Altered chloroplast development and delayed fruit ripening caused by mutations in a zinc metalloprotease at the lutescent2 locus of tomato

Plant Physiol. 2012 Jul;159(3):1086-98. doi: 10.1104/pp.112.197483. Epub 2012 May 22.

Abstract

The chloroplast is the site of photosynthesis in higher plants but also functions as the center of synthesis for primary and specialized metabolites including amino acids, fatty acids, starch, and diverse isoprenoids. Mutants that disrupt aspects of chloroplast function represent valuable tools for defining structural and biochemical regulation of the chloroplast and its interplay with whole-plant structure and function. The lutescent1 (l1) and l2 mutants of tomato (Solanum lycopersicum) possess a range of chlorophyll-deficient phenotypes including reduced rates of chlorophyll synthesis during deetiolation and enhanced rates of chlorophyll loss in leaves and fruits as they age, particularly in response to high-light stress and darkness. In addition, the onset of fruit ripening is delayed in lutescent mutants by approximately 1 week although once ripening is initiated they ripen at a normal rate and accumulation of carotenoids is not impaired. The l2 locus was mapped to the long arm of chromosome 10 and positional cloning revealed the existence of a premature stop codon in a chloroplast-targeted zinc metalloprotease of the M50 family that is homologous to the Arabidopsis (Arabidopsis thaliana) gene ETHYLENE-DEPENDENT GRAVITROPISM DEFICIENT AND YELLOW-GREEN1. Screening of tomato germplasm identified two additional l2 mutant alleles. This study suggests a role for the chloroplast in mediating the onset of fruit ripening in tomato and indicates that chromoplast development in fruit does not depend on functional chloroplasts.

Publication types

  • Research Support, Non-U.S. Gov't
  • Research Support, U.S. Gov't, Non-P.H.S.

MeSH terms

  • Alleles
  • Amino Acid Sequence
  • Arabidopsis Proteins / chemistry
  • Chlorophyll / metabolism
  • Chloroplasts / enzymology*
  • Chloroplasts / radiation effects
  • Cloning, Molecular
  • Fruit / enzymology
  • Fruit / growth & development*
  • Fruit / radiation effects
  • Genetic Loci / genetics*
  • Genetic Pleiotropy / radiation effects
  • Light
  • Metalloendopeptidases / chemistry
  • Metalloendopeptidases / metabolism*
  • Metalloproteases / chemistry
  • Molecular Sequence Data
  • Morphogenesis / radiation effects
  • Mutation / genetics*
  • Phenotype
  • Photosynthesis / radiation effects
  • Plant Proteins / chemistry
  • Plant Proteins / metabolism
  • Sequence Alignment
  • Sequence Homology, Amino Acid
  • Solanum lycopersicum / enzymology*
  • Solanum lycopersicum / genetics
  • Solanum lycopersicum / growth & development
  • Thylakoids / metabolism
  • Thylakoids / radiation effects
  • Zinc / metabolism*

Substances

  • Arabidopsis Proteins
  • Plant Proteins
  • Chlorophyll
  • EGY1 protein, Arabidopsis
  • Metalloproteases
  • Metalloendopeptidases
  • Zinc

Associated data

  • GENBANK/JQ683149