Virus-Free Potatoes Through Meristem Culture

Abstract

Among the common viruses that infect potato, some, like potato viruses A and Y, cause distinctive symptoms; others, like potato viruses M and S, are latent, causing no visible symptoms. These can be detected only by transmission to indicator plants, by electron microscopy or by serology. Others, like potato virus X and potato leaf roll, occur in strains of varying severity, some of which are latent. Viruses that cause foliar symptoms have been controlled by devising certification schemes that include periodic inspection and rogueing out abnormal plants. Until recently, however, latent viruses have been accepted, not only because detection was difficult, but also because no virus-free source plants were available, and techniques for virus eradication had not been developed. With the advent of nutrient culture of meristematic buds excised from heat-treated plants, developing virusfree plantlets from infected source plants became relatively easy and virus-free plants of most major cultivars are now available (see Mellor and Stace-Smith 1977).