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Purpose: Broomrape produces serious damage to many legume crops and, particularly, becomes a limiting factor for faba bean (Vicia faba L.) production in the Mediterranean basin. Currently, several traditional methods of control have been developed, but none has proved to be effective for this parasite. However, breeding for resistance to this pest remains as one of the most feasible and environment-friendly methods for managing broomrape, but the mechanisms governing the interaction between the parasite and the host are not yet well understood. Therefore, we studied the behavior and molecular and enzymatic changes associated with the resistance to Orobanche foetida in faba bean mutants, which were obtained through radiation mutagenesis. Materials and methods: Three faba bean genotypes were used in this study, the variety ‘Badï’, characterized by high productivity in Orobanche-free soils and susceptibility to O. foetida, and two mutant lines P2M3 and P7M3 (derived from radio mutagenesis program), selected for their higher resistance to O. foetida in a field evaluation. The infection progress and the relative changes in the co-culture response, the enzymatic activities changes and the efficiency of the root extract stimulants from the host plant were followed and evaluated in all the genotypes. Results: Experiments showed that low induction of seed germination is a major component of resistance in these lines against O. foetida. This is confirmed by the in vitro experiments with root exudates. The parallel reduction in infection was accompanied by the continuous enhancement of the peroxidase activity, the polyphenol oxidase activity and the phenylalanine ammonia lyase activity in faba bean roots. Conclusion: These data suggest the contribution of these enzymes in faba bean resistance to O. foetida broomrape induced by the use of gamma rays. Management of Orobanche by way of crop selection, based on these enzyme systems is a possible option. [ABSTRACT FROM AUTHOR]

BACKGROUND Some radiation-mutagenised chickpea mutants potentially resistant to the broomrape, Orobanche foetida Poir., were selected through field trials. The objectives of this work were to confirm resistance under artificial infestation, in pots and mini-rhizotron systems, and to determine the developmental stages of broomrape affected by resistance and the relevant resistance mechanisms induced by radiation mutagenesis. RESULTS Among 30 mutants tested for resistance to O. foetida, five shared strong resistance in both pot experiments and mini-rhizotron systems. Resistance was not complete, but the few individuals that escaped resistance displayed high disorders of shoot development. Results demonstrated a 2-3-fold decrease in stimulatory activity of root exudates towards broomrape seed germination in resistant mutants in comparison with non-irradiated control plants and susceptible mutants. Resistance was associated with an induction of broomrape necrosis early during infection. When infested, most of the resistant mutants shared enhanced levels of soluble phenolic contents, phenylalanine ammonia lyase activity, guaiacol peroxidase activity and polyphenol oxidase activity, in addition to glutathione and notably ascorbate peroxidase gene expression in roots. CONCLUSION Results confirmed enhanced resistance in chickpea radiation-mutagenised mutants, and demonstrated that resistance is based on alteration of root exudation, presumed cell-wall reinforcement and change in root oxidative status in response to infection. © 2016 Society of Chemical Industry [ABSTRACT FROM AUTHOR]

This study examined the capacity of Rliizobium sp. strain PchAZM to reduce parasitism of chickpea by Orobanche foetida under greenhouse conditions, and assessed the relative impact of rhizobia on the expression of chickpea defense response against broomrape. Growth chamber experiments using Petri dishes revealed that rhizobia infection on chickpea roots reduced broomrape seed germination, and restricted the broomrape attachment to host roots while retarding tubercle formation and development by the parasite. In pot experiments, chickpea roots inoculated with rhizobia reduced the total number of broomrape by up to 90%. Broomrape necrosis was observed both before and after parasite attachment to inoculated chickpea roots in Petri dishes and pot experiments. Reduction in infection was accompanied by enhanced levels of the defence-related enzymes phenylalanine ammonia lyase (PAL) and peroxidase (POX). Increased levels of phenoiics were recorded in the roots of rhizobia-inocuiated plants grown in the presence of broomrape. The results suggest that rhizobia could be used for protection of chickpea against O. foetida. [ABSTRACT FROM AUTHOR]