Mapping, complementation, and targets of the cysteine protease actinidin in kiwifruit

Plant Physiol. 2012 Jan;158(1):376-88. doi: 10.1104/pp.111.187989. Epub 2011 Oct 28.


Cysteine proteases (CPs) accumulate to high concentration in many fruit, where they are believed to play a role in fungal and insect defense. The fruit of Actinidia species (kiwifruit) exhibit a range of CP activities (e.g. the Actinidia chinensis variety YellowA shows less than 2% of the activity of Actinidia deliciosa variety Hayward). A major quantitative trait locus for CP activity was mapped to linkage group 16 in a segregating population of A. chinensis. This quantitative trait locus colocated with the gene encoding actinidin, the major acidic CP in ripe Hayward fruit encoded by the ACT1A-1 allele. Sequence analysis indicated that the ACT1A locus in the segregating A. chinensis population contained one functional allele (A-2) and three nonfunctional alleles (a-3, a-4, and a-5) each containing a unique frameshift mutation. YellowA kiwifruit contained two further alleles: a-6, which was nonfunctional because of a large insertion, and a-7, which produced an inactive enzyme. Site-directed mutagenesis of the act1a-7 protein revealed a residue that restored CP activity. Expression of the functional ACT1A-1 cDNA in transgenic plants complemented the natural YellowA mutations and partially restored CP activity in fruit. Two consequences of the increase in CP activity were enhanced degradation of gelatin-based jellies in vitro and an increase in the processing of a class IV chitinase in planta. These results provide new insight into key residues required for CP activity and the in vivo protein targets of actinidin.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Actinidia / genetics*
  • Actinidia / metabolism
  • Alleles
  • Chitinases / metabolism
  • Chromosome Mapping
  • Cysteine Endopeptidases / genetics*
  • Cysteine Endopeptidases / metabolism*
  • DNA, Complementary
  • Frameshift Mutation
  • Gelatin / metabolism
  • Genetic Complementation Test
  • Molecular Sequence Data
  • Mutagenesis, Site-Directed
  • Plant Proteins / genetics
  • Plant Proteins / metabolism
  • Plants, Genetically Modified
  • Quantitative Trait Loci
  • Sequence Analysis, DNA


  • DNA, Complementary
  • Plant Proteins
  • Gelatin
  • Chitinases
  • Cysteine Endopeptidases
  • actinidain

Associated data

  • GENBANK/GU201520
  • GENBANK/GU201526
  • GENBANK/GU201527
  • GENBANK/GU201528
  • GENBANK/JN701537