Introduction of a novel pathway for IAA biosynthesis to rhizobia alters vetch root nodule development.
We introduced into Rhizobium leguminosarum bv. viciae LPR1105 a new pathway for the biosynthesis of the auxin, indole-3-acetic acid (IAA), under the control of a stationary phase-activated promoter active both in free-living bacteria and bacteroids. The newly introduced genes are the iaaM gene from Pseudomonas savastanoi and the tms2 gene from Agrobacterium tumefaciens. Free-living bacteria harbouring the promoter-iaaMtms2 construct release into the growth medium 14-fold more IAA than the wild-type parental strain. This IAA overproducing R. l. viciae, the RD20 strain, elicits the development of vetch root nodules containing up to 60-fold more IAA than nodules infected by the wild-type strain LPR1105. Vetch root nodules derived from RD20 are fewer in number per plant, heavier in terms of dry weight and show an enlarged and more active meristem. A significant increase in acetylene reduction activity was measured in nodules elicited in vetch by RD20.
Camerini
Serena
S
Institute of Genetics and Biophysics, CNR, via P. Castellino 111, 80131, Naples, Italy.
Senatore
Beatrice
B
Lonardo
Enza
E
Imperlini
Esther
E
Bianco
Carmen
C
Moschetti
Giancarlo
G
Rotino
Giuseppe L
GL
Campion
Bruno
B
Defez
Roberto
R
D000114:Acetylene / Q000378:metabolism; D016960:Agrobacterium tumefaciens / Q000235:genetics; D001426:Bacterial Proteins / Q000235:genetics; D004269:DNA, Bacterial / Q000235:genetics; D005798:Genes, Bacterial; D007210:Indoleacetic Acids / Q000378:metabolism*; D009586:Nitrogen Fixation; D010937:Plant Growth Regulators / Q000378:metabolism; D010957:Plasmids; D011401:Promoter Regions, Genetic; D011549:Pseudomonas / Q000235:genetics; D011994:Recombinant Proteins / Q000235:genetics; D016961:Rhizobium leguminosarum / Q000235:genetics* / Q000378:metabolism*; D053204:Root Nodules, Plant / Q000254:growth & development* / Q000382:microbiology; D013559:Symbiosis; D031306:Vicia / Q000254:growth & development / Q000382:microbiology*
D001426:Bacterial Proteins; D004269:DNA, Bacterial; D007210:Indoleacetic Acids; D010937:Plant Growth Regulators; D011994:Recombinant Proteins; C030737:indoleacetic acid; D000114:Acetylene