Molecular Mechanism Underlying Symptom Development in Phytoplasma Associated Diseases - The Key Players and their Role

Abstract

Phytoplasma, plant pathogenic Mollicutes that have a trans-kingdom life cycle, are insect transmittedand have been found to be associated with yield affecting traits in a large number of taxa. Many peculiar symptoms observed in the host taxa are often results of dramatic alterations in the normal development program that are generally controlled at the meristematic regions located in the shoot apices. Phytoplasma being vasculature limited are thus able to bring about genetic reprogramming in the regions of host plant that are far removed from their natural niche namely sieve elements of the phloem. Several proteins secreted by phytoplasma in the host plants have been identified and termed as effector molecules namely SAP54, SAP11, TENGU, SAP21 etc. that enable the colonisation, survival, spread of phytoplasma and also bring about dramatic alterations in the host plant. Nevertheless, the mechanisms underlying these peculiar phenomena are far from understood and remain a challenging area for the phytoplasma biologists. A thorough understanding of the processes involved is needed to provide platforms for developing control measures for phytoplasma associated diseases that will also enhance basic understanding on the plant developmental programs affected.