Geminiviruses are a family of plant viruses that cause devastating diseases in many economically important crops worldwide.These pathogens encapsidate circular,single-stranded DNAs (ssDNAs) of 2.5-3.0 kb that replicate through double-stranded DNA (dsDNA) intermediates.Members of the genus Begomovirus,which comprises by far the largest number of species in the family,are transmitted by whiteflies and have genomes consisting of one or two DNAs.Most monopartite begomoviruses associate with betasatellites,which have circular ssDNA genomes that are half the size (～1.3 kb) of their helper viruses.Betasatellites encode a single protein (βC1)that reprograms cellular processes to facilitate infection and is both a target and a repressor of host defenses.During the long-term arms race between plants and geminiviruses,plants have evolved multiple defense mechanisms to safeguard against infection.Here,we discuss several recent reports that provide new insight into plant defenses against geminivirus-betasatellite complexes and viral counter-defense measures.