ISSN:
1573-5028
Keywords:
elongation growth
;
gene expression
;
Hordeum vulgare
;
protochlorophyllide oxidoreductase
;
slender mutant
;
tonoplast intrinsic protein
Source:
Springer Online Journal Archives 1860-2000
Topics:
Biology
Notes:
Abstract Three cDNA clones have been isolated on the basis of altered patterns of expression in the leaf extension zone of the developmental mutant,slender barley, compared with the wild type. mRNAs corresponding to two of the cDNAs, 7s and 8s, are increased inslender compared with normal. 7s encodes a putative γ-TIP and is expressed throughout the elongation zone. γ-TIPs form transmembrane channels which allow the passive transfer of water. Although expression of 7s was increased inslender leaf tissue, the increase was much less extreme than that shown by Phillips and Huttly (1994) following the application of GA to an extreme dwarf ofArabidopsis. 8s is maximally expressed in the region of early cell elongation and has 66% encoded protein identity with MFS18, a cDNA encoding a putative cell wall structural protein isolated from male flowers of maize. Both 8s and MFS18 encode small (128 amino acids) basic proteins rich in glycine, alanine, proline and serine. mRNA corresponding to the third cDNA, 24n, is present at a greatly reduced level inslender compared with normal and encodes protochlorophyllide oxidoreductase (POR). POR catalyses the conversion of protochlorophyllide into chlorophyllide. The reduced level of POR mRNA is not correlated with a similar reduction in expanded leaf blade chlorophyll levels. Western analysis identified two POR proteins present in light-grown seedlings. Whilst the larger of the proteins is present throughout most of the leaf, the smaller protein mimics the mRNA results, being both maximally present in the elongation tissue and present at a reduced level inslender. An antagonistic relationship between chlorophyll biosynthesis and extension growth is suggested.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1007/BF00042226
Permalink
