Registration of La Burley 21 Tobacco Germplasm<sup>1</sup> Registration No. (GP 8)

Legg, Paul D.; Collins, G. B.; Litton, C. C.

doi:10.2135/cropsci1970.0011183x001000020041x

Cited by 40 publications

(21 citation statements)

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“…This breeding To whorn correspondence should be addressed at: Graduate School of Biological Sciences, Nara lnstitute of Science and Technology, 8916-5, Takayama-cho, lkorna City, Nara 630-01, Japan. line is not different from parenta1 Burley 21 in days to flower, number of leaves, leaf size, and plant height, but is more susceptible to insect damage, probably due to its low nicotine content (Legg et al, 1970). Thorough genetic studies have demonstrated that the nicotine leve1 is controlled by two nonlinked loci (Legg et al, 1969).…”

Section: Introductionmentioning

confidence: 96%

Gene expression in tobacco low-nicotine mutants.

et al. 1994

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Two nuclear genes, Nicl and Nic2, regulate nicotine levels in tobacco. nicl and nic2 are semidominant mutations in Burley 21 that reduce leaf nicotine levels and the activities of multiple enzymes in the nicotine pathway and simultaneously increase polyamine levels in cultured roots. Cultured roots homozygous for both mutations were used to isolate two cDNAs by subtraction hybridization; the transcript levels of these two cDNAs were much lower in the mutant roots than in the wild-type roots. The A411 gene encodes a 41-kD protein with considerable homology to mammalian spermidine synthase, whereas the A622 gene encodes a 35-kD protein with high homology to isoflavone reductase. When these genes were expressed in Escherichia coli, A411 had no spermidine synthase activity but did show putrescine N-methyltransferase activity, which is the first enzyme committed to the nicotine biosynthetic pathway, and A622 did not show isoflavone reductase activity. Both the methyltransferase and A622 genes are predominantly expressed in the root, and their expression levels in cultured roots are coordinately decreased by the nic mutations in the order of wild type > nic2 > nicl > nicl nic2. Removal of tobacco flower heads and young leaves rapidly and coordinately induced both genes in the root. Further, exogenous supply of auxin down-regulated both genes in cultured tobacco roots. These results suggest that N i c l and Nic2 are regulatory genes for nicotine biosynthesis.

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Section: Introductionmentioning

confidence: 96%

Gene expression in tobacco low-nicotine mutants.

et al. 1994

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“…LA Burley 21 plants contain only~5.7% of the total alkaloid levels found in the normal-alkaloid (NA) wild-type variety (Legg, Collins, & Littion, 1970). In LA plants, the synergistic effect of the nic1 − and nic2 − deletions also causes an unfavorable leaf phenotype characterized by lower yields, delayed ripening and senescence, higher susceptibility to insect herbivory, and poor end-product quality after curing (Chaplin & Burk, 1983;Chaplin & Weeks, 1976;Legg et al, 1970). A better understanding of the differences between LA and NA plants could facilitate strategies to improve the quality of LA leaf and its resulting tobacco products and allow the development of new tobacco cultivars with lower alkaloid levels combined with comparable or superior product characteristics.…”

Section: Introductionmentioning

confidence: 99%

Polyamines delay leaf maturation in low‐alkaloid tobacco varieties

et al. 2018

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The development of low-alkaloid (LA) tobacco varieties is an important target in the tobacco breeding industry. However, LA Burley 21 plants, in which the Nic1 and Nic2 loci controlling nicotine biosynthesis are deleted, are characterized by impaired leaf maturation that leads to poor leaf quality before and after curing. K E Y W O R D Sethylene, inhibition of biosynthesis, maturation, nic1/nic2 mutation, nicotine, ornithine

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“…Low-nicotine traits initially found in strains of Cuban cigar tobacco varieties were introduced into cigarette varieties through a series of backcrosses (Valleau, 1949). Low-nicotine tobacco germplasms were subsequently registered in the genetic backgrounds of cultivars Burley 21 (Legg et al, 1970) and NC 95 (Chaplin, 1975). Careful genetic studies using the lownicotine Burley 21 lines indicated that two unlinked loci contribute to nicotine levels in the tobacco leaf (Legg and Collins, 1971).…”

Section: Introductionmentioning

confidence: 99%

Clustered Transcription Factor Genes Regulate Nicotine Biosynthesis in Tobacco

2010

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Tobacco (Nicotiana tabacum) synthesizes nicotine and related pyridine alkaloids in the root, and their synthesis increases upon herbivory on the leaf via a jasmonate-mediated signaling cascade. Regulatory NIC loci that positively regulate nicotine biosynthesis have been genetically identified, and their mutant alleles have been used to breed low-nicotine tobacco varieties. Here, we report that the NIC2 locus, originally called locus B, comprises clustered transcription factor genes of an ethylene response factor (ERF) subfamily; in the nic2 mutant, at least seven ERF genes are deleted altogether. Overexpression, suppression, and dominant repression experiments using transgenic tobacco roots showed both functional redundancy and divergence among the NIC2-locus ERF genes. These transcription factors recognized a GCC-box element in the promoter of a nicotine pathway gene and specifically activated all known structural genes in the pathway. The NIC2-locus ERF genes are expressed in the root and upregulated by jasmonate with kinetics that are distinct among the members. Thus, gene duplication events generated a cluster of highly homologous transcription factor genes with transcriptional and functional diversity. The NIC2-locus ERFs are close homologs of ORCA3, a jasmonate-responsive transcriptional activator of indole alkaloid biosynthesis in Catharanthus roseus, indicating that the NIC2/ORCA3 ERF subfamily was recruited independently to regulate jasmonate-inducible secondary metabolism in distinct plant lineages.

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Registration of La Burley 21 Tobacco Germplasm¹ Registration No. (GP 8)

Cited by 40 publications

References 0 publications

Gene expression in tobacco low-nicotine mutants.

Gene expression in tobacco low-nicotine mutants.

Polyamines delay leaf maturation in low‐alkaloid tobacco varieties

Clustered Transcription Factor Genes Regulate Nicotine Biosynthesis in Tobacco

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Registration of La Burley 21 Tobacco Germplasm1 Registration No. (GP 8)

Cited by 40 publications

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Gene expression in tobacco low-nicotine mutants.

Gene expression in tobacco low-nicotine mutants.

Polyamines delay leaf maturation in low‐alkaloid tobacco varieties

Clustered Transcription Factor Genes Regulate Nicotine Biosynthesis in Tobacco

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Product

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Registration of La Burley 21 Tobacco Germplasm¹ Registration No. (GP 8)