Resistance to Citrus psorosis virus in transgenic sweet orange plants is triggered by coat protein?RNA silencing

REYES, C.A.; DE FRANCESCO, A.; PEÑA, J.E.; COSTA, N.; PLATA, M.I.; SENDIN, L.; CASTAGNARO A.P.; GARCIA , M.L.

JOURNAL OF BIOTECHNOLOGY

ELSEVIER SCIENCE BV

Lugar: Amsterdam; Año: 2011 p. 151 - 158

0168-1656

The lack of naturally occurring resistance to Citrus psorosis virus (CPsV) has demanded exploitation of atransgenic approach for the development of CPsV-resistant sweet orange plants. Transgenic sweet orangeplants producing intron-hairpin RNA transcripts (ihpRNA) corresponding to viral cp, 54K or 24K geneswere generated and analyzed at the molecular and phenotypic levels. Two independent CPsV challengeassays demonstrated that expression of ihpRNA derived from the cp gene (ihpCP) provided a high levelof virus resistance, while those derived from 54K and 24K genes (ihp54K and ihp24K) provided partial orno resistance. The presence of small interfering RNA molecules (siRNAs) in the ihpCP transgenic sweetorange plants prior to virus challenge, indicated that CPsV resistance was due to pre-activated RNAsilencing, but siRNAs accumulation level was not directly correlated to the degree of the triggered virusresistance among the different lines. However, pre-activation of the RNA-silencing machinery and acertain minimum accumulation level of siRNA molecules targeting the viral genome are key factors forcreating virus-resistant plants. This is the first report of resistance in citrus plants against a negativestrandRNA virus as CPsV.