**12.2 Protection of plants from predatory animals and phytopathogens**

Abrin, a type-II ribosome-inactivating protein (RIP), was the first lectin to be recognized as a defence protein (Peumans and Van Damme, 1995). Soon afterwards ricin also came to be recognized as a defence protein (Olsnes, 2004). Type-II RIPs which belong to the plant lectin family with β-trefoil fold are known to be toxic to animals and insects (Hartley and Lord, 2004; and Stirpe, 2004). Lectins from *Phaselous vulgaris* (PHA), *Robinia pseudocacia* and *Sambuscus nigra* have been reported to be toxic to higher animals (Peumans and Van Damme, 1995). Lectins from many plants, when ingested by animals, have resulted in toxic effects (Lis and Sharon, 1998), fungal growth in *Trichoderma viride* is inhibited by wheat germ aggiutinin (WGA) (Mirelman el al., 1975). Brambl and Gade (1985) have shown that eleven purified lectins, representing a wide spectrum of sugar specificity, inhibited the growth of fungal species *Neurospora crassa*, *Aspergilius amsteldomi* and *Botryodiplodia theobromae*. Known antifungal lectins include those which bind chitin (Peumans and Van Damme, 1995; Hirsch et al., 1995; Eijsden et al., 1995; Kijne, 1997; and Selitrennikoff, 2001). The anti-insect activity of many plants has been attributed to the presence of lectins in them. For example PHA (Chrispeels and Raikhel, 1991) pea nut agglutinin (PNA), WGA, *Maclura pomifera* agglutinin (MPA) and lectins from potato, thorn apple and osage orange show anti-insect activity against cowpea weevil. WGA and *Bauhinea purpurea* agglutinm are toxic to *Ostrinia nubilalis* larvae. Snow drop and garlic lectin show toxic effects on cowpea weevil and tobacco hornworm (Hilder et al., 1995; and Peumans and Van Damme, 1995).
