Mir1-CP, a novel defense cysteine protease accumulates in maize vascular tissues in response to herbivory

Lorena Lopez, Alberto Camas, Renuka Shivaji, Arunkanth Ankala, Paul Williams, Dawn Luthe

Research output: Contribution to journalArticlepeer-review

67 Scopus citations


When lepidopteran larvae feed on the insect-resistant maize genotype Mp708 there is a rapid accumulation of a defensive cysteine protease, Maize insect resistance 1-cysteine protease (Mir1-CP), at the feeding site. Silver-enhanced immunolocalization visualized with both light and transmission electron microscopy was used to determine the location of Mir1-CP in the maize leaf. The results indicated that Mir1-CP is localized predominantly in the phloem of minor and intermediate veins. After 24 h of larval feeding, Mir1-CP increased in abundance in the vascular parenchyma cells and in the thick-walled sieve element (TSE); it was also found localized to the bundle sheath and mesophyll cells. In situ hybridization of mRNA encoding Mir1-CP indicated that the primary sites of Mir1-CP synthesis in the whorl are the vascular parenchyma and bundle sheath cells. In addition to the phloem, Mir1-CP was also found in the metaxylem of the leaf and root. After 24 h of foliar feeding, the amount of Mir1-CP in the root xylem increased and it appeared to move from xylem parenchyma into the root metaxylem elements. The accumulation of Mir1-CP in maize vascular elements suggests Mir1-CP may move through these tissues to defend against insect herbivores.

Original languageEnglish (US)
Pages (from-to)517-527
Number of pages11
Issue number2
StatePublished - Jul 2007

All Science Journal Classification (ASJC) codes

  • Genetics
  • Plant Science


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