Glucosinolates in cauliflower as biochemical markers for resistance against downy mildew (original) (raw)

Seedling and adult plant resistance to downy mildew (Peronospora parasitica) in cauliflower (Brassica oleracea convar. botrytis var. botrytis)

Plant Pathology, 1999

Seedlings of six cauliflower cultivars (Brassica oleracea convar. botrytis var. botrytis) were assessed for resistance to a Danish isolate of Peronospora parasitica, under controlled conditions. Resistance, characterized by restricted sporulation and necrotic dark flecks at the inoculation site on the cotyledons, was expressed in the hybrids 9306 F1, 9311 F1, and the open pollinated cultivar Perfection. Testing of the parent lines and F2 generations of the two resistant hybrids suggested that resistance was a dominantly inherited trait controlled by a single gene. Inoculation of the cultivars with seven isolates, from different geographical origins, showed that the resistance was isolate specific. The two hybrid cultivars expressing cotyledon resistance and two hybrids expressing susceptibility were assessed for adult plant resistance under field conditions. The AUDPC (Area Under the Disease Progress Curve), based on disease incidence and severity, revealed significant differences between the cultivars. At harvest, the cultivars exhibited significantly different levels of defoliation and curd attack. The cultivars 9306 F1 and 9311 F1 showed high levels of resistance in all assessments, whereas the two cultivars exhibiting susceptibility at the seedling stage, 9304 F1 and 9305 F1, also exhibited susceptibility through the adult plant stage. Thus, the resistance exhibited under field conditions resembled that identified at the seedling stage under controlled conditions. The results suggest that cotyledon resistance similar to that described could provide resistance throughout the adult plant stage, including curds.

Seed treatment with ?-aminobutyric acid protectsPennisetum glaucum systemically fromSclerospora graminicola

Pest Management Science, 2001

b-Aminobutyric acid (BABA) treatment of pearl millet [Pennisetum glaucum (L) R Br] seeds in¯uenced seedling vigour and protected the seedlings from downy mildew disease caused by the oomycetous biotropic fungus Sclerospora graminicola (Sacc) Schroet. Of the different concentrations of BABA tested, viz 25, 50, 75 and 100 mM, seeds treated with 50 mM for 6 h resulted in the maximum of 1428 seedling vigour and showed 23% disease incidence in comparison with the control which recorded a seedling vigour of 1260 and 98% disease incidence ie 75% protection from disease. Seeds treated with BABA when challenged for downy mildew disease using zoospores of S graminicola required 48 h after inducer treatment to develop maximum resistance. Durability of induced resistance was also tested in plants raised from seeds treated with the inducer and identi®ed as resistant, by second challenge inoculation with the downy mildew pathogen at tillers and in¯orescence axes. Reduced disease incidence of only 10 and 12% in these plants, compared with 71 and 76% disease in control plants inoculated at the tillers and in¯orescence axes, respectively, suggested that resistance induced in seeds with BABA remained operative through vegetative and reproductive growth of pearl millet plants. Induction of resistance by seed treatment with BABA enhanced vegetative growth, viz height, fresh weight, leaf area and tillering, and reproductive growth, viz early¯owering, number of productive ear heads and 1000 seed weight. Studies on induction of resistance in different cultivars of pearl millet with varying resistance reaction to downy mildew indicated that the protection offered by BABA is independent of the nature of cultivars used and not dependent on their constitutive resistance.

History and Perspectives on the Use of Disease Resistance Inducers in Horticultural Crops

HortTechnology, 2005

A major challenge facing horticultural crop production is the need to provide field and postharvest disease control measures that help maintain high quality plant products. Producers and consumers also expect high quality produce with minimal or no pesticide residues and competitive prices. The chemical management of disease is further complicated by the development of fungicide resistance in many important pathogens. Because of these concerns, an alternative or complementary approach is the use of disease resistance inducers that activate the natural defenses of the plant. Induced disease resistance in plants has been studied in many different pathosystems for nearly a century. Resistance to plant disease can be induced systemically by prior infection with pathogens, by certain non-pathogenic microbes that colonize the surface of roots and leaves, or by chemicals. The application of resistance inducers should protect plants through the induction of defenses that are effective again...

Phytogard®(K2HPO3) induces localized resistance in cauliflower to downy mildew of crucifers

Crop Protection, 2000

Phytogard, a formulation containing 58% potassium phosphonate (K HPO) and 42% water was tested for its ability to protect cauli#ower (Brassica oleracea var. botrytis) from downy mildew of crucifers (Peronospora parasitica). A dose-response analysis was conducted and concentrations of 0.0, 0.5, 5.0, 6.0, 7.0 and 10.0 ml/l of water were tested on seven-day old seedlings using the spray method. On 30-day old plants, concentrations of 7.0, 10.0 and 20.0 ml/l were tested using the same spray method. Results showed that when applied before or after inoculation, Phytogard provided complete protection (no sporulation) of seedlings with concentrations of 7.0 ml/l or higher. On young plants, complete protection was obtained at 10 ml/l. It was also shown that the induced resistance was not systemic but lasted at least 15 days after treatment. However, when Phytogard was applied on roots of 30-day old plants, all leaf stages were completely protected probably due to the ascendant transport of the compound. In another experiment, it was shown that Phytogard at 7 ml/l inhibits germination of 53% of the spores. SDS}PAGE gels colored with silver nitrate revealed that the protein pro"le of treated plants was not modi"ed by treatment with the compound. However, when the protein extracts were concentrated (10;), results obtained showed that-1,3 glucanase activity and PR2 proteins were weakly induced. These results suggest that resistance induced by Phytogard is probably strongly localized.

Analysis of Biochemical Changes in Cultivars of Black Gram, Green Gram and Pea against Powdery Mildew 1

Plantae Scientia, 2019

Powdery mildew disease of the Black gram, Mung bean and Pea are a major constraint in the production. The resistance of plants to various pathogens depends on synthesis and level of various defence enzymes like hydrolases; peroxidases and antimicrobial compounds like phytoalexins (Kuc, l991 et al Kauffmann et al. l987; Boiler, l987; Mauch et al., l988; Kale and Choudhary 200l, Koche and Choudhary, 2005). The present study focused on visual screening of selected crop cultivars against the powdery mildew and its biochemical correlation with chlorophyll content, sugars, phenols content, PR-proteins and Phytoalexin activities. From the field studies, it was observed that selected crop was found with powdery mildew incidence. This disease incidence data was correlated with biochemical changes and level of chlorophyll, sugars, phenols, PR-protein and Phytoalexin activities.