INFIVE   05416
Unidad Ejecutora - UE
Induced resistance against Fusarium Head blight in ITMI population
Annual Wheat Newsletter
Kansas State University
Lugar: Kansas; Año: 2015 vol. 61 p. 8 - 8
Fusarium head blight (FHB) or scab, caused mainly by Fusarium graminearum (Schwabe) and F. culmorum (WG Smith) Sacc, is one of the most important fungal diseases affecting wheat in cereal producing areas of the world. The economic losses caused by FHB include yield and quality reduction. The damages induced by the disease are further aggravated by the frequent presence of mycotoxins in affected grains. In the recent years, monoculture, reduced tillage and maize/wheat rotations have greatly increased the level of inoculum in the soil and, hence, the risk for epidemics of FHB in Argentina. Wheat resistance to FHB is inherited as a quantitative trait governed by polygenes, and quantitative trait loci (QTLs) have been detected on all wheat chromosomes. Since the genetic base of resistance is complex, we selected the most tolerant RILs from the ITMI population to see if their defences can be elicited by applying hormonal inducers or a bacterial suspension. Several of the resistance mechanisms are constitutively expressed or these are elicitated by a previous aspersion with hormonal or bacterial treatments. After the treatment plant defences are ´primed´ and respond faster in a more efficient mode when occur a pathogen attack. Several RILs selected by their FHB tolerance were treated them with hormonal inductors of defences and a bacterial suspension (Pseudomonas spp) before the inoculation with one aggressive strain of F. graminearum. A complete factorial design was performed with untreated plants (Controls), inoculated with Fusarium (I), pre-treated with Ethylene (E), treated with E and inoculated (E+I), treated with Salicilic Acid (SA), sprayed with SA and inoculated (SA+I), sprayed with bacterial suspension (B) and inoculated after B treatment (B+ I).Elicitation was performed 48 hours before anthesis (Zadoks growth stage 65). Afterwards, each spike was sprayed with 1 ml of the macroconidial suspension using a manual atomizer (constant volume). At harvest the total number of grains per spike (GS), the number of damaged kernels (DK), the Fusarium index (FI= DK/GS), the total weight per spike and thousand kernel weight (TKW) were calculated.Part of the tolerant RILs showed similar GS in the complete set of treatments. These lines also had lower DK and FI except when inoculated after SA induction which showed a slightly higher damage. The TKW was not affected by inoculation in the treated and control plants.On the other hand, inoculated plants of a second group of RILs produced similar GS than control plants, except those ones sprayed with E, hormone that reduced significantly the GS. The SA and B treatments induced a better performance in this group of RILs either in the inoculated or un-inoculated plants.Tolerant RILs would have two different types of inducible defense mechanisms, in the first group the defenses seem to be mediated by ethylene and in the second group by the salicylic acid.