Essay, Research Paper
Research Proposal for Aspects of Arabidopsis thaliana Introduction The mouse
ear cress Arabidopsis thaliana is a member of the Brassicaeae that lends
itself well to genetic study in that it has only a small quantity of DNA. The
plant itself has little commercial value aside from that as a research tool,
and it has no aesthetic horticultural value at all. It is a small plant that
can be grown by the hundreds in cells on a laboratory bench, and its small
quantity of DNA makes it useful in identifying genes of other organisms
(Wheeler, 1994). Normal
flower color varies between solid white petals to green petals only tinged with
white. Manipulation of flower color is of interest not because of any potential
ornamental value, but because of the mechanisms of gene expression in the
visible appearance of the yellow pigment anthocyanin. In like
manner, information regarding cold tolerance and the biochemical changes that
occur within the plant in response to cold are not of interest primarily for
culture of the plant itself except as it applies to cultural conditions that
need to be maintained for optimum life cycle completion time. Rather, Arabidopsis?
response to cold stress is of interest because facts learned from it can be
applied to investigations in human systems (Stockinger, Gilmour and Thomashow,
1997). This investigation seeks to determine if enough anthocyanin can be
concentrated in petal cells so that they express a visible yellow color, and if
cold stress has any effect on visible levels of anthocyanin concentrations in
petal cells. Literature
Review
Arabidopsis
naturally contains anthocyanin, and Lloyd, Walbot and Davis (1992) were able to
cause anthocyanin "pathway-specific transcriptional activators R and C1
from the monocot maize were expressed in two dicots, Arabidopsis thaliana
and Nicotiana tabacum. Expression of R caused augmented anthocyanin
pigmentation in both plant species and augmented trichome (hair) production in Arabidopsis"
(p. 1773), but C1 had no effect alone. Expression of both in Arabidopsis
resulted in expression of anthocyanins in tissues that normally contain none,
such as root, petal and stamen tissues. In more recent research, Walker,
Davison, Bolognesi-Winfield, James, Srinivasean, Blundell, Esch, Marks and Gray
(1999), the researchers isolated by positional cloning the transparent testa
glabra1 (TTG1) locus they had previously determined as regulating development
of anthocyanins in Arabidopsis.