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Plant defense elicitors purification in soybean and bean from pathogenic nematode

Plant resistance induction against pathogens is an alternative disease control method, which involves the activation of the plant defense mechanisms, such as the phytoalexins induction. The eliciting molecules have the capacity of inducing and activating such responses and thus, techniques have searched to isolate and characterize fractions with eliciting aspect. This study aimed to purify, through ion exchange chromatography and gel filtration chromatography, eliciting molecules from phytopathogenic nematodes, and test them in the induction of phaseolin in bean hypocotyls and gliceolin in soybeans cotyledons. A Tris HCl 0.05 M (pH 6.8) buffer was used as control treatment and acibenzolar-S-methly (50 mg i.a. L-1) and Saccharomyces cerevisiae (20 mg m L-1) was used as induction standard treatment. Ion exchange chromatography (IEC) and gel filtration chromatography (GFC) were applied to separate power eliciting fractions from five hundred female root knot nematodes (Meloidogyne javanica). The purification of elicitors, through IEC, resulted in sixty glicidic fractions and six glycoprotein ones. They were classified according to their nature, being twenty-six glicidic fractions and thirty-seven glycoprotein ones, with molecular masses ranging from 29.19 to 2,989.25 kDa. From the purified fractions, eight of them presented phaseolin inducing effect potential, whereas fifteen fractions presented gliceolin inducing effect. Chromatography proved to be efficient in purifying the eliciting compounds. Compounds having gliceolin and phaseolin suppressing characteristics were verified in the bioassays. For those fractions obtained through IEC and posteriorly submitted to GFC that did not induce phytoalexin, it is suggested that the molecules need to act jointly so there is eliciting effect and thus induce a defense response in the plant. 
 
 Key words: gel filtration chromatography, ion exchange chromatography, Meloidogyne javanica, phytoalexins, resistance induction.