Tomato root exudates induce transcriptional changes of Meloidogyne hispanica genes

Abstract

Meloidogyne hispanica is a polyphagous root-knot nematode of emerging importance that has the ability to infect a broad range of plants, and tomato ( Solanum lycopersicum L.) crops can be severely damaged. This study investigated whether tomato root exudates regulate the expression of five candidate parasitism genes previously identified and sequenced in M. Hispanica . These were; calreticulin ( crt-1 ), cathepsin L cysteine protease ( cpl-1 ), β -1,4 endoglucanase-1 ( eng-1 ), fatty acid retinol binding protein ( far-1 ) and venom allergen-like protein ( vap-1 ). One thousand M. hispanica second-stage juveniles (J2) were exposed overnight to tomato root exudates, obtained from the root systems of 4-week-old plants during 4 h of agitation in sterilized distilled water, and the relative expression of the parasitism genes was determined by quantitative real-time PCR. The cpl-1 , crt-1 , far-1 and vap-1 genes were differentially up-regulated ( P <0.05) in the pre-parasitic J2 after exposure to tomato root exudates, while expression of eng-1 was largely unaffected ( P =0.05) by the treatment. This results suggests that tomato root exudates induce changes in the expression of candidate parasitism genes. Gene silencing by RNAi will elucidate the exact function of these candidate parasitism genes in nematode penetration and survival. Identification of the plant signal molecules in the tomato root exudates responsible for the up-regulation of these parasitism genes may lead to the development of novel approaches for the management of M. hispanica .