ROLE OF PLANT TISSUE CULTURE IN PRODUCTION OF VIRUS-FREE PLANTING MATERIAL IN HORTICULTURAL CROPS: A REVIEW

Abstract

Plant viruses and viroids are among the major constrains to sustainable cultivation of horticultural crops, especially those vegetatively propagated via tubers, bulbs, rhizomes, runners, suckers, cuttings, grafts and other clonal propagules. Continuous usage of infected planting materials leads to the build-up and spread of viruses from generation to generation, resulting in decreased vigor, yield, fruit quality, and life span of plants. Since systemic viruses are not easily controlled once they establish in perennial or vegetatively propagated crops, virus free planting material becomes a key component in modern horticulture. Plant tissue culture, especially meristem and shoot-tip culture, offers an effective strategy for the elimination of viruses and the regeneration of healthy plants from infected plants. Efficiency of virus elimination can be increased by the combination of tissue culture with thermotherapy, chemotherapy, cryotherapy, electrotherapy, and micrografting. Efficiency of virus elimination reported in literature varies depending on crop, virus, genotype, explant size and treatment conditions. Recent reviews report about 50-100% success rate in various combinations. Molecular diagnostics like ELISA, PCR, RT-PCR, qRT-PCR, high throughput sequencing becomes an important part of virus elimination. Recent studies on apple, grapevine, pear, apricot and ornamentals also illustrate the importance of tissue culture combined with molecular indexing. This review discusses the principle, mechanism, methodologies, crop-wise application, advantages, limitations, and prospects of plant tissue culture for the production of virus-free planting material in horticultural crops.