Submitted to: Plant Cell Reports
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 10/15/2009
Publication Date: 1/23/2010
Citation: Kamo, K., Jordan, R., Guaragna, M.A., Hsu, H.T., Ueng, P. 2010. Resistance to cucumber mosaic virus in Gladiolus plants transformed with either a defective replicase or coat protein subgroup II gene from Cucumber mosaic virus. Plant Cell Reports. 29:695-704. Interpretive Summary: Cucumber mosaic virus (CMV) is one of the most important plant viruses because it infects approximately 1000 plant species, including food crops and ornamentals. Plant viruses, and CMV in particular, are a major problem in many flower bulb crops, including Gladiolus. Gladiolus is an important floral crop world-wide and is used both in the landscape and as a cutflower. In 2008 the wholesale value of Gladiolus cutflowers sold in the U.S. was $19,936,000 which is 4.9% of the total value of all cutflowers in the US. Viruses result in streaking of the flowers making them unmarketable, and infected plants have decreased vigor resulting in a poor bulb yield. It is very difficult to eliminate viruses from infected plants because they are propagated each year within the flower bulb. In addition, few species have any genetic basis for resistance to these viruses. Genetic engineering for virus resistance has been shown by others to be a useful means of plant protection. In this study Gladiolus plants were successfully engineered for resistance to CMV.
Technical Abstract: Transgenic Gladiolus plants that contain either Cucumber mosaic virus (CMV) subgroup I coat protein, CMV subgroup II coat protein, CMV replicase, a combination of the CMV subgroups I and II coat proteins, or a combination of the CMV subgroup II coat protein and replicase genes were developed. These plants were multiplied in vitro and challenged with purified CMV isolated from Gladiolus using a hand-held gene gun. Three plants, each independently transformed, expressing the replicase gene under control of the duplicated CaMV 35S promoter were found to be resistant to CMV subgroup I out of 19 independently transformed plants tested. Three independently transformed plants with the CMV subgroup II coat protein gene under control of the Arabidopsis UBQ3 promoter were resistant to CMV subgroup II out of 21 independently transformed plants tested. Eighteen independently transformed plants with either the CMV subgroup I coat protein or a combination of CMV subgroups I and II coat proteins were challenged and found to be susceptible to both CMV subgroups I or II. Virus resistant plants with the CMV replicase transgene expressed much lower RNA levels than resistant plants expressing the CMV subgroup II coat protein. This work will facilitate the evaluation of virus resistance in transgenic Gladiolus plants to yield improved floral quality and productivity.