The ram1 mutant of Arabidopsis exhibits severely decreased β-amylase activity

Ron J. Laby, Donggiun Kim, Sue Gibson

Research output: Contribution to journalArticle

53 Citations (Scopus)

Abstract

Despite extensive biochemical analyses, the biological function(s) of plant β-amylases remains unclear. The fact that β-amylases degrade starch in vitro suggests that they may play a role in starch metabolism in vivo. β-Amylases have also been suggested to prevent the accumulation of highly polymerized polysaccharides that might otherwise impede flux through phloem sieve pores. The identification and characterization of a mutant of Arabidopsis var. Columbia with greatly reduced levels of β-amylase activity is reported here. The reduced β-amylase 1 (ram1) mutation lies in the gene encoding the major form of β-amylase in Arabidopsis. Although the Arabidopsis genome contains nine known or putative β-amylase genes, the fact that the ram1 mutation results in almost complete loss of β-amylase activity in rosette leaves and inflorescences (stems) indicates that the gene affected by the ram1 mutation is responsible for most of the β-amylase activity present in these tissues. The leaves of ram1 plants accumulate wild-type levels of starch, soluble sugars, anthocyanin, and chlorophyll. Plants carrying the ram1 mutation also exhibit wild-type rates of phloem exudation and of overall growth. These results suggest that little to no β-amylase activity is required to maintain normal starch levels, rates of phloem exudation, and overall plant growth.

Original languageEnglish (US)
Pages (from-to)1798-1807
Number of pages10
JournalPlant Physiology
Volume127
Issue number4
DOIs
StatePublished - Jan 1 2001
Externally publishedYes

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Amylases
Arabidopsis
amylases
mutants
Phloem
Starch
starch
phloem
mutation
Mutation
exudation
Genes
Inflorescence
Anthocyanins
sieves
wild plants
major genes
Chlorophyll
Growth
Polysaccharides

Cite this

The ram1 mutant of Arabidopsis exhibits severely decreased β-amylase activity. / Laby, Ron J.; Kim, Donggiun; Gibson, Sue.

In: Plant Physiology, Vol. 127, No. 4, 01.01.2001, p. 1798-1807.

Research output: Contribution to journalArticle

Laby, Ron J. ; Kim, Donggiun ; Gibson, Sue. / The ram1 mutant of Arabidopsis exhibits severely decreased β-amylase activity. In: Plant Physiology. 2001 ; Vol. 127, No. 4. pp. 1798-1807.
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