Inhibition of Orobanche crenata Seed Germination and Radicle Growth by Allelochemicals Identified in Cereals

Orobanche crenata is a parasitic weed that causes severe yield losses in important grain and forage legume crops. Cereals have been reported to inhibit O. crenata parasitism when grown intercropped with susceptible legumes, but the responsible metabolites have not been identified. A number of metabolites have been reported in cereals that have allelopathic properties against weeds, pests, and pathogens. We tested the effect of several allelochemicals identified in cereals on O. crenata seed germination and radicle development. We found that 2-benzoxazolinone, its derivative 6-chloroacetyl-2-benzoxazolinone, and scopoletin significantly inhibited O. crenata seed germination. Benzoxazolinones, l-tryptophan, and coumalic acid caused the stronger inhibition of radicle growth. Also, other metabolites reduced radicle length, this inhibition being dose-dependent. Only scopoletin caused cell necrotic-like darkening in the young radicles. Prospects for their application to parasitic weed management are discussed. © 2013 American Chemical Society.This research is supported by projects FP7-ARIMNet-MEDILEG and AGL2011-22524 (cofinanced by FEDER funds).Peer Reviewe

Efficacy of a pyrimidine derivative to control spot disease on Solanum melongena caused by Alternaria alternata

The pyrimidine derivative (4,6-dimethyl-N-phenyldiethyl pyrimidine, DPDP) was tested as a foliar spray fungicide at 50 mg l−1 for protection of eggplant (Solanum melongena) from spot disease caused by Alternaria alternata. Varied concentrations of DPDP (10–50 mg l−1) differentially inhibited mycelial growth, conidial count and conidial germination of A. alternata growth in vitro; the magnitude of inhibition increased with increasing concentration. In vivo, an experiment was conducted in pots using a complete block randomized design and repeated twice with three replications and four treatments (control, A. alternata alone, DPDP alone and combination of DPDP and A. alternata) for 5 weeks (1 plant in pot × 3 pots per set (3 replications per treatment) × 4 sets (4 treatments) × 5 weeks × 2 experimental repetitions = 120 pots). In this experiment, 10-day-old eggplant seedlings were transplanted in pots and then inoculated with A. alternata, DPDP or their combination 1 week later. Leaves of the A. alternata-infected eggplant suffered from chlorosis, necrosis and brown spots during the subsequent 5 weeks. Disease intensity was obvious in infected leaves but withdrawn by DPDP. There were relationships between incidence and severity, greater in plant leaves infected A. alternata alone and diminished with the presence of DPDP. Moreover, the infection resulted in reductions in growth, decreases in contents of anthocyanins, chlorophylls, carotenoids and thiols as well as inhibitions in activities of superoxide dismutase (SOD), glutathione peroxidase (GPX) and glutathione-S-transferase (GST). Nonetheless, the application of DPDP at 50 mg led to a recovery of the infected eggplant; the infection-induced deleterious effects were mostly reversed by DPDP. However, treatment with DPDP alone seemed with no significant impacts. Due to its safe use to host and the inhibition for the pathogen, DPDP could be suggested as an efficient fungicide for protection of eggplant to control A. alternata spot disease

Roles of dehydrin genes in whe

Physiological parameters and expression levels of drought related genes were analyzed in early vegetative stage of two bread wheat cultivars (Sids and Gmiza) differ in drought tolerance capacity. Both cultivars were imposed to gradual water depletion started on day 17 till day 32 after sowing. Sids, the more tolerant cultivar to drought showed higher fresh and dry weights than the drought sensitive genotype, Gmiza. Under water stress, Sids had higher membrane stability index (MSI), lower accumulated H2O2 and higher activity of the antioxidant enzymes; catalase (CAT), guaiacol peroxidase (GPX), ascorbate peroxidase (APX) and superoxide dismutase (SOD) than Gmiza. On the other hand, the differential expression patterns of the genes dhn, wcor and dreb were observed due to water deficit intensity according to cultivar’s tolerance to drought. The DNA sequence alignment of dun showed high similarity of about 80–92% identities with other related plants. The most striking overall observed trend was the highly induction in the expression of dun, wcor and dreb in leaves of the tolerant genotype, Sids under severe water stress