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  1. Transcriptome-wide effect of DE-ETIOLATED1 (DET1) suppression in embryogenic callus of Carica papaya
    Jamaluddin ND, Rohani ER, Mohd Noor N, Goh HH
    J Plant Res, 2019 Mar;132(2):181-195.
    PMID: 30649676 DOI: 10.1007/s10265-019-01086-x
    Papaya is one of the most nutritional fruits, rich in vitamins, carotenoids, flavonoids and other antioxidants. Previous studies showed phytonutrient improvement without affecting quality in tomato fruit and rapeseed through the suppression of DE-ETIOLATED-1 (DET1), a negative regulator in photomorphogenesis. This study is conducted to study the effects of DET1 gene suppression in papaya embryogenic callus. Immature zygotic embryos were transformed with constitutive expression of a hairpin DET1 construct (hpDET1). PCR screening of transformed calli and reverse transcription quantitative PCR (RT-qPCR) verified that DET1 gene downregulation in two of the positive transformants. High-throughput cDNA 3' ends sequencing on DET1-suppressed and control calli for transcriptomic analysis of global gene expression identified a total of 452 significant (FDR developmental processes, lipid metabolism, and response to various stimuli. This is the first study to demonstrate transcriptome-wide relationship between light-regulated pathway and secondary metabolite biosynthetic pathways in papaya. This further supports that the manipulation of regulatory gene involved in light-regulated pathway is possible for phytonutrient improvement of tropical fruit crops.
    Matched MeSH terms: Carica/growth & development
  2. Characterisation of an alpha-galactosidase with potential relevance to ripening related texture changes
    Soh CP, Ali ZM, Lazan H
    Phytochemistry, 2006 Feb;67(3):242-54.
    PMID: 16325871
    alpha-Galactosidase (EC 3.2.1.22) from ripe papaya (Carica papaya L.) fruit was fractionated by a combination of ion exchange and gel filtration chromatography into three forms, viz., alpha-galactosidase 1, 2 and 3. The predominant isoform, alpha-gal 2, was probably a tetramer with a native molecular mass of about 170 kDa and 52 kDa-sized subunits and an estimated pI of 7.3. The subunit's N-terminal amino acid sequence shared high identity (97%) with the deduced sequence of a papaya cDNA clone encoding a putative alpha-galactosidase PAG2 as well as with an Ajuga reptans L. GGT1 clone encoding a galactan: galactan galactosyltransferase (66%). During ripening, alpha-galactosidase activity increased concomitantly with firmness loss and this increase was largely ascribed to alpha-gal 2. The protein level of alpha-gal 2 as estimated by immunoblot was low in developing fruits and generally increased with ripening. alpha-Galactosidase 2 also had the ability to markedly catalyse increased pectin solubility and depolymerisation while the polymers were still structurally attached to the cell walls mimicking, in part, the changes that occur during ripening. The close correlation between texture changes, alpha-gal 2 activity and protein levels as well as capability to modify intact cell walls suggest that the enzyme might contribute to papaya fruit softening during ripening. The purported mechanism of alpha-gal 2 action as a softening enzyme was discussed in terms of its functional capacity as a glycanase or perhaps, as a transglycosylase.
    Matched MeSH terms: Carica/growth & development
  3. Effect of calcium chloride treatments on calcium content, anthracnose severity and antioxidant activity in papaya fruit during ambient storage
    Madani B, Mirshekari A, Yahia E
    J Sci Food Agric, 2016 Jul;96(9):2963-8.
    PMID: 26374618 DOI: 10.1002/jsfa.7462
    BACKGROUND: There have been no reports on the effects of preharvest calcium application on anthracnose disease severity, antioxidant activity and cellular changes during ambient storage of papaya, and therefore the objective of this study was to investigate these effects.

    RESULTS: Higher calcium concentrations (1.5 and 2% w/v) increased calcium concentration in the peel and pulp tissues, maintained firmness, and reduced anthracnose incidence and severity. While leakage of calcium-treated fruit was lower for 1.5 and 2% calcium treatments compared to the control, microscopic results confirmed that pulp cell wall thickness was higher after 6 days in storage, for the 2% calcium treatment compared to the control. Calcium-treated fruit also had higher total antioxidant activity and total phenolic compounds during storage.

    CONCLUSION: Calcium chloride, especially at higher concentrations, is effective in maintaining papaya fruit quality during ambient storage. © 2015 Society of Chemical Industry.

    Matched MeSH terms: Carica/growth & development
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