natural-products-in-plant-pest-management

Control of Virus Diseases of Plants 157Kumar, 1980). A 50–60% reduction of the virus content in the treated plantswas observed in the infectivity assays. M. jalapa extract was able to check thepopulation of aphids and whiteflies and, thereby, control the natural spreadof a few viruses on the systemic hosts (Verma and Kumar, 1980).MAP isolated from root inhibits mechanical transmission of TMV, PVY,cucumber green mottle mosaic virus, and turnip mosaic virus on local-lesionand systemic hosts and can induce systemic resistance of a low order whenapplied to basal leaves (Kubo et al., 1990). The purified protein consists of asingle polypeptide without a sugar moiety and has a molecular weight of24.2 kDa. It is a basic protein rich in lysine content, with a PI of 9.8 (Kubo etal., 1990). The complete amino acid sequence of MAP has been determined.It consists of 250 amino acids and its molecular weight as determined fromthe sequence is 27,833 kDa. The native MAP was resistant to proteasedigestion (Habuka et al., 1989).MAP produced by M. jalapa cells in suspension culture showed comparablebiological activity with that of the roots and leaves and also reactedpositively with anti-MAP serum (Ikeda et al., 1987). Several nutritional andhormonal factors also affect the formation of MAP by M. jalapa cells in suspensionculture (Ikeda et al., 1987). Bolognesi et al. (2002) reported ribosomeinactivatingand adenine polynucleotide glycosylase activities in M. jalapa L.tissues.Ricinus (RICIN A) antiviral proteinThe ricinus antiviral protein is a type II RIP isolated from Ricinus communisthat has a molecular weight of 65 kDa. Its is a heterodimer consisting of chainA similar to the type-I RIP and chain B linked together by a disulfide bond.Chain B has great similarity to mammalian lectins A. Once inside the cellchain A acts as a type-I RIP and inactivates protein translation machinery.The cDNA for ricin has been cloned (Lamb et al., 1985). Both A and B chainsare encoded by a single gene which has no intron. Detection of ricin andother ribosome-inactivating proteins by an immuno-polymerase chainreaction assay was reported by Lubelli et al. (2006).Role of RIPsThe above examples of RIPs show their important role against both plantviruses and also RNA- and DNA-containing animal viruses (Barbieri et al.1993). The mechanism of antiviral activity suggested for both plant andanimal system involves increased permeability of and easier entry of RIPsinto virus-infected cells, blocking of protein synthesis and reduced virusmultiplication (Barbieri et al., 1993).Virus resistance previously observed in transgenic plants expressing coatprotein genes, and so on, has been specific for the virus from which the genesare derived or for closely related viruses (Beachy et al., 1990) but transgenic