Detection of Nigrospora sphaerica in the Philippines and the susceptibility of three Hylocereus species to reddish-brown spot disease

John Darby  Taguiam; Edzel  Evallo; Jennelyn  Bengoa; Rodel  Maghirang; Mark Angelo  Balendres

doi:10.56890/jpacd.v22i.321

Authors

John Darby Taguiam Institute of Plant Breeding, College of Agriculture and Food Science, University of the Philippines Los Baños, College Laguna, Philippines 4031
Edzel Evallo Institute of Plant Breeding, College of Agriculture and Food Science, University of the Philippines Los Baños, College Laguna, Philippines 4031
Jennelyn Bengoa Institute of Plant Breeding, College of Agriculture and Food Science, University of the Philippines Los Baños, College Laguna, Philippines 4031
Rodel Maghirang Institute of Plant Breeding, College of Agriculture and Food Science, University of the Philippines Los Baños, College Laguna, Philippines 4031
Mark Angelo Balendres Institute of Plant Breeding, College of Agriculture and Food Science, University of the Philippines Los Baños, College Laguna, Philippines 4031

DOI:

https://doi.org/10.56890/jpacd.v22i.321

Keywords:

Dragon fruit; ITS gene; H. megalanthus; H. polyrhizus; H. undatus.

Abstract

Diseases are among the major problems that negatively affect dragon fruit profitability worldwide. Diseases of dragon fruit in the Philippines are yet to be identified and reported. This study elucidates the causal agent of a disease infecting stems of dragon fruit grown in Los Baños, Laguna, Philippines. The fungus was isolated and identified as Nigrospora sp. based on morphological and cultural characteristics in potato dextrose agar medium. Using the DNA sequence of the internal transcribed spacer (ITS) gene region, isolate MBDF0016b was identified as Nigrospora sphaerica. The Philippines strain was closely related to the Malaysian strain, which also causes reddish-brown spot in dragon fruit (H. polyrhizus), and to other N. sphaerica isolates from other host-plant species. Nigrospora sphaerica MBDF0016b was pathogenic to H. megalanthus, H. undatus, and H. polyrhizus in detached stem and glasshouse assays. The same fungus was re-isolated from the inoculated stems and thus, establishing Koch’s postulate. This paper is the first confirmed scientific record of a dragon fruit disease in the Philippines and the first report of N. sphaerica as a dragon fruit pathogen causing reddishbrown spot disease in H. megalanthus.