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Modified Organism
Antisense hybrid aspen modified for altered circadian rhythms
Record information and status
Record ID
Date of creation
2019-06-19 20:22 UTC (austein.mcloughlin@cbd.int)
Date of publication
2019-06-19 20:22 UTC (austein.mcloughlin@cbd.int)

Living Modified Organism identity
The image below identifies the LMO through its unique identifier, trade name and a link to this page of the BCH. Click on it to download a larger image on your computer. For help on how to use it go to the LMO quick-links page.

LMO name
Antisense hybrid aspen modified for altered circadian rhythms
Transformation event
Dr Stefan Jansson
Professor in plant cell and mollecular biology
Umeå Plant Science Centre, Physioogical Botany
Swedish Agricultural University, Umeå (SLU)
Umeå University
Umeå Plant Science Centre
Physiological Botany
Umeå, Umeå
Sweden, 901 87
The modified aspens grow similarly to wild-type hybrid aspens, except demonstrating an altered seasonally-regulated growth. The antisense expression of a Phytochrome A (PttPHYA) transcript, which elicits gene silencing of the endogenous PttPHYA, causes the modified trees to show an earlier growth cessation, earlier bud formation in response to shorter daylengths, reduced red-light sensitivity, longer period of leaf motion, invertion at a longer day than wild-type trees, an altered expression of clock related genes, and a longer period of clock-controlled gene expression.
Recipient Organism or Parental Organisms
The term Recipient organism refers to an organism (either already modified or non-modified) that was subjected to genetic modification, whereas Parental organisms refers to those that were involved in cross breeding or cell fusion.
Populus tremula x Populus tremuloides - Hybrid aspen
Point of collection or acquisition of the recipient organism
Populus tremula x Populus tremuloides WT clone T89
Characteristics of the transformation process
Techniques used for the modification
  • Agrobacterium-mediated DNA transfer
Genetic elements construct
CaMV 35S promoter
0.92 Kb
Phytochome A
3.90 Kb
Nopaline Synthase Gene Terminator
0.27 Kb
Nopaline Synthase Gene Promoter
0.29 Kb
Neomycin Phosphotransferase II
0.80 Kb
Gene 4 transcription terminator
0.41 Kb
Beta-lactamase promoter
0.11 Kb
Beta-lactamase gene
0.86 Kb
Beta-lactamase terminator
0.24 Kb
Further details
Notes regarding the genetic elements introduced or modified in this LMO
The transformation of the aspen trees introduced three gene cassettes: an antisense (Populus tremula x Populus tremuloides) PHYTOCHROMEA (PttPHYA) cassette, an Escherichia coli neomycin phosphotransferase II (NptII) cassette, and an E. coli beta-lactamase (AmpR) cassette.

Transcription of the antisense PttPHYA is driven by the Cauliflower Mosaic Virus 35S promoter and terminates at the Agrobacterium tumefaciens nopaline synthase (nos) gene terminator.  PttPHYA is the full-length sequence synthesized as cDNA from the mRNA and therefore no introns are present. PttPHYA was inserted in reverse to create an RNA with a complementary sequence to the endogenous messenger RNA.

Transcription of NptII is under the control of the A. tumefaciens nos promoter and the A. tumefaciens gene 4 terminator. NptII is used as a selectable marker for plant transformation events as it confers resistance to kanamycin.

AmpR expression is under the control of the native beta-lactamase promoter and terminator. Expression is restrained to bacterial systems and transcription is not expected to occur in eukaryotic systems. This allows for  selection using beta-lactam containing antibiotics during bacterial transformation. The cassette was taken from the pBR322 plasmid.
LMO characteristics
Modified traits
  • Reduced red light perception
Other gene(s) whose expression was affected by the transformation
Phytochome A - Populus tremula x Populus tremuloides - Hybrid aspen
Changes in physiology and/or production - Growth rate, Photoperiod response
How the expression of the gene(s) was affected
Due to the reverse orientation of the PttPHYA sequence in the vector, RNA molecules are produced with complementarity to the endogenous  PttPHYA transcript. The complementary RNA molecules will base pair to the endogenous transcript and form double stranded RNA molecules, which can elicit an RNA interference response and cause targeted degradation of mRNA molecules with similar sequence. Thus, silencing of the endogenous PttPHYA expression will occur.
Common use(s)
  • Research
Additional Information