Cytokinin induces expansin gene expression in Melilotus alba Desr. wild-type and the non-nodulating, non-mycorrhizal (NodMyc) mutant Masym3.
نویسندگان
چکیده
We previously showed that applying 10(-6) M of the cytokinin 6-benzylaminopurine (BAP) to uninoculated roots of Masym3, a Nod(-)Myc(-)Melilotus alba (Desr.) mutant, resulted in the accumulation of MaENOD40 transcripts to levels similar to BAP-treated wild-type roots. In contrast, inoculation with a Nod(-)S. meliloti mutant expressing the trans-zeatin synthase gene of Agrobacterium tumefaciens (Nod(-)/pTZS(+)) did not induce MaENOD40 transcript accumulation in either wild-type or Masym3 roots. However, Masym3 root hairs became swollen at their tips following inoculation with wild-type or Nod(-)/pTZS(+) rhizobia. Because root hair distention and elongation are often correlated with increased expansin activity, we investigated whether BAP treatment or inoculation with Nod(-)/pTZS(+)S. meliloti upregulated the expression of expansin mRNAs. We first determined that treating wild-type roots with 10(-5) or 10(-6) M BAP resulted in greater MaEXPA1 transcript accumulation than treating roots with comparable concentrations of the auxin NAA. When Masym3 roots were treated with 10(-6) M BAP, MaEXPA mRNAs accumulated to levels comparable to wild-type roots. We then showed that MaEXPA1 mRNAs accumulated in wild-type M. alba roots in response to the Nod(-)/pTZS(+)S. meliloti strain. Masym3 mutant roots inoculated with Nod(-)/pTZS(+) rhizobia were also upregulated for MaEXPA1 expression.
منابع مشابه
ENOD40 Gene Expression and Cytokinin Responses in the Nonnodulating, Nonmycorrhizal (NodMyc) Mutant, Masym3, of Melilotus alba Desr.
Several nonnodulating, nonmycorrhizal (Nod(-)Myc(-)) mutants of Melilotus alba Desr. (white sweetclover) have been described. However, the details of their responses to Sinorhizobium meliloti have not been fully elucidated. We investigated rhizobial entry and colonization using Confocal Scanning Laser Microscopy on the Masym1-5 mutants and isolated an early nodulin (ENOD40) gene from wild-type ...
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Expansins are a highly conserved group of cell wall-localized proteins that appear to mediate changes in cell wall plasticity during cell expansion or differentiation. The accumulation of expansin protein or the mRNA for specific expansin gene family members has been correlated with the growth of various plant organs. Because expansin proteins are closely associated with plant cell wall expansi...
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ورودعنوان ژورنال:
- Plant signaling & behavior
دوره 3 4 شماره
صفحات -
تاریخ انتشار 2008