Flax and Linseed - Industrial Crops: Breeding for BioEnergy and Bioproducts - page 238

30) is also uncertain
[ 29 ]. Many authors reported that cultivated flax was derived from two or more
ancestral forms [ 31 , 33 , 34 ]. The species cultivated by ancient Egyptians were
believed to be different from those indigenous to Russia and Siberia. Alternatively,
it was suggested that cultivated flax originated from a single wild species
L. angustifolium [ 33 , 35 - 39 ]. This hypothesis is supported by morphological [ 40 ,
41 ] and cytological studies [ 38 , 39 , 42 , 43 ]. Some authors consider L. bienne
(2 n

The progenitor of cultivated flax L. usitatissimum (2 n ¼

30) as the progenitor of small seeded flax, originating from Kurdistan and
Iran, whereas others consider L. angustifolium (2 n

¼

¼ 30) containing high oil content
and seed weight, as progenitor, originating from the Mediterranean region [ 32 ,
44 ]. Other authors suggest that L. bienne and L. angustifolium are the same species,
and both are widely distributed over western Europe, the Mediterranean basin,
North Africa, the Near East, Iran, and Caucasus [ 45 , 46 ]. Recently, a study using
molecular markers suggested that the three species originated from one common
ancestor, with L. angustifolium being the most ancient [ 47 ]. While L. usitatissimum
is an annual crop species, the wild forms can also be biennial or perennial. All
species are predominantly self-pollinated [ 46 ]. However, cross-pollination may
occur via honeybees [ 48 ] or by artificial means. A RAPD marker analysis of
seven Linum species revealed that L. angustifolium and L. usitatissimum have
high genetic similarity and these two species consistently clustered in the same
group [ 49 , 50 ]. A different AFLP study indicated that L. bienne is the sister species
to L. usitatissimum [ 51 ] although some consider L. angustifolium and L. bienne to
be the same species [ 45 , 46 ]. However, genome comparisons using molecular
markers of these three species confirmed that they are very closely related genet-
ically and L. bienne can be considered as a subspecies of L. usitatissimum, rather
than a separate species [ 47 ].
The distribution of flax from the Near East into Europe is well documented
[ 46 ]. It is thought that flax cultivation in western Europe (i.e., the Netherlands,
northern France, Belgium, and Switzerland) started about 5000-3000 BC when
seminomads from the Middle East settled in Flanders and introduced flax cultiva-
tion [ 2 ]. Since the domestication of flax, there has been a preference for growing
flax either for its fiber or oil. In the western region of Eurasia, flax is mainly grown
for its fiber, whereas in the eastern region of Eurasia, it is grown for its oil
[ 29 ]. Fiber flax has a long unbranched growth habit, whereas linseed (oil flax) is
much shorter and highly branched. Throughout this chapter, the distinction between
fiber flax and linseed is made. Based on molecular studies concerning the conver-
sion of stearoyl ACP to oleoyl ACP [ 52 ], it was estimated that flax was domesti-
cated first for oil [ 53 ]. This analysis supported the antiquity of oil flax over fiber use.
On the other hand, from ancient times until the twentieth century, flax was the
important source of fiber for the textile industry in temperate regions, rather than
cultivated for oil use [ 54 ]