Biology Reference
In-Depth Information
demonstrated that MALDI/TOF-MS can com-
pletely replace conventional HPLC (largely due
to the fact that lycopene and β-carotene have
identical m/z values), this technique offers
rapid identification of high- or low-accumulating
genotypes and also has the ability to detect other
carotenoids in tandem.
With the advent of genotyping by sequencing
and SNP arrays, the inability to obtain extremely
large sets of informative polymorphic markers
within the tomato cultigen is no longer an issue.
There is no reason why a similar overall approach
to that of Davuluri and colleagues (2005) can-
not be executed for carotenoid regulatory tar-
gets identified by correlational networks while
using publicly acceptable sources of genetic
variation, rather than genetic engineering. Early
applied TILLING studies have produced tomato
materials with altered carotenoid content (Gaby
et al. 2012) and potyvirus resistance (Piron et al.
2010). Other examples include the development
of melon materials with improved shelf life char-
acteristics (Dahmani-Mardas et al. 2010). This
effort will require a well-coordinated collabo-
rative effort among bioinformaticians, chemists,
molecular biologists, and breeders, and align-
ment on a practical, concrete breeding objective
to pursue with such an approach.
In general, tomato fruit quality is considered
by practical tomato breeders to be a lower pri-
ority than yield, disease resistance, and other
production-related traits. There are extremely
valid and unavoidable reasons for this. How-
ever, consumers are increasingly dissatisfied
with the quality of fresh tomatoes available to
them (Kolata 2012). With the technologies avail-
able to applied research and development enti-
ties (public and private), it is now feasible to
generate high-yielding, durable tomato varieties
with superior fruit quality if the desire to do so
exists. In the case of altering tomato carotenoid
accumulation, we speculate that the main reason
this has not been widely pursued is that con-
sumers are unwilling to pay more for increased
antioxidant content, and thus this trait has not
been a priority for breeders, growers, or pro-
cessors. As a result, currently, private research
and development firms are not willing to invest
heavily in this area, nor are seed companies
willing to license such traits for hefty sums
from the public sector, though this may not be
the case in the future. On the other hand, pri-
mary metabolic traits can be related to yield and
Future Directions
It is hoped that subsequent studies adopt the
systems biology approach of Schauer and col-
leagues (Schauer et al. 2005, 2006, 2007) in con-
junction with the carotenoid profiling techniques
pioneered by Fraser and colleagues (Fraser and
Bramley 2004; Fraser et al. 2007a,b, 2008),
and utilize relevant genetic backgrounds if there
is truly a desire to translate forward genetics
findings into breeding practices. The systems
approach takes advantage of genetic variation to
produce correlational networks and infers key
regulators of important traits from these net-
works. Research teams can then employ contem-
porary high-throughput techniques to identify (or
generate) genetic variation within these regula-
tory genes, in order to produce novel metabolic
traits that can be tested under relevant agricul-
tural conditions. It is not out of the realm of con-
sideration that continued tomato omics studies
can, by exploiting the well-developed genomics
resources for tomato (Mueller et al. 2005) and
the continuously-maturing techniques for inte-
grating various types of omics data, fuel the
development of tomato omics resources similar
to those developed for yeast (Myers et al. 2005)
or other biological systems.
The exploration, characterization and incor-
poration of abundantly available natural genetic
variation, or generation of variation using muta-
genesis in agriculturally relevant genetic back-
grounds, still represents an opportunity for prac-
tical breeders to identify and incorporate novel
alleles for fruit quality traits into the cultigen.
As described above, genomic and metabolomic
experimental tools have been developed using
tomato as a model system to mine this variation.
Search WWH ::
Custom Search