Potential of cassava clones enriched with ß-carotene and lycopene for zinc biofortification under different soil Zn conditions.

BACKGROUND: Zinc (Zn) deficiency is a major human health concern worldwide, and biofortification (genetic and agronomic) is a complementary solution for increasing micronutrient contents, including Zn. Cassava (Manihot esculenta Crantz) has been used for Zn biofortification because it is an important staple crop in most countries affected by malnutrition and Zn deficiency. Thus studies on biofortification of this crop can improve its nutritional quality. Zn content in cassava clones enriched with ß-carotene or lycopene and cultivated under different areas and soil managements was investigated to evaluate the influence of genotypic variation and agronomic management on Zn status in the plant. RESULTS: A clone-specific response to total Zn content in the soil was found, with clones 26, 215, and 240 (ß-carotene enriched) and clones 341 and 395 (lycopene enriched) being the most responsive. For both experiments, there was a positive interaction between total soil Zn and Zn content in the roots. CONCLUSIONS: Our results suggest that, by combining plant breeding and agronomic strategies, it is possible to enrich cassava roots with both zinc and ß-carotene or lycopene. © 2018 Society of Chemical Industry.

Natural variation in expression of genes associated with carotenoid biosynthesis and accumulation in cassava (Manihot esculenta Crantz) storage root.

BACKGROUND: Cassava (Manihot esculenta Crantz) storage root provides a staple food source for millions of people worldwide. Increasing the carotenoid content in storage root of cassava could provide improved nutritional and health benefits. Because carotenoid accumulation has been associated with storage root color, this study characterized carotenoid profiles, and abundance of key transcripts associated with carotenoid biosynthesis, from 23 landraces of cassava storage root ranging in color from white-to-yellow-to-pink. This study provides important information to plant breeding programs aimed at improving cassava storage root nutritional quality. RESULTS: Among the 23 landraces, five carotenoid types were detected in storage root with white color, while carotenoid types ranged from 1 to 21 in storage root with pink and yellow color. The majority of storage root in these landraces ranged in color from pale-to-intense yellow. In this color group, total ß-carotene, containing all-E-, 9-Z-, and 13-Z-ß-carotene isomers, was the major carotenoid type detected, varying from 26.13 to 76.72 %. Although no α-carotene was observed, variable amounts of a α-ring derived xanthophyll, lutein, was detected; with greater accumulation of α-ring xanthophylls than of ß-ring xanthophyll. Lycopene was detected in a landrace (Cas51) with pink color storage root, but it was not detected in storage root with yellow color. Based on microarray and qRT-PCR analyses, abundance of transcripts coding for enzymes involved in carotenoid biosynthesis were consistent with carotenoid composition determined by contrasting HPLC-Diode Array profiles from storage root of landraces IAC12, Cas64, and Cas51. Abundance of transcripts encoding for proteins regulating plastid division were also consistent with the observed differences in total ß-carotene accumulation. CONCLUSIONS: Among the 23 cassava landraces with varying storage root color and diverse carotenoid types and profiles, landrace Cas51 (pink color storage root) had low LYCb transcript abundance, whereas landrace Cas64 (intense yellow storage root) had decreased HYb transcript abundance. These results may explain the increased amounts of lycopene and total ß-carotene observed in landraces Cas51 and Cas64, respectively. Overall, total carotenoid content in cassava storage root of color class representatives were associated with spatial patterns of secondary growth, color, and abundance of transcripts linked to plastid division. Finally, a partial carotenoid biosynthesis pathway is proposed.

A Species of the Genus Eubulus (Coleoptera: Curculionidae): A New and More Destructive Cassava Pest in the Brazilian Cerrado.

In 2009, a new pest of cassava crops was observed in the Federal District (Brazil) and identified as Eubulus (Kirsch) sp. (Coleoptera: Curculionidae). The pest is currently distributed in the states of Goiás, Minas Gerais, Mato Grosso do Sul, and Paraná. The larvae consume roots, causing the tissue to rot and making it unfit for consumption. The damage can extend to 100% of the roots. Owing to the potential losses that this pest is capable of causing, studies are needed on its biology, ecology, and future management strategies aimed at minimizing the losses, allowing the continuity of cassava cultivation in Brazil. This study reports on the occurrence of the pest in Brazilian Cerrado, its distribution in Brazil, the symptoms of its infestation and estimates the damage caused.

Expression in Escherichia coli, purification, refolding and antifungal activity of an osmotin from Solanum nigrum.

BACKGROUND: Heterologous protein expression in microorganisms may contribute to identify and demonstrate antifungal activity of novel proteins. The Solanum nigrum osmotin-like protein (SnOLP) gene encodes a member of pathogenesis-related (PR) proteins, from the PR-5 sub-group, the last comprising several proteins with different functions, including antifungal activity. Based on deduced amino acid sequence of SnOLP, computer modeling produced a tertiary structure which is indicative of antifungal activity. RESULTS: To validate the potential antifungal activity of SnOLP, a hexahistidine-tagged mature SnOLP form was overexpressed in Escherichia coli M15 strain carried out by a pQE30 vector construction. The urea solubilized His6-tagged mature SnOLP protein was affinity-purified by immobilized-metal (Ni2+) affinity column chromatography. As SnOLP requires the correct formation of eight disulfide bonds, not correctly formed in bacterial cells, we adapted an in vitro method to refold the E. coli expressed SnOLP by using reduced:oxidized gluthatione redox buffer. This method generated biologically active conformations of the recombinant mature SnOLP, which exerted antifungal action towards plant pathogenic fungi (Fusarium solani f. sp.glycines, Colletotrichum spp., Macrophomina phaseolina) and oomycete (Phytophthora nicotiana var. parasitica) under in vitro conditions. CONCLUSION: Since SnOLP displays activity against economically important plant pathogenic fungi and oomycete, it represents a novel PR-5 protein with promising utility for biotechnological applications.

IRAP and REMAP assessments of genetic similarity in rice.

Rice is a model genome for cereal research, providing important information about genome structure and evolution. Retrotransposons are common components of grass genomes, showing activity at transcription, translation and integration levels. Their abundance and ability to transpose make them good potential markers. In this study, we used 2 multilocus PCR-based techniques that detect retrotransposon integration events in the genome: IRAP (inter-retrotransposon amplified polymorphism) and REMAP (retrotransposon-microsatellite amplified polymorphism). Markers derived from Tos17, a copia-like endogenous retrotransposon of rice, were used to identify genetic similarity among 51 rice cultivars (Oryza sativa L.). Genetic similarity analysis was performed by means of the Dice coefficient, and dendrograms were developed by using the average linkage distance method. A cophenetic correlation coefficient was also calculated. The clustering techniques revealed a good adjustment between matrices, with correlation coefficients of 0.74 and 0.80, or lower (0.21) but still significant, between IRAP and REMAP-based techniques. Consistent clusters were found for Japanese genotypes, while a subgroup clustered the irrigated Brazilian genotypes.

Characterization of Carotenoid-protein Complexes and Gene Expression Analysis Associated with Carotenoid Sequestration in Pigmented Cassava (Manihot Esculenta Crantz) Storage Root.

Carotenoid-protein complex (CPC) was isolated from chromoplast-enriched suspensions of cassava storage root (CSR) using size exclusion chromatography and characterized. Peptide sequences (LC_MS/MS spectrum) obtained from CPC and their corresponding proteins were obtained using publically available databases. Small Heat Shock Proteins (sHSPs) were the most abundant proteins identified in the CPC. Western blot analysis showed that Fribrillin and Or-protein were present in chromoplast-enriched suspensions of yellow root but not in the complex or white root. Results from qRT-PCR helped identify an isoform of HSP21 possessing four single point mutations in the intense yellow CSR that may be responsible for increased sequestration of b-carotene.

Análise da estrutura e diversidade molecular de populações de Spodoptera frugiperda (J.E. Smith) (Lepidoptera: Noctuidae) associadas às culturas de milho e arroz no Rio Grande do Sul / Analysis of the molecular structure and diversity of Spodoptera frugiperda (J.E. Smith) (Lepidoptera: Noctuidae) populations associated to the corn and rice crops in Rio Grande do Sul State, Brazil

O objetivo do trabalho foi analisar a estrutura e a diversidade molecular de quatro populações de Spodoptera frugiperda (J.E. Smith) associadas às culturas de milho e arroz no Rio Grande do Sul. Foram coletadas lagartas de quatro populações em áreas isoladas (distanciadas em mais de 300 km) nos municípios de Santa Rosa (milho) e Uruguaiana (arroz irrigado) e em áreas adjacentes, no município de Pelotas (milho e arroz irrigado). A análise de 40 lagartas (10 de cada população), com cinco combinações de oligonucleotídios iniciadores geraram o total de 241 locos, dentre os quais 229 (95 por cento) foram polimórficos. O dendrograma gerado pelo método de agrupamento UPGMA, baseado na matriz de similaridade de Dice, mostrou sobreposições entre as lagartas das populações estudadas. Os índices de diversidade evidenciaram que 88 por cento da diversidade genética foi observada dentro das populações e 12 por cento entre as populações de S. frugiperda. O dendrograma gerado pelo método de agrupamento UPGMA, baseado na matriz de dissimilaridade das distâncias euclidianas, evidenciou a existência de uma diferenciação entre as populações de acordo com a planta hospedeira, sendo os locos 42 e 47 (M-CTG/E-ACC) capazes de detectar 100 por cento das diferenças genéticas. Esses resultados sugerem que a variação genética das populações de S. frugiperda está associada às plantas hospedeiras, confirmando a presença dos biótipos "milho" e "arroz" de S. frugiperda no Rio Grande do Sul.

The goal of this work was to analyze the molecular structure and diversity of four Spodoptera frugiperda (J.E. Smith) populations associated to the corn and rice crops in Rio Grande do Sul State. Four populations of caterpillars were collected from distinct areas (more than 300 km apart), from the counties of Santa Rosa (corn) and Uruguaiana (irrigated rice), and in adjacent areas in Pelotas county (corn and irrigated rice). The analysis of 40 caterpillars (10 from each population), with five combinations of primers generated a total of 241 loci, among then 229 (95 percent) were polymorphic. The dendrogram generated by the clustering method UPGMA, based on the Dice similarity matrix, showed overlappings among the studied populations. The diversity indexes evidenced that 88 percent of the genetic diversity was observed within populations and 12 percent between S. frugiperda populations. The dendrogram generated by clustering UPGMA method, based on the dissimilarity matrix from the euclydean distances, evidenced the existence of a differentiation among populations according to the host plant, being the loci 42 and 47 (M-CTG/E-ACC) capable of detecting 100 percent of the genetic differences. These results showed that the genetic variation of S. frugiperda populations is associated to host plants, confirming the presence of the "corn" and "rice" biotypes of S. frugiperda in Rio Grande do Sul State.