ACPFG Annual Report

Cold and Frost
cold and frost
Ulrik John
Ulrik John has broad experience in molecular and cellular biology and in functional
genomics in a range of organisms from yeasts through to fruit flies and wheat. Ulrik
obtained his PhD from the University of Adelaide, and has worked at the Plant
Breeding Institute in Cambridge, UK (now the Cambridge Laboratory at the John
Innes Institute), the Wellcome/Cancer Research Council Institute and the Peter
MacCallum Cancer Institute. His research focus at DPI Victoria, and within ACPFG,
is the molecular mechanisms of abiotic stress tolerance in indigenous and Antarctic
grasses with adaptations to extreme environments.
Background
Frost leading to cereal crop damage is a consistent
problem in south-eastern Australia and in Western Australia.
The sporadic nature of frost means it can have a devastating
impact on specific regions, farms or even particular fields
in certain years. Taking into account financial costs from
indirect losses due to delayed sowing, down grading or crop
protection, the total economic impact of frost on wheat and
barley production in Victoria and South Australia is estimated
at $95.8m and $33.6m per annum, respectively. Thus, even
modest increases in cold and frost tolerance in cereals have
the potential to deliver tens of millions of dollars of benefit to
the cropping industries of southern Australia.
Research and activities
The Cold and Frost Program has focused on the isolation
of novel genes and gene variants from barley, Arabidopsis,
and Antarctic hair grass (Deschampsia antarctica). We have
investigated functions of the genes and their promoters and
have defined properties of proteins and cellular metabolites
correlated with cold and frost tolerance. We have also defined
the molecular structure and function of key cold and frost
tolerance conferring proteins and the gene promoters that
drive their expression, and we have used this information to
engineer novel and more efficient variants.
Map based cloning
We are using map based cloning to isolate the gene(s)
controlling reproductive frost tolerance on barley
chromosome 2H. Variation in frost tolerance exists
across barley genotypes, with germplasm of Japanese
origin harbouring significant tolerance to frost damage of
reproductive tissues. This project builds upon earlier work
at the Waite Campus in which a major QTL for reproductive
frost tolerance was mapped. The experimental approach
exploits co-linearity between related regions in the barley
and rice genomes to generate PCR markers close to the Fr-2H
locus. This, in combination with phenotyping, is being used to
define and refine the interval in mapping populations, which
allow segregation of the trait.
Three loci influencing flowering related traits, earliness
per se (eps-3), clystogamy (cly) and rachis internode length
(ril), are clustered close to the putative reproductive frost
tolerance locus on chromosome 2H. In 2007 we have been
investigating whether one or more of these loci can account
for the original ‘frost tolerance’ QTL effect, or whether they
are unrelated to frost tolerance. Additional markers were
developed in the region, extending coverage of markers to
the entire 2H long arm, and additional inversions and breaks
in co-linearity with rice were discovered. We genotyped
recombinants for the 3cM eps-3 interval for: tiller height;
rachis internode length; and time of awn emergence revealing
all of these traits to be essentially co-segregating at the
same locus. Twenty genes are present in the corresponding
rice interval, one of which has a barley orthologue that is a
credible co-segregating candidate for the controlling gene.
We are isolating and defining the functions of candidate cold
and freezing tolerance conferring genes from Deschampsia
antarctica (the only grass species native to Antarctica) and
assessing their potential to enhance tolerance in sensitive
species. A gene discovery and functional genomics program
in D. antarctica has produced 10,704 high quality ESTs,
representing 4,811 non-redundant unigenes. We will test the
phenotypic consequences of gain-of-function expression of
candidate genes, including those encoding variants of ice
26 2007 ACPFG ANNUAL REPORT