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<p>Downy mildew caused by <i>Pseudoperonospora cubensis</i> (Berk. &amp; Curt.) Rostow is a major constraint to cucumber production due to rapid disease development and unstable resistance. Host plant resistance represents the most effective and sustainable management strategy. This study investigated disease resistance responses in selected Indian slicing cucumber genotypes, viz., IC527431, IC572024, IC527400, IC613488 and Gol Kheera 1, identified as potential sources of resistance to downy mildew, along with Swarna Agethi as a susceptible check and uninoculated control plants. At 16 dpi, Swarna Agethi (71.72%), IC344894 (69.47%) and Pusa Uday (64.28%) recorded the highest average disease incidence (≈ 65–70%), classifying them as highly susceptible, whereas IC527400 (4.02%), IC613488 (6.6%), IC572024 (9.4%) and IC527431 (6.86%) showed minimal average disease incidence (≈ 4–7%), indicating strong downy mildew resistance. Control plants remained asymptomatic for disease incidence with normal growth, while biochemical parameters, including Peroxidase (POD), Polyphenol Oxidase (PPO), Superoxide Dismutase (SOD) activities and total phenol and flavonoid content, showed an exponential increase at 12 days post-inoculation. Among the evaluated genotypes, IC527431 (210.43&#xa0;mg/100&#xa0;g) exhibited the highest levels of phenolic compounds and antioxidant enzyme activities, followed by IC527400 (204.76&#xa0;mg/100&#xa0;g), IC613488 (190.45&#xa0;mg/100&#xa0;g), IC572024 (186.06&#xa0;mg/100&#xa0;g) and Gol Kheera 1 (171.55&#xa0;mg/100&#xa0;g). In contrast, the susceptible genotypes Swarna Agethi and IC344894 showed comparatively lower biochemical activity with no significant induction of defence-related enzymes, while total sugar content showed only minor and inconsistent variation among genotypes. Disease severity and key biochemical parameters, including total phenols, flavonoids, total sugars, and the activities of enzyme assays, were evaluated at four-day intervals from 0 to 16 days post-inoculation. Resistant genotypes had exhibited lower disease severity and enhanced antioxidant responses, identifying IC527400, IC527431, IC572024 and IC613488 as promising core genotypes for downy mildew resistance breeding in Indian slicing cucumber.</p>

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Integrated screening of Indian slicing cucumber core genotypes for downy mildew resistance (Pseudoperonospora cubensis) and associated biochemical defence mechanisms

  • 期刊论文

  • 发表日期：

    2026年7月17日

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  • Kishor Varotariya,
  • Mottaiyan Pitchaimuthu,
  • D. C. Manjunatha Gowda,
  • Budhavaram Varalakshmi,
  • Kundapura V. Ravishankar,
  • G. M. Sandeep Kumar,
  • Vivek Hegde,
  • Lingapatna T. Chaithra

摘要

Downy mildew caused by Pseudoperonospora cubensis (Berk. & Curt.) Rostow is a major constraint to cucumber production due to rapid disease development and unstable resistance. Host plant resistance represents the most effective and sustainable management strategy. This study investigated disease resistance responses in selected Indian slicing cucumber genotypes, viz., IC527431, IC572024, IC527400, IC613488 and Gol Kheera 1, identified as potential sources of resistance to downy mildew, along with Swarna Agethi as a susceptible check and uninoculated control plants. At 16 dpi, Swarna Agethi (71.72%), IC344894 (69.47%) and Pusa Uday (64.28%) recorded the highest average disease incidence (≈ 65–70%), classifying them as highly susceptible, whereas IC527400 (4.02%), IC613488 (6.6%), IC572024 (9.4%) and IC527431 (6.86%) showed minimal average disease incidence (≈ 4–7%), indicating strong downy mildew resistance. Control plants remained asymptomatic for disease incidence with normal growth, while biochemical parameters, including Peroxidase (POD), Polyphenol Oxidase (PPO), Superoxide Dismutase (SOD) activities and total phenol and flavonoid content, showed an exponential increase at 12 days post-inoculation. Among the evaluated genotypes, IC527431 (210.43 mg/100 g) exhibited the highest levels of phenolic compounds and antioxidant enzyme activities, followed by IC527400 (204.76 mg/100 g), IC613488 (190.45 mg/100 g), IC572024 (186.06 mg/100 g) and Gol Kheera 1 (171.55 mg/100 g). In contrast, the susceptible genotypes Swarna Agethi and IC344894 showed comparatively lower biochemical activity with no significant induction of defence-related enzymes, while total sugar content showed only minor and inconsistent variation among genotypes. Disease severity and key biochemical parameters, including total phenols, flavonoids, total sugars, and the activities of enzyme assays, were evaluated at four-day intervals from 0 to 16 days post-inoculation. Resistant genotypes had exhibited lower disease severity and enhanced antioxidant responses, identifying IC527400, IC527431, IC572024 and IC613488 as promising core genotypes for downy mildew resistance breeding in Indian slicing cucumber.