206
putting together some 30 to 50 different genotypes (clones) in nuclei on the shores
of the rivers, we will manage to obtain seeds from the native willow with a higher
degree of purity than the current natural production. Although the exotic willow
clones have invaded most of the Patagonian rivers, with the conformation of these
nuclei, we could obtain a good amount of seeds to give the native willow a chance
to recover part of the river shores.
So far, restoration activities have started at five sites of five Patagonian rivers:
(Chos Malal, 37°23′49″ S, 70°16′15″ W; Plottier, 38°58′42″ S, 68°13′17″ W; Isla
Jordan, 38°59′ 28″S, 67°59′22″W; Pichi Leufu, 41°08′37″S, 70°51′13″ W; Piedra
Parada, 42°39′33″ S, 70° 05′43″ W). In each of them, plantations were carried out
with the collaboration of the local community and different institutions (INTA,
University of Flores, Province of Neuquén, Province of Río Negro, Province of
Chubut, Intercultural Botanic Garden Bariloche, Botanic Garden Plottier, Gualjaina
Village, Plottier City, Cipolletti City, Conesa City, Viedma City, Bariloche City,
rural schools and private nurseries, among others).
Taking into account the first genetic diversity studies with molecular markers
(nSSR) in some Patagonian rivers (Bozzi et al. 2012) and the recent report on
genetic structuration of the species in Central Mexico (cpDNA, nSSR) (HernándezLeal et al. 2019), we decided to consider all the individuals coming from the same
river as a “population”. This is because of the unidirectional gene flow that tends to
homogenize the genetic information within the same river and that promotes genetic
differentiation among rivers and hydrological basins (Hernández-Leal et al. 2019).
The genetic material that is being used for restoration purposes in one river is therefore a sampling of at least 30 to 50 clones coming from the same river or basin.
Since the vegetative propagation ability of S. humboldtiana is lower than that of
other Salix species (Thomas et al. 2012), it was necessary to search for other possible propagation methods, such as in vitro culture of plant tissues. The use of this
technique in forest species has facilitated the cloning of selected phenotypes. It
allows large-scale multiplication of clones in a short time, at any time of the year,
with a reduced amount of tissue from very old dying trees, in a limited space, thus
constituting a very important tool in conservation and germplasm exchange (Sharry
et al. 2011).
Cloning can be done by somatic embryogenesis and adventitia organogenesis,
two morphogenic processes widely used in in vitro culture of plant species.
Preliminary results of an in vitro vegetative propagation assay by means of micro
cuttings showed a rooting proportion of 55% of the explants (Marianelen Cedres,
data not published). After 10 days, the material could grow with culture media with
and without additional hormones. Differences were found according to the thickness of the micro cuttings (> 9 mm; between 9 and 5 mm, < 5 mm), thicker ones
presenting more contamination.
In order to produce seeds of absolute specific purity, which can hardly be found
in nature, the installation of clonal seed orchards is taken into account for advanced
stages of the Programme. One orchard of 41 clones (with 8 replicates each) from the
Chubut River has been already installed in Trevelin Forest Station in an isolated site,
P. Marchelli et al.
putting together some 30 to 50 different genotypes (clones) in nuclei on the shores
of the rivers, we will manage to obtain seeds from the native willow with a higher
degree of purity than the current natural production. Although the exotic willow
clones have invaded most of the Patagonian rivers, with the conformation of these
nuclei, we could obtain a good amount of seeds to give the native willow a chance
to recover part of the river shores.
So far, restoration activities have started at five sites of five Patagonian rivers:
(Chos Malal, 37°23′49″ S, 70°16′15″ W; Plottier, 38°58′42″ S, 68°13′17″ W; Isla
Jordan, 38°59′ 28″S, 67°59′22″W; Pichi Leufu, 41°08′37″S, 70°51′13″ W; Piedra
Parada, 42°39′33″ S, 70° 05′43″ W). In each of them, plantations were carried out
with the collaboration of the local community and different institutions (INTA,
University of Flores, Province of Neuquén, Province of Río Negro, Province of
Chubut, Intercultural Botanic Garden Bariloche, Botanic Garden Plottier, Gualjaina
Village, Plottier City, Cipolletti City, Conesa City, Viedma City, Bariloche City,
rural schools and private nurseries, among others).
Taking into account the first genetic diversity studies with molecular markers
(nSSR) in some Patagonian rivers (Bozzi et al. 2012) and the recent report on
genetic structuration of the species in Central Mexico (cpDNA, nSSR) (HernándezLeal et al. 2019), we decided to consider all the individuals coming from the same
river as a “population”. This is because of the unidirectional gene flow that tends to
homogenize the genetic information within the same river and that promotes genetic
differentiation among rivers and hydrological basins (Hernández-Leal et al. 2019).
The genetic material that is being used for restoration purposes in one river is therefore a sampling of at least 30 to 50 clones coming from the same river or basin.
Since the vegetative propagation ability of S. humboldtiana is lower than that of
other Salix species (Thomas et al. 2012), it was necessary to search for other possible propagation methods, such as in vitro culture of plant tissues. The use of this
technique in forest species has facilitated the cloning of selected phenotypes. It
allows large-scale multiplication of clones in a short time, at any time of the year,
with a reduced amount of tissue from very old dying trees, in a limited space, thus
constituting a very important tool in conservation and germplasm exchange (Sharry
et al. 2011).
Cloning can be done by somatic embryogenesis and adventitia organogenesis,
two morphogenic processes widely used in in vitro culture of plant species.
Preliminary results of an in vitro vegetative propagation assay by means of micro
cuttings showed a rooting proportion of 55% of the explants (Marianelen Cedres,
data not published). After 10 days, the material could grow with culture media with
and without additional hormones. Differences were found according to the thickness of the micro cuttings (> 9 mm; between 9 and 5 mm, < 5 mm), thicker ones
presenting more contamination.
In order to produce seeds of absolute specific purity, which can hardly be found
in nature, the installation of clonal seed orchards is taken into account for advanced
stages of the Programme. One orchard of 41 clones (with 8 replicates each) from the
Chubut River has been already installed in Trevelin Forest Station in an isolated site,
P. Marchelli et al.