Phytoplasmas are wall-less bacteria living in plants and insects. Their ability to successfully invade, multiply intracellularly and colonize two such dissimilar host environments is remarkable and implies the evolution of mechanisms that enable the bacteria to modulate cellular processes in both hosts. Chrysanthemum yellows phytoplasma (CYP) multiplies rapidly in the plant and in several leafhopper vectors and it is able to spread fast to young developing sink leaves and roots in plant and to colonize the entire body of the leafhopper vector. In the vectors, fastest CYP multiplication rates and highest phytoplasma titres correlate with shortest latent periods and best vector efficiencies. Similar transmission efficiencies are achieved following feeding or abdominal microinjection, suggesting that salivary glands may be the major barrier to transmission. Phytoplasmas interact with the plant host by secretion of effector proteins that may act at different levels. Secretion of effectors during the vector infection stage is hypothesized. Microarray analyses suggest that phytoplasma genome expression can be modulated according to the infection stage, and expression analyses of 14 CYP genes involved in several metabolic activities in two vectors and the host plant has shown that CYP is more active during the infection of the plant than of the leafhoppers. Moreover, gene expression is more variable with time in plant than in the leafhoppers. It is still not clear how phytoplasma sense the switch between the plant and the leafhopper, but phytoplasma membrane proteins are presumably involved in host recognition thus triggering adaptation to the insect or plant host.
Living in two worlds: the insect and plant lifestyles of the chrysanthemum yellows phytoplasma
Galetto L;Bosco D
2013
Abstract
Phytoplasmas are wall-less bacteria living in plants and insects. Their ability to successfully invade, multiply intracellularly and colonize two such dissimilar host environments is remarkable and implies the evolution of mechanisms that enable the bacteria to modulate cellular processes in both hosts. Chrysanthemum yellows phytoplasma (CYP) multiplies rapidly in the plant and in several leafhopper vectors and it is able to spread fast to young developing sink leaves and roots in plant and to colonize the entire body of the leafhopper vector. In the vectors, fastest CYP multiplication rates and highest phytoplasma titres correlate with shortest latent periods and best vector efficiencies. Similar transmission efficiencies are achieved following feeding or abdominal microinjection, suggesting that salivary glands may be the major barrier to transmission. Phytoplasmas interact with the plant host by secretion of effector proteins that may act at different levels. Secretion of effectors during the vector infection stage is hypothesized. Microarray analyses suggest that phytoplasma genome expression can be modulated according to the infection stage, and expression analyses of 14 CYP genes involved in several metabolic activities in two vectors and the host plant has shown that CYP is more active during the infection of the plant than of the leafhoppers. Moreover, gene expression is more variable with time in plant than in the leafhoppers. It is still not clear how phytoplasma sense the switch between the plant and the leafhopper, but phytoplasma membrane proteins are presumably involved in host recognition thus triggering adaptation to the insect or plant host.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
