African oil palm has the highest productivity amongst cultivated oleaginous crops. Species can constitute a single crop capable to fulfill the growing global demand for vegetable oils, which is estimated to reach 240 million tons by 2050. Two types of vegetable oil are extracted from the palm fruit on commercial scale. The crude palm oil and kernel palm oil have different fatty acid profiles, which increases versatility of the crop in industrial applications. Plantations of the current varieties have economic life-span around 25–30 years and produce fruits around the year. Thus, predictable annual palm oil supply enables marketing plans and adjustments in line with the economic forecasts. Oil palm cultivation is one of the most profitable land uses in the humid tropics. Oil palm fruits are the richest plant source of pro-vitamin A and vitamin E. Hence, crop both alleviates poverty, and could provide a simple practical solution to eliminate global pro-vitamin A deficiency. Oil palm is a perennial, evergreen tree adapted to cultivation in biodiversity rich equatorial land areas. The growing demand for the palm oil threatens the future of the rain forests and has a large negative impact on biodiversity. Plant science faces three major challenges to make oil palm the key element of building the future sustainable world. The global average yield of 3.5 tons of oil per hectare (t) should be raised to the full yield potential estimated at 11–18t. The tree architecture must be changed to lower labor intensity and improve mechanization of the harvest. Oil composition should be tailored to the evolving needs of the food, oleochemical and fuel industries. The release of the oil palm reference genome sequence in 2013 was the key step toward this goal. The molecular bases of agronomically important traits can be and are beginning to be understood at the single base pair resolution, enabling gene-centered breeding and engineering of this remarkable crop.

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Macaw palm (Acrocomia aculeata (Jacq.) Lodd. ex Mart.) is a tropical species with multiple uses, including oil supply for biodiesel production. However, structural and physiological studies of the seed are still scarce, as well as in vitro propagation techniques. The aim of this study was to characterize the anatomy, histochemistry and ultrastructure of the seed and the in vitro somatic embryo of A. aculeata, gaining insight into relationships between the post-harvest seed behavior and the somatic embryo conversion to plant. The zygotic embryo and the endosperm show high quantities of protein and lipids, stored in protein and lipid bodies, respectively. The cell wall storage polysaccharides occur in the thickened cell wall of the endosperm. The absence of vacuoles and the few organelles, except for the storage ones, indicate low metabolic state of the zygotic embryo, which suggests a orthodox behavior of the seed at maturity. The somatic embryo shows a shoot meristem with few leaf primordia, vacuolated cells and, occasionally, amyloplasts , but not lipid or protein reserves. These characteristics, common in somatic embryogenesis, could be associated with the maturation phase, and, consequently, with the low conversion of these embryos into plants. Key words: macaw palm, zygotic embryo, endosperm, storage reserves Anatomia, histoquímica e ultra-estrutura da semente e do embrião somático de Acrocomia aculeata (Arecaceae)RESUMO: A macaúba (Acrocomia aculeata (Jacq.) Lodd. ex Mart.) é uma espécie tropical com múltiplos usos, incluindo a geração de óleo para a produção de biodiesel. Entretanto, estudos estruturais e fisiológicos da semente ainda são escassos, assim como as técnicas de propagação in vitro. Caracterizaram-se a anatomia, a histoquímica e ultraestrutura da semente e do embrião somático de A. aculeata obtido in vitro, visando a obter relações entre o comportamento pós-colheita da semente e a conversão em planta a partir do embrião somático. O embrião zigótico e o endosperma apresentam alta quantidade de proteínas e lipídios, estocados em corpos protéicos e lipídicos, respectivamente. Os polissacarídeos de reserva da parede celular estão presentes nas paredes celulares espessadas do endosperma. A ausência de vacúolos e as poucas organelas visualizadas, exceto as organelas de reserva, indicam baixo estado metabólico do embrião zigótico, o que sugere comportamento ortodoxo da semente madura. O embrião somático apresenta meristema apical com poucos primórdios foliares, células com vacúolos conspícuos e, ocasionalmente, amiloplastos, mas não há reservas protéicas ou lipídicas. Essas características, comuns na embriogênese somática, podem estar associadas à fase de maturação dos embriões e, consequentemente, com a baixa conversão desses embriões em plantas. Palavras-chave: macaúba, embrião zigótico, endosperma, substâncias de reserva

The Acrocomia aculeata is one of the most promising plants for sustainable production of renewable energy. In order to understand patterns of the distribution of the allelic diversity of A. aculeata ex situ germplasm collection, the present study investigated the hypothesis that the genetic variability of the accessions may match their geographical origin. A genotypic analysis of 77 A. aculeata accessions was conducted with 6 simple sequence repeat markers. A high degree of molecular diversity among the accessions was found, with an average of 9 alleles per locus and a polymorphic information content with a mean of 0.76. A total of 4 clusters was identified by the Bayesian analysis of population structure. The highest subpopulation diversity was identified in Pop1, mainly formed by accessions from State of Mato Grosso do Sul. The populations Pop2A, Pop2B, and Pop2C, all from the State of Minas Gerais, showed high genetic variability as determined by a higher F st, and a wide genetic variance, which were identified within and among the population by analysis of molecular variance. Based on our results and on Vavilov's theory on crop origins, one possible diversity center for A. aculeata is proposed to be in a region in southeast Brazil.

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Estimativas do coeficiente de repetibilidade têm sido utilizadas no estudo de caracteres de várias espécies de palmeiras, auxiliando na definição do número e período adequado de avaliações dos genótipos para maior eficiência dos programas de melhoramento. Para macaúba, não há relatos de estudos dessa natureza. Nesse contexto, faz-se importante a determinação do coeficiente de repetibilidade das seguintes características biométricas dos frutos: peso do fruto, volume do fruto, diâmetro equatorial do fruto, peso da amêndoa, volume da amêndoa, diâmetro da amêndoa e espessura do endocarpo; e a determinação do número mínimo de avaliações para um eficiente processo de seleção e avaliação de subamostras de macaúba. O trabalho foi desenvolvido no Departamento de Fitotecnia da Universidade Federal de Viçosa, analisando-se 145 subamostras de macaúba, provenientes de coletas realizadas nos estados de Minas Gerais, São Paulo, Mato Grosso do Sul, Pará, Maranhão e Pernambuco. Houve diferença significativa para todas as características analisadas e observou-se concordância nas magnitudes dos coeficientes de repetibilidade de cada característica, obtidos pelos diferentes métodos. No entanto, os coeficientes de repetibilidade variam entre as oito características, de 0,68 a 0,99, observados para a característica espessura do endocarpo e volume da amêndoa, respectivamente. As estimativas dos coeficientes de determinação obtidas a partir das 10 repetições para as oito características e pelos quatro métodos foram superiores a 95%. A avaliação de quatro frutos é suficiente para compreensão das características estudadas das subamostras de macaúba com 90% de acurácia.

Acrocomia aculeata (Arecaceae), a palm endemic to South and Central America, is a potential oil crop. Knowledge of the mating system of this species is limited to its reproductive biology and to studies using molecular markers. The present study analyzed genetic diversity between its developmental stages and determined its prevailing mating system in order to support genetic conservation and breeding programs. We tested 9 microsatellite markers in 27 mother trees (adult plants) and 157 offspring (juvenile plants) from the southeastern region of Brazil. Heterozygosity levels differed between the 2 studied life stages, as indicated by the fixation index of adult and juvenile trees, suggesting that selection against homozygotes occurs during the plant life cycle. The mating system parameters analyzed indicate that A. aculeata is predominantly outcrossing (allogamous). However, its low levels of selfing suggest that there is individual variation with regard to self-incompatibility, which can be a survival strategy in isolated or fragmented habitats. Deviations in variance effective size were detected because of high mating rates among relatives and correlated matings. These findings indicate that the main source of inbreeding results from biparental inbreeding in the population and that the progenies are predominantly composed of full-sibs. The information provided by this study on the ecology and reproduction dynamics of A. aculeata should be useful to both breeding and genetic conservation programs, allowing the development of more precise mathematical models and the estimation of the appropriate number of mother trees for seed collection.