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Morpho-Molecular Identification of Plant Pathogen Infecting Bulb Onion (Allium cepa L.) Production Under Protected Cultivation Jennifer P. Celades; Marilyn M. Belarmino; Catherine C. Arradaza; Robelyn T. Piamonte; Zenaida C. Gonzaga
International Journal of Multidisciplinary: Applied Business and Education Research Vol. 7 No. 6 (2026): International Journal of Multidisciplinary: Applied Business and Education Rese
Publisher : Future Science / FSH-PH Publications

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.11594/ijmaber.07.06.11

Abstract

This study was conducted to identify the fungal pathogen associated with bulb onion production under protected cultivation through combined morphological and molecular identification. Onion leaves showing yellowing, wilting, and purple-to-black lesions were collected from infected plants and subjected to fungal isolation, morphological examination, pathogenicity testing, and molecular analysis. Based on colony and spore characteristics, together with the results of pathogenicity test, the pathogen was identified as Alternaria porri, which is the causal agent of purple blotch disease, fulfilling Koch’s postulates. However, molecular identification based on Internal Transcribed Spacer (ITS) ribosomal DNA sequencing revealed high similarity (98.58– 98.79%) to Nigrospora sphaerica. This difference may be attributed to the faster growth rate and dominance of N. sphaerica in vitro, which likely overshadowed the slower-growing A. porri during DNA amplification and sequencing. Phylogenetic analysis additionally supported the clustering of isolates within the N. sphaerica clade, distinct from A. porri. The contrasting morphological and molecular findings show the occurrence of mixed fungal infections, where A. porri acts as the primary pathogen, and N. sphaerica functions as a secondary colonizer or opportunistic fungus. These results show the limitations of single-method identification and point out the need to integrate morphological, pathogenicity, and molecular approaches for accurate pathogen diagnosis in complex disease systems.
Stomatal and Morphological Characteristics of In-Vitro Grown Tomato (Solanum lycopersicum L.) Treated with Different Concentrations of Colchicine and Pendimethalin Jessa R. Gines; Catherine C. Arradaza; Marilyn M. Belarmino; Marilou M. Benitez; Rosemarie B. Gonzaga
International Journal of Multidisciplinary: Applied Business and Education Research Vol. 7 No. 6 (2026): International Journal of Multidisciplinary: Applied Business and Education Rese
Publisher : Future Science / FSH-PH Publications

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.11594/ijmaber.07.06.25

Abstract

This research investigated the stomatal and morphological response of in vitro grown tomato (Solanum lycopersicum L.) plantlets to different concentrations of colchicine and pendimethalin. The effects of treatments on stomatal parameters, chlorophyll content and morphological characteristics were studied. The study was conducted using a Completely Randomized Design (CRD) with seven treatments replicated three times with ten samples per replicate at the Plant Tissue Culture Laboratory, Department of Horticulture, Visayas State University. To evaluate the responses of various concentrations of colchicine (1.5, 3.0 and 5.0 mM) and pendimethalin (10, 20 and 30 µM), induced polyploid-associated traits and overall plant growth and development rate on tomato plantlets have also been compared with normal diploid plantlet used as control in subsequent measurement. The results indicated that the mutagen treatments have a substantial effect on explant viability, stomatal traits and chlorophyll content as well as vegetative growth of tomato plants. Moderate concentrations had more profound effect with higher survival percentages of explants found for 20 µM pendimethalin (91%) and 5.0 mM colchicine (84%), which produced regeneration and adaptation, as compared to other concentrations in this study. It was found out with an increased stomatal length, width and aperture on mutation treated plantlets but decreased stomatal density shows induction of polyploid trait. Colchicine resulted in the greatest stomatal size together with favourable impact on chlorophyll content. In contrast, at the highest concentrations of pendimethalin (30 µM), growth was inhibited and chlorophyll was decreased as a result of phytotoxicity.