Alexandre Alonso Alves

Potential and challenges in making physic nut (Jatropha curcas L.) a viable biofuel crop: the Brazilian perspective

Fossil-derived fuels currently supply 86% of the world’s energy, even though it represents a finite resource. With the aim of reducing the fossil fuels dependency, alternative sources of energy have been pursued in recent years. In view of the urgent need to develop new technologies that may enable environmentally friendly forms of energy to become widespread, biofuels in general and biodiesel in particular are receiving considerable attention throughout the world and especially in Brazil. Given the high quality of its oil, which meets the rapeseed quality standard and can be easily converted into biodiesel, and because of its wide adaptability, physic nut has been considered a potential crop to serve as feedstock for biodiesel production. Popular claims, e.g. enhanced drought tolerance, low nutrient requirements, pest and disease resistance, have also helped to increase the expectations of the crop, even though most of these claims are yet to be supported by scientific evidence. However, the fact is that besides its advantageous characteristics, physic nut cultivation is challenging as it is a quasi-undomesticated species. In that context, this review seeks to demonstrate the physic nut potential as a biofuel crop, highlighting, however, the challenges to its wide adoption as a fuel crop. Despite facing enormous challenges (as detailed below), our cautiously optimistic vision is that a substantial and focused research programme may make physic nut a viable feedstock for biodiesel production. We detail the Brazilian research initiative that is addressing many of these challenges.

Seleção simultânea de clones de eucalipto de acordo com produtividade, estabilidade e adaptabilidade

The objective of this work was to estimate genetic parameters and to determine the efficiency of the simultaneous selection of eucalyptus clones based on yield, stability, and adaptability. Twenty-one clones, with 36 months of age, from the genetic breeding program of the company Cenibra were used. The experiment was done in a randomized complete block design, in four environments, with 21 replicates of one plant per plot. The clones were evaluated as to the variables: diameter at breast height, plant height, and total volume with bark. The genetic parameters were estimated using the mixed model procedure (REML/BLUP), and selection was based on the harmonic mean of the relative performance of the genetic values (HMRPGV), with three strategies: selection based on the predicted genetic gain, considering the average performance of genotypes in all environments (without interaction effect) or the performance on each environment (with interaction effect); and simultaneous selection based on productivity, stability, and adaptability. Environment particularities influenced the phenotypic expression of the clones. The heritability estimates indicated good perspectives for selecting clones with high yield, stability, and adaptability. Simultaneous selection optimizes clone selection and can be used in the construction of breeding populations and in the recommendation of genetic materials for commercial plantations.

Leaf gas exchange and chlorophyll a fluorescence of Eucalyptus urophylla in response to Puccinia psidii infection

One of the most important diseases of eucalyptus plantations is caused by the rust fungus Puccinia psidii. While the genetic basis of rust resistance has been addressed recently, little is known about the physiological aspects of Eucalyptus–P. psidii interaction. In order to fill this gap, we undertook a study investigating the effects of P. psidii infection on photosynthetic processes of two E. urophylla clones with contrasting resistance to the pathogen. Our results show that gas exchange and chlorophyll a fluorescence parameters were virtually unaffected in the resistant clone. In the susceptible clone, photosynthetic rates were chiefly constrained by biochemical limitations to carbon fixation. Photosynthesis was impaired only in symptomatic tissues since the reductions in photosynthetic rates were proportional to the diseased leaf area. Rust infection provoked chronic photoinhibition to photosynthesis in the susceptible clone. Overall, differences in the ability for light capture, use and dissipation may play a significant role in explaining the clonal differences in Eucalyptus in response to P. psidii infection. To our knowledge, this is the first report of the effect of rust infection on gas exchange and chlorophyll a fluorescence parameters in Eucalyptus.

Estimates of genetic parameters for physic nut traits based in the germplasm two years evaluation

In spite of increasingly widespread interest in planting physic nut, breeding efforts are still in its infancy. In that context, an important resource recently established aiming future breeding efforts was the assembly of a germplasm bank with near 200 accessions. The objective of this study was to estimate genetic parameters, repeatibility coefficients and genetic correlation between seven traits, measured in 110 accessions (half sib families) of this germplasm bank in different stages of development. The results show that higher relative values of additive variance were only found for yield and height, and the existence of low environmental variation (either of temporary or permanent nature) among plots within blocks. Given the high repeatibility values found for all traits, on average three measurements are necessary to predict, accurately and efficiently, the true breeding value of an individual. Based on the results of genetic correlations, breeding effort should initially be use track trees with increased stem diameter, elevated number of branches and canopy volume so as to increase the chances of finding an exceptionally highly productive tree.

Genetic mapping provides evidence for the role of additive and non-additive QTLs in the response of inter-specific hybrids of Eucalyptus to Puccinia psidii rust infection

Eucalypts are susceptible to a wide range of diseases. One of the most important diseases that affect Eucalyptus plantations worldwide is caused by the rust fungus Puccinia psidii. Here, we provide evidence on the complex genetic control of rust resistance in Eucalyptus inter-specific hybrids, by analyzing a number of full-sib families that display different patterns of segregation for rust resistance. These families are totally unrelated to those previously used in other inheritance studies of rust resistance. By using a full genome scan with 114 genetic markers (microsatellites and expressed sequence tag derived microsatellites) we also corroborated the existence and segregation of a resistance locus, explaining 11.5% of the phenotypic variation, on linkage group 3, corresponding to Ppr1. This find represents an additional validation of this locus in totally unrelated pedigree. We have also detected significant additive × additive digenic interactions with LOD >10.0 on several linkage groups. The additive and epistatic QTLs identified explain between 29.8 and 44.8% of the phenotypic variability for rust resistance. The recognition that both additive and non-additive genetic variation (epistasis) are important contributors to rust resistance in eucalypts reveals the complexity of this host-pathogen interaction and helps explain the success that breeding has achieved by selecting rust-resistant clones, where all the additive and non-additive effects are readily captured. The positioning of epistatic QTLs also provides starting points to look for the underlying genes or genomic regions controlling this phenotype on the upcoming E. grandis genome sequence.

Genetic gains in physic nut using selection indexes

Abstract – The objective of this work was to estimate genetic gains in physic nut ( Jatropha curcas ) using selection indexes and to establish the best selection strategy for the species. Direct and indirect selection was carried out using different selection indexes, totalizing 14 strategies. One hundred and seventy five families from the active germplasm bank of Embrapa Agroenergy, Brasilia, Brazil, were analyzed in a randomized complete block design with two replicates. The evaluated traits were: grain yield; seeds per fruit; endosperm/seed ratio; seed weight, length, width, and thickness; branches per plant at 0.5, 1.0, and 1.5 m; plant height; stem diameter; canopy projection on rows and between lines; canopy volume; juvenility (days to the first flowering); and height of the first inflorescence. Evaluations were done during the second year of cultivation. The use of selection indexes is relevant to maximize the genetic gains in physic nut, favoring a better distribution of desirable traits. The multiplicative and restrictive indexes are considered the most promising for selection.Index terms:

Joint analysis of phenotypic and molecular diversity provides new insights on the genetic variability of the brazilian physic nut germplasm bank

The genetic variability of the Brazilian physic nut (Jatropha curcas) germplasm bank (117 accessions) was assessed using a combination of phenotypic and molecular data. The joint dissimilarity matrix showed moderate correlation with the original matrices of phenotypic and molecular data. However, the correlation between the phenotypic dissimilarity matrix and the genotypic dissimilarity matrix was low. This finding indicated that molecular markers (RAPD and SSR) did not adequately sample the genomic regions that were relevant for phenotypic differentiation of the accessions. The dissimilarity values of the joint dissimilarity matrix were used to measure phenotypic + molecular diversity. This diversity varied from 0 to 1.29 among the 117 accessions, with an average dissimilarity among genotypes of 0.51. Joint analysis of phenotypic and molecular diversity indicated that the genetic diversity of the physic nut germplasm was 156% and 64% higher than the diversity estimated from phenotypic and molecular data, respectively. These results show that Jatropha genetic variability in Brazil is not as limited as previously thought.

Estimate of genetic parameters and predicted gains with early selection of physic nut families.

An initial evaluation of early selection of physic nut genotypes based on phenotypic data is presented. In order to predict the genetic gains with early selection, genetic parameters, e.g. additive genetic variance, were first obtained for grain yield along with other numerous traits. The results demonstrated that additive genetic variance exists not only for grain yield, which is considered to be the most important trait for oil and biodiesel production, but also for numerous other traits. The predicted genetic gains for grain yield, considering the selection of the 30, 20, 10 and 5 best families in the second crop year are respectively, 40.47, 48.43, 61.78 and 70.28%. With the selection of highly yielding physic nut genotypes indirectly genotypes with enhanced volume would be also selected, because yield exhibits moderate to high genetic correlations with height e canopy volume. The results here presented demonstrate the potential of the population gathered in the Brazilian physic nut germplasm bank for genetic breeding purposes and that superior physic nut families can be selected with high accuracy based on the evaluation of its second crop.

Desempenho agronômico e ganho genético pela seleção de pinhão‑manso em três regiões do Brasil

The objective of this study was to evaluate the agronomic performance and genetic gain by the selection of half-sib families of physic nut grown in three Brazilian regions. Based on previous phenotypic selection, three progeny tests were performed, in 2008, in the municipalities of Planaltina, DF, Nova Porteirinha, MG, and Pelotas, RS. A randomized complete block design was used, with three replicates, and five plants per plot. Randomly collected seeds from a population without selection were used as control. There was a significant interaction between the effects of genotypes and environments. Estimates of variance components and genetic parameters indicated that it is possible to obtain genetic gains from selection of the best families in the evaluated environments. In each environment, at least one family was selected with a higher performance than the control treatment. Mass selection in the three environments provided 72% of genetic gains. The agronomic performance had a high correlation coefficient between the environments of Planaltina and Nova Porteirinha, which did not occur in Pelotas. Genotype x environment interaction should be considered in the recommendations of physic nut genetic material for different environments.

Perennial plants for biofuel production: Bridging genomics and field research

Development of dedicated perennial crops has been indicated as a strategic action to meet the growing demand for biofuels. Breeding of perennial crops,however, is often time- and resource-consuming. As genomics offers a platform from which to learn more about the relationships of genes and phenotypes,its operational use in the context of breeding programs through strategies such as genomic selection promises to foster the development of perennial crops dedicated to biodiesel production by increasing the efficiency of breeding programs and by shortening the length of the breeding cycles.