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T‐DNA tagging reveals a novel cDNA triggering cytokinin‐ and auxin‐independent protoplast division
Author(s) -
Miklashevichs Edvins,
Czaja Inge,
Cordeiro Alexandra,
Prinsen Els,
Schell Jeff,
Walden Richard
Publication year - 1997
Publication title -
the plant journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 3.058
H-Index - 269
eISSN - 1365-313X
pISSN - 0960-7412
DOI - 10.1111/j.1365-3156.1997.tb00263.x
Subject(s) - auxin , biology , cytokinin , protoplast , cell division , mutant , callus , complementary dna , open reading frame , arabidopsis , microbiology and biotechnology , genetics , cell , gene , peptide sequence
Activation T‐DNA tagging was used to generate four cytokinin‐independent cyi 1–4 tobacco cell lines. Plants regenerated from the mutant lines displayed similar phenotypes: reduced apical dominance, poorly developed roots, delayed growth and flowering, and male and female sterility. Tissue culture experiments demonstrated that the mutations in the different lines uncouple cell proliferation from the effects of both cytokinin and auxin. No significant increase of cytokinin or auxin was found in transgenic calli in comparison with untransformed callus. The functional plant sequence tagged in one of the mutant lines, cyi1 , was used to isolate an active cDNA, cyi1 a, that was able to trigger cytokinin‐ and auxin‐independent protoplast division. Northern analysis shows that the transcript corresponding to cyi1 a accumulates to high levels in the untransformed protoplasts shortly before the onset of cell division, and that these levels decrease when protoplasts reach maximum rates of cell division. A small putative open reading frame, starting with the first ATG in cyi1 a and encoding a 22 amino acid peptide, has the same activity in tobacco protoplasts as the whole cDNA. This activity is destroyed by a frame shift mutation. Apparently cyi1 a encodes a peptide which participates in the events downstream of a joint point of cytokinin and auxin action leading to cell division.