Agriculture Reference
In-Depth Information
28) of the Pleionathera section, which share the C
U
genome;
the most abundant species in this group in Israel are
Aegilops variabilis
,
Aegilops ovata
,and
Aegilops biuncialis
. The authors concluded that in
addition to the common diploid genome, each of these species carries
another genome that has been thoroughly modi
species (2
n
=
ed by hybridization and
introgression with neighboring species of the same group. The diploid
outbreeding species
Aegilops speltoides
(2
n
14, carrying the S genome)
and the selfer
Aegilops longissima
(S
1
genome)were both shown to exist as
mixed populations, consisting of
speltoides
and
ligustica
plants in
Ae.
speltoides
,and
longissima
and
sharonensis
plants in
Ae. longissima
(Ankory and Zohary 1962; Zohary and Imber 1962); natural intercrossing
within each pair was demonstrated in these studies. In other cereals,
natural hybridization and evidence for genetic introgression were found
between
Hordeum spontaneum
and the cultivated barley,
Hordeum
vulgare
(Zohary 1959; Tovia and Zohary 1962), as well as among diploid,
tetraploid, and hexaploid barley (
Avena
) species (Ladizinsky and Zohary
1968, 1971).
One signi
=
cant feature common to most of these natural cases
of hybridization and introgression was their occurrence in human-
disturbed habitats, where new ecological niches were available to the
hybrids and their descendants. In later years, Zohary collaborated with
Eviatar Nevo and his colleagues and with plant pathologists, on evalua-
tion of genetic variation in plant populations in such human-interfered
habitats. Thus, for instance, allozyme variation and disease resistance
genes were investigated in natural populations of wild barley and
Emmer wheat, in relation to their ecology and interaction with the
corresponding cultivated crops (Nevo et al. 1979, 1982; and numerous
other joint publications).
III. DOMESTICATION OF CROPS AND FRUIT TREES
The major contributions of Daniel Zohary, for which he is most widely
known, relate to the domestication of plants in the Old World and the
role of plant domestication in the origin and rise of agriculture and of
organized human society. There were numerous studies by Zohary and
his associates on these issues that were later summarized in
Domestica-
tion of Plants in the Old World
, published by Oxford University Press in
four editions. This topic will be discussed in a later section of this
chapter. Here we shall only highlight major
findings by Zohary and
colleagues in this area, and the interested reader may refer to the recent
edition of the topic for further details.
