Page 268 - PC2019 Program & Proceedings

PLANT CANADA 2019

P109. Characterizing the role of Striga hermonthica gibberellic acid receptors
*
Adityani, C. ; T. Pender; S. Lumba; P. McCourt
University of Toronto

Hormones play a crucial role in the signal transduction of plant germination. In autotrophic plants,
gibberellic acid (GA) is perceived by its receptor called GA-INSENSITIVE DWARF1 (GID1) and
transduced by core signalling components to trigger germination. Conversely, a destructive parasitic plant
to sub-Saharan Africa staple crops, Striga hermonthica, does not germinate in the presence of GA but
rather, is dependent on strigolactones (SLs) emitted by nearby plant roots. In addition to the ability to
synthesize GA, transcriptome analysis revealed that S. hermonthica has Arabidopsis homologs of GA
core signalling components including GA receptors (GID1), downstream transcriptional repressors
(DELLA) proteins and F-box proteins. To analyze the function of S. hermonthica GID1 genes, we
expressed them in Arabidopsis loss-of-function gid1 double mutants background. Furthermore, based
on in vivo experiments, S. hermonthica GID1 receptors interact with DELLA proteins in a hormone
dependent manner and is comparable to the protein interactions seen in Arabidopsis. Ultimately,
identifying the role of GID1 genes in parasitic plant species germination will open up the field in
understanding GA signalling in other plant species.

Claresta Adityani (claresta.adityani@mail.utoronto.ca)

TOPIC 9: Controlled-Environment Crop Production
(Posters P110-P113)

P110. Elongation and flowering promoted by blue light are independent of photoperiod: a
comparison with red light in four bedding plant species
Zheng, Y.; Y. Kong; D. Kamath
University of Guelph

Our previous study on bedding plants indicates that under 24-h lighting, pure blue light, compared to red
light, can promote elongation or flowering. The objective of this study was to investigate whether the blue
light promotion effects are independent of photoperiod. The growth and morphology traits of petunia,
calibrachoa, geranium, and marigold were compared under two light quality treatments: (1) R, “pure” red
light (665 nm); and (2) B, “pure” blue light (440 nm) using continuous (24-h light/0-h dark) or periodic
(16-h light/8-h dark) light-emitting diode lighting. A photosynthetic photon flux density of approximately
−1
−2
100 μmol m s and an air temperature of approximately 22°C was used for the above treatments. For
either transplants or mature plants, regardless of photoperiod, B promoted elongation growth compared to
R, as demonstrated by a greater daily stem elongation rate, main stem length, internode length, or petiole
length, with varying sensitivity among species. Also, after transplanting, the plants under B light showed
an earlier flowering time than those under R light, regardless of photoperiod. However, the magnitude of
B light promotion was greater under 24-h than 16-h lighting in many cases. This suggests that the
promoted elongation and flowering by blue light is not specifically from 24-h lighting, although the
promotion degrees differ between photoperiods and among species.

Youbin Zheng (yzheng@uoguelph.ca)

Page 266 of 339