282
of new progeny tests corresponding to each morphological group, developing each
one as the base population of its own taxonomic group. In addition, and because
there are traceability records of the seed used in the most recent plantations, plus
trees are being evaluated and selected within the plantations to incorporate them
into the base populations of each morphological group.
These two schemes are not excluding, and their simultaneous development can
serve to face two challenges. On the one hand, with the original scheme (i.e., a mixture of provenances), a high genetic diversity is maintained improving adaptation to
a large number of environments with high resilience to climate change. With the
new scheme (i.e., separate morphological groups), on the other hand, the hope is to
give a better response to the pursuit of specific objectives related to market demands
and high growth rates. This new scheme began to be applied in particular to the
outstanding population Campo Durán, which corresponds to the morphological
group P. alba “salteño.” Thus, in 2018, a progeny trial with 45 open-pollinated families from Campo Durán was installed in Sáenz Peña Experimental Station of INTA
(26° 51′ 15.3″ S; 60° 25′ 16.8″ W). The experimental design includes the identification of the family and also of the seedlings from seeds of the same pod, since it is
known that 64% of the seeds from the same fruit correspond to complete siblings
(Bessega et al. 2012). This design allows to increase the accuracy in the estimation
of breeding values from separately considering the treatments of complete siblings
from those of half siblings.
Advanced forest genetic evaluation involves analyzing data from progeny tests
using mixed linear models to estimate the best linear unbiased predictors (BLUPs)
of tree breeding values (BVs). The high number of provenances and families in the
INTA net not only allows these estimations but also contains ex situ and in vivo
conservation material representative of the genetic variation of the species in the
Argentine Chaco (Verga et al. 2009). In 2005, the first genetic markers for Prosopis
species were published (Mottura et al. 2005); later, more molecular markers were
developed (Suja et al. 2007; Bessega et al. 2013; Torales et al. 2013; Pomponio et al.
2015). These markers are mainly used for studies of genetic structure of the different Prosopis species and their interspecific hybrids (Chap. 9). Although the number
of specific markers is still very limited, the challenge is to incorporate them into the
breeding program through marker-assisted breeding and, at the same time, implement next-generation sequencing techniques for the development of large-scale
markers (SNPs) and shorten the breeding cycle through genomic selection. With the
current genomic resources, kinship matrices between individuals will be established, instead of using the theoretical values of the kinship relationships for the
calculation of BVs, increasing the accuracy in their estimation (Marcucci Poltri and
Gallo 2016; Grattapaglia et al. 2018).
As P. alba is a multipurpose resource (Galera 2000), its breeding process involves
different strategies according to the product to be improved (wood quality, fruit
production, etc.). One of the first evaluations of P. alba progeny trials considering
its multiple uses included total biomass production, height, rate of pod production,
D. López Lauenstein et al.
of new progeny tests corresponding to each morphological group, developing each
one as the base population of its own taxonomic group. In addition, and because
there are traceability records of the seed used in the most recent plantations, plus
trees are being evaluated and selected within the plantations to incorporate them
into the base populations of each morphological group.
These two schemes are not excluding, and their simultaneous development can
serve to face two challenges. On the one hand, with the original scheme (i.e., a mixture of provenances), a high genetic diversity is maintained improving adaptation to
a large number of environments with high resilience to climate change. With the
new scheme (i.e., separate morphological groups), on the other hand, the hope is to
give a better response to the pursuit of specific objectives related to market demands
and high growth rates. This new scheme began to be applied in particular to the
outstanding population Campo Durán, which corresponds to the morphological
group P. alba “salteño.” Thus, in 2018, a progeny trial with 45 open-pollinated families from Campo Durán was installed in Sáenz Peña Experimental Station of INTA
(26° 51′ 15.3″ S; 60° 25′ 16.8″ W). The experimental design includes the identification of the family and also of the seedlings from seeds of the same pod, since it is
known that 64% of the seeds from the same fruit correspond to complete siblings
(Bessega et al. 2012). This design allows to increase the accuracy in the estimation
of breeding values from separately considering the treatments of complete siblings
from those of half siblings.
Advanced forest genetic evaluation involves analyzing data from progeny tests
using mixed linear models to estimate the best linear unbiased predictors (BLUPs)
of tree breeding values (BVs). The high number of provenances and families in the
INTA net not only allows these estimations but also contains ex situ and in vivo
conservation material representative of the genetic variation of the species in the
Argentine Chaco (Verga et al. 2009). In 2005, the first genetic markers for Prosopis
species were published (Mottura et al. 2005); later, more molecular markers were
developed (Suja et al. 2007; Bessega et al. 2013; Torales et al. 2013; Pomponio et al.
2015). These markers are mainly used for studies of genetic structure of the different Prosopis species and their interspecific hybrids (Chap. 9). Although the number
of specific markers is still very limited, the challenge is to incorporate them into the
breeding program through marker-assisted breeding and, at the same time, implement next-generation sequencing techniques for the development of large-scale
markers (SNPs) and shorten the breeding cycle through genomic selection. With the
current genomic resources, kinship matrices between individuals will be established, instead of using the theoretical values of the kinship relationships for the
calculation of BVs, increasing the accuracy in their estimation (Marcucci Poltri and
Gallo 2016; Grattapaglia et al. 2018).
As P. alba is a multipurpose resource (Galera 2000), its breeding process involves
different strategies according to the product to be improved (wood quality, fruit
production, etc.). One of the first evaluations of P. alba progeny trials considering
its multiple uses included total biomass production, height, rate of pod production,
D. López Lauenstein et al.