Cryptochrome 1 from Brassica napus is up-regulated by blue light and controls hypocotyl/stem growth and anthocyanin accumulation.
Cryptochromes are blue/ultraviolet-A light sensing photoreceptors involved in regulating various growth and developmental responses in plants. Investigations on the structure and functions of cryptochromes in plants have been largely confined to Arabidopsis (Arabidopsis thaliana), tomato (Lycopersicon esculentum), and pea (Pisum sativum). We report here the characterization of the cryptochrome 1 gene from Brassica napus (BnCRY1), an oilseed crop, and its functional validation in transgenics. The predicted BnCRY1 protein sequence shows a high degree of sequence identity (94%) to Arabidopsis CRY1. A semiquantitative reverse transcription-polymerase chain reaction and the western-blot analysis revealed that blue light up-regulates its transcript and protein levels in young seedlings. The BnCRY1 promoter harbors conventional light-responsive cis-acting elements, which presumably impart light activation to the GUS (beta-glucuronidase) reporter gene expressed in Arabidopsis. Although the BnCRY1 transcript could be detected in all the tissues examined, its protein was virtually undetectable in mature leaves and the root, indicating a tissue-specific translational control or protein turnover. The antisense-BnCRY1 Brassica transgenic seedlings accumulated negligible levels of CRY1 protein and displayed an elongated hypocotyl when grown under continuous white or blue light (but not under red or far-red light); the accumulation of anthocyanins was also reduced significantly. The adult transformants were also found to be tall when grown under natural light environment in a containment facility without any artificial illumination. These data provide functional evidence for a role of blue light up-regulated cry1 in controlling photomorphogenesis in Brassica species.
Interdisciplinary Centre for Plant Genomics, Department of Plant Molecular Biology, University of Delhi South Campus, New Delhi 110021, India.
Mithu
M
Chatterjee
Pooja
P
Sharma
Jitendra P
JP
Khurana
D000595:Amino Acid Sequence; D000872:Anthocyanins / Q000378:metabolism*; D029688:Brassica napus / Q000235:genetics / Q000254:growth & development* / Q000378:metabolism; D056931:Cryptochromes; D005420:Flavoproteins / Q000737:chemistry / Q000235:genetics / Q000502:physiology*; D018628:Gene Dosage; D018506:Gene Expression Regulation, Plant; D005966:Glucuronidase / Q000378:metabolism; D018546:Hypocotyl / Q000033:anatomy & histology / Q000254:growth & development / Q000378:metabolism; D008027:Light; D008969:Molecular Sequence Data; D010802:Phylogeny; D018515:Plant Leaves / Q000033:anatomy & histology / Q000378:metabolism; D010940:Plant Proteins / Q000737:chemistry / Q000235:genetics / Q000502:physiology*; D018517:Plant Roots / Q000033:anatomy & histology / Q000378:metabolism; D030821:Plants, Genetically Modified / Q000378:metabolism; D011123:Polyploidy; D011401:Promoter Regions, Genetic; D016415:Sequence Alignment; D020539:Sequence Analysis, Protein; D015854:Up-Regulation
D000872:Anthocyanins; D056931:Cryptochromes; D005420:Flavoproteins; D010940:Plant Proteins; D005966:Glucuronidase