Page 188 - PC2019 Program & Proceedings

PLANT CANADA 2019

S161. Family Ties: the expression of AROGENATE DEHYDRATASES
*
Van Brenk, J. ; E. Cornelius; S. Kohalmi
The University of Western Ontario

Phenylalanine (Phe) is a precursor to many specialized metabolites in plants, including lignin and
flavonoids. The last step of Phe synthesis is a decarboxylation/dehydration reaction performed by
AROGENATE DEHYDRATASES (ADTs) named ADT1-ADT6 in Arabidopsis thaliana. In silico
analyses of publicly available ADT expression data suggest differential tissue-specific ADT expression
patterns. Unsurprisingly, we were able to identify individual compositions of promoter motifs associated
with endogenous and exogenous responses for each ADT. To confirm and add more resolution to these in
silico data, in vivo experiments using each ADT promoter were performed. Either the intergenic region or
up to approximately 1 kb upstream of the translational start site was cloned into an EGFP/GUS
expression vector and stably transformed into wild-type Arabidopsis. For ADTs with introns, the start of
the promoter to the end of the first intron was also cloned. Expression of reporter genes under standard
growth conditions was determined by confocal microscopy (EGFP) or light microscopy (GUS), for each
ADT across all tissues and stages of development. Already, initial analyses show that each ADT has a
unique expression pattern, and we propose that they are linked to metabolomic requirements of specific
tissues. Most surprisingly for essential enzymes, not a single ADT is constitutively expressed. In the
future, our catalogue of standard ADT expression patterns will be compared to those of plants grown
under stress growth conditions.

Jordan Van Brenk (jvanbre@uwo.ca)

S162. Magic blue light: A versatile mediator of plant elongation
Kong, Y.; K. Schiestel; D. Kamath; R, Johnson; Y. Zheng
University of Guelph

It’s commonly stated that “blue” light causes more compact plants than red light (R) in plant lighting
related literatures. This is challenged by our recent studies on many species using light emitting diodes in
growth chambers. We found that pure blue light (B), compared to R, promoted plant elongation at
−1
−2
different growth stages under light intensities of 20–650 μmol·m ·s , and photoperiods of either 24 or
16 h. However, unpure blue light, BR, by mixing B with 6% or 10% R, showed a similar or greater
inhibition effect relative to R. Unpure blue light, BRF, by adding low-level far-red light (FR) to BR (with
R/FR = 1), reversed the inhibition effect of BR, and showed a similar or greater promotion effect relative
to B. Phytochrome photostationary state (PPS) values were around 0.89, 0.69, 0.60, and 0.50 for R, BR,
BRF, and B, respectively. With the decreasing PPS, the plant elongation under “blue” (pure and unpure)
light increased, and gradually became saturated once the PPS < 0.60. Furthermore, unpure blue light by
mixing B with a low-level FR, UV-B, UV-A, or Green light resulted in PPS < 0.60, and showed a
promotion effect similar to B. Therefore, our studies demonstrate that blue-light-mediated plant
elongation is related to phytochrome activity; there is a promotion effect under lower PPS, but an
inhibition effect under higher PPS.

Yun Kong (ky0257@gmail.com)

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