TY - JOUR

T1 - Mesorhizobium loti increases root-specific expression of a calcium-binding protein homologue identified by promoter tagging in Lotus japonicus

AU - Webb, K. Judith

AU - Skøt, Leif

AU - Nicholson, Margaret N.

AU - Jørgensen, Bodil

AU - Mizen, Sue

PY - 2000/6

Y1 - 2000/6

N2 - A promoter tagging program in the legume Lotus japonicus was initiated to identify plant genes involved in the nitrogen-fixing symbiosis between legumes and rhizobia. Seven transformed plant lines expressing the promoterless reporter gene uidA (β-glucuronidase; GUS) specifically in roots and/or nodules were identified. Four of these expressed GUS in the roots only after inoculation with nodule-forming Mesorhizobium loti. In one line (T90), GUS activity was found in the root epidermis, including root hairs. During seedling growth, GUS expression gradually became focused in developing nodules and disappeared from root tissue. No GUS activity was detected when a non-nodulating mutant of M. loti was used to inoculate the plants. The T-DNA insertion in this plant line was located 1.3 kb upstream of a putative coding sequence with strong homology to calcium-binding proteins. Four motifs were identified, which were very similar to the 'EF hands' in calmodulin-related proteins, each binding one Ca2+. We have named the gene LjCbp1 (calcium-binding protein). Northern (RNA) analyses showed that this gene is expressed specifically in roots of L. japonicus. Expression was reduced in roots inoculated with non-nodulating M. loti mutants and in progeny homozygous for the T-DNA insertion, suggesting a link between the T-DNA insertion and this gene.

AB - A promoter tagging program in the legume Lotus japonicus was initiated to identify plant genes involved in the nitrogen-fixing symbiosis between legumes and rhizobia. Seven transformed plant lines expressing the promoterless reporter gene uidA (β-glucuronidase; GUS) specifically in roots and/or nodules were identified. Four of these expressed GUS in the roots only after inoculation with nodule-forming Mesorhizobium loti. In one line (T90), GUS activity was found in the root epidermis, including root hairs. During seedling growth, GUS expression gradually became focused in developing nodules and disappeared from root tissue. No GUS activity was detected when a non-nodulating mutant of M. loti was used to inoculate the plants. The T-DNA insertion in this plant line was located 1.3 kb upstream of a putative coding sequence with strong homology to calcium-binding proteins. Four motifs were identified, which were very similar to the 'EF hands' in calmodulin-related proteins, each binding one Ca2+. We have named the gene LjCbp1 (calcium-binding protein). Northern (RNA) analyses showed that this gene is expressed specifically in roots of L. japonicus. Expression was reduced in roots inoculated with non-nodulating M. loti mutants and in progeny homozygous for the T-DNA insertion, suggesting a link between the T-DNA insertion and this gene.

KW - Agrobacterium tumefaciens

UR - http://www.scopus.com/inward/record.url?scp=0034115568&partnerID=8YFLogxK

U2 - 10.1094/MPMI.2000.13.6.606

DO - 10.1094/MPMI.2000.13.6.606

M3 - Journal article

C2 - 10830260

AN - SCOPUS:0034115568

VL - 13

SP - 606

EP - 616

JO - Molecular Plant - Microbe Interactions

JF - Molecular Plant - Microbe Interactions

SN - 0894-0282

IS - 6

ER -