Jean Kleber de Abreu Mattos

Avaliação agronômica e identificação de quimiotipos de erva cidreira no Distrito Federal

Agronomic evaluation and identification of Lippia alba chemotypes from Distrito Federal, Brazil The main objective of this work was to describe the essential oil profile of 16 genotypes of Lippia alba from the germplasm collection of the Universidade de Brasilia and to analyze its potential of production. A field assay was carried out in the rural area of Distrito Federal and the following parameters were analyzed: flowering period, growing habit, foliar area, length of the main branch, fresh and dry weight of the biomass (leaves and branches), essential oil content and profile of the constituent volatile oils. Essential oil was extracted using a modified Clevenger apparatus and the constituent volatile oils were analyzed by gas chromatography and GC/MS. The experimental design was randomized blocks with three plants per plot. The following chemotypes were reported: citral-limonene, citral-myrcene, limonene-carvone, citral, linalool, myrcene and linalool-limonene. Higher levels of linalool were found in genotype L.16 (89.8%); myrcene in L.37 (47.6%); limonene in L.27 (36.0%); carvone in L.27 (46.9%) and citral in L.17 (56.7%). The genotypes with the highest leaf area and leaf length of the main branch seem to be correlated with the best yield of essential oil and the higher level of linalool. The yield of essential oil was inversely proportional to the dry weight of biomass. The accessions which presented the highest average yield of the major essential constituent oils were: L.16 (0.77 g pl -1 ) as a source of raw material for linalool production; L.17 (0.17 g pl -1 ) as source of myrcene; L. 27 as source of limonene (0.17 g pl -1 ) and carvone (0.21 g pl -1 ); and L.38 (0.24 g pl -1 ) as a citral source.

Host status of different crops for Meloidogyne ethiopica control

Two greenhouse experiments were carried out to characterize the resistance or susceptibility reactions of 52 species of plants to Meloidogyne ethiopica and their possible adverse effect on nematode population under greenhouse conditions. Tested plants with Reproduction Factor less than one (RF<1.0) were rated as non-hosts or resistant, including: peanut (Arachis hypogaea) ‘Cavalo Vermelho’, forage pigeon peas (Cajanus cajan) ‘IAPAR 43’and ‘PPI 832’, Crotalaria grantiana, C. apioclice, C. spectabilis, dwarf velvet bean (Mucuna deeringiana), castor bean (Ricinus communis) ‘IAC 80’, sorghum (Sorghum bicolor) ‘SARA’, cowpea (Vigna unguiculata) ‘Espace 10’ and ‘Australian’, black oat (Avena strigosa) ‘IAPAR’ 61’, ryegrass (Lolium multiflorum ) ‘Italian’, forage radish (Raphanus sativus var. oleiferus) IPR116’ and rye (Secale cereale) ‘IPR 69’. The first 11 are summer plants and the last four winter plants. The other 37 species/cultivars tested were good hosts or susceptible. Some crop succession systems alternating summer and winter non-host plants are suggested for field experiments to validate these greenhouse results.

Concentration of β-ecydisone (20E) in susceptible and resistant accessions of Pfaffia glomerata infected with Meloidogyne incognita and histological characterisation of resistance

Pfaffia glomerata is a medicinal plant widely distributed in Brazil, which is considered the worlds greatest supplier of P. glomerata roots. Among active ingredients contained in this plant, the steroid β -ecydisone (20E) is the most important compound extracted from roots. This steroid presents therapeutic properties for the treatment of diabetes and haemorrhoids, besides having bioenergy, tonic and aphrodisiac effects. The root-knot nematode Meloidogyne spp. is a major limiting factor in root production. Recent studies showed resistance of accessions of P. glomerata to Meloidogyne incognita . The aims of this work were: i ) to correlate the concentration of 20E with resistance and susceptibility of P. glomerata accessions to M. incognita in inoculated and non-inoculated plants; ii ) to study the effect of the parasitism of M. incognita on the concentration of the steroid 20E in the roots; and iii ) to clarify resistance mechanisms by comparing the response of a highly resistant UFV with a highly susceptible accession (Farm) to nematode infection. The concentration of 20E in the healthy susceptible Farm accession was significantly higher than in the healthy resistant UFV accession, showing that the resistance mechanism was not related to 20E concentrations. Plants of the Farm accession infected with M. incognita showed higher levels of 20E than the non-infected control. A positive and significant Pearson correlation coefficient was observed between 20E concentrations and gall indexes. Resistance of UFV to the root-knot nematode M. incognita was associated with unidentified factors that limited nematode penetration or emigration of second-stage juveniles and with post-penetration responses, including the hypersensitive response. Giant cells were sometimes found in the resistant cultivar, but displayed a highly vacuolated and degraded cytoplasm with thinner cell walls than those induced in the susceptible accession. Microscope observations under UV light showed a strong autofluorescence, suggesting that phenolic compounds may be involved in ginseng UFV resistance.

Chemical characterization of the essential oils from leaves of mandarins Sunki, Cleopatra and their hybrids

Sunki Mandarin [Citrus sunki (Hayata) hort. ex Tanaka] is a type of micromandarin from South China largely used as a rootstock in Brazil. Cleopatra mandarin (Citrus reshni hort. ex. Tanaka) is a well-formed tree, ornamental, with red-orange fruits. The main objective of this work was to analyze the chemical composition of the essential oil in leaves of accessions of Sunki and Cleopatra mandarins and hybrids. The essential oils were obtained from the leaves by hydrodistillation in a Clevenger-type apparatus and analyzed by gas chromatography/flame ionization detector (GC/FID) and GC/mass spectrometry (GC/MS). The oil yields ranged from 1.27% (BCG562 – Hybrid of ‘Sunki’ C12080) to 0.33% (BCG564 – Sunki from Florida) (dry weight basis), and fifty-five constituents were detected. The major constituents were β-pinene (2.5–49.9%), limonene (0–49.0%), sabinene (0.5–35.2%), linalool (0.7–27.3%), thymol methyl ether (0–22.3%), p-cymene (0.2–21.2%), γ-terpinene (0–15.1%), 1.8-cineole (0–11.0%), terpinen-4-ol (0.5–9.4%), (E)-β-ocimene (0.6–6.4%), α-pinene (1.1–4.4%), (E)-nerolidol (1.0–3.2%), α-terpineol (0.4–3.0%) and myrcene (0.7–2.4%).

Reassessment of the Genome Size in Elaeis guineensis and Elaeis oleifera, and Its Interspecific Hybrid

Aiming at generating a comprehensive genomic database on Elaeis spp., our group is leading several R&D initiatives with Elaeis guineensis (African oil palm) and Elaeis oleifera (American oil palm), including the whole-genome sequencing of the last. Genome size estimates currently available for this genus are controversial, as they indicate that American oil palm genome is about half the size of the African oil palm genome and that the genome of the interspecific hybrid is bigger than both the parental species genomes. We estimated the genome size of three E. guineensis genotypes, five E. oleifera genotypes, and two interspecific hybrids genotypes. On average, the genome size of E. guineensis is 4.32 ± 0.173 pg, while that of E. oleifera is 4.43 ± 0.018 pg. This indicates that both genomes are similar in size, even though E. oleifera is in fact bigger. As expected, the hybrid genome size is around the average of the two genomes, 4.40 ± 0.016 pg. Additionally, we demonstrate that both species present around 38% of GC content. As our results contradict the currently available data on Elaeis spp. genome sizes, we propose that the actual genome size of the Elaeis species is around 4 pg and that American oil palm possesses a larger genome than African oil palm.

Seed biometric parameters in oil palm accessions from a Brazilian germplasm bank

The objective of this work was to evaluate the morphological diversity of oil palm seeds and to cluster the accessions according to their morphological characteristics. Forty-one accessions from the oil palm germplasm bank of Embrapa Amazonia Ocidental were evaluated - 18 of Elaeis oleifera and 23 of E. guineensis. The groups were formed based on morphological characteristics, by principal component analysis. In E. oleifera, four groups were formed, tied to their region of origin, but with significant morphological differences between accessions from the same population. For tenera-type E. guineensis seeds, three widely divergent groups were formed, especially as to external parameters, which differentiated them from the other ones. The parameter endocarp thickness stood out in intra- and inter-population differentiation. For dura-type E. guineensis, three groups were formed, with larger seeds and thicker endocarps, which differed from all the other ones. The variability observed for seed characteristics in the analyzed accessions allows the establishment of different groups, to define strategies for genetic improvement.

Primeiro relato de Plasmopara halstedii em Ageratum houstonianum (Asteraceae) no Distrito Federal, Brasil

First report of Plasmopara halstedii on Ageratum houstonianum (Asteraceae) in Distrito Federal, Brazil The occurrence of the sunflower mildew caused by Plasmopara halstedii on Ageratum houstonianum (Asteraceae) is reported for the first time in Brasilia, DF, Brazil. The etiological agent was identified according to its morphological