title: Identification, cloning and characterization of an ultrapetala transcription factor CsULT1 from Crocus: a novel regulator of apocarotenoid biosynthesis.
abstract: BACKGROUND
  Crocus sativus is a triploid sterile plant with long red stigmas which form commercial saffron. Saffron is the site for synthesis and accumulation of apocarotenoids like crocin, picrocrin and safranal which are responsible for its color, flavour and aroma making it world's most expensive spice. These compounds are formed by oxidative cleavage of zeaxanthin by carotenoid cleavage dioxygenases. Although the biosynthetic pathway of apocarotenoids is known to a considerable extent, the mechanism that regulates its tissue and developmental stage specific expression is not known.
  
  
  RESULTS
  In the present work, we identified, cloned and characterized ultrapetala transcription factor called CsULT1 from Crocus. The gene contains an 80 amino acid long conserved SAND domain. The CsULT1 transcript was more abundant in stigma and showed increase in expression from pre anthesis stage till anthesis and decreased in post anthesis stage which corroborated with the accumulation pattern of crocin indicating its possible role in regulation of apocarotenoid biosynthesis. CsULT1 was found to be transcriptionally active and localized in nucleus. Its expression is induced in response to phytohormones like auxin, methyljasmonate and salicylic acid. Overexpression of CsULT1 in Crocus calli resulted in enhanced expression of key pathway genes like phytoene synthase (PSY), phytoene desaturase (PDS), beta carotene hydroxylase (BCH) and carotenoid cleavage dioxygenases (CCDs) indicating its role in regulation of apocarotenoid biosynthesis.
  
  
  CONCLUSIONS
  This work presents first report on isolation and characterization of ultrapetala gene from Crocus. Our results suggest that CsULT1 is a novel regulator of Crocus apocarotenoid biosynthesis. We show for the first time involvement of plant SAND domain proteins in regulating secondary metabolic pathways.
authors: Plant Biotechnology Division, CSIR- Indian Institute of Integrative Medicine, Sanat Nagar, Srinagar, J&K-190005, India. nashraf@iiim.ac.in.
authors: Nasheeman
authors: N
authors: Ashraf
authors: National Institute of Plant Genome Research, Aruna Asaf Ali Marg, New Delhi, 110067, India. deeptivjain@gmail.com.
authors: Deepti
authors: D
authors: Jain
authors: Medicinal Chemisrty Division, CSIR- Indian Institute of Integrative Medicine, Canal Road, Jammu, J&K 180001, India. ram@iiim.ac.in.
authors: Ram A
authors: RA
authors: Vishwakarma
mesh_terms: D000595:Amino Acid Sequence; D002338:Carotenoids / Q000096:biosynthesis* / Q000378:metabolism; D003001:Cloning, Molecular; D027622:Crocus / Q000235:genetics*; D020869:Gene Expression Profiling; D008969:Molecular Sequence Data; D010940:Plant Proteins / Q000737:chemistry / Q000235:genetics* / Q000378:metabolism / Q000502:physiology*; D017386:Sequence Homology, Amino Acid; D013347:Subcellular Fractions / Q000378:metabolism; D014157:Transcription Factors / Q000235:genetics* / Q000502:physiology*; D015533:Transcriptional Activation
chemical_list: D010940:Plant Proteins; D014157:Transcription Factors; D002338:Carotenoids; C029036:crocin
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