Agrobacterium tumefaciens-mediated transformation of `Brewster¿ litchi (Litchi chinensis Sonn.) with the PISTILLATA gene in antisense

Abstract

In order to address the need for production of parthenocarpic fruits, embryogenic cultures of 'Brewster' ('Chen Tze') litchi derived from leaves of a mature tree were transformed with the PISTILLATA (PI) cDNA in antisense orientation through Agrobacterium-mediated transformation. In four independently transformed lines, transgene integration was confirmed by conventional and quantitative PCR. The four transgenic lines differed with respect to the relative copy number of the transgene and expression levels, and there was no correlation between the two traits. The expression of the litchi PI homolog was detected in transformed and non-transformed embryogenic cultures. Although expression levels were low overall, they were significantly higher in wild-type plants compared to lines that were transformed. This result suggests that post-transcriptional silencing of the litchi PI homolog induced by an antisense oriented transgene could be a successful strategy; however, silencing in floral primordia to produce parthenocarpic fruits can only be confirmed in mature plants after several years.