Practice question

Meristem culture technique involves aseptic excision of apical dome typically 0.1-0.5 millimeter containing tunica corpus but no differentiated leaf primordia and culture on MS based medium for regenerating plants principally to obtain virus free stocks. Foundation lies in observation that meristematic dome lacks differentiated vascular sieve elements through which many systemic viruses like Potato Virus Y, Tobacco Mosaic Virus, Cucumber Mosaic Virus travel long distance and also that rapid mitotic activity outpaces viral replication. High endogenous auxin and cytokinin concentration plus RNA silencing machinery Dicer like DCL proteins Argonaute AGO targeting viral RNAs creates antiviral niche. Protocol often combined with thermotherapy incubating donor at 35-38 degrees for weeks reducing virus titer or chemotherapy with antiviral ribavirin. Regenerants are indexed by ELISA RT PCR to confirm elimination. Because meristem cells maintain genetic stability avoiding callus mediated somaclonal variation, meristem derived plants retain true to type phenotype valuable for certified seed programs for potato garlic banana strawberry where vegetative propagation accumulates viruses causing yield decline, thus meristem culture ensures healthy foundation material.