tomentosiformis. Four distinct PMT genes are already identified in N. taba cum and, based mostly on sequence analogy, 3 of them possible originate from N. sylvestris. Remarkably, the 2 copies of PMT that happen to be pre sent in N. tomentosiformis are just like just one PMT gene in N. tabacum. This discovering suggests that due to the lack of your three other PMT copies in N. tomentosiformis, the complete pathway for nicotine synthesis is obviously distinctive in N. tomentosiformis than in N. sylvestris, which has three PMT copies that happen to be associated with N. tabacum, NtPMT 1, 3 and four. The up regulation of PMTs, AO and QS in N. sylves tris compared with N. tomentosiformis attests that the early ways in the pathway that result in the synthesis of nicotinic acid may also be notably lively in N.
sylvestris straight from the source and absolutely play a significant position in nicotine synthesis. Recent information reported by Shoji and Hashimoto sug gest that tobacco MYC2 regulates PMT 2 and QPT two by interacting with exact promoter regions. Its there fore tempting to speculate that regulation takes place vary ently via MYC2 in N. sylvestris and N. tomentosiformis. Conversely, because AO and QS are positioned within the plas tids and are concerned in NAD synthesis from aspartate by way of quinolinic acid, these are likely regulated via nuclear cross talk which is potentially more lively in N. syl vestris than in N. tomentosiformis. In species in the Nicotiana genus, the conversion of nicotine to nornicotine, that’s the precursor from the tobacco nitrosamine N nitrosonornicotine, is mediated by nicotine N demethylase enzymes encoded from the CYP82E subfamily of cytochrome P450 genes.
4 genes from this gene relatives are reported for being distributed within the N. sylvestris and N. tomentosiformis genomes. CYP82E4 will be the dominant aspect in senescence inducible nornicotine production, whereas CYP82E5v2 LY500307 is involved in nicotine conversion during the green leaves, the two of them are noticed in N. tomentosiformis, in conjunction with CYP82E3. In N. sylvestris, one this kind of gene, CYP82E2, has been discovered. Searches in both these Nicotiana genomes revealed that N. sylvestris has 5 related genes, and N. tomentosi formis has 4. A comparison in the phylogenetic trees confirms that three of the N. tomento siformis genes are associated with the N. tabacum CYP82E3, CYP82E4 and CYP82E5 genes and that one of many N. syl vestris genes corresponds to N. tabacum CYP82E10. The data presented in Further file 14 and Added file 16 display that NtomNND 1 is evolutionarily near to 1 copy of CYP82E4and really expressed in flowers, whereas its expression in leaves is simply not supported by Affy metrix data. To our practical knowledge, the high expression of the nicotine demethylase gene in flowers has not nevertheless been described, the gene item probably plays a role in protection against insects.