Morphological characterization, pathogenicity screening, and molecular identification of Fusarium spp. isolates causing post-flowering stalk rot in maize

Abstract

Post flowering stalk rot (PFSR) of maize caused by the Fusarium species complex is a serious threat to maize production worldwide. The identification of Fusarium species causing PFSR based on morphology traditionally relies on a small set of phenomic characteristics with only minor morphological variations among distinct Fusarium species. Seventy-one isolates were collected from 40 sites in five agro-climatic zones of India to assess the diversity of Fusarium spp. associated with maize crops showing symptoms of PFSR in the field. To investigate the pathogenicity of Fusarium spp. causing PFSR sixty isolates were toothpick inoculated between the first and second node at 55 days after sowing during the tassel formation stage of the crop in Kharif (Rainy season), and Rabi (Winter season) season field trials. Ten most virulent Fusarium isolates, based on the highest observed disease index, were identified by homology and phylogenetic analyses of partial sequences of the translation elongation factor 1 α (Tef-1α). Based on morphological traits such as mycelial growth patterns and mycelial pigmentation, Fusarium isolates were divided into nine clusters. The isolates were judged to be virulent based on their ability to decrease seedling vigour in in-vivo situations and high disease severity in field experiments. Pathogenicity test during the Kharif season showed 12 isolates with virulent disease symptoms with a mean severity ranging between 50 to 67 percent disease index (PDI) whereas in Rabi season, only five isolates were considered virulent, and the mean severity ranged between 52 to 67 PDI. Based on pathological characterization and molecular identification, 10 strains of Fusarium species namely, Fusarium acutatum (2/10), Fusarium verticillioides (Syn. Gibberella fujikuroi var. moniliformis) (7/10), Fusarium andiyazi (2/10) recorded the highest diseases index. All these species are part of the Fusarium fujikuroi species complex (FFSC). The distribution of virulent isolates is specific to a geographical location with a hot humid climate. Increased knowledge regarding the variability of Fusarium spp. responsible for PFSR of maize occurring across wide geographical locations of India will enable more informed decisions to be made to support the management of the disease, including screening for resistance in maize-inbred lines.

Epidemiology and Genetic Relationship of Toxigenic Fungi in Maize Grains From North Central Nigerian States

“…This study, conducted in the North Central States of Nigeria identified 7 major fungi genera isolated from stored maize seeds ( Figure 1 ). The findings are consistent with previous studies conducted by Giorni et al, 15 Harish et al, 16 Katati et al, 17 and Price et al 3 which reported the presence of Fusarium, Aspergillus , and Penicillium as the primary genera isolated from maize grain. The growth of these isolated fungi is influenced by such factors as the temperature of storage and storage duration, and the degree of fungal contamination before storage, as well as insects and mites’ activities all have an impact on the development of these fungi.…”

Virulent Fusarium isolates with diverse morphologies show similar invasion and colonization strategies in alfalfa

“…In contrast, the shape of their microconidia was mostly oval without septate, with length ranging from 1.917 mm to 9.277 mm. Our result was similar to that of pathogen characterization of post-flowering stalk rot in maize from agro-climatic zones of India, in which 71 isolates from four Fusarium species were identified (Harish et al, 2023). In addition, we found that the macroconidia from F. acuminatum were the largest with length up to 49.788 mm among our isolates.…”

Karakter Morfologi dan Depresi Silang dalam Galur F4 Jagung Ungu Hasil Persilangan Bersari Bebas

“…Seleksi F1 mendapatkan 14 galur jagung berbiji ungu dengan daya hasil tinggi (Anirban, Hayward, et al 2023;Showkath Babu et al 2023). Seleksi F2 selanjutnya mendapatkan 9 galur jagung berbiji ungu yang berdaya hasil tinggi (Harish et al 2023). Jagung seleksi F3 dengan kriteria sempit pada karakter jumlah daun per tanaman, umur tanaman berbunga jantan, umur tanaman berbunga betina, dan umur panen .…”