| Southern blot |
Nodule formation |
down-regulated |
N/A |
ENOD40, an early nodulin gene, is expressed following inoculation with Rhizobium meliloti or by adding R.meliloti-produced nodulation (Nod) factors or the plant hormone cytokinin to uninoculated roots. We isolated two MsENOD40 clones, designated MsENOD40–1 and MsENOD40–2, with distinct promoters from an alfalfa (Medicago sativa cv Chief) genomic library. The promoters were fused to the reporter gene uidA (gus), and the constructs were introduced into alfalfa. We observed that the MsENOD40–1 construct was expressed almost exclusively under symbiotic conditions. Under nonsymbiotic conditions MsENOD40–1 was usually not expressed in the uninoculated root of the transgenic alfalfa plants, but was activated when lateral roots or nodule primordia are initiated. The expression of MsENOD40–1 as well as MsENOD40–2 was induced by BAP or Nod factor treatment, and the extent of induction is similar for both genes (2- to 3-fold), although the basal level of MsENOD40–2 expression is generally higher (Fig. 6). In addition, both genes were also expressed in a similar pattern in roots following treatment with cytokinin or Nod factor for 4d (see Fig. 3, G–Q). |
9449836 |
PLNlncRbase
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