May
2002
, Volume
15
, Number
5
Pages
428
-
436
Authors
Alberto
Camas
,
1
Luis
Cárdenas
,
2
Carmen
Quinto
,
2
and
Miguel
Lara
1
Affiliations
1Centro de Investigación sobre Fijación de Nitrógeno, Universidad Nacional Autónoma de México, Apartado postal 565-A, Cuernavaca, Morelos, México; 2Instituto de Biotecnología, Universidad Nacional Autónoma de México, Apartado postal 565-A, Cuernavaca, Morelos, México
Go to article:
RelatedArticle
Accepted 28 January 2002.
Abstract
Three calmodulin (PvCaM-1, PvCaM-2, and PvCaM-3) clones were isolated from a Phaseolus vulgaris nodule cDNA library. All clones contain the complete coding region and are 62 to 74% homologous within this region. Compared to plant CaM consensus sequences, PvCaM-2 has a novel tyrosine118 residue, representing a putative phosphorylation site. Southern analysis suggested that calmodulin is encoded by a gene family. These three CaM clones are expressed mainly in young tissues and meristems. The expression pattern of PvCaM-2 and PvCaM-3 is almost identical but different from that of PvCaM-1, suggesting that PvCaM-1 is a well-defined CaM gene, whereas PvCaM-2 and PvCaM-3 could be alleles. PvCaM clones are expressed early in nodules, and transcript levels increase from nodule primordia to nodule-like structures induced by the Nod factor. Conversely, in roots, Nod factor lowers mRNA levels of all three PvCaM clones, but especially of PvCaM-1. Inhibition of PvCaM-1 expression also is observed when 2,3,5-triiodobenzoic acid is added and is prevented when roots are treated with indole-3-acetic acid, suggesting that PvCaM-1 regulation is related to the Nod factor inhibition of polar auxin transport. These results could suggest that CaM clones do not participate in the early signaling generated by the Nod factor but do participate in early events of nodule formation.
JnArticleKeywords
Additional keywords:
auxin transport inhibition
,
lipochitooligosaccharide
,
Rhizobium etli.
Page Content
ArticleCopyright
© 2002 The American Phytopathological Society