Host Plant Adaptation Drives Changes in Proteome Regulation, Proteoform Expression, and Transmission of ' Liberibacter asiaticus', the Citrus Greening Pathogen.

The Asian citrus psyllid () is a pest of citrus and the primary insect vector of the bacterial pathogen, ' Liberibacter asiaticus' (Las), which is associated with citrus greening disease. The citrus relative (orange jasmine) is a host plant of but is more resistant to Las compared with all tested genotypes. The effect of host switching of between (citron) and plants on the acquisition and transmission of Las was investigated. The psyllid Las titer and the proportion of Las-infected psyllids decreased in the generations after transfer from Las-infected citron to healthy plants. Furthermore, after several generations of feeding on , pathogen acquisition (20 to 40% reduction) and transmission rates (15 to 20% reduction) in psyllids transferred to Las-infected citron were reduced compared with psyllids continually maintained on infected citron. Top-down (difference gel electrophoresis) and bottom-up (shotgun MS/MS) proteomics methods were used to identify changes in protein expression resulting from host plant switching between and . Changes in expression of insect metabolism, immunity, and cytoskeleton proteins were associated with host plant switching. Both transient and sustained feeding on induced distinct patterns of protein expression in compared with psyllids reared on . The results point to complex interactions that affect vector competence and may lead to strategies to control the spread of citrus greening disease.