Systemic Induced Resistance to the Root-Knot Nematode in Tomato by Chemical Inducers

Systemic Acquired Resistance (SAR) as a management strategy for plant parasitic nematode is a state of resistance increased after a previous infection of plant to a biotic pathogen. Induction of SAR is accompanied by local and systemic enhancement of Salicylic Acid (SA). SA increase in plant is concomitant with PR1 expression. We examined the effect of three chemicals including SA, Abscisic Acid (ABA), and DL-β-Amino-n-Butyric Acid (BABA) on the root-knot nematode Meloidogyne incognita on tomato plants. The expression of PR1 genes and 9-Cis-Epoxycarotenoid Dioxygenase (NCED) as markers for SAR and ABA-related activity genes was investigated in growth chamber conditions. Results showed that all elicitors reduced the population of nematode as compared to the control. Shoot length, shoot fresh and dry weight of nematode infected tomatoes pre-treated with BABA increased by 20, 25, and 8 % and number of eggs, galls, egg masses and reproduction factor decreased by 33, 18, 18, and 20%, respectively. All elicitors increased the expression of PR1 and NCED genes in nematode infected tomato. These data suggest that SA, BABA and ABA activate similar defenses in tomato plants, which is partly SA- and ABA-related. SA, BABA, and ABA pretreated tomatoes infected with M. incognita trigger a SAR-response and lead to the control of the nematode under controlled conditions.