RESUMO
Climbing plants are being increasingly viewed as models for bioinspired growing robots capable of spanning voids and attaching to diverse substrates. We explore the functional traits of the climbing cactus Selenicereus setaceus (Cactaceae) from the Atlantic forest of Brazil and discuss the potential of these traits for robotics applications. The plant is capable of growing through highly unstructured habitats and attaching to variable substrates including soil, leaf litter, tree surfaces, rocks, and fine branches of tree canopies in wind-blown conditions. Stems develop highly variable cross-sectional geometries at different stages of growth. They include cylindrical basal stems, triangular climbing stems and apical star-shaped stems searching for supports. Searcher stems develop relatively rigid properties for a given cross-sectional area and are capable of spanning voids of up to 1 m. Optimization of rigidity in searcher stems provide some potential design ideas for additive engineering technologies where climbing robotic artifacts must limit materials and mass for curbing bending moments and buckling while climbing and searching. A two-step attachment mechanism involves deployment of recurved, multi-angled spines that grapple on to wide ranging surfaces holding the stem in place for more solid attachment via root growth from the stem. The cactus is an instructive example of how light mass searchers with a winged profile and two step attachment strategies can facilitate traversing voids and making reliable attachment to a wide range of supports and surfaces.
RESUMO
Indeterminate root growth depends on the stem cell niche (SCN) and root apical meristem (RAM) maintenance whose regulation permits plasticity in root system formation. Using a forward genetics approach, we isolated the moots koom1 ('short root' in Mayan) mutant that shows complete primary RAM exhaustion and abolished SCN activity. We identified that this phenotype is caused by a point mutation in the METHIONINE OVERACCUMULATOR2 (MTO2) gene that encodes THREONINE SYNTHASE1 and renamed the mutant as mto2-2. The amino acid profile showed drastic changes, most notorious of which was accumulation of methionine. In non-allelic mto1-1 (Arabidopsis thaliana cystathionine gamma-synthetase1) and mto3-1 (S-adenosylmethionine synthetase) mutants, both with an increased methionine level, the RAM size was similar to that of the wild type, suggesting that methionine overaccumulation itself did not cause RAM exhaustion in mto2 mutants. When mto2-2 RAM is not yet completely exhausted, exogenous threonine induced de novo SCN establishment and root growth recovery. The threonine-dependent RAM re-establishment in mto2-2 suggests that threonine is a limiting factor for RAM maintenance. In the root, MTO2 was predominantly expressed in the RAM. The essential role of threonine in mouse embryonic stem cells and in RAM maintenance suggests that common regulatory mechanisms may operate in plant and animal SCN maintenance.
Assuntos
Proteínas de Arabidopsis/metabolismo , Arabidopsis/citologia , Arabidopsis/metabolismo , Meristema/citologia , Meristema/metabolismo , Nicho de Células-Tronco/fisiologia , Proteínas de Arabidopsis/genética , Regulação da Expressão Gênica de Plantas/genética , Regulação da Expressão Gênica de Plantas/fisiologia , Mutação/genética , Sementes/citologia , Sementes/metabolismo , Transdução de Sinais/genética , Transdução de Sinais/fisiologiaRESUMO
O objetivo do trabalho foi avaliar a dinâmica da cobertura do solo por plantas e NDVI de duas cultivares de soja com tipo de crescimento indeterminado, em diferentes arranjos espaciais de plantas, compostos por espaçamentos entre fileiras e densidades de semeadura. O experimento foi conduzido nas safras 2013/14 e 2014/15 com delineamento experimental em blocos completos casualizados, esquema fatorial 2 x 4 x 3, com três repetições. Os tratamentos constituíram-se da combinação de duas cultivares: BRS 359 RR e BMX Potência RR, de quatro espaçamentos entre fileiras: 20 cm (reduzido); 20/80 cm (fileira dupla); 50 cm (usual) e 50 x 50 cm (cruzado) e três densidades de semeadura: 150, 300 e 450 mil sementes viáveis ha-1. Foram avaliados o índice de vegetação por diferença normalizada (NDVI) e a porcentagem da cobertura do solo pelo dossel. O NDVI e a porcentagem de cobertura do solo pelo dossel de cultivares modernas de soja, com tipo de crescimento indeterminado, são mais afetados pelos espaçamentos entre fileiras no início do ciclo de desenvolvimento, mas na fase de enchimento de grãos as diferenças são menores. A densidade de 150 mil sementes viáveis ha-1 ocasiona menor NDVI e cobertura do dossel no início do ciclo, entretanto no final do ciclo essa diferença se dissipa e todas as densidades apresentam pleno fechamento do dossel.Palavras-chave: densidade de semeadura; espaçamentos entre fileiras; Glycine max L.; NDVI; tipo de crescimento indeterminado.(AU)
The aim of this work was to evaluate the dynamics of soil coverage by plants and NDVI in two soybean cultivars of indeterminate growth type in different spatial plant arrangement, composed by different row spacing and seeding rates. The experiment was conducted in 2013/14 and 2014/15 growing seasons in a randomized complete block design, with the treatments in a 2 x 4 x 3 factorial arrangement, and with three replications. The treatments consisted of the combination of two soybean cultivars: BRS 359 RR and BMX Potência RR, four row spacings: 20 cm (reduced); 20/80 cm (twin row); 50 cm (standard) and 50 x 50 cm (crossed lines) and three seeding rates (150, 300 and 450 thousand viable seeds ha-1). Were evaluated the Normalized Difference Vegetation Index (NDVI) and the percentage of ground cover by canopy. The NDVI and the percentage of soil covered by the canopy of modern soybean cultivars of indeterminate growth type, are most affected by the row spacing at the beginning of the development cycle, but in the grain filling stage the differences disappear. The density of 150 thousand viable seeds ha-1 leads to lower NDVI and canopy cover early in the cycle, however at the end of the cycle this difference vanishes and all densities have full canopy closure.(AU)
Assuntos
Glycine max/crescimento & desenvolvimento , Análise Espacial , 24444RESUMO
O objetivo do trabalho foi avaliar a dinâmica da cobertura do solo por plantas e NDVI de duas cultivares de soja com tipo de crescimento indeterminado, em diferentes arranjos espaciais de plantas, compostos por espaçamentos entre fileiras e densidades de semeadura. O experimento foi conduzido nas safras 2013/14 e 2014/15 com delineamento experimental em blocos completos casualizados, esquema fatorial 2 x 4 x 3, com três repetições. Os tratamentos constituíram-se da combinação de duas cultivares: BRS 359 RR e BMX Potência RR, de quatro espaçamentos entre fileiras: 20 cm (reduzido); 20/80 cm (fileira dupla); 50 cm (usual) e 50 x 50 cm (cruzado) e três densidades de semeadura: 150, 300 e 450 mil sementes viáveis ha-1. Foram avaliados o índice de vegetação por diferença normalizada (NDVI) e a porcentagem da cobertura do solo pelo dossel. O NDVI e a porcentagem de cobertura do solo pelo dossel de cultivares modernas de soja, com tipo de crescimento indeterminado, são mais afetados pelos espaçamentos entre fileiras no início do ciclo de desenvolvimento, mas na fase de enchimento de grãos as diferenças são menores. A densidade de 150 mil sementes viáveis ha-1 ocasiona menor NDVI e cobertura do dossel no início do ciclo, entretanto no final do ciclo essa diferença se dissipa e todas as densidades apresentam pleno fechamento do dossel.Palavras-chave: densidade de semeadura; espaçamentos entre fileiras; Glycine max L.; NDVI; tipo de crescimento indeterminado.
The aim of this work was to evaluate the dynamics of soil coverage by plants and NDVI in two soybean cultivars of indeterminate growth type in different spatial plant arrangement, composed by different row spacing and seeding rates. The experiment was conducted in 2013/14 and 2014/15 growing seasons in a randomized complete block design, with the treatments in a 2 x 4 x 3 factorial arrangement, and with three replications. The treatments consisted of the combination of two soybean cultivars: BRS 359 RR and BMX Potência RR, four row spacings: 20 cm (reduced); 20/80 cm (twin row); 50 cm (standard) and 50 x 50 cm (crossed lines) and three seeding rates (150, 300 and 450 thousand viable seeds ha-1). Were evaluated the Normalized Difference Vegetation Index (NDVI) and the percentage of ground cover by canopy. The NDVI and the percentage of soil covered by the canopy of modern soybean cultivars of indeterminate growth type, are most affected by the row spacing at the beginning of the development cycle, but in the grain filling stage the differences disappear. The density of 150 thousand viable seeds ha-1 leads to lower NDVI and canopy cover early in the cycle, however at the end of the cycle this difference vanishes and all densities have full canopy closure.