Reducing the content of nornicotine in tobacco via targeted mutation breeding

Three nicotine demethylase genes mediate nornicotine biosynthesis in Nicotiana tabacum L.: Functional characterization of the CYP82E10 gene

“…In addition to targeting the specific gene against which the construct was directly made, closely related members of a gene family are also typically silenced using RNAi technologies (Xu et al, 2006). This characteristic of RNAimediated gene suppression provided a reasonable explanation of why lower levels of nornicotine were observed in the transgenic tobacco plants expressing the CYP82E4 RNAi construct ($0.5% nicotine conversion; Lewis et al, 2008) than that which was observed in plants possessing a CYP82E4 knockout mutation ($3.1% nicotine conversion; Julio et al, 2008). To determine the degree with which the CYP82E5v2 gene may be responsible for the 2-5% nornicotine content that is commonly found in nonconverter plants, a mutagenesis approach was employed.…”

“…In conventional, or 'nonconverter' tobacco plants, transcript accumulation of CYP82E4 is negligible, whereas in 'converter' plants, a high level of transcript accumulation is observed during senescence and air-curing. Furthermore, inactivation of CYP82E4 through chemical mutagenesis in a strong converter background leads to a reduction in the nicotine to nornicotine conversion rate from an average of 77.5%, to $3.1%, a level typical of that observed in nonconverter plants (Julio et al, 2008). Analysis of the CYP82E4 promoter showed that the gene is regulated in a highly senescence specific manner, induced only by abiotic (e.g., air-curing) and biotic (e.g., ethylene and tobacco mosaic virus infection) treatments that result in leaf senescence (Chakrabarti et al, 2008).…”

Targeted mutation breeding of horticultural plants

“…Suzuki et al, 2008;Julio et al, 2008), and supported commercial applications . Increasing the sensitivity of mismatch detection would permit more accurate analysis of large sample pools.…”

“…Techniques such as conformation-sensitive capillary electrophoresis (CSCE), single-strand conformation polymorphism (SSCP), and denaturing high performance liquid chromatography (dHPLC) detect polymorphisms in candidate genes based on changes in conformation of PCR-amplified sequences. CSCE, SSCP, and dHPLC have been used to find sequence variation in specific genes of tomato (Gady et al, 2009), tobacco (Julio et al, 2008), and sunflower (Fusari et al, 2010), respectively.…”

Effect of In Vitro Mutagenesis on In Vivo Growth Characteristics of Strawberry cv. Camarosa

“…Another mutagen, EMS also has been applied in various plants, such as soybean (Patil et al, 2007) tobacco (Julio et al, 2008) and strawberry (Murti et al, 2013).…”