A major function of the tobacco floral nectary is defense against microbial attack

Robert W. Thornburg, Clay Carter, Ann Powell, Ron Mittler, Ludmila Rizhsky, Harry T. Horner

Research output: Contribution to journalArticlepeer-review

79 Scopus citations


We have characterized the major nectar protein (Nectarin I) from ornamental tobacco as a superoxide dismutase that functions to generate high levels of hydrogen peroxide in nectar. Other nectar functions include an anti-polygalacturonase activity that may be due to a polygalacturonase inhibiting protein (PGIP). We also examined the expression of defense related genes in the nectary gland by two independent methods. We isolated a sample of nectary-expressed cDNAs and found that 21% of these cDNAs were defense related clones. Finally, we examined the expression of a number of specific defense-related genes by hybridization to specific cDNAs. These results demonstrated that a number of specific defense genes were more strongly expressed in the floral nectary than in the foliage. Taken together these results indicate that the floral nectary gland can have specific functions in plant defense.

Original languageEnglish (US)
Pages (from-to)211-218
Number of pages8
JournalPlant Systematics and Evolution
Issue number1-4
StatePublished - Jun 2003


  • Flower
  • Gynoecium
  • Nectar
  • Nectary
  • PGIP
  • Plant defense


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