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Abstract

Maize (Zea mays L.) is a vital cereal crop in Pakistan, but its production is severely affected by stalk rot disease, a complex condition caused by soil and seed-borne fungi. This investigation was conducted to isolate and characterize the fungal pathogens responsible for maize stalk rot in the Haripur area, and to study their effect on host physiology and metabolism. Fifty symptomatic maize plants were collected from various fields. The results revealed the consistent occurrence of three pathogenic fungi, with Fusarium moniliforme and Macrophomina phaseolina being the most predominant, and Fusarium oxysporum being less frequent. Soil samples from the area also contained Aspergillus flavus and Aspergillus niger. Sequencing analysis confirmed the morphological identification, showing 100% identity of one isolate with F. oxysporum (Accession number PZ049446) and 99.78% identity of another with Fusarium verticillioides (syn. F. moniliforme) (Accession number PZ039329). Infected plants exhibited significant structural degradation, including a thinner epidermis and vacuolated cells in the leaves. Biochemically, a marked decrease in chlorophyll content was observed in infected plants. Conversely, the activity of defense-related enzymes was significantly increased; peroxidase and catalase activities were substantially higher in infected plants compared to healthy ones, indicating a strong oxidative stress response. Gas Chromatography Mass Spectrometry (GC–MS) metabolite profiling revealed a distinct reprogramming in infected tissues, which accumulated stress-related compounds such as Butanoic acid-3-amino, Cystamine, and 3-nitropropanoic acid etc. In contrast, tissues of controlled plants contained metabolites indicative of normal metabolism, such as Urea, Acetic acid, and Hexanoic acid. Cyclobutanol was found in both control and diseased plants. The integrated approach of morphological, molecular, and biochemical characterization confirmed that F. moniliforme and M. phaseolina were the primary causal agents of stalk rot in Haripur. This study may be useful for developing the management strategies to control stalk rot disease of maize. Identification of stalk rotting pathogen of maize at molecular level may be useful to diagnose, treat, and control the disease. Farmers could relate the detection of stalk rot disease in maize directly to its management decisions, because early and accurate detection helps reduce yield losses and prevent further spread

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