Journal Article

Molecular Cloning of β-Galactosidase from Japanese Pear (<i>Pyrus pyrifolia</i>) and its Gene Expression with Fruit Ripening

Akira Tateishi, Hiroaki Inoue, Hajime Shiba and Shohei Yamaki

in Plant and Cell Physiology

Published on behalf of Japanese Society of Plant Physiologists

Volume 42, issue 5, pages 492-498
Published in print May 2001 | ISSN: 0032-0781
Published online May 2001 | e-ISSN: 1471-9053 | DOI:
Molecular Cloning of β-Galactosidase from Japanese Pear
(Pyrus pyrifolia) and its Gene Expression with Fruit

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  • Biochemistry
  • Molecular and Cell Biology
  • Plant Sciences and Forestry


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We have cloned a cDNA fragment encoding a β-galactosidase from Japanese pear (Pyrus pyrifolia) fruit (JP-GAL). It contained an untranslated sequence of 182 nucleotides at the 5′ end, a presumptive coding sequence of 2,193 nucleotides and an untranslated sequence of 268 nucleotides including a polyadenylation signal and a poly (A) tail at the 3′ end. It encoded a protein with a calculated molecular weight of 80.9 kDa which consists of 731 amino acids. Both the nucleotide and the deduced amino acid sequences showed a 98% sequence identity with that obtained from the apple β-galactosidase cDNA. The peptide sequence obtained from the purified Japanese pear β-galactosidase III matched the deduced amino acid sequence of SVSYDHKAIIINGQKRILISG (amino acid 25–45). Northern blot analysis showed that the probe derived from JP-GAL hybridized to a single 2.6 kb RNA. The mRNA was detected solely in the fruit; none was detected in the buds, leaves, roots or shoots of the Japanese pear. The steady-state level of the β-galactosidase mRNA was measured during fruit ripening in three cultivars, Housui, Kousui (early ripening) and Niitaka (late ripening). The results showed that regardless of the cultivar, no JP-GAL mRNA was detected in the immature fruit. Increment of the mRNA level with fruit ripening coincided with the increase in the β-galactosidase III activity. Our results showed that the expression of JP-GAL correlated with fruit softening and JP-GAL may be β-galactosidase III.

Keywords: Key words: Fruit — β-Galactosidase (EC — Gene expression — Pyrus pyrifolia — Softening.; Abbreviation: β-GAL III, β-galactosidase III.; The nucleotide sequence reported in this paper has been submitted to DDBJ, EMBL and GenBank under accession number AB046543.

Journal Article.  4679 words.  Illustrated.

Subjects: Biochemistry ; Molecular and Cell Biology ; Plant Sciences and Forestry

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