Agriculture Reference
In-Depth Information
ancing, and cyclical selection over space and time
according to the two- or multiple-niche ecological
models. Natural selection interacts with muta-
tion, migration, and stochastic factors, but it over-
rides them in orienting the evolutionary processes
of wheat.
REFERENCES
Aaronsohn, A. 1910. Agricultural and botanical explorations
in Palestine. USDA, Bureau of Plant Industry Bull. 180.
Aaronsohn, A. 1913. The discovery of wild wheat. City Club
Bull. Chicago 6:167-173.
Aaronsohn, A., and G. Schweinfurth. 1906. Die Auffi ndung
des wilden Emmers (
Triticum dicoccum
) in Nordpalästina.
p. 213-220. Altneuland Monatsschrift für die Wirtschaftli-
cher Erschliessung Palästinas, No. 7-8, Berlin.
Anamthawat-Jonsson, K., and J.S. Heslop-Harrison. 1993.
Isolation and characterization of genome-specifi c DNA
sequences in Triticeae species. Mol. Gen. Genet.
240:151-158.
Appels, R., and E.S. Lagudah. 1990. Manipulation of chro-
mosomal segments from wild wheat for the improvement
of bread wheat. Aust. J. Plant Physiol. 17:253-366.
Appels, R., P. Reddy, C.L. McIntyre, L.B. Moran, O.H.
Frankel, and B.C. Clarke. 1989. The molecular-
cytogenetic analysis of grasses and its applications to
studying relationships among species of the Triticeae.
Genome 31:122-133.
Averbeck, K.T., and T.H. Eickbush. 2005. Monitoring the
mode and tempo of concerted evolution in the
Drosophila
melanogaster
rDNA locus. Genetics 171:1837-1846.
Avery, D. 1985. Farm dilemma: The global bad news is
wrong. Science 230:408-412.
Avivi, L. 1978. High grain protein content in wild tetraploid
wheat,
Triticum dicoccoides
Korn. p. 372-380.
In
S.
Ramanujam (ed.) Proc. Int. Wheat Genetic Symp., 5th.,
New Delhi, India. 23-28 Feb. 1987. Indian Soc. Genet.
and Plant Breeding, Indian Agric. Res. Inst., New Delhi,
India.
Avivi, L. 1979. Utilization of
Triticum dicoccoides
for the
improvement of grain protein quantity and quality in cul-
tivated wheats. Monogr. Genet. Agrar. 4:27-38.
Avivi, L., A.A. Levy, and M. Feldman. 1983. Studies on high
protein durum wheat derived from crosses with the wild
tetraploid wheat
Triticum turgidum
var.
dicoccoides
. p. 199-
204.
In
S. Sakamoto (ed.) Proc. Int. Wheat Genet. Symp.,
6th, Kyoto, Japan. 28 Nov.-3 Dec. 1983. Plant Germ-
Plasm Inst., Fac. Agric., Kyoto Univ., Kyoto, Japan.
Badaeva, E.D., A.V. Amosova, O.V. Muravenko, T.E.
Samatadze, N.N. Chikida, A.V. Zelenin, B. Friebe, and
B.S. Gill. 2002. Genome differentiation in
Aegilops
: 3.
Evolution of the D-genome cluster. Plant Syst. Evol.
231:163-190.
Badaeva, E.D., A.V. Amosova, T.E. Samatadze, S.A.
Zoshchuk, N.G. Shostak, N.N. Chikida, A.V. Zelenin,
W.J. Raupp, B. Friebe, and B.S. Gill. 2004. Genome
differentiation in
Aegilops
: 4. Evolution of the U-genome
cluster. Plant Syst. Evol. 246:45-76.
Badaeva, E.D., O.S. Dedkova, G. Gay, V.A. Pukhalskyi,
A.V. Zelenin, S. Bernard, and M. Bernard. 2007. Chro-
mosomal rearrangements in wheat: Their types and distri-
bution. Genome 50:907-926.
Badaeva, E.D., B. Friebe, and B.S. Gill. 1996. Genome dif-
ferentiation in
Aegilops
: 2. Physical mapping of 5S and
18S-26S ribosomal RNA gene families in diploid species.
Genome 39:1150-1158.
FUTURE PERSPECTIVES
What will be the next step in wheat improvement
in the current genomic and postgenomic eras?
Conceptually, in-depth probing of comparative
genome structure and function are the major
challenges, including analyses of the intimate
relationship between the coding and noncoding
regions of the wheat genomes. Such studies will
unravel genome evolution and highlight the rich
genetic potentials for wheat improvement resid-
ing in wheat and various wheat relatives, includ-
ing
Triticum
and
Aegilops
species as well as other
Triticeae.
We believe that the theoretical and applied per-
spectives for future wheat improvement will
encompass the following. First is characterization
of the genome structure, function, regulation, and
evolution at macro- and microgeographic scales
of wheat and wheat-related species. Second is to
combine multilocus markers and fi tness-related
traits to produce direct estimates of adaptive
fi tness differentiations within and between popu-
lations. Third, a critical activity will be to analyze
the genetic system determining the enormous
genetic fl exibility of the various wheat and wheat-
related species in diverse ecological contexts,
mutation rates in different elements of the
genome, recombination properties of the genome
with their genetic and ecological control, and
genomic distribution and function of structural
genes (primarily abiotic and biotic stress genes).
Fourth, it would be prudent to characterize the
interface between ecological and genomic spatio-
temporal dynamics and adaptive systems, to char-
acterize genome evolution and the polyploidization
processes, and to conduct colinearity studies
between the grasses, including model species with
small genome size such as rice and
Brachypodium
distachyon
.
