Submitted to: Plant Molecular Biology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 11/10/1998
Publication Date: N/A
Interpretive Summary: Fall armyworm damage to corn can result in substantial yield losses, especially late-planted corn in the South. Several corn germplasm lines have been developed and released by USDA-ARS scientists at Mississippi State, Mississippi. Efforts to identify specific genes associated with this resistance were initiated several years ago. A protein associated with resistance was found in the resistance lines and determined to be a cysteine proteinase. The amino acid sequence of the protein was determined. The gene encoding this protein was given the designation mirl. The sequence for two related genes, mir2 and mir3, were also determined. The three genes map to distinct sites of the corn genome. Having identified these genes will aid in their transfer into elite corn germplasm and the development of commercially available corn hybrids with resistance to fall armyworm.
Technical Abstract: In previous work, a 33 kD cysteine proteinase was found in callus initiated from corn (Zea mays L.) resistant to fall armyworm feeding. A callus cDNA library from the corn inbred Mp708 was screened with oligonucleotides derived from the N-terminal amino acid sequence of the 33 kD proteinase and several cDNA clones were isolated and sequenced. A cDNA encoding the 33 kD cysteine proteinase, mirl, was identified. Two additional clones, mir3 and mir 3, encoding putative cysteine proteinases were also identified. Mir2 and mir3 are distinct from mir1 and each other, but show a high degree of homology. All of the mir cDNA clones map to distinct sites on the corn genome. Amino acid sequences encoded by the mir clones are similar to other known cysteine proteinases and are most closely related to the oryzain-a and -B chain precursors. The ERFNIN motif and 12 amino acid conserved sequences are present in the polypeptide region of the putative proteinases encoded by mir clones. Mir2 and mir3 appear to have C-terminal extensions. The phylogenetic tree of nucleotide sequences of mir1, mir2, mir3 and other representative cysteine proteinases from protozoa, plants and animals was constructed.