APS Homepage

Poster: Epidemiology: Pathogen-Vector Interations


Composition of leaf fibrous ring mediates Diaphorina citri preference of Citrus sinensis over Citrus aurantium.
H. SHUGART (1), M. Rogers (1) (1) University of Florida- Citrus Research & Education Center, U.S.A.

Candidatus Liberibacter asiaticus, causal agent of citrus greening disease, is transmitted by Diaphorina citri, and together they pose the greatest risk to Citrus production worldwide. Currently research into host plant resistance to the vector and bacterial pathogen is ongoing, with the aim of developing resistant Citrus selections. Our objective was to test the influence of leaf anatomy on D. citri probing behaviors that regulate bacterial transmission. Leaf morphometrics might inhibit bacterial transmission, and thus could be candidates for resistance breeding. We performed an electropenetrographic study and histological examination of leaves of two Citrus species differently preferred by the psyllid, C. sinensis (var. Valencia) and C. aurantium (var. Sour orange). We quantified durations, frequencies, and order of probing behaviors associated with bacterial transmission, and correlated those behaviors with leaf anatomy. Young Sour Orange leaves were less preferred and exhibited a thicker and more complete fibrous ring than did same-aged Valencia leaves. This more developed barrier impacted probing behaviors such that D. citri took longer to reach the phloem and ingested from it for shorter durations. Delay and reduction of phloem associated behaviors influences the success of bacterial transmission by D. citri. Future resistant varieties could use fibrous ring morphometrics as an anatomical marker for resistance to pathogen transmission.