Transgenic tobacco expressing geminiviral RNAs are resistant to the serious viral pathogen causing cotton leaf curl disease

Abstract

Cotton, the major cash crop in Pakistan, suffers 30% losses to cotton leaf curl disease, caused by the geminivirus, cotton leaf curl virus DNA A, plus a satellite component, DNA beta responsible for symptom development with plants failing to produce cotton bolls. We constructed transgenic tobacco expressing sense and antisense RNAs representing: [i] the 5' half of the viral DNA replication gene, AC1, [ii] the 3' half of AC1, [iii] two overlapping genes, AC2, a transcription activator, and AC3, a replication enhancer. In contrast to controls, 25% of 72 transgenic tobacco lines tested showed heritable resistance [T(1) - T(3) generations]: symptom-free and no replication of DNA A or DNA beta even after 120 days of continuous exposure to viruliferous whiteflies. As geminiviral and transgene RNAs are not detected in resistant lines following infection, and selected uninfected resistant tobacco sense lines reveal double-stranded and small interfering RNAs, the most likely mechanism is via post-transcriptional gene silencing.

Tomato Chlorotic Mottle Virus Is a Target of RNA Silencing but the Presence of Specific Short Interfering RNAs Does Not Guarantee Resistance in Transgenic Plants

“…Even though transgenic resistance associated with gene silencing can be achieved successfully (4,15), it is dependent on the virus-host combination, possibly the strength of the RNA si-VOL. 81,2007 ToCMoV AS TARGET OF RNA SILENCING 1571…”

Banana bunchy top disease (BBTD) symptom expression in banana and strategies for transgenic resistance: A review

“…The transcripts targeted have included those of tobacco mosaic virus (TMV) rep in N. tabacum (Day et al, 1991), tomato yellow leaf curl virus (TYLCV) rep in N. benthamiana and tomato (Bendahmane andGronenborn, 1997 andYang et al, 2004); tomato leaf curl virus (ToLCV) rep in tomato (Bendahmane and Gronenborn,1997); tomato golden mosaic virus (TGMV) and beet curly top virus (BCTV) rep, TrAP and REn (the last of which encodes a replication enhancer protein in begomo viruses in tobacco (Bejarano and Lichtenstein,1994), BGMV rep, TrAP, REn, and MP in beans (Araga˜o et al, 1998); cotton leaf curl Kokhran virus (CLCuKV) (REP, TrAP and REn in N. tabacum (Asad et al,2003), and ACMV REP, TrAP and REn in cassava (Zhang et al, 2005).…”

RNAi-mediated resistance to SMV and BYMV in transgenic tobacco

“…RNAi is a process of post-transcriptional gene silencing (PTGS) triggered by double-stranded RNA (dsRNA) (Baulcombe 2004). Numerous groups have successfully applied RNAi strategies in generating transgenic plants resistant to viruses (Asad et al 2003, Kasai et al 2012. Transgenic plants have slowed the accumulation of disease symptoms or reduced them.…”