Biomedical Engineering Reference
In-Depth Information
sequence and chloroplast DNA analysis, the plants were confirmed as hybrids
between
M. sinensis
and
M. sacchariflorus
[
33
]. One of these three hybrids showed
the good biomass potential in Sapporo (unpublished). Finding new natural hybrids
is important to help broaden the genetic resources of
M.
giganteus
.
In parallel to finding natural triploids, artificial hybridizations have been
attempted. Flowering time synchronization, parent compatibility, pollen amount,
and morphological structure are important factors in determining seed-setting rate
in hybridization [
31
,
37
]. Two cultivars of
M.
giganteus
“Amuri” and “Nagara”
were released by M. Deuter at Tinplant 2006. “Amuri” was derived from a cross
between North Asian
M. sacchariflorus
and
M. sinensis
, while “Nagara” was
derived from a Japanese
M.
giganteus
(described as
M. sacchariflorus
) crossed
with
M. sinensis
[
69
].
Besides
M. sinensis
and
M. sacchariflorus
, hybrids have been created between
other
Miscanthus
species. These hybrids may be useful for cultivation in specific
locations, such as sodic soils and tropical regions. Hybridization between
M. sinensis
and
M. sinensis
var.
condensatus
,
M. sinensis
, and
M. tinctorius
,
resulted in F
1
hybrids that were self-incompatible but could produce fertile pollen
[
39
]. A triploid and unexpected tetraploid were obtained from crossing between
M. sacchariflorus
and
M. sinensis
var.
condensatus
[
40
]. The culm length, leaf
length, leaf width, and ear size of both polyploids exceeded those of the parents.
However, the triploid was sterile, and the hair length of spikelets, silky lustre, width
of lemma, length of awn, grass type, and evergreeness resembled
M. sacchariflorus
.
Meanwhile, the tetraploid resembled more
M. sinensis
var.
condensatus
in those
characteristics and the pollens were fertile. Matumura et al. [
110
] investigated the
rhizome structure of triploid, tetraploid, and their parents and found that triploid
resembled
M. sacchariflorus
more while the tetraploid resembled
M. sinensis
var.
condensatus
. Adati and Shiotani [
41
] also reported hybridization between
M. floridulus
and
M. sinensis
, producing F
1
hybrids with regular meiotic division
showing 19 bivalents at first metaphase.
Polyploidization
Chromosome doubling is a valuable breeding approach for increasing vegetative
biomass production. Głowacka et al. [
26
] applied colchicine treatment to induce
polyploids from
M. sinensis
and
M.
giganteus
. Higher colchicine concentrations
reduced the survival rate and tillering rate of the plants. Plant genotypes influenced
the polyploidization rate in
M. sinensis
genotypes. Generating hexaploid
M.
giganteus
to restore fertility may be a way to improve
M.
giganteus
through
conventional breeding. Yu et al. [
27
] generated hexaploid plants from
M.
giganteus
. The team induced calli growth from immature inflorescence tissue and
treated the calli with colchicine or oryzalin in various concentrations and exposure
time. The rate of calli survival was generally higher in calli treated with colchicine,
but more hexaploids were generated from calli treated with oryzalin at the concen-
trations tested. The hexaploid plants had slightly broader stems and larger stomatal
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