Changes in Physiology of Burley Tobacco Plants Genetically Engineered to Express a Functional NtEGY2 Gene
Nitrogen physiology is important in tobacco because of its role in generation of leaf yield and accumulation of nitrogen-containing alkaloids and that can react with nitrosating agents in the formation of carcinogenic tobacco specific nitrosamines. Cultivars of the burley tobacco market class are homozygous for deleterious alleles at the duplicate Yb1 and Yb2 loci which have previously been associated with decreased nitrogen use and utilization efficiency,; increased leaf nitrate, total nitrogen, and alkaloid levels,; and reduced yields. How mutant alleles at these two loci affect these traits is not well understood. Recent identification of the Yb1 and Yb2 genes enabled overexpression of the wild-type Yb1 allele in yb1yb1yb2yb2 plants to determine if observed unfavorable effects were due to linkage or pleiotropy, and to determine if overexpression could lead to beneficial modifications in any of these traits in transgenic plants relative to naturally-occurring wild-type genotypes. Yb1 overexpression was found to confer an agronomic benefit to yb1yb1yb2yb2 genotypes but no advantage to wild-type genotypes. RNA-Seq was used to carry out a comparative transcriptome analyses of genetically engineered and wild-type NILs to gain insight on metabolic pathways affecting carbon and nitrogen metabolism that might be altered as the result of genetic variability at the Yb1 and Yb2 loci. Results indicate that complex changes in the transcriptome of tobacco can be manifested by altered expression of Yb1. Overall design: RNA-Seq was used to carry out a comparative transcriptome analyses of genetically engineered and wild-type NILs to gain insight on metabolic pathways affecting carbon and nitrogen metabolism that might be altered as the result of genetic variability at the Yb1 and Yb2 loci.