Chapter 13 - Update on phytoplasma diseases associated with starchy root and tuber crops in Asia

Abstract

Starchy roots and tuber crops play a pivotal role in the human diet and offer numerous desirable nutritional and health benefits. Many starchy tuber crops, except the common potatoes, sweet potatoes, and cassava, are not yet fully explored for their nutritional and health benefits. Tubers have an immense potential as functional food and nutraceutical ingredients to be explored in disease risk reduction and wellness. A variety of foods can be prepared using tubers and root crops and they may also be used in industrial applications. Several diseases have been reported of viral, bacterial, and fungal origin on these crops. But the literature on phytoplasma diseases is very meager. Since the tuber and starchy root are very important crops in all Asian countries, an updated information on phytoplasmas diseases associated with tuber them in Asian countries was reported. Among the phytoplasma diseases, potato leaf yellows, potato purple top, cassava witches' broom, sweet potato little leaf, elephant foot yam leaf yellows, and declining and yams decline are the prominent phytoplasma diseases reported in the Asian countries. Because of unspecific symptoms, the identification and characterization of the phytoplasmas associated with these tuber and starchy root crops are problematic and challenging. Here the progress made in understanding biology, economic importance, distribution, symptomatology, diagnosis, epidemiology, and control of phytoplasmas infecting tuber and starchy root crops in Asian countries is summarized.