Chapter 21 - Diversity analysis of begomoviruses infecting papaya and its mechanisms of resistance

Abstract

Papaya (Carica papaya L.) has extensive economic importance to agriculture and is widely grown in tropical and sub-tropical regions of the world. Plant viruses that belong to the Begomovirus genus (family Geminiviridae), like papaya leaf curl virus, cause leaf curl diseases and major losses of fruit production. Sequence diversity among begomoviruses, phylogenetic and recombination studies, along with their distribution, help understanding the origin of the virus, its dispersion and disease etiology. This information is useful in developing effective virus disease management programmes. One of the prominent approaches for plant virus management is pathogen derived resistance (PDR), which involves the expression of viral sequence in host plants, thus promoting resistance against this virus. RNA silencing was proved to be a significant cellular pathway for defense against foreign nucleic acids, including plant viruses. These pathways promote the effective protection against viral infection in plants. New approaches, such as the CRISPR-Cas-9 system engineered in plants to target geminiviruses, have consistently moderated virus accumulation, thus providing increased resistance against viral infection.