Publications of NIPGR Scientists

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Author: search.filters.author.Kumar, VinaySubject: search.filters.subject.RIN

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    Fruit ripening specific expression of β-D-N-acetylhexosaminidase (β-Hex) gene in tomato is transcriptionally regulated by Ethylene Response Factor SlERF.E4
    (Elsevier B.V., 2022) Irfan, Mohammad; Kumar, Pankaj; Kumar, Vinay; Datta, Asis
    N-glycans and N-glycan processing enzymes are key players in regulating the ripening of tomato (Solanum lycopersicum) fruits, a model for fleshy fruit ripening. β-D-N-acetylhexosaminidase (β-Hex) is a N-glycan processing enzyme involved in fruit ripening. The suppression of β-Hex results in enhanced fruit shelf life and firmness in both climacteric and non-climacteric fruits. Previously, we have shown that ripening specific expression of β-Hex is regulated by RIPENING INHIBITOR (RIN), ABSCISIC ACID STRESS RIPENING 1 (SlASR1) and ethylene. However, the precise mechanism of ethylene-mediated regulation of β-Hex remains elusive. To gain insights into this, we have performed 5’ deletion mapping of tomato β-Hex promoter and a shorter promoter fragment (pD-200, 200 bp upstream to translational start site) is identified, which was found critical for spatio-temporal transcriptional regulation of β-Hex. Further, site specific mutagenesis in RIN and ASR1 binding sites in pD-200 provides key insights into ripening specific promoter activity. Furthermore, induction of GUS activity by ethylene, yeast one hybrid assay and EMSA identify Ethylene Response Factor SlERF.E4 as a positive regulator of β-Hex. Taken together, our study suggest that SlERF.E4 together with RIN and SlASR1 transcriptionally regulates β-Hex and all these three proteins are essential for fruit ripening specific expression of β-Hex in tomato.
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    Fruit ripening regulation of α-Mannosidase expression by the MADS box transcription factor RIPENING INHIBITOR and ethylene
    (Frontiers Media S.A., 2016) Irfan, Mohammad; Ghosh, Sumit; Meli, Vijaykumar S.; Kumar, Anil; Kumar, Vinay; Chakraborty, Niranjan; Chakraborty, Subhra; Datta, Asis
    α-Mannosidase (α-Man), a fruit ripening-specific N-glycan processing enzyme, is involved in ripening-associated fruit softening process. However, the regulation of fruit-ripening specific expression of α-Man is not well understood. We have identified and functionally characterized the promoter of tomato (Solanum lycopersicum) α-Man to provide molecular insights into its transcriptional regulation during fruit ripening. Fruit ripening-specific activation of the α-Man promoter was revealed by analysing promoter driven expression of beta-glucuronidase (GUS) reporter in transgenic tomato. We found that RIPENING INHIBITOR (RIN), a MADS box family transcription factor acts as positive transcriptional regulator of α-Man during fruit ripening. RIN directly bound to the α-Man promoter sequence and promoter activation/α-Man expression was compromised in rin mutant fruit. Deletion analysis revealed that a promoter fragment (567 bp upstream of translational start site) that contained three CArG boxes (binding sites for RIN) was sufficient to drive GUS expression in fruits. In addition, α-Man expression was down-regulated in fruits of Nr mutant which is impaired in ethylene perception and promoter activation/α-Man expression was induced in wild type following treatment with a precursor of ethylene biosynthesis, 1-aminocyclopropane-1-carboxylic acid (ACC). Although, α-Man expression was induced in rin mutant after ACC treatment, the transcript level was less as compared to ACC-treated wild type. Taken together, these results suggest RIN-mediated direct transcriptional regulation of α-Man during fruit ripening and ethylene may acts in RIN-dependent and -independent ways to regulate α-Man expression.
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    Insights into transcriptional regulation of β-D-N-acetylhexosaminidase, an N-glycan-processing enzyme involved in ripening-associated fruit softening
    (Oxford University Press, 2014) Irfan, Mohammad; Ghosh, Sumit; Kumar, Vinay; Chakraborty, Niranjan; Chakraborty, Subhra; Datta, Asis
    Tomato (Solanum lycopersicum) fruit ripening-specific N-glycan processing enzyme, β-D-N-acetylhexosaminidase (β-Hex), plays an important role in the ripening-associated fruit-softening process. However, the regulation of fruit ripening-specific expression of β-Hex is not well understood. We have identified and functionally characterized the fruit ripening-specific promoter of β-Hex and provided insights into its transcriptional regulation during fruit ripening. Our results demonstrate that RIPENING INHIBITOR (RIN), a global fruit ripening regulator, and ABSCISIC ACID STRESS RIPENING 1 (SlASR1), a poorly characterized ripening-related protein, are the transcriptional regulators of β-Hex. Both RIN and SlASR1 directly bound to the β-Hex promoter fragments containing CArG and C₂₋₃(C/G)A cis-acting elements, the binding sites for RIN and SlASR1, respectively. Moreover, β-Hex expression/promoter activity in tomato fruits was downregulated once expression of either RIN or SlASR1 was suppressed; indicating that RIN and SlASR1 positively regulate the transcription of β-Hex during fruit ripening. Interestingly, RIN could also bind to the SlASR1 promoter, which contains several CArG cis-acting elements, and SlASR1 expression was suppressed in rin mutant fruits, indicating that RIN also acts as a positive regulator of SlASR1 expression during fruit ripening. Taken together, these results suggest that RIN, both directly and indirectly, through SlASR1, regulates the transcription of β-Hex during fruit ripening. The fruit ripening-specific promoter of β-Hex could be a useful tool in regulating gene expression during fruit ripening.