert antifungal activity and to inhibit the growth of fruitworm and other insects (Friedman et al., 1994). The method consists of lyophilization of the tomatoes followed by grinding and sieving. The extraction is aqueous and reversed-phase C-18 is the sorbent used for the isolation of the a-tomatine. 

Aside from the steroid alkaloids from Solatium, little work has been done on other groups of steroid alkaloids (Table XLVII). Roddick and Butcher (802) reported the isolation of tomatine from a callus culture of tomato cell suspension cultures and several other callus cell lines did not contain this glycoalkaloid. 

Fontaine TD, Irving GW, Ma R, Poole JB, Doolittle SP. Isolation and characterization of crystalline tomatine, an antibiotic agent from the tomato plant. Arch Biochem Biophys 1948 18 467-75. 

Tomatine and dehydrotomatine were isolated fix)m tomato plants and separated on a C g column (A = 210nm). A 14-min 90/10/0.1- 50/50/0.1 water/aceto-nitrile/TFA gradient generated good separation. The content of leaf and green fhiit extracts were compared. Spike standards of 1-12.5 pg injected were cited [1086]. ... 

The enzymatic glycosylation of steroid alkaloids by extracts from S. lacini-atum 337) as well as in the potato tuber 338) has been investigated. A fungal j8-glucosidase capable of hydrolyzing a-tomatine and demissine has been isolated and purified and its properties studied 339). 

Pregnane Type Sapogenins/Saponins. 5a-Pregn-16-en-3P-ol-20-one was isolated from Solanum pimpinellifolium Jussl. sub nom. Lycopersicon pimpinellifo-lium (Jussl.) Mill, by Schreiber and Aurich (1966) and also by Bennett et al. (1967). The authors speculated that this aglycone could be a metabolite of the steroidal glycoalkaloid tomatine. Heftmann and Schwimmer (1972) added that... 

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