Agriculture Reference
In-Depth Information
using platforms like NimbleGen, Invitrogen
and Affymetrix custom apple arrays.
These transcriptional approaches solved
important issues in plant sciences.
Proteomics studies in the Rosaceae have
been more limited. Proteomic analyses of
apple pseudocarp tissue have combined
two-dimensional gel electrophoresis with
matrix-assisted laser desorption/ionization-
time of fl ight mass spectrometry and liquid
chromatography/electrospray ionization
mass spectrometry (Guarino
et al.
, 2007).
Although many pseudocarp proteins
remain unidentifi ed, this study highlights
the link between proteomics and
functional genomics by linking identifi ed
proteins to their associated genes.
A proteomics approach was also
employed to determine fl esh browning in
stored Conference pears (Pedreschi
et al.
,
2007), to identify novel isoforms of major
cherry allergens (Reuter
et al.
, 2005) and to
examine the role of dehydrins in cold
temperature stress responses (Renaut
et al.
,
2008).
Rosaceous plants are rich in specialized
metabolites important for human health
and nutrition. Metabolomics involves
global analysis and interrogation of
metabolic networks. This technique has
been used to study the metabolic transition
from immature to ripe fruit (Aharoni and
O'Connell, 2002), and the effects of UV/
white light irradiation and cold storage on
primary and secondary pathways, ethylene
synthesis, acid metabolism, fl avonoid
pigment synthesis and fruit texture.
Metabolomics can help identify novel gene
functions in primary and secondary
metabolism and model metabolic networks
that regulate human health-promoting
metabolites.
fi eld cultivation. Marker-assisted breeding
allows marker-assisted introgression of
important and/or favourable genes from
wild species into cultivated ones to
improve breeding material (Lecomte
et al.
,
2004). Several apple genetic maps have
been developed by positioning genetic
markers linked to genes of interest. Such
markers are used for genetic mapping,
localization of major genes and QTL
detection. High-quality, accurate, high-
density genetic linkage maps allow genetic
markers to be linked to desired traits and
both to be localized on the chromosome.
18.10.4 Genome-wide single-nucleotide
polymorphism (SNP) arrays in apple
Recent progress in high-throughput
sequencing for genome-wide assays of
single-nucleotide mutations have helped
link phenotypic variation with the
underlying DNA variation. Genomics tools
can greatly help breeders to improve
important agronomic traits and clarify their
genetic structure. SNP screening is
composed of detection, validation and fi nal
selection for marker development. During
detection, a large pool of SNPs is detected
in the crop using high-resolution melting
or resequencing techniques. Validation
informs SNP assay development by
increasing the number of functional
polymorphic markers in the genome.
Because of the high costs, the validation
can be performed only for a subset of
SNPs. For genome-wide SNP assays,
adequate genome coverage is essential. For
cultivated species that have a sequenced
genome and high-dense genetic maps,
genome coverage can be based on physical
and/or genetic factors, as preferred. Once
SNP sets are available, screening uses
highly parallel techniques for analysing
germplasm needed for the specifi c research
purposes. High-throughput technologies
have increased the effi ciency of SNP
genotyping and several platforms for large-
scale analysis can now genotype up to 1
million SNPs at the same time. The
International RosBREED SNP Consortium
18.10.3 Marker-assisted breeding
Marker-assisted breeding is the genetic
improvement of crops using information
generated by molecular marker technology.
It is particularly useful for perennial tree
crops like apple, as many important traits
are expressed only after several years of
Search WWH ::
Custom Search