ACADEMIA Letters
Breeding chestnut for resistance to Phytophthora
cinnamomi for improving the productivity of chestnut
stands
Rita Lourenço Costa
Abel Rodrigues
Chestnuts are multipurpose trees having a major economic impact in south-western Europe,
acting as an important income for the rural populations, of mountainous Mediterranean regions sometimes the only one, contributing for inverting the tendency of depopulation of those
regions, being also important barriers for fire progression. European chestnut constitutes a
valuable source of genetic variation for Castanea in Mediterranean regions. It is associated
with a number of favourable characters such as: adaptation to local conditions, enabling the
creation of commercial networks within and between regions, and increasing the value chain
for high quality products with organoleptic and health qualities. The economy based on nut
production is very important in Northern regions of Portugal. The production is nowadays
about 47,500 tones, representing approximately 70 M€ of turnover. Portugal and Italy are the
leading European producers, being Portugal in the second place worldwide nowadays, after
the introduction of gall wasp in Italy. Portugal is also a major exporter of nuts, having, according to the INE (2016), exported in 2015, 18 186 tones, corresponding to 41 M€. This
value may be duplicated, at least, if the losses caused by pests and diseases, the main threats
for the species, may be reduced, as there is a market in Europe and in the rest the world for
Portuguese chestnuts as fresh and transformed products with added value.
A serious decline of chestnut growing area and productivity per hectare has been observed
since the last century in Portugal; according to the last inventory of 2015, the current area
is 34,000 ha for fruit production and 48,300 ha for the total area (including forest); while
at the beginning of 20th century it was 80,000 ha, before the introduction of Phytophthora
Academia Letters, July 2021
©2021 by the authors — Open Access — Distributed under CC BY 4.0
Corresponding Author: Rita Lourenço Costa, rita.lcosta@iniav.pt
Citation: Lourenço Costa, R., Rodrigues, A. (2021). Breeding chestnut for resistance to Phytophthora
cinnamomi for improving the productivity of chestnut stands. Academia Letters, Article 2159.
https://doi.org/10.20935/AL2159.
1
cinnamomi Rands (Pc), the causal agent of root rot also known as ink disease. The actual area
is less than half of the country’s potential as well as the productivity per hectare, which is,
on average, 1.5 Ton/ha less than half of the productivity of French and Italian orchards. The
dominant area of chestnut for fruit production is located in the North with about 30.000 ha, in
Trás-os-Montes e Alto Douro region, mainly in sites with altitude higher than 500m. In the
South-Eastern region of Marvão and São Mamede, a smaller area of about 850 hectares has
been also traditionally allocated to chestnut stands for fruit production. This minor productive
area corresponded to a typical physiography of landscape in terms of altitudes higher than 400
m, climate and an edaphic profiling with prevalence of undifferentiated soils, e.g. cambisols,
luvisols and rocky outcrops.
The main threats that contributed for the decline of chestnut growing area and productivity
have been diseases and pests: ink disease (Phytophthora spp), blight disease (Cryphonectria
parasitica (Murr.) M.E. Barr) and more recently gall wasp (Dryocosmus kuriphilus (Yasumatsu)). For the latter two, biological control is available and is being used with success
in different European countries. On the contrary, for Phytophthora species there is no option of biological control, adding the fact that to cope with different hosts and host tissues,
Phytophthora species have evolved sophisticated mechanisms to manipulate plant cells and
cause infections. It has been noted that many of these pathogens grow as hemibiotrophics
under certain circumstances with an initial biotrophic interaction with the host plant and later
switching to a destructive necrotrophic lifestyle (Shearer & Crane, 2012).
The genus Castanea belongs to Fagaceae, a plant family that dominates much of the climax
hardwood forests of the Northern Hemisphere (Manos et al., 2008). The European chestnut
(Castanea sativa Mill.) is considered to be the only native species of Castanea in Europe.
Chestnuts are multipurpose trees being used in the food industry, for its edible nuts that present
high quotation in international markets; in the wood industry, as timber; and also for ecological
and landscaping purposes. Taken together, chestnuts have a major economic importance in the
Mediterranean region. Chestnut fruit production has declined considerably during the 20th
century to the current level of about 200,000 t (Conedera et al., 2004) in South-western Europe
due particularly to the emergence of heavily damaging diseases and pests already referred.
Ink disease, caused by Phytophthora spp. is one of the most destructive diseases affecting
European chestnut. Pcis an aggressive root pathogen, originally from the Southeast Asian
tropics (Hardham, 2005) classified in the Top 10 oomycete pathogens in molecular plant
pathology (Kamon et al., 2014). Nowadays, Pc is widespread and continues to be destructive in forests of Mediterranean countries; as well as in Australia, the south-eastern region of
the United States, Southern California in the U.S., and more recently it was recognized as a
danger to forests in western North America (Hardham, 2005). Pc has an exceptionally wide
Academia Letters, July 2021
©2021 by the authors — Open Access — Distributed under CC BY 4.0
Corresponding Author: Rita Lourenço Costa, rita.lcosta@iniav.pt
Citation: Lourenço Costa, R., Rodrigues, A. (2021). Breeding chestnut for resistance to Phytophthora
cinnamomi for improving the productivity of chestnut stands. Academia Letters, Article 2159.
https://doi.org/10.20935/AL2159.
2
host range, being able to invade more than 3000 plant species around the world (Kamon et al.,
2014). Currently, it is the most important Phytophthora pathogen of forest trees and besides
chestnut, Pc causes root diseases in eucalyptus, oaks, pines and members of the Ericaceae
family, as well as several agricultural crops (Robin et al., 2012).The pathogen spreads slowly
through root-to-root contact and more rapidly in the presence of water. Human activities that
move soil and the planting of infested nursery stock intensify pathogen spread. With changing climates, Pc is expected to expand its area of destruction, mainly in Europe and North
America (Robin et al., 2012). Chestnuts have different susceptibility levels to Pc, with the
Asian species (C. crenata Siebold et Zucc.; C. mollissima Blume) exhibiting the highest level
of resistance (Crandall et al. 1945).Therefore, since the last century, these species have been
used as donors of resistance to Pcin several breeding programs in Europe. It has long been
recognized that a deepunderstanding of the pathogen biology, host-pathogen interactions, and
of the resistancemechanisms are of key importance to improve the efficiency of the breeding
process for improved genotypes.
We have been working for the improving of chestnut resistance to root rot with the implementation of a traditional breeding program in 2006, assisted by molecular tools (Costa et al.,
2011). The main goal of the research program supported by the breeding program is to understand the mechanisms of resistance that the Asian resistant species have, in order to identify
molecular markers linked to the resistance, to be used for a more efficient and expedite selection of improved genotypes, from the breeding program on course. Different approaches have
being used to achieve that goal. From the work performed till now, new genetic and genomic
resources related with Castanea response to Pc were developed namely: I - a segregating
population derived from controlled crosses between the sensitive European species C. sativa
and the resistant Asian species, phenotyped for resistance to Pc (Santos et al., 2015); II - new
genotypes with improved resistance to Pc were selected from the hybrid progenies, three of
them will be launched to the market in 2022/2023 as new rootstocks with improved resistance
to root rot - NewCastRootstocks (Fernandes et al., 2020a); III-Transcriptomic and genomic
studies have provided the first genetic insights into mechanisms underlying susceptible and
resistant chestnut species responses to Pc (Santos et al. 2015a; Santos et al. 2017b; Serrazina
et al. 2015). Santos et al. (2017) proposed a molecular mechanism involving several layers of
defence, which includes hypersensitive response-like cell death (HR). The authors report the
up-regulation of a set of genes (e.g. Cast_Gnk2-like and Calcium-dependent protein kinase),
after Pcinfection, which may trigger HR-like cell death in C. crenata cells. Structural barriers,
likeactive reinforcement of cell walls, are also suggested to have an important role in chestnut’s defenseto Pc(Santos et al. 2017a). IV - Castanea root transcriptomes were developed
in response to Pc infection, where EST-SSR markers were designed (Santos et al., 2015b),
Academia Letters, July 2021
©2021 by the authors — Open Access — Distributed under CC BY 4.0
Corresponding Author: Rita Lourenço Costa, rita.lcosta@iniav.pt
Citation: Lourenço Costa, R., Rodrigues, A. (2021). Breeding chestnut for resistance to Phytophthora
cinnamomi for improving the productivity of chestnut stands. Academia Letters, Article 2159.
https://doi.org/10.20935/AL2159.
3
and we also studied V - the cellular progression of Pc in the susceptible species Castanea
sativa in comparison with the resistant species Castanea crenata. Penetration was observed,
in both species, at 0.5hours after inoculation (hai) and 3.5hai with mycelium and zoospore
inoculations, respectively. In both inoculation methods, following the penetration into the
rhizodermis, P. cinnamomi hyphae grew inter- and intracellularly through the cortex and into
the vascular cylinder. C. crenata, cells displayed a delay in the pattern of infection, by having
fewer cell layers colonized when compared with C. sativa. At 72hai, the collapse of the first
layers of C. sativa cortical cells was observed, indicating the beginning of necrotrophy. C. crenata was able to respond more efficiently to Pc than C. sativa, by restricting the pathogen’s
growth area through the early activation of resistance responses, such as callose deposition
around some intracellular hyphae, HR-like cell death, cell wall thickening and accumulation
of phenolic-like compounds (Fernandes et al, 2020b). Genetic transformation is also being
used to insert Cast_Gnk2-like gene, which encodes for an antifungal protein, in C. sativa and
C. dentata genomes, to be tested for Pc putative tolerance (McGuigan et al., 2020).
The research program described for improving the sanitary and productive status of chestnut stands for fruit production was appropriate to the Marvão productive area, where we also
did the installation of field trial plots for studying the adaptation of the new genotypes with
improved resistance to root rot. This area was shown to be potentially enlarged from the actual 850 ha to about a tenfold order of magnitude 9900ha, through a GIS-based methodology
(data submitted for publication). This estimation was based on an expansion of the actual
productive area based on the similitude in terms of physiography, soil type and climate of
other potential areas in the Marvão and São Mamede region. Slope intervals between 0 –
8% or higher and altitude classes between 400 and 500 m or higher, were considered as the
more distinctive factors for profiling the chestnut areas aiming fruit or timber/environmental
forestry in terms of soil protection or biodiversity in higher altitudes.
From the potentially expanded area about 4590 ha were allocated to fruit production under
coppice forestry with a possible adding of about 600 ha from high quality sites of temporary
dry/irrigated cultivations in altitudes higher than 500 m. The remaining potential area would
be allocated to timber/protective coppice forestry. This approach aiming the expansion of
the cultivation area of chestnut could be interesting for land management in other European
Mediterranean countries with ecological similarities with Portugal, such as Spain, France,
or Italy, allowing to recover marginal lands and enhancing the common European market
of chestnut products and services. A positive impact should occur with the improvement
of landscape biodiversity, with the boosting of sustainable socio-economical development in
rural areas (data under publication)
All the results and the new genetic and molecular resources are the basilar foundations to
Academia Letters, July 2021
©2021 by the authors — Open Access — Distributed under CC BY 4.0
Corresponding Author: Rita Lourenço Costa, rita.lcosta@iniav.pt
Citation: Lourenço Costa, R., Rodrigues, A. (2021). Breeding chestnut for resistance to Phytophthora
cinnamomi for improving the productivity of chestnut stands. Academia Letters, Article 2159.
https://doi.org/10.20935/AL2159.
4
achieve the goals of improving the resistance of Castanea to root rot in order to increase the
productivity of chestnut stands, with a positive impact in economy of mountainous Mediterranean regions of Europe.
References
Conedera, M., Krebs, P., Tinner, W. Padrela M & Toriani D. (2004). The cultivation of
Castanea sativa (Mill.) in Europe, from its origin to its diffusion on a continental scale.
Veget Hist Archaeobot 13, 161–179 https://doi.org/10.1007/s00334-004-0038-7
Costa R, Santos C, Tavares F et al., 2011. Mapping and transcriptomic approaches implemented for understanding disease resistance to Phytophthora cinnamomi in Castanea sp.
In: Grattapaglia D, ed. Proceedings of IUFRO Tree Biotechnology Conference: From
Genomes to Integration and Delivery, 2011. Bahia, Brasil: BioMed Central, 5 (Suppl 7),
O18. doi: 10.1186/1753-6561-5-S7-O18.
Fernandes P., Amaral A., Colavolpe B., Balonas D., Serra M., Pereira A., Costa R.L. (2020a)
- Propagation of New Chestnut Rootstocks with Improved Resistance Phytophthora cinnamomi – New Cast Rootstocks. Silva Lusitana, 28(1): 15–29 DOI: https://doi.org/10.
1051/silu/20202801015.
Fernandes P., Machado H., Silva M.C., Costa R.L. (2020b). Histopathological study reveals
new insights into responses of chestnut (Castanea spp.) to root infection by Phytophthora
cinnamomi. Phytopathology. https://doi.org/10.1094/PHYTO-04-20-0115-R
Hardham A. (2005). Phytophthora cinamomi. Molecular Plant pathology. Volume 6, Issue
6 Pages 589-604 https://doi.org/10.1111/j.1364-3703.2005.00308.x
Kamoun, S., Furzer, O., Jones, J. D. G., Judelson, H. S., Ali, G. S., Dalio, R. J. D.,et al.
(2014). The Top 10 oomycete pathogens in molecular plant pathology. Mol. Plant Pathol.
16, 413–434. doi: 10.1111/mpp.12190
Manos PS, Cannon CH, Oh S-H, 2008. Phylogenetic relationships and taxonomic status
of the paleoendemic Fagaceae of western North America: recognition of a new genus,
Notholithocarpus. Madroño 55 (3), 181–90. https://doi.org/10.3120/0024-9637-55.3.181
McGuigan, L.; Fernandes, P.; Oakes, A.; Stewart, K.; Powell, W. Transformation of American Chestnut (Castanea dentata (Marsh.) Borkh) Using RITA® Temporary Immersion
Academia Letters, July 2021
©2021 by the authors — Open Access — Distributed under CC BY 4.0
Corresponding Author: Rita Lourenço Costa, rita.lcosta@iniav.pt
Citation: Lourenço Costa, R., Rodrigues, A. (2021). Breeding chestnut for resistance to Phytophthora
cinnamomi for improving the productivity of chestnut stands. Academia Letters, Article 2159.
https://doi.org/10.20935/AL2159.
5
Bioreactors and We Vitro Containers. Forests 2020, 11, 1196. https://doi.org/10.3390/
f11111196
Paul S. Manos, Charles H. Cannon, and Sang-Hun Oh (2008) Phylogenetic Relationships and
Taxonomic Status Of the Paleoendemic Fagaceae Of Western North America: Recognition
Of A New Genus, Notholithocarpus, Madroño 55(3), 181-190, https://doi.org/10.3120/
0024-9637-55.3.181
Robin, C., Smith, I., and Hansen, E.M. (2012). Phythophthora cinnamomi. Forest Phytophthoras 2(1). doi: 10.5399/osu/fp.2.1.3041.
Santos, C, Machado, H., Correia, I., Gomes, F., Gomes-Laranjo, J., and Costa, R. (2015a).
Phenotyping Castanea hybrids for Phytophthora cinnamomi resistance. Plant Pathol.
64:901–910.
Santos C, Zhebentyayeva T, Serrazina S, Nelson C. Dana, Costa RL (2015b) - Development and characterization of EST-SSR markers for mapping reaction to Phytophthora cinnamomi in Castanea spp. Scientia Horticulturae. 194: 181–187 doi.org/10.1016/j.scienta.2015.07.043
Santos, C., Nelson, C. D., Zhebentyayeva, T., Machado, H., Gomes-Laranjo, J., and Costa, R.
L. (2017). First interspecific genetic linkage map for Castanea sativa x Castanea crenata
revealed QTLs for resistance to Phytophthora cinnamomi. PLoS One. 12:e0184381.
Serrazina, S., Santos, C., Machado, H., Pesquita, C., Vicentini, R., Pais, M. S., and Costa, R.
(2015). Castanea root transcriptome in response to Phytophthora cinnamomi challenge.
Tree Genet. Genomes. 11:1–19.
Shearer, B.L., Crane, C.E. (2012) Phytophthora cinnamomi visible necrotic lesion-colonisation
relationships in native flora. Australasian Plant Pathol. 41, 633–644. https://doi.org/10.
1007/s13313-012-0151-5
Academia Letters, July 2021
©2021 by the authors — Open Access — Distributed under CC BY 4.0
Corresponding Author: Rita Lourenço Costa, rita.lcosta@iniav.pt
Citation: Lourenço Costa, R., Rodrigues, A. (2021). Breeding chestnut for resistance to Phytophthora
cinnamomi for improving the productivity of chestnut stands. Academia Letters, Article 2159.
https://doi.org/10.20935/AL2159.
6
ACADEMIA Letters
Breeding chestnut for resistance to Phytophthora
cinnamomi for improving the productivity of chestnut
stands
Rita Lourenço Costa
Abel Rodrigues
Chestnuts are multipurpose trees having a major economic impact in south-western Europe,
acting as an important income for the rural populations, of mountainous Mediterranean regions sometimes the only one, contributing for inverting the tendency of depopulation of those
regions, being also important barriers for fire progression. European chestnut constitutes a
valuable source of genetic variation for Castanea in Mediterranean regions. It is associated
with a number of favourable characters such as: adaptation to local conditions, enabling the
creation of commercial networks within and between regions, and increasing the value chain
for high quality products with organoleptic and health qualities. The economy based on nut
production is very important in Northern regions of Portugal. The production is nowadays
about 47,500 tones, representing approximately 70 M€ of turnover. Portugal and Italy are the
leading European producers, being Portugal in the second place worldwide nowadays, after
the introduction of gall wasp in Italy. Portugal is also a major exporter of nuts, having, according to the INE (2016), exported in 2015, 18 186 tones, corresponding to 41 M€. This
value may be duplicated, at least, if the losses caused by pests and diseases, the main threats
for the species, may be reduced, as there is a market in Europe and in the rest the world for
Portuguese chestnuts as fresh and transformed products with added value.
A serious decline of chestnut growing area and productivity per hectare has been observed
since the last century in Portugal; according to the last inventory of 2015, the current area
is 34,000 ha for fruit production and 48,300 ha for the total area (including forest); while
at the beginning of 20th century it was 80,000 ha, before the introduction of Phytophthora
Academia Letters, July 2021
©2021 by the authors — Open Access — Distributed under CC BY 4.0
Corresponding Author: Rita Lourenço Costa, rita.lcosta@iniav.pt
Citation: Lourenço Costa, R., Rodrigues, A. (2021). Breeding chestnut for resistance to Phytophthora
cinnamomi for improving the productivity of chestnut stands. Academia Letters, Article 2159.
https://doi.org/10.20935/AL2159.
1
cinnamomi Rands (Pc), the causal agent of root rot also known as ink disease. The actual area
is less than half of the country’s potential as well as the productivity per hectare, which is,
on average, 1.5 Ton/ha less than half of the productivity of French and Italian orchards. The
dominant area of chestnut for fruit production is located in the North with about 30.000 ha, in
Trás-os-Montes e Alto Douro region, mainly in sites with altitude higher than 500m. In the
South-Eastern region of Marvão and São Mamede, a smaller area of about 850 hectares has
been also traditionally allocated to chestnut stands for fruit production. This minor productive
area corresponded to a typical physiography of landscape in terms of altitudes higher than 400
m, climate and an edaphic profiling with prevalence of undifferentiated soils, e.g. cambisols,
luvisols and rocky outcrops.
The main threats that contributed for the decline of chestnut growing area and productivity
have been diseases and pests: ink disease (Phytophthora spp), blight disease (Cryphonectria
parasitica (Murr.) M.E. Barr) and more recently gall wasp (Dryocosmus kuriphilus (Yasumatsu)). For the latter two, biological control is available and is being used with success
in different European countries. On the contrary, for Phytophthora species there is no option of biological control, adding the fact that to cope with different hosts and host tissues,
Phytophthora species have evolved sophisticated mechanisms to manipulate plant cells and
cause infections. It has been noted that many of these pathogens grow as hemibiotrophics
under certain circumstances with an initial biotrophic interaction with the host plant and later
switching to a destructive necrotrophic lifestyle (Shearer & Crane, 2012).
The genus Castanea belongs to Fagaceae, a plant family that dominates much of the climax
hardwood forests of the Northern Hemisphere (Manos et al., 2008). The European chestnut
(Castanea sativa Mill.) is considered to be the only native species of Castanea in Europe.
Chestnuts are multipurpose trees being used in the food industry, for its edible nuts that present
high quotation in international markets; in the wood industry, as timber; and also for ecological
and landscaping purposes. Taken together, chestnuts have a major economic importance in the
Mediterranean region. Chestnut fruit production has declined considerably during the 20th
century to the current level of about 200,000 t (Conedera et al., 2004) in South-western Europe
due particularly to the emergence of heavily damaging diseases and pests already referred.
Ink disease, caused by Phytophthora spp. is one of the most destructive diseases affecting
European chestnut. Pcis an aggressive root pathogen, originally from the Southeast Asian
tropics (Hardham, 2005) classified in the Top 10 oomycete pathogens in molecular plant
pathology (Kamon et al., 2014). Nowadays, Pc is widespread and continues to be destructive in forests of Mediterranean countries; as well as in Australia, the south-eastern region of
the United States, Southern California in the U.S., and more recently it was recognized as a
danger to forests in western North America (Hardham, 2005). Pc has an exceptionally wide
Academia Letters, July 2021
©2021 by the authors — Open Access — Distributed under CC BY 4.0
Corresponding Author: Rita Lourenço Costa, rita.lcosta@iniav.pt
Citation: Lourenço Costa, R., Rodrigues, A. (2021). Breeding chestnut for resistance to Phytophthora
cinnamomi for improving the productivity of chestnut stands. Academia Letters, Article 2159.
https://doi.org/10.20935/AL2159.
2
host range, being able to invade more than 3000 plant species around the world (Kamon et al.,
2014). Currently, it is the most important Phytophthora pathogen of forest trees and besides
chestnut, Pc causes root diseases in eucalyptus, oaks, pines and members of the Ericaceae
family, as well as several agricultural crops (Robin et al., 2012).The pathogen spreads slowly
through root-to-root contact and more rapidly in the presence of water. Human activities that
move soil and the planting of infested nursery stock intensify pathogen spread. With changing climates, Pc is expected to expand its area of destruction, mainly in Europe and North
America (Robin et al., 2012). Chestnuts have different susceptibility levels to Pc, with the
Asian species (C. crenata Siebold et Zucc.; C. mollissima Blume) exhibiting the highest level
of resistance (Crandall et al. 1945).Therefore, since the last century, these species have been
used as donors of resistance to Pcin several breeding programs in Europe. It has long been
recognized that a deepunderstanding of the pathogen biology, host-pathogen interactions, and
of the resistancemechanisms are of key importance to improve the efficiency of the breeding
process for improved genotypes.
We have been working for the improving of chestnut resistance to root rot with the implementation of a traditional breeding program in 2006, assisted by molecular tools (Costa et al.,
2011). The main goal of the research program supported by the breeding program is to understand the mechanisms of resistance that the Asian resistant species have, in order to identify
molecular markers linked to the resistance, to be used for a more efficient and expedite selection of improved genotypes, from the breeding program on course. Different approaches have
being used to achieve that goal. From the work performed till now, new genetic and genomic
resources related with Castanea response to Pc were developed namely: I - a segregating
population derived from controlled crosses between the sensitive European species C. sativa
and the resistant Asian species, phenotyped for resistance to Pc (Santos et al., 2015); II - new
genotypes with improved resistance to Pc were selected from the hybrid progenies, three of
them will be launched to the market in 2022/2023 as new rootstocks with improved resistance
to root rot - NewCastRootstocks (Fernandes et al., 2020a); III-Transcriptomic and genomic
studies have provided the first genetic insights into mechanisms underlying susceptible and
resistant chestnut species responses to Pc (Santos et al. 2015a; Santos et al. 2017b; Serrazina
et al. 2015). Santos et al. (2017) proposed a molecular mechanism involving several layers of
defence, which includes hypersensitive response-like cell death (HR). The authors report the
up-regulation of a set of genes (e.g. Cast_Gnk2-like and Calcium-dependent protein kinase),
after Pcinfection, which may trigger HR-like cell death in C. crenata cells. Structural barriers,
likeactive reinforcement of cell walls, are also suggested to have an important role in chestnut’s defenseto Pc(Santos et al. 2017a). IV - Castanea root transcriptomes were developed
in response to Pc infection, where EST-SSR markers were designed (Santos et al., 2015b),
Academia Letters, July 2021
©2021 by the authors — Open Access — Distributed under CC BY 4.0
Corresponding Author: Rita Lourenço Costa, rita.lcosta@iniav.pt
Citation: Lourenço Costa, R., Rodrigues, A. (2021). Breeding chestnut for resistance to Phytophthora
cinnamomi for improving the productivity of chestnut stands. Academia Letters, Article 2159.
https://doi.org/10.20935/AL2159.
3
and we also studied V - the cellular progression of Pc in the susceptible species Castanea
sativa in comparison with the resistant species Castanea crenata. Penetration was observed,
in both species, at 0.5hours after inoculation (hai) and 3.5hai with mycelium and zoospore
inoculations, respectively. In both inoculation methods, following the penetration into the
rhizodermis, P. cinnamomi hyphae grew inter- and intracellularly through the cortex and into
the vascular cylinder. C. crenata, cells displayed a delay in the pattern of infection, by having
fewer cell layers colonized when compared with C. sativa. At 72hai, the collapse of the first
layers of C. sativa cortical cells was observed, indicating the beginning of necrotrophy. C. crenata was able to respond more efficiently to Pc than C. sativa, by restricting the pathogen’s
growth area through the early activation of resistance responses, such as callose deposition
around some intracellular hyphae, HR-like cell death, cell wall thickening and accumulation
of phenolic-like compounds (Fernandes et al, 2020b). Genetic transformation is also being
used to insert Cast_Gnk2-like gene, which encodes for an antifungal protein, in C. sativa and
C. dentata genomes, to be tested for Pc putative tolerance (McGuigan et al., 2020).
The research program described for improving the sanitary and productive status of chestnut stands for fruit production was appropriate to the Marvão productive area, where we also
did the installation of field trial plots for studying the adaptation of the new genotypes with
improved resistance to root rot. This area was shown to be potentially enlarged from the actual 850 ha to about a tenfold order of magnitude 9900ha, through a GIS-based methodology
(data submitted for publication). This estimation was based on an expansion of the actual
productive area based on the similitude in terms of physiography, soil type and climate of
other potential areas in the Marvão and São Mamede region. Slope intervals between 0 –
8% or higher and altitude classes between 400 and 500 m or higher, were considered as the
more distinctive factors for profiling the chestnut areas aiming fruit or timber/environmental
forestry in terms of soil protection or biodiversity in higher altitudes.
From the potentially expanded area about 4590 ha were allocated to fruit production under
coppice forestry with a possible adding of about 600 ha from high quality sites of temporary
dry/irrigated cultivations in altitudes higher than 500 m. The remaining potential area would
be allocated to timber/protective coppice forestry. This approach aiming the expansion of
the cultivation area of chestnut could be interesting for land management in other European
Mediterranean countries with ecological similarities with Portugal, such as Spain, France,
or Italy, allowing to recover marginal lands and enhancing the common European market
of chestnut products and services. A positive impact should occur with the improvement
of landscape biodiversity, with the boosting of sustainable socio-economical development in
rural areas (data under publication)
All the results and the new genetic and molecular resources are the basilar foundations to
Academia Letters, July 2021
©2021 by the authors — Open Access — Distributed under CC BY 4.0
Corresponding Author: Rita Lourenço Costa, rita.lcosta@iniav.pt
Citation: Lourenço Costa, R., Rodrigues, A. (2021). Breeding chestnut for resistance to Phytophthora
cinnamomi for improving the productivity of chestnut stands. Academia Letters, Article 2159.
https://doi.org/10.20935/AL2159.
4
achieve the goals of improving the resistance of Castanea to root rot in order to increase the
productivity of chestnut stands, with a positive impact in economy of mountainous Mediterranean regions of Europe.
References
Conedera, M., Krebs, P., Tinner, W. Padrela M & Toriani D. (2004). The cultivation of
Castanea sativa (Mill.) in Europe, from its origin to its diffusion on a continental scale.
Veget Hist Archaeobot 13, 161–179 https://doi.org/10.1007/s00334-004-0038-7
Costa R, Santos C, Tavares F et al., 2011. Mapping and transcriptomic approaches implemented for understanding disease resistance to Phytophthora cinnamomi in Castanea sp.
In: Grattapaglia D, ed. Proceedings of IUFRO Tree Biotechnology Conference: From
Genomes to Integration and Delivery, 2011. Bahia, Brasil: BioMed Central, 5 (Suppl 7),
O18. doi: 10.1186/1753-6561-5-S7-O18.
Fernandes P., Amaral A., Colavolpe B., Balonas D., Serra M., Pereira A., Costa R.L. (2020a)
- Propagation of New Chestnut Rootstocks with Improved Resistance Phytophthora cinnamomi – New Cast Rootstocks. Silva Lusitana, 28(1): 15–29 DOI: https://doi.org/10.
1051/silu/20202801015.
Fernandes P., Machado H., Silva M.C., Costa R.L. (2020b). Histopathological study reveals
new insights into responses of chestnut (Castanea spp.) to root infection by Phytophthora
cinnamomi. Phytopathology. https://doi.org/10.1094/PHYTO-04-20-0115-R
Hardham A. (2005). Phytophthora cinamomi. Molecular Plant pathology. Volume 6, Issue
6 Pages 589-604 https://doi.org/10.1111/j.1364-3703.2005.00308.x
Kamoun, S., Furzer, O., Jones, J. D. G., Judelson, H. S., Ali, G. S., Dalio, R. J. D.,et al.
(2014). The Top 10 oomycete pathogens in molecular plant pathology. Mol. Plant Pathol.
16, 413–434. doi: 10.1111/mpp.12190
Manos PS, Cannon CH, Oh S-H, 2008. Phylogenetic relationships and taxonomic status
of the paleoendemic Fagaceae of western North America: recognition of a new genus,
Notholithocarpus. Madroño 55 (3), 181–90. https://doi.org/10.3120/0024-9637-55.3.181
McGuigan, L.; Fernandes, P.; Oakes, A.; Stewart, K.; Powell, W. Transformation of American Chestnut (Castanea dentata (Marsh.) Borkh) Using RITA® Temporary Immersion
Academia Letters, July 2021
©2021 by the authors — Open Access — Distributed under CC BY 4.0
Corresponding Author: Rita Lourenço Costa, rita.lcosta@iniav.pt
Citation: Lourenço Costa, R., Rodrigues, A. (2021). Breeding chestnut for resistance to Phytophthora
cinnamomi for improving the productivity of chestnut stands. Academia Letters, Article 2159.
https://doi.org/10.20935/AL2159.
5
Bioreactors and We Vitro Containers. Forests 2020, 11, 1196. https://doi.org/10.3390/
f11111196
Paul S. Manos, Charles H. Cannon, and Sang-Hun Oh (2008) Phylogenetic Relationships and
Taxonomic Status Of the Paleoendemic Fagaceae Of Western North America: Recognition
Of A New Genus, Notholithocarpus, Madroño 55(3), 181-190, https://doi.org/10.3120/
0024-9637-55.3.181
Robin, C., Smith, I., and Hansen, E.M. (2012). Phythophthora cinnamomi. Forest Phytophthoras 2(1). doi: 10.5399/osu/fp.2.1.3041.
Santos, C, Machado, H., Correia, I., Gomes, F., Gomes-Laranjo, J., and Costa, R. (2015a).
Phenotyping Castanea hybrids for Phytophthora cinnamomi resistance. Plant Pathol.
64:901–910.
Santos C, Zhebentyayeva T, Serrazina S, Nelson C. Dana, Costa RL (2015b) - Development and characterization of EST-SSR markers for mapping reaction to Phytophthora cinnamomi in Castanea spp. Scientia Horticulturae. 194: 181–187 doi.org/10.1016/j.scienta.2015.07.043
Santos, C., Nelson, C. D., Zhebentyayeva, T., Machado, H., Gomes-Laranjo, J., and Costa, R.
L. (2017). First interspecific genetic linkage map for Castanea sativa x Castanea crenata
revealed QTLs for resistance to Phytophthora cinnamomi. PLoS One. 12:e0184381.
Serrazina, S., Santos, C., Machado, H., Pesquita, C., Vicentini, R., Pais, M. S., and Costa, R.
(2015). Castanea root transcriptome in response to Phytophthora cinnamomi challenge.
Tree Genet. Genomes. 11:1–19.
Shearer, B.L., Crane, C.E. (2012) Phytophthora cinnamomi visible necrotic lesion-colonisation
relationships in native flora. Australasian Plant Pathol. 41, 633–644. https://doi.org/10.
1007/s13313-012-0151-5
Academia Letters, July 2021
©2021 by the authors — Open Access — Distributed under CC BY 4.0
Corresponding Author: Rita Lourenço Costa, rita.lcosta@iniav.pt
Citation: Lourenço Costa, R., Rodrigues, A. (2021). Breeding chestnut for resistance to Phytophthora
cinnamomi for improving the productivity of chestnut stands. Academia Letters, Article 2159.
https://doi.org/10.20935/AL2159.
6
Abel Rodrigues