Agriculture Reference
In-Depth Information
Chapter 16
Synthetic Wheat—An Emerging
Genetic Resource
Richard M. Trethowan and Maarten van Ginkel
SUMMARY
diversity in synthetic wheat is novel.
Synthetic derivatives, developed by cross-
ing primary synthetics with adapted
cultivars, have been developed with en-
hanced resistance to biotic and abiotic
stresses.
(4) The exploitation of synthetic wheat is
still in its infancy. In the future, combin-
ing novel genetic diversity in synthetic
wheat with that existing in the wheat
gene pool can be expected to signifi cantly
enhance the adaptation and marketability
of wheat.
(1) Hexaploid wheat can be reconstituted by
natural intercrossing, induced chromo-
some doubling, and embryo rescue to
produce primary “synthetic” wheat.
(2) Combining variability from both modern
durum wheat and ancestral tetraploids
with
Aegilops tauschii
has produced new
genetic variation for a range of biotic,
abiotic, and quality-related traits.
(3) Direct and indirect evidence indicates
that much of the newly observed genetic
INTRODUCTION
(Marathee and Gomez-MacPherson 2001). Hexa-
ploid bread wheat (
Triticum aestivum
L.) is the
primary species grown and consumed, although
tetraploid durum wheat (
T. turgidum
ssp.
durum
),
comprising approximately 6% to 8% of total
wheat production, is an important commodity in
some areas, such as the Mediterranean region
(Elias and Manthey 2005).
A range of different wheat products are made
and consumed, as further discussed in Chapters
20 and 21. Flat bread (such as chapattis), noodles,
and steamed bread tend to dominate in develop-
ing countries, refl ecting consumer preferences in
India and China, the world's largest wheat pro-
ducers. In contrast, leavened bread made from
hard-grained wheat fl our, and biscuits, cakes,
and confectionary products produced from soft-
grained wheat, are prevalent in western countries,
though increasingly these are being consumed in
Wheat is grown on more than 220 million hect-
ares globally, producing more than 600 million
tonnes of grain annually (Rajaram and van Ginkel
2001; Pfeiffer et al., 2005). It is the most traded
cereal grain, with 10% of total production sold in
international markets (Marathee and Gomez-
MacPherson 2001), and is the most widely grown
of all the cereals; production spans the equator to
latitudes of more than 60ºN and 50ºS, and alti-
tudes of up to 3,000 m above sea level. Wheat is
grown in dry, rainfed environments and under
irrigation in highly productive river valleys, pri-
marily in the developing world, and is the primary
source of calories for millions of people. Average
global wheat consumption is 73 kg per capita per
annum and can be as high as 166 kg per capita in
some North African and central Asian countries
