Functional genomics analysis in an N-end rule protein (GhCBD2) putatively involved in
viral resistance in Gossypium hirsutum
Anna K. S. Fausto1, Marianna Moura1, Tatiane Franca2, Emmanuelle Graciet3, Elisson
Romanel2 and Maite V.F. S. Vaslin1*
1
Laboratório de Virologia Molecular Vegetal, Departamento de Virologia, Instituto de
Microbiologia, Universidade Federal do Rio de Janeiro, RJ. 2Laboratório de Genética e
Biotecnologia, Departamento de Biotecnologia (DEBIQ), Escola de Engenharia de
Lorena/Universidade de São Paulo (EEL/USP), SP, Brazil. 3Plant Biochemistry
Laboratory, National University of Ireland Maynooth, Ireland.
*E-mail: maite@micro.ufrj.br
Key words: Gossypium hirsutum, N-end rule, CBD, ubiquitination, CLRDV
Cotton blue disease (CBD) is a major cotton disease in Brazil. It is transmitted by Aphis
gossypii and its causal agent is the Cotton leaf roll dwarf virus (CLRDV). CBD
resistance is controlled by one single dominant locus, however nothing is known about
it. Previously, we mapped the Cbd resistance locus in Gossypium hirsutum chromosome
10, identifying two ORFs, Cbd1 and Cbd2. Phylogenetic analysis revealed that CBD2
is an arginyl tRNA transferase (ATE) implicated in the N-end rule leading target
proteins to the 26S proteasome. Expression analysis of GhCBD2 in a resistant (Delta
Opal) and susceptible (FM966) cotton vs during CLRDV infection showed a strong
suppression of GhCBD2 after 24 hpi in susceptible cv although a small reduction was
observed in the resistant one. Five dpi, however, the expression was strongly induced in
susceptible cultivar (280 x), although it was basal to the resistant cultivar. After 15 and
25 dpi GhCBD2 remained induced in both cultivars. Investigation of similar effects in
Arabidopsis thaliana Col. under CLRDV infection showed a strongly increase of
AtATE1 after virus infection. Arabidopsis ATE1:GUS plants revealed, an increase GUS
activity in shoot and root apical meristems as well in young leaves compared with noninfected leaves. 35S:ATE1 plants blocked viral infectivity. These data shed new lights
into CBD genetics resistance. Cbd2 seems to be a good putative candidate for achieve
CBD resistance, probably leading virus replication essential host proteins for
degradation via N-end rule pathway.
Fundings: FAPERJ, CNPq and CAPES.