The new kid on the block: a dominant-negative mutation of phototropin1 enhances carotenoid content in tomato fruits

Himabindu Vasuki Kilambi, Alekhya Dindu, Kapil Sharma, Narasimha Rao Nizampatnam, Neha Gupta, Nikhil Padmanabhan Thazath, Ajayakumar Jaya Dhanya, Kamal Tyagi, Sulabha Sharma, Sumit Kumar, Rameshwar Sharma, Yellamaraju Sreelakshmi*

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

Abstract

Phototropins, the UVA-blue light photoreceptors, endow plants to detect the direction of light and optimize photosynthesis by regulating positioning of chloroplasts and stomatal gas exchange. Little is known about their functions in other developmental responses. A tomato Non-phototropic seedling1 (Nps1) mutant, bearing an Arg495His substitution in the vicinity of LOV2 domain in phototropin1, dominant-negatively blocks phototropin1 responses. The fruits of Nps1 mutant were enriched in carotenoids, particularly lycopene, compared with its parent, Ailsa Craig. On the contrary, CRISPR/CAS9-edited loss of function phototropin1 mutants displayed subdued carotenoids compared with the parent. The enrichment of carotenoids in Nps1 fruits is genetically linked with the mutation and exerted in a dominant-negative fashion. Nps1 also altered volatile profiles with high levels of lycopene-derived 6-methyl 5-hepten2-one. The transcript levels of several MEP and carotenogenesis pathway genes were upregulated in Nps1. Nps1 fruits showed altered hormonal profiles with subdued ethylene emission and reduced respiration. Proteome profiles showed a causal link between higher carotenogenesis and increased levels of protein protection machinery, which may stabilize proteins contributing to MEP and carotenogenesis pathways. The enhancement of carotenoid content by Nps1 in a dominant-negative fashion offers a potential tool for high lycopene-bearing hybrid tomatoes.

Original languageEnglish
Pages (from-to)844-861
Number of pages18
JournalPlant Journal
Volume106
Issue number3
DOIs
StatePublished - May 2021

Keywords

  • Solanum lycopersicum
  • carotenoid content
  • fruit ripening
  • gene editing
  • phototropins
  • primary metabolites
  • protein protection machinery
  • tomato

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