Density and wood anatomy of romeron pine [Retrophyllum rospigliosii (Pilger) C.N. Page] trees eight years old

Se estudió la variación de la densidad y dimensiones de las traqueidas en madera de dos procedencias de pino romerón de ocho años y tres clases de diámetro. En secciones transversales de seis árboles por procedencia, en la base, altura del pecho (AP) y 25, 50 y 75% de la altura total, se extrajeron secciones diametrales para determinar la densidad en su primera mitad, en submuestras a 25, 50, 75 y 100% de la longitud del radio. En la segunda mitad se seleccionaron las maderas temprana y tardía en los anillos de crecimiento pares, para medir las dimensiones de las traqueidas. Los resultados mostraron: (a) disminución radial de la densidad desde el 25% del radio hacia la corteza. Mayor densidad en la base, disminución hasta la altura del pecho (AP), valores intermedios hasta el 50%, y disminución hacia el 75% final; (b) densidad media sin diferencia significativa entre las procedencias Jericó (0,37 g•cm-3) y Mesitas del Colegio (0,36 g•cm-3); (c) incremento radial de las dimensiones de las traqueidas, diferencia significativa entre las procedencias sólo para la longitud, mayores valores en la madera tardía e incremento axial hasta el 75%; (d) formación de dos tipos de madera, una desde la médula hasta el octavo anillo de crecimiento, asociada con madera juvenil o juvenil interna; y otra cerca a la corteza, asociada con madera de transición hacia madera madura o juvenil externa; (e) el análisis de la variación de las características, no permitió observar diferencia marcada entre las procedencias.Variation of density and dimensions of tracheids in wood of pine romeron from two provenances of eight year-old and three diameter classes were studied. In transverse sections of six trees per provenance, in the base, height breast (HB) and 25, 50 and 75% of total height, diametrical sections were took to determine the density in the first half, in subsamples, to 25, 50, 75 and 100% of radial length. In the second half were selected early and late woods in the pair growth rings to measure tracheid dimensions. The results showed: (a) radial decrease of density from the 25% of the radio toward bark. Higher density at the base, decline until the breast high (AP), intermediate values of 50 %, and decreased to final 75%; (b) average density with no significant differences between provenances Jericó (0.37 g/cm3) and Mesitas del Colegio (0.36 g•cm-3), (c) radial increment of tracheids dimensions, significant difference between the provenances only for the length, higher values in late wood and final axial increment to 75%, (d) formation of two wooden types, one from pith until the eighth growth ring, associated with juvenile or internal juvenile wood, and another near the bark, associated with transition wood toward the mature or external juvenile wood, (e) analysis of the variation of characteristics, showed no marked difference among provenance

Comparative Study of Several Fe Deficiency Responses in the Arabidopsis thaliana Ethylene Insensitive Mutants ein2-1 and ein2-5

Iron (Fe) is an essential micronutrient for plants since it participates in essential processes such as photosynthesis, respiration and nitrogen assimilation. Fe is an abundant element in most soils, but its availability for plants is low, especially in calcareous soils. Fe deficiency causes Fe chlorosis, which can affect the productivity of the affected crops. Plants favor Fe acquisition by developing morphological and physiological responses in their roots. Ethylene (ET) and nitric oxide (NO) have been involved in the induction of Fe deficiency responses in dicot (Strategy I) plants, such as Arabidopsis. In this work, we have conducted a comparative study on the development of subapical root hairs, of the expression of the main Fe acquisition genes FRO2 and IRT1, and of the master transcription factor FIT, in two Arabidopsis thaliana ET insensitive mutants, ein2-1 and ein2-5, affected in EIN2, a critical component of the ET transduction pathway. The results obtained show that both mutants do not induce subapical root hairs either under Fe deficiency or upon treatments with the ET precursor 1-aminocyclopropane-1-carboxylate (ACC) and the NO donor S-nitrosoglutathione (GSNO). By contrast, both of them upregulate the Fe acquisition genes FRO2 and IRT1 (and FIT) under Fe deficiency. However, the upregulation was different when the mutants were exposed to ET [ACC and cobalt (Co), an ET synthesis inhibitor] and GSNO treatments. All these results clearly support the participation of ET and NO, through EIN2, in the regulation of subapical root hairs and Fe acquisition genes. The results will be discussed, taking into account the role of both ET and NO in the regulation of Fe deficiency responses

Elucidating the Effect of Nutritional Imbalances of N and K on the Infection of Verticillium dahliae in Olive

The effect of mineral nutrition on wilt diseases has been previously reported in many herbaceous hosts, though such an effect on Verticillium wilt in olive (Olea europaea L.; VWO), caused by Verticillium dahliae, is still uncertain. Field observations reveal that nitrogen (N) excess or imbalances of N-potassium (K) favour VWO epidemics. However, this has yet to be demonstrated. Thus, the aim of this study was to evaluate the influences of nutritional imbalances of N and K in V. dahliae infection of olive. To this end, adjusted treatments with N excess (↑N+↑Na), K deficiency (↓K) and their combination (↑N+↑Na+↓K) were evaluated on the viability of V. dahliae microsclerotia (MS), as well as on disease development in olive plants. In parallel, the potential indirect effect of the treatments on the viability of conidia and MS of V. dahliae was evaluated through the stimuli of root exudates. Treatments ↑N+↑Na and ↑N+↑Na+↓K decreased MS germination and disease progress, whereas ↓K significantly increased both parameters. Root exudates from treated plants increased the conidia germination of V. dahliae but reduced the MS germination. The results of this study will be the basis for planning further research towards a better understanding of the effect of mineral nutrition on VWO

Induced Systemic Resistance (ISR) and Fe Deficiency Responses in Dicot Plants

Plants develop responses to abiotic stresses, like Fe deficiency. Similarly, plants also develop responses to cope with biotic stresses provoked by biological agents, like pathogens and insects. Some of these responses are limited to the infested damaged organ, but other responses systemically spread far from the infested organ and affect the whole plant. These latter responses include the Systemic Acquired Resistance (SAR) and the Induced Systemic Resistance (ISR). SAR is induced by pathogens and insects while ISR is mediated by beneficial microbes living in the rhizosphere, like bacteria and fungi. These root-associated mutualistic microbes, besides impacting on plant nutrition and growth, can further boost plant defenses, rendering the entire plant more resistant to pathogens and pests. In the last years, it has been found that ISReliciting microbes can induce both physiological and morphological responses to Fe deficiency in dicot plants. These results suggest that the regulation of both ISR and Fe deficiency responses overlap, at least partially. Indeed, several hormones and signaling molecules, like ethylene (ET), auxin, and nitric oxide (NO), and the transcription factor MYB72, emerged as key regulators of both processes. This convergence between ISR and Fe deficiency responses opens the way to the use of ISR-eliciting microbes as Fe biofertilizers as well as biopesticides. This review summarizes the progress in the understanding of the molecular overlap in the regulation of ISR and Fe deficiency responses in dicot plants. Root-associated mutualistic microbes, rhizobacteria and rhizofungi species, known for their ability to induce morphological and/or physiological responses to Fe deficiency in dicot plant species are also reviewed herei

Influência de formas de nitrogênio e do ph na correção da deficiência de ferro no girassol Influence of nitrogen forms and ph in the correction of iron deficiency in sunflower

Objetivou-se avaliar o efeito do uso de solução nutritiva com ácido, amônio, nitrato e aplicação de solução ácida foliar em plantas de girassol com deficiência de ferro. O experimento foi realizado com a cultura do girassol (Sungro 393) em câmera de crescimento do Laboratório de Nutrição Vegetal da Universidade de Córdoba, Espanha. Inicialmente, as plantas foram cultivadas durante 11 dias, em vasos contendo 0,5 L de solução nutritiva completa (40 µM de Fe). Em seguida, as plantas foram submetidas ao estresse, renovando com a mesma solução nutritiva, diminuindo a concentração de Fe a 5 µM e acrescentando 15 mM de NaHCO3 e CaCO3 a 0,5 g L-1. Nas plantas com a deficiência de ferro, foram aplicados cinco tratamentos, sendo: (a) controle sem Fe, mantendo a mesma solução nutritiva anterior; (b) solução nutritiva com nitrato 2mM Ca(NO3)2; (c) solução nutritiva com amônio, 2mM (NH4)2SO4; (d) solução nutritiva com HCl diluído, pH 3,5; (e) pulverização das folhas com 0,5 mM H2SO4 e com 5 repetições. Realizou-se avaliação da medida indireta da clorofila e a medida do valor pH da solução nutritiva, a partir de 0; 2; 5 e 7 dias após a aplicação dos tratamentos e, na última avaliação, realizou-se a análise química foliar, determinando o teor de Fe total e a matéria seca da planta. O emprego da solução nutritiva com amônio diminuiu o valor pH da solução nutritiva e incrementou o teor foliar de ferro e o valor SPAD das folhas, eliminando os sintomas visuais de deficiência de ferro em plantas de girassol. O uso de amônio na solução nutritiva, durante sete dias, foi mais efetivo na correção da deficiência de ferro em plantas de girassol, comparado com a solução nutritiva com nitrato e com ácido diluído a pH 3,5 e solução ácida foliar.<br>The objective was to evaluate the effect of using a nutrient solution with acid, ammonium nitrate and foliar application of acid solution in sunflower plants with iron deficiency. The experiment was performed with the culture of sunflower (Sungro 393) in slow growth of the Laboratory of Plant Nutrition, University of Cordoba, Spain. Initially the plants were cultivated for 11 days in pots containing 0.5 L of nutrient solution (40 mM Fe). Then the plants were subjected to stress, renewing with the same nutrient solution, decreasing the concentration of 5 mM Fe and adding 15 mM NaHCO3 and CaCO3 0.5 g L-1. In plants with iron deficiency, was submitted to five treatments, consisting of (a) control without Fe, maintaining the same nutrient solution before (b) nitrate nutrient solution with 2 mM Ca (NO3)2, (c) nutrient solution with ammonium 2 mM (NH4)2SO4 (d) nutrient solution with dilute HCl, pH 3.5 (e) spraying the leaves with 0.5 mM H2SO4 and with five replications. We conducted assessment of indirect measurement of chlorophyll and the measured pH value of the nutrient solution, from 0, 2, 5 and 7 days after treatment application and at last assessment was conducted on the foliar analysis by determining the Fe and total plant dry matter. The use of ammonium nutrient solution decreased the pH of nutrient solution and increased the leaf content of iron and the SPAD value of leaves, eliminating the visual symptoms of iron deficiency in sunflower. The use of ammonium in nutrient solution for seven days, was more effective in correcting iron deficiency in sunflower plants, compared with nitrate and with dilute acid at pH 3.5 and acidic leaf

Anatomía y densidad de la madera de árboles de pino romerón [retrophyllum rospigliosii (pilger) c.n. page] de ocho años de edad

Se estudió la variación de la densidad y dimensiones de las traqueidas en madera de dos procedencias de pino romerón de ocho años y tres clases de diámetro. En secciones transversales de seis árboles por procedencia, en la base, altura del pecho (AP) y 25, 50 y 75% de la altura total, se extrajeron secciones diametrales para determinar la densidad en su primera mitad, en submuestras a 25, 50, 75 y 100% de la longitud del radio. En la segunda mitad se seleccionaron las maderas temprana y tardía en los anillos de crecimiento pares, para medir las dimensiones de las traqueidas. Los resultados mostraron: (a) disminución radial de la densidad desde el 25% del radio hacia la corteza. Mayor densidad en la base, disminución hasta la altura del pecho (AP), valores intermedios hasta el 50%, y disminución hacia el 75% final; (b) densidad media sin diferencia significativa entre las procedencias Jericó (0,37 g•cm-3) y Mesitas del Colegio (0,36 g•cm-3); (c) incremento radial de las dimensiones de las traqueidas, diferencia significativa entre las procedencias sólo para la longitud, mayores valores en la madera tardía e incremento axial hasta el 75%; (d) formación de dos tipos de madera, una desde la médula hasta el octavo anillo de crecimiento, asociada con madera juvenil o juvenil interna; y otra cerca a la corteza, asociada con madera de transición hacia madera madura o juvenil externa; (e) el análisis de la variación de las características, no permitió observar diferencia marcada entre las procedencias

Deficiencias nutritivas en plantas de una savia de tres especies del género Pinus sp. en cultivo hidropónico

El objeto del presente trabajo es el estudio de los efectos de las deficiencias de nitrógeno, fósforo, potasio y hierro en tres especies de pinos mediterráneos: Pinus pinaster Ait., Pinus pinea L. y Pinus halepensis Mill. Las semillas se sembraron en turba con perlita y cuando las plántulas alcanzaron un tamaño medio (P. halepensis: 4,7 cm.; P. pinaster: 4,32 cm.; P. pinea: 4,8 cm.) se trasplantaron al cultivo hidropónico en medio líquido, utilizando soluciones nutritivas deficientes en N, P, K y Fe y una solución control. El cultivo se mantuvo durante 4 meses aproximadamente (abril a julio, 1998) en un umbráculo con un 50 % de sombra. Durante este período se determinaron atributos morfológicos (altura, diámetro, longitud de acículas, peso seco de parte aérea y raíz) y fisiológicos (concentración de clorofila y de nutrientes en hoja), así como los síntomas visibles provocados por las respectivas carencias nutricionales. Las deficiencias nutritivas afectaron a los atributos morfológicos y fisiológicos, produciendo en general una disminución del crecimiento y la aparición de síntomas. Sin embargo estos efectos tuvieron distinta magnitud dependiendo del elemento deficiente y de la especie. Así, la deficiencia de Fe es la que provocó efectos mayores y más rápidos, mientras que la de K tuvo muy poco efecto. Asimismo, los efectos fueron mayores sobre el crecimiento de la parte aérea que sobre la raíz. P. pinaster fue la especie más afectada

Vessel Anatomical Features of ‘Picual’ and ‘Frantoio’, Two Olive Cultivars Different in Resistance against Verticillium Wilt of Olive

The olive tree (Olea europaea), a non-tropical woody crop that occupies the largest area in the world, is severely affected by the fungus Verticillium dahliae worldwide. In this regard, there is currently detailed information on the level of resistance to this pathogen in the main olive varieties. However, there is little information on quantitative aspects of its anatomy and on the existence of anatomical differences between varieties that could be related to the differential resistance response observed. In the present work, a quantitative study of the xylem of ‘Picual’, susceptible, and ‘Frantoio’, resistant, to V. dahliae is carried out. This study also provides quantitative data on the xylem in different areas of the plant, an aspect on which there is not much information for the olive tree. Among the parameters evaluated, it is probably the greater conductive capacity in the xylem tissue that ‘Frantoio’ presents, mainly due to the greater density of its vessels, which has a more relevant role in the resistance and natural recovery that this cultivar manifests to the disease. In any case, these constitutive anatomical differences, and those others that can be induced in plants during infections, should be investigated in future work that includes inoculation with the pathogen