Ciência Rural, Santa Maria,Brief v.46, history n.9, p.1585-1593, of Eucalyptus set, breeding 2016 in Brazil under perspective of http://dx.doi.org/10.1590/0103-8478cr20150645 biometric advances. 1585 ISSN 1678-4596 FORESTRY SCIENCE
Brief history of Eucalyptus breeding in Brazil under perspective of biometric advances
Breve histórico do melhoramento genético do eucalipto no Brasil sob a ótica dos avanços biométricos
Carla Aparecida de Oliveira CastroI Rafael Tassinari ResendeII Leonardo Lopes BheringII Cosme Damião CruzII
— REVIEW —
ABSTRACT Palavras-chave: genética, cruzamento, história, cenário corrente, biometria, genômica. Forest breeding is a science that has been developing in Brazil since 1941 being the Eucalyptus a highlighted genus in this scenario. In a global scene, Brazil is displayed prominently in productivity of Eucalyptus planting, due to favorable environmental INTRODUCTION conditions to cultivation development, and the incentive in research for improvement of traits of interest t observed in it species and It is hard to precisely define theEucalyptus hybrids. This research included a historical review of Eucalyptus introduction time in Brazil, due the record differences breeding over the years under genetic biometric perspective in Brazil, from reports describing the pioneer planting up to the (made by several authors) and the lack of documents current genome wide selection (GWS) that came as a complement proving the citations concerning possible entry dates of forest breeding success. This review showed some of the tracks of seeds and seedlings in the country. It is believed performed by researchers aiming to improve the productive and that the first Eucalyptus seedlings were planted in quality of phenotypic traits from Eucalyptus genus. Brazil in 1824 at Rio de Janeiro Botanical Garden Key words: genetics, crossing, history, current scenario, (BERTOLA, 2013; MARCHIORI, 2014). biometry, genomic. Studies with Eucalyptus in Brazil began at 1904 by Edmundo Navarro de Andrade (in the RESUMO Companhia Paulista de Estradas de Ferro), who O melhoramento florestal é uma ciência que tem introduced several species and origins of the genus tido desenvolvimento no Brasil desde o ano de 1941 e um gênero in Jundiaí Garden, São Paulo. In this pioneer study, que obteve grande repercussão neste cenário foi o Eucalyptus. O he aimed to establish the Eucalyptus usage in order Brasil apresenta-se em destaque no panorama mundial quanto à produtividade dos plantios de eucalipto, em virtude das condições to attend the existed wood demand that would be ambientais favoráveis ao desenvolvimento da cultura e ao incentivo intended to railways construction (SAMPAIO, 1961). em pesquisas destinadas às melhorias dos caracteres de interesse, The interest in these studies emerged due presentes em suas espécies e híbridos. Este trabalho inclui uma to Eucalyptus species presents an easy adaptation to revisão histórica do melhoramento do eucalipto ao longo dos anos no Brasil, sob a ótica da genética biométrica, desde o relato que different environmental conditions existed in Brazil, descreve o plantio pioneiro de suas espécies no país, até a atual similar latitude with Australia and due to properties aplicação de seleção genômica ampla (SGA), que surgiu como um that give it several possibilities on wood usage. complemento de sucesso no melhoramento florestal. A pesquisa Currently, this genus is considered one of the most ilustra ainda alguns dos caminhos percorridos por pesquisadores a fim de aumentar a produtividade e a qualidade dos caracteres important planted in the country and in other tropical fenotípicos do gênero Eucalyptus. and subtropical regions of the world.
IDepartamento de Engenharia Florestal, Centro de Ciências Agrárias (CCA), Universidade Federal de Viçosa (UFV), 36570-900, Viçosa, MG, Brasil. E-mail: [email protected]. Corresponding author. IIDepartamento de Biologia Geral, Centro de Ciências Biológicas e da Saúde (CCB), Universidade Federal de Viçosa (UFV), Viçosa, MG, Brasil.
Received 05.05.15 Approved 03.11.16 Returned by the author 05.25.16 CR-2015-0645.R1 Ciência Rural, v.46, n.9, set, 2016. 1586 Castro et al.
In the last years, planted areas with those during the same period is shown in figure 1B. These culture genotypes are in expansion process but with less numbers were obtained from research in current intensity, due the increase of wood production costs. journals, using keywords related to breeding, Moreover, this negative factor related to Eucalyptus biometrics and Eucalyptus. It is noted that the cultivation stimulates research in genetic breeding and volumetric productivity tends to stabilize in the forest management to step-up this scenario. coming years, while the total number of publications The use of breeding tools supported by keep increasing, showing that other traits such as the biometric statistics and the incentive of breeding technological quality of the wood, have the potential programs (looking for production of high force to be improved. We can see also that publications hybrids) places Brazil among the most efficient in Brazilian Portuguese language are stagnating countries for production of raw material from suggesting that native researchers have opted for Eucalyptus. This scenario demonstrates the foreign journals. economical and social importance of Eucalyptus cultivation and the historical landmark that represents Eucalyptus breeding history in Brazil the introduction of its species in Brazil (ASSIS, 2014). In 1941, Edmundo Navarro invited Carlos Arnaldo Krug, from the Instituto Agronômico de DEVELOPMENT Campinas (IAC), to start a Eucalyptus breeding program in Brazil. To this aim, they held provenances Eucalyptus breeding overview testing, evaluating which would be the genus of Eucalyptus breeding aims to increase species able to be planted in Brazil. productivity, enabling to obtain higher traits The Forestry Institute of São Paulo State performance and reduce environmental impacts assigned the activities of the Companhia Paulista (GOLLE et al., 2009). In this sense, different strategies de Estradas de Ferro in 1964. But only from 1967, are established combining crossing designs, selection with implementation of the Law of Tax Incentives methods and populations structure; aiming to increase for Reforestation, an intensive program of genetic alleles frequency of interest (RESENDE, 2000), which breeding through the selection of superior trees result in genotypic improvements of offspring. started (beginning of national scientific publications, By the same perspective, biotechnology shown in Figure 1). has emerged as a complement in order to provide In order to produce improved seeds and better understanding of genotype species and to know the provenances, some private forestry companies enable indirect obtaining of predicted genotypic data founded the Instituto de Pesquisas e Estudos Florestais with high reliability at each cycle, reducing its time (IPEF), located at Escola Superior de Agricultura “Luiz (GOLLE et al., 2009). de Queiroz” (ESALQ) in 1968 (FERREIRA, 1993). The evidence of efficiency in Eucalyptus Planting were performed with seeds; however, they breeding programs can be obtained from individuals quickly observed that trees from this type of spread genetic values predictions using BLUP (best had low productivity and problems with pathogens. linear unbiased prediction), which allows selective In order to minimize this issue, different species were accuracy maximization, use of information from crossed to form hybrids, aiming to use the best potential different locations and is superior to the least square of each (ASSIS et al, 1987; MARTINS & IKEMORI, method (RESENDE, 2007). Effectiveness can also 1987). This promoted the increased force and reduced be measured by genetic gains estimation for a time the susceptibility to diseases due heterosis, having the period, so that it is possible to perform selection of canker resistance (Chrysoporthecubensis) as example. traits of interest in the species. Therefore, it is crucial Canker resistance was a relevant trait for that time, as to understand the variability between and within the first major outbreak of that disease appeared at the populations as well as the related genetic control end of 60s; subsequently described by the HODGES & (VENCOVSKY, 1986). REIS (1974) work. At figure 1A is possible to observe the In the mid-70s, research on biometrics mean annual increment (MAI) of Eucalyptus and quantitative genetics gained strength with the productivity in the last 45 years (IBÁ, 2015). This partnership between Paulo Yoshio Kageyama and increase may be explained by the management Roland Vencovsky, both researchers from ESALQ, techniques and forestry improvements, and mainly who performed genetic parameters calculations and by the genetic breeding of planted trees. The number studies about the optimal implementation of genetic of publications produced in Brazil and in the world, experiments with Eucalyptus.
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Figure 1 - (A) Mean annual increment (MAI) of Eucalyptus productivity (Source: adapted from IBÁ, 2015). (B) Scientific Publications with keywords related with genetic breeding, biometric and Eucalyptus. Dashed line corresponds to publications in both English and Portuguese; dotted line corresponds to publications only in Portuguese-Brazil language. Both A and B periods range from 1970 to 2015.
With the premise that genetic material during planting process. Because of that, there was of Eucalyptus populations was being improved a growing interest in studies aiming to compare the by crosses that combined genotypes of interest interaction between genotypes of different species within and between families, a growing interest and the environment in which they were inserted. in conducting progeny tests was observed aiming (KAGEYAMA, 1983; PATIÑO & VALERA, 1986; to analyze the genetic gains obtained across MORI et al, 1886; VALERA & KAGEYAMA, 1988; generations. It was observed that the expected gains SANTOS et al., 1990). in a population were not always consistent with those The 1980-1995 period was characterized observed in the field; being these differences caused by less emphasis related to breeding strategies by the interference of environmental conditions using crossing methods, giving greater emphasis on
Ciência Rural, v.46, n.9, set, 2016. 1588 Castro et al. clonal propagation, since it was proved that cloning programs are used to calculate these parameters and originated greater uniformity and enabled great gains genotypic values predictions. in selection cycle. However, companies and research REML/BLUP procedure and least squares groups have reported that high selective intensity method (LSM) allowed the genetic evaluation causes variability decrease in the base population regarding the selection gains obtained from breeding, making it impossible to maintain the gains during the prioritizing individuals with higher genetic additive breeding program. values. It is believed that the REML/BLUP efficiently As a result, breeding and selection selects individuals, families and progeny even in the programs were encouraged in order to enhance the presence of unbalanced data (very common event population to obtain better interspecific hybrids. in Eucalyptus stands). In the research performed Several selection methods were studied for by ROCHA et al. (2006), it was observed genetic defining viability of Eucalyptus breeding programs variability existence and possibility of selection by (RESENDE et al., 1990; RODRIGUES et al., 2008; gains in diameter at breast height (DBH), height and ROSADO et al., 2009; MASSARO et al., 2010; volume traits, with accuracies above 70%. PINTO et al., 2014). Among these methods, those In many Eucalyptus species, biometric using genetic additive values, based on the known parameters were estimated using progeny tests, population structures or molecular and genomic which showed that E. camaldulensis and E. descriptions, have been highlighted due to advantages resinifera have high potential to be explored by in the individuals characterization in the population selection and thus can be used in breeding programs compared to the selection only based on phenotypic (MORAES et al., 2007, SATO et al., 2007). There values (RESENDE & HIGA, 1994). has also been interest in identifying Eucalyptus From a detailed historical analysis, it is clones that are wide adapted, that is, the most possible to see the incentive to technical findings stable to environmental changes (TOLER, 1990). that were fundamental to obtain an increase in forest This specification may be used to evaluate the productivity (ASSIS, 2014). Thus, selection of more effect of different conditions in clones (genotype productive genotypes became a goal for breeding, x environment interaction, or G × E) and how this reducing the planting area and the use of supplies. affects wood volume (NUNES et al., 2002). Pulp and paper industry are very important Biometric advances based on phenotypic traits study for biometric studies. It should be remembered that To evaluate the genetic material, some several traits like pulp yield, lignin, extractives information is obtained directly from individual and fibers length (HILLIS, 1972) are critical to be phenotype in the experiment, such as growth, tree considered in breeding. Companies commonly use shape, resistance to biotic and abiotic factors and E. grandis and E. urophylla for cellulose production, wood properties. Being that, used as a criteria for but genetic gains in several traits of interest inter- different phenotypes selection to evaluate genetic specific crosses are made in order to form promising gains (NUNES et al., 2002; ROSADO, 2009). hybrids for better pulp quality production (BISON, Genetic gain depends on heritability (h²), 2007; RESENDE& DE ASSIS, 2008). which assists in strategies of breeding program Another important product from planning, requiring attention when dealing with low h² Eucalyptus wood is charcoal, and aspects of traits. Some h² values of Eucalyptus traits are presented phenotype, genotype, environmental and to indirect in table 1 (RAYMOND (1995) and CORNELLIUS genetic gains should be analyzed to obtain superior (1994) cited by PIRES et al. (2011). Besides this features. The most used species for charcoal biometric parameter, repeatability and genetic production are E. urophylla, E. camaldulensis, correlation are also relevant in Eucalyptus breeding; E. cloeziana and E. pellita. In biometric studies, whereas, several variables and measurements can be selection is based on gravimetric yield of charcoal, taken from the same tree. Moreover, being a long basic and relative apparent density, lignin content and cycle cultivation, wait 6 or 7 years of production fixed carbon yield (CAIXETA et al., 2003; BOTREL cycle to perform the variables measurement becomes et al., 2007; RODRIGUES et al., 2008). economically unfeasible, while using early selection As could be seen, among the species of is feasible to get it after 3 or 2 years of planting Eucalyptus spp. genus there are those with particular (KAGEYAMA, 1983; MASSARO et al., 2010; properties for several uses, including the possibility of PINTO et al., 2014.). Usually, GENES (CRUZ, using for essential oil production (E. citriodora) and 2013) and Selegen REML/BLUP (RESENDE, 2002) lumber (E. grandis, E. saligna and E. pirulalis). This
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2 Table 1 - Narrow-sense individual heritability estimates (h a) of breeding have significantly contributed to an technological and Eucalyptus wood growth traits. improved knowledge of Eucalyptus cultivation, and for improved genotypes generation. 2 2 Trait h a (Mean) h a (Amplitude) One of the proposals of molecular markers Height 0.25 - usage is the ability to identify the genetic relationship Diameter 0.23 - between individuals in a population, not requiring Volume 0.21 - detailed information of kinship/pedigree among Basic density 0.57 0.05 a 0.84 the trees (MUÑOZ et al., 2014). STEANE et al. Kraft Pulp yield 0.43 0.30 a 0.56 (2011) proposed an approach to identify Eucalyptus Fiber length 0.39 0.12 a 0.59 species and its hybrids with high reliability; a Pilodyn penetration 0.49 0.21 a 0.78 valuable information on Eucalyptus breeding, as the Soda Demand 0.50 0.20 a 0.74 knowledge of rates from different species and hybrids Moisture Content 0.48 0.28 a 0.82 is often missed along the program. Fiber diameter 0.89 - Genetic variability knowledge is Lumen diameter 0.59 - Vessel Diameter 0.67 - important at many stages of reproductive cycle, being enhanced by the use of molecular markers. In Source: RAYMOND (1995) and CORNELLIUS (1994). Cited this sense, techniques can be performed as the use by PIRES et al., 2011. of Eucalyptus spp. microsatellite (SSR), in terms of a co-dominant marker and highly polymorphic (SANTOS et al., 2007). The GENOLYPTUS project (National information is important for inter-specific crosses Network of Eucalyptus Genome Research) has guidance aiming to get the best of each species. emerged as a strategic maneuver of Brazilian Disease resistance is another issue forestry companies, aiming to encourage research that is studied, since the incidence of pathogens and development in genetic, breeding, molecular affect forest productivity. Rust, canker and wilt of markers and cloning of this genus in the country Eucalyptus are examples that can be cited among (GRATTAPAGLIA, 2001). the common incidence of diseases in its plantations MYBURG et al. (2014) revolutionized that are widely disseminated throughout Brazil. the genotyping process by performing the complete Breeders attempted to select resistant individuals mapping of E. grandis genome, being this to these and other pathogens, and implement information highly relevant to other species of the new breeding techniques to ensure plantations Eucalyptus genus and its hybrids. In this context, an health, as it causes serious damage in nurseries, Illumina 60K chip for large-scale genotyping of 12 plantations, and wood quality (ZAUZA et al., Eucalyptus species were developed (SILVA-JUNIOR 2004; ZAMPROGNO et al., 2008; TEIXEIRA et et al., 2015), being the landmark that consolidates the al., 2009; GUIMARÃES et al., 2010). use of single nucleotides polymorphisms (SNP) in Such evaluated traits in Eucalyptus genomic studies of the genus. species have particular genetic properties as Individual DNA is the source that different h² (Table 1), additive genetic variance, determines their traits expression at a first moment; and dominance (LYNCH & WALSH, 1998). In however, it is known that the environment in which this context, RESENDE & BARBOSA (2005) it is inserted influences the phenotype expression. summarizes in their book (Melhoramento Genético In order to perform Eucalyptus breeding programs, de Plantas de Propagação Assexuada) strategies phenotypes knowledge is essential in addition to based on recurrent selection that are perfectly genotype-markers, so it is possible to select trees that suitable to these traits improvement. tend to be genetically superior within the population. Furthermore, the genomic approach allows detailed Biometric advances based on genetic information study understanding of genetics aspects as heterosis Evaluating the current economic and and inbreeding (GRATTAPAGLIA et al., 2012; environmental importance of Eucalyptus species HEDRICK et al., 2015). cultivation, it is noted the need to link breeding Mapping and detection of quantitative practices with existing and emerging genomic tools trait loci (QTL) is a biometric procedure that allows (GRATTAPAGLIA, 2004). Thus, both technology inferring about the genetic architecture of the trait, of molecular markers and techniques of classical indicating genes and the effects related to it expression.
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Authors identified QTLs for Eucalyptus traits, such studies related to genetic improvements in wood as growth, disease resistance and wood properties technological traits. (GRATTAPAGLIA et al., 1996; THAMARUS et al., 2004; THUMMA et al., 2010; ZARPELON et ACKNOWLEDGMENTS al., 2015). However, for selection purposes, QTLs have not shown good results for traits with low h² Authors thank Guilherme Simiqueli and Haroldo (RESENDE et al., 2008). Silva Rodrigues for his help in proof reading; Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq), Coordenação Seminal studies in Brazil performed by de Aperfeiçoamento de Pessoal de Nível Superior (CAPES) and RESENDE et al. (2008), indicated that the use of Fundação de Amparo à Pesquisa do Estado de Minas Gerais Genome Wide Selection method called (GWS) (FAPEMIG) for providing research grants and Professor Marcos gave positive results for traits with both high and Deon Vilela Resende by scientific advice. low h² in Eucalyptus spp. Unlike other molecular breeding methods, GWS has achieved high REFERENCES predictive accuracies due the ability to capture ASSIS, F.T. et al. Produção de híbridos interespecíficos em three sources of genetic variation: (i) Linkage Eucalyptus spp. In: REUNIÃO SOBRE TÉCNICAS PARA disequilibrium (ii) Co-segregation and (iii) genetic PRODUÇÃO DE HÍBRIDOS, 1987, Piracicaba, São Paulo. relationship (kinship via identity by state). For Anais... Piracicaba: IPEF, 1987. p.2-5. this, all markers of the genome should be used ASSIS, T.F. Melhoramento genético de Eucalyptus: desafios e simultaneously (RESENDE, 2010). perspectivas. Nova Lima: Embrapa Florestas, 2014. 22p. Available Genomic selection effectiveness has been from:
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