Biomedical Engineering Reference
In-Depth Information
transformation systems as well as aid recovery of interspecific hybrids [
95
]. Ovule
cultures of interspecific hybrids from the following species -
P. auriculata,
P. lindheimeri, P. lyrata, P. pallida
, and
P. fendleri
- were obtained and used in
breeding activities [
96
]. Embryo rescue was utilized to obtain intertribal hybrids
between
P. fendleri
and
B. napus
after hand pollination [
31
]. Somatic hybrids
between
P. fendleri
and
Brassica napus
have also been developed through poly-
ethylene glycol-induced protoplast fusion. Somatic hybridization between these
species had an efficiency of 1.5-7.3 % with the hybrids reaching reproductive stage
in the greenhouse and able to produce seeds [
97
].
P. fendleri
has been demonstrated to be amenable to
Agrobacterium-
mediated
transformation as well as biolistic methods. Transplastomic
P. fendleri
plants have
been obtained from biolistic approach and the resulting plants were found fertile
and successfully produced seeds [
98
].
Agrobacterium
transformation protocols
have also been reported by Wang et al. [
99
] and substantial progress to refine the
system has been made [
100
-
102
].
P. fendleri
calli were noted to be responsive to
the
Agrobacterium
transformation system, but chimeric regenerants have been
noted. These were later addressed by screening for non-transformed cells in mul-
tiple rounds of shoot regeneration to obtain stable transgenic
P. fendleri
lines
[
101
]. Transgenic approaches have helped provide initial information on the mech-
anisms of HFA synthesis in
P. fendleri
[
103
].
Seed Production
Lesquerella is a predominantly outcrossing species, but the seed setting ability was
determined to be influenced by how much pollen has been transferred on a flower.
The seed set per fruit was correlated to the amount of available pollen grains, but
the relationship was determined to be very loose and highly dependent on the
variability among plants [
104
].
One area that received considerable focus after the crop was identified as a
promising oilseed is how to break seed dormancy in several species
[
105
]. Lesquerella does not exhibit planting density-dependent germination [
89
],
but the persistence of seed dormancy has been identified as a significant barrier to
obtain adequate plant densities in the field and a challenge for seed production
[
105
]. Lesquerella seed dormancy has been observed to last up to 5 years after
harvest, although this has not been observed in
P. fendleri
but an issue with
P. gordonii
and
P. palmeri
[
106
]. The positive effect of gibberellic acid (GA) to
break seed dormancy has been determined and the effect of applying GA to seeds
was found to last up to 72 months at 5
C and 35 % relative humidity [
105
]. GA was
found to eliminate the light and temperature requirement for lesquerella seed
germination in
P. fendleri
,
P. gordonii
,
P. palmeri
[
106
,
107
], as well as
P. argyraea
,
P. gracilis
,
P. rectipes
,
P. recurvata
,
P. sessilis
, and
P. thamnophila
[
108
]. GA can be applied to seeds by either soaking the seeds for 8-24 h or spraying
it with a concentration of 1,000 ppm [
106
]. Other studies found that immersion to
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