PJB-2023-226
HISTO-PATHOLOGI-CAL OBSERVATION OF RESISTANT AND SUSCEPTIBLE MAIZE (ZEA MAYS L.) GENOTYPES UNDER EXEROHILIUM TURCICUM STRESS
Tahsin Razzaq
Abstract
Abstract
Northern Corn Leaf Blight (NCLB) is the most common fungal disease of maize in the temperate world, including Azad Kashmir. It is caused by the fungus Exserohilum turcicum, which produces spores that colonizes maize leaf surface. This pathogen damages the leaf structure, causing chlorosis and loss of photosynthetic activity. Compromised maize germplasm demonstrates a variety of NCLB symptoms as well as mechanisms of disease resistance. Planting resistant maize varieties has been demonstrated to be the most effective method of NCLB management. In this report, histochemical studies were conducted to identify the genetic source of maize resistance to E.turcicum. Plant susceptibility to NCLB was evaluated on a scale of 0–5.The reaction of each tested genotype was evaluated using histochemical observations, number of infections (NI), fungal colony area (FCA), necrotic area (NA), and the calculated hypersensitivity index (HI). Leaf samples were collected at 10 and 20 days post infection (dpi), allowing comparison of early and full progression of the disease. Results at 10 dpi demonstrated that resistant genotypes had few-to-no infections while demonstrating the highest necrotic area. Largest NA was measured in the genotypes Karamat-Bar (3456.66µm), NCEV-1530-11 (726.57µm), and SZP-13200 (625.68µm). Smallest FCAs were observed in Karamat-Bar (50.67µm), NCEV-1530-11 (59.12µm), and SZP-13200 (97.68 µm) at10dpi. Resistance was indicated by HI, highest in Karamat-Bar (93.37%), SZP-13200 (93.09%), and NCEV-1530-11 (90.36%). Genotypes previously identified as susceptible in field research showed larger NI (16 in Soan-3) and greater FCAs (Soan-3 at 3943.04µm, Ghuariat 2302.73µm, and Kissanat 1947.14µm).These genotypes exhibited the lowest HI (2.6% in Soan-3, 2.51% in Ghuari, and 2.41% in Kissan). At 20 dpi, NA reduction was observed in resistant genotypes. Decreased disease progression and infection delay is linked to the presence of a resistant gene. Identification of resistant maize strains and their implementation in future breeding programs is critical in preventing significant future yield losses.
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