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Archives (2001)

Catching the invisible enemy with ELISA by Junelyn S. de la Rosa

October-December 2001 Volume 3 No. 4

Viruses cannot be seen with the naked eye. They are so minute that you will need a powerful microscope such as the electron microscope to be able to see them. Viruses are extremely simple organisms, consisting only of the genetic material necessary for multiplication (ribonucleic acid or deoxyribonucleic acid) and a protein coat for protection. The fact that they are basically life's building blocks place them among the smallest organisms known to science.

More than 25 viruses have been reported to infect orchids. The two most common orchid viruses are: Cymbidium mosaic potexvirus (CymMV) and Odontoglossum ringspot tobamovirus (ORSV). They vary in length and are between 450 and 300 nanometers long (one nanometer is one millionth of a millimeter).

Orchids that are infected with viruses often exhibit these symptoms: yellow, brownish line patterns on foliage, with discolored areas often sunken. Likewise, infected plants may be streaked or have discolored flowers.

However, each virus does not produce characteristic symptoms on orchids. It is impossible to make a precise diagnosis by looking at the symptoms alone. Ringspot symptoms or sunken brown spots may lead you to suspect that your orchid is infected with a virus, but it does not tell you what kind of virus it is. To make sure if your orchid is infected with a certain virus, you can use the enzyme-linked immunosorbent assay (ELISA). A recent study by two scientists from the Department of Plant Pathology of the University of the Philippines at Los Baños (UPLB)-Mr. Narceo Bajet and Ms. Priscilla Barcial developed a local antiserum of CymMV and ORSV for the ELISA kit.

The ELISA kit was used to test 623 orchid samples that were collected from commercial and university orchid nurseries around the Philippines. The orchid samples were either apparently healthy or exhibited virus-like symptoms. Most of the orchids belong to the genera Dendrobium, Cattleya, Mokara, Oncidium, and Vanda.

Results of the survey showed that almost half of the samples were infected by either CymMV or ORSV or by both. Some orchid samples (169) that did not exhibit any viral symptoms or looked healthy were also found infected. The researchers also tested micropagated orchids for the two viruses while they are still inside the flasks. They found that 4.2% and 6.4% were infected with CymMV and ORSV confirming that viruses can be transmitted through tissue culture. By developing the local antisera for the two viruses, it will be easier and cheaper for orchid growers to include the ELISA tests in their safety regimen.

(Source: ELISA kit: a local technology to counteract the threat of viruses to the Philippine orchid industry by Dr. Narceo Bajet and Ms. Priscilla Barcial of the Department of Plant Pathology, College of Agriculture, University of the Philippines Los Baños)

More Articles:

Vol. 3 No. 4 October-December 2001

»» Outstanding technologies identified in nat'l R&D week
»» Thailand, Philippines convene for agri cooperation
»» Prospects for the ornamental industry in the new millennium
»» UPLB scientists develop new hybrids of Philippine ornamentals
»» New management techniques for exportable foliage plants
»» In focus: a date with the "king of cut flowers"
»» Brighten your homes with aglaonema
»» King in red and green
»» Cashing in with the 'lucky bamboo'
»» Turfgrasses: the preferred ground cover
»» Catching the invisible enemy with ELISA
»» Grow dracaena godseffiana the easy way
»» Bromeliads: the exotic plant
»» Wag that fish-tail fern
»» Mass propagating the 'doñas' through kulob system
»» Beauveria mold bioinsecticide: safer control against orchid pests
»» Orchids and mycorrhiza: a lesson from the wild
»» Controlling white rust in chrysanthemums
»» Ways to enhance palm seed germination
»» Prolonging the vase life of cut flowers with ethylene adsorbent and Florafresh
»» Mass producing the fragrant kamuning
»» The national RDE program for ornamental crops
»» GMA presents 2001 Gawad Saka awards

[More 2001 Articles]