Biomedical Engineering Reference
In-Depth Information
member species of the genus have been identified as endangered including
P. pallida
,
P. douglasii
subsp.
tuplashensis
,
P. thamnophila
, and
P. globosa
[
46
].
There was a previous proposal to conserve the name
Lesquerella
over
Physaria
since the former genus has a larger number of species than the latter [
47
]. However,
the request was not recommended by the Committee for Spermatophyta who ruled
that “the name
Physaria
is already well known and the advantages of conservation
are not sufficient to justify over-ruling the principle of priority” [
48
].
Because of the taxonomic revision, most of the
Lesquerella
species were moved
into the genus
Physaria
, while others transferred to
Paysonia
. The species that were
moved to
Physaria
have the HFA lesquerolic acid (C20:1 OH) as the primary
component of the seed-oil profile, as do all of the previously existing
Physaria
species. The previous
Physaria
species are perennials and do not flower until the
second year of growth. The newer
Physaria
species are both annuals and
perennials.
Five species with auriculated leaves native to the southeastern United States
(mostly Tennessee) that were previously classified as
Lesquerella
are now part of
Paysonia
[
49
]. These species have the HFA densipolic acid (C18:2 OH) as the
primary component of the seed-oil profile. Also included in this genus are two other
species native to Texas which contain lesquerolic acid as the primary seed-oil
component and another species from Oklahoma,
Paysonia auriculata
. This species
is the only one containing significant amounts of auricolic acid (C20:2 OH), the
third HFA type found in this taxon.
The expansion of
Physaria
by combining
Lesquerella
is based on molecular data
using nuclear ribosomal DNA sequences of internal transcribed spacer (ITS) [
49
,
50
]. Based on these results,
Physaria
was found to be different from
Paysonia
. The
results from using diversity array technology (DArT) markers and subsequently
DArTseq molecular markers supported the taxonomic classification by O'Kane
Jr. and Al-Shebaz [
51
,
52
].
Native Populations and Areas of Production
Wild populations of
P. fendleri
are usually associated with moisture availability in
mixed, sparse vegetation, and the plants can be easily recognized by their glabrous
siliques and fused trichomes which set the species apart from other
Physaria.
P. fenderi
plants are found in its native environment on calcareous, well-drained
soils in the southwestern states of Arizona, New Mexico, and Texas, and these are
the areas identified as suitable for lesquerella crop production. There have been
collections of
P. fendleri
germplasm from southern Utah and Colorado made by
Rollins and Shaw [
35
], but cropping experiments have not been done on these areas.
Plant collections from the states of Coahuila, Chihuahua, Nuevo Leon, Zacatecas,
and Durango, Mexico, were also made [
35
,
53
].
In addition to being suitable in the southwest United States,
P. fendleri
has been
tested to be a promising crop in Southwest Oregon [
54
] and Northern Mexico
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