Truncated Rep gene originated from Tomato yellow leaf curl virus‐Israel [Mild] confers strain‐specific resistance in transgenic tomato

Abstract

Transgenic tomato plants carrying a truncated replication associated protein (T-Rep) gene of the mild strain of Tomato yellow leaf curl virus-Israel (TYLCV-Is [Mild]) were prepared. The transgene encoding the first 129 amino acids of Rep conferred resistance only against the virus strain from which it was derived, while these plants were susceptible to the severe strain of TYLCV-Is. This strain-specific effect may be the result of high sequence divergence within the N-terminal domains of the Rep genes of the two virus isolates which share a mere 78% sequence identity at the nucleotide level and 77% at the amino acid level. Although the transgenic tomato plants were totally resistant to whitefly inoculation with the mild strain of TYLCV-Is, agroinoculation with the same virus strain resulted in variable resistance responses in the tested plants: while 21% of plants were totally immune to the virus, 33% were susceptible and 46% expressed a wide range of intermediate resistance characteristics. The applicability of TYLCV-Is derived resistance in tomato is discussed.

Management of Bemisia tabaci Whiteflies

“…A similar approach was used by Antignus et al (2004b), who transformed tomato plants with a truncated Rep derived from TYLCV-Is mild. In both cases, the expression of the Rep genes interfered specifically with the cognate viral infection and not with virus strains with lower identities at the amino acid level.…”

Immunity to tomato yellow leaf curl virus in transgenic tomato is associated with accumulation of transgene small RNA

“…To evaluate the specificity of the resistance triggered by the silencing construct developed in this study to other closely related begomoviruses, highly resistant tomato lines were inoculated with TYLCV-Mld [10] and with tomato yellow leaf curl Sardinia virus (TYLCSV) [37]. TYLCV-Mld and TYLCSV share 98 % and 80 % sequence identity, respectively, with the TYLCV-Is-derived transgene sequence, (Fig.…”

“…Several approaches to transgenic pathogen-derived resistance were examined in the case of TYLCV: a. coat-protein-mediated Diana Leibman, Shanmugam Prakash and Dalia Wolf have contributed equally to this work. [7], b. antisense RNA [8,9], c. defective-interfering (DI) of replication initiator protein (Rep) [9][10][11][12][13][14], d. hairpin-RNA (hpRNA) (dsRNA expression)-induced gene silencing [14][15][16] and e. peptide aptamers that suppressed virus replication [17]. In most of these strategies, transgenic plants provided a wide range of resistance to TYLCV; the hpRNA approach was most effective in triggering high levels of TYLCV resistance [15,18].…”

Intron–hairpin RNA Derived from Replication Associated Protein C1 Gene Confers Immunity to Tomato Yellow Leaf Curl Virus Infection in Transgenic Tomato Plants

“…Some of the transgenic tomato lines expressing TYLCV coat protein showed delaying of symptoms and recovery from the disease after whitefly-mediated inoculation (Kunik et al, 1994). However, the most favorable resistance response to TYLCV infection by genetic engineering appears to be the expression of antisense or truncated versions of TYLCV replication associated protein gene (and other flanking genomic fragments) (Bendahmane & Gronenborn, 1997;Antignus et al, 2004). In one of these cases, when the post-transcriptional gene silencing (PTGS) mechanism was induced, transgenic tomato plants showed no symptoms and no viral genomic DNA was detected after field challenges (Yang et al, 2004).…”