Identification and expression of different dehydrin subclasses involved in the drought response of Trifolium repens

Reverse transcribed RNAs coding for YnKn, YnSKn, SKn, and KS dehydrin types in drought-stressed white clover (Trifolium repens) were identified and characterized. The nucleotide analyses revealed the complex nature of dehydrin-coding sequences, often featured with alternative start and stop codons within the open reading frames, which could be a prerequisite for high variability among the transcripts originating from a single gene. For some dehydrin sequences, the existence of natural antisense transcripts was predicted. The differential distribution of dehydrin homologues in roots and leaves from a single white clover stolon under normal and drought conditions was evaluated by semi-quantitative RT-PCR and immunoblots with antibodies against the conserved K-, Y- and S-segments. The data suggest that different dehydrin classes have distinct roles in the drought stress response and vegetative development, demonstrating some specific characteristic features. Substantial levels of YSK-type proteins with different molecular weights were immunodetected in the non-stressed developing leaves. The acidic SK2 and KS dehydrin transcripts exhibited some developmental gradient in leaves. A strong increase of YK transcripts was documented in the fully expanded leaves and roots of drought-stressed individuals. The immunodetected drought-induced signals imply that Y- and K-segment containing dehydrins could be the major inducible Late Embryogenesis Abundant class 2 proteins (LEA 2) that accumulate predominantly under drought.

Microclima de la canopia de la vid : influencia del manejo del suelo y coberturas vegetales.

Para determinar la influencia del manejo del suelo sobre el microclima de la canopia se estableció un experimento en un viñedo de Cabernet Sauvignon conducido en doble cordón de pitones en espladero alto. Se aplicaron tres tratamientos: Testigo (TR)-suelo sin maleza; (CVP)-cobertura de suelo espontánea y control del desarrollo vegetativo por desbrozado y (CA)-cobertura de flora espontánea y control del desarrollo vegetativo con aplicación de herbicida de contacto desecante. Se midió la radiación fotosintéticamente activa (PAR), la composición espectral de la radiación directa y reflejada, y la temperatura a nivel de racimos en el interior de la canopia. El TR reflejó más radiación en la zona del UV y del visible. El CVP reflejó entre un 8 y 9%, el CA entre el 16 y 18% y el TR entre 18 y 19%. En la radiación reflejada, la relación rojo/rojo lejano fue mayor en CA y TR, mientras que la relación azul/rojo fue mayor en CVP. La temperatura en el interior de la canopia fue mayor en TR (30,8°C) que en CVP (26,7°C). La utilización de coberturas vegetales de raíces superficiales y permanentemente desbrozadas sería de utilidad para reducir la radiación reflejada y la temperatura de la canopia sin competir con el viñedo por agua y nutrimentos.

Influencia del manejo del suelo y las coberturas vegetales en el microclima de la canopia de la vid, la composición de la uva y el vino

Para determinar la influencia del manejo del suelo sobre la composición de la uva y el vino se estableció un experimento en un viñedo de Cabernet Sauvignon conducido en doble cordón de pitones en espaldero alto. Se aplicaron tres tratamientos: TR-suelo sin maleza; CVP-cobertura de suelo espontánea y control del desarrollo vegetativo por desbrozado y CA-cobertura de flora espontánea y control del desarrollo vegetativo con aplicación de herbicida de contacto desecante. En la uva se determinó el contenido de azúcar, acidez total, pH y la composición fenólica (índice de polifenoles totales (IPT), grado de polimerización, flavonoles, flavan-3-oles, antocianos y proantocianidoles). Se elaboraron vinos que fueron evaluados físico-química y sensorialmente por jueces expertos. CVP tuvo el mayor contenido de antocianas y TR el de flavonoles, flavan-3-oles, proantocianidoles, IPT y grado de polimerización; CA presentó valores intermedios. Los vinos del tratamiento TR tuvieron mayor contenido de alcohol y menor de acidez total, con el color rojo (DO520) más bajo y una intensidad colorante más pequeña. Los vinos de CA y TR resultaron más amargos, más astringentes y más ásperos, y los de CVP tuvieron mayor carácter varietal. Resultó útil el empleo de coberturas de raíces superficiales y permanentemente desbrozadas para provocar cierta disminución en los valores de radiación reflejada y de la temperatura de la canopia. Las elevadas temperaturas y alta radiación solar son perjudiciales para la uva, porque aumentan la producción de quercetina y afectan el metabolismo y la degradación de antocianos.

Comportamiento agrícola y toxicidad de algunos sorgos ensayados en Mendoza

En el presente trabajo se estudia el poder tóxico de 14 sorgos cultivados en dos localidades de la Provincia de Mendoza, complementando con observaciones fenológicas y de desarrollo vegetativo. Se establece la mayor o menor precocidad de cada uno de los sorgos, especialmente durante el período de aprovechamiento como forraje. Se determina el grado de peligrosidad por su ingestión en verde, en dos estados de crecimiento, estableciéndose asimismo el porcentaje de disminución del ácido cianhídrico entre dichos dos estados.

Respuesta fisiológica, productiva y cualitativa del cultivar Syrah (Vitis vinifera L) con diferentes frecuencias de riego y densidad de goteros en suelos arcillosos

La disponibilidad hídrica es uno de los principales factores que determinan el rendimiento del viñedo en muchas regiones vitícolas, por lo que sus consecuencias han sido ampliamente estudiadas. Sin embargo, para una cantidad de agua de riego determinada, otros aspectos como la frecuencia de aplicación, o la combinación entre el caudal de los goteros y la distancia entre los mismos (es decir, el patrón de distribución de agua en el suelo), pueden jugar un papel relevante, pero estos factores han sido poco estudiados. El objetivo de este trabajo ha sido evaluar las implicaciones agronómicas y fisiológicas de dos frecuencias de riego (IrrF, cada 2 y 4 días) y dos patrones de distribución de agua (DisP, goteros de 2 L h-1 separados 0,6 m vs. goteros de 4 L h-1 separados 1,2 m). El experimento se llevó a cabo durante cuatro temporadas consecutivas en un viñedo cv. Syrah con un suelo arcilloso en el centro de España, y los dos factores fueron evaluados bajo dos condiciones de disponibilidad hídrica (Baja: 20% de ETo y Media: 40% de ETo). El efecto de la frecuencia de riego y el patrón de distribución de agua en la respuesta agronómica del cv. Syrah se ha estudiado en el capítulo 1. La frecuencia de riego y el patrón de distribución de agua en el suelo afectaron a algunos aspectos de los componentes de rendimiento y desarrollo vegetativo en las dos condiciones de disponibilidad hídrica, aunque los efectos observados no fueron los mismos todos los años. Los efectos fueron más evidentes para IrrF en condiciones de baja disponibilidad hídrica y para DisP en condiciones de disponibilidad hídrica media. Dos de los cuatro años del experimento, el pasar de frecuencia de riego de 2 días a 4 días causó un incremento medio de rendimiento del 20% para la situación de baja disponibilidad hídrica. La textura del suelo, sin duda ha condicionado los resultados obtenidos en los tratamientos regados con el 20% de la ETo, ya que regar cada dos días implicaba la aplicación de pequeñas cantidades de agua y se formaban bulbos de riego superficiales, probablemente favoreciendo las pérdidas por evaporación. En el capítulo 2, se ha analizado el efecto de la frecuencia de riego y del patrón de distribución de agua en el estado hídrico de la planta y el intercambio gaseoso a nivel de hoja con el fin de explicar las diferencias observadas en la respuesta agronómica. En lo que respecta a la frecuencia de riego, en condiciones de baja disponibilidad hídrica, las plantas regadas cada 4 días (plantas 4d), mostraron mayores tasas de asimilación neta y conductancia estomática que las plantas regadas cada 2 días (plantas 2d), lo que es consistente con la hipótesis de que con la frecuencia de riego de 2 días se produjo una pérdida de eficiencia del uso del agua, probablemente debido a una mayor evaporación como consecuencia del hecho de que el volumen de suelo mojado creado era pequeño y cerca de la superficie. En condiciones de disponibilidad hídrica media, las diferencias en el intercambio gaseoso a nivel de hoja fueron mucho más pequeñas. Al comienzo del verano cada frecuencia de riego se comportó mejor uno de los días de medida, compensando al final del ciclo de riego de 4 días. Sin embargo, a medida que avanzó el verano y el déficit de agua se hizo más alto, las diferencias significativas aparecieron sólo en el 'día 4' del ciclo de riego, cuando las plantas 2d se comportaron mejor que las plantas regadas 4d que llevaban tres días sin regarse. Estas diferencias fisiológicas fueron menores que en condiciones de baja disponibilidad hídrica y al parecer no suficientes para afectar el comportamiento agronómico. En cuanto al patrón de distribución de agua, el efecto fue poco significativo, pero la mayor densidad de goteros tendió a presentar un mayor intercambio gaseoso a nivel de hoja, especialmente a media mañana. El efecto fue más importante para las condiciones de disponibilidad hídrica media. En el capítulo 3, se han comparado las relaciones entre el intercambio gaseoso a nivel de hoja, el estado hídrico y la demanda atmosférica, con el fin de explicar los cambios en la intensidad de la respuesta fisiológica observados en el Capítulo 2. No se han encontrado diferencias en dichas relaciones para el patrón de distribución de agua, por lo que sólo se ha analizado el efecto de la frecuencia de riego. El estudio se ha centrado fundamentalmente en si las plantas mostraron una respuesta fisiológica diferente a los cambios en el estado hídrico y en la demanda atmosférica según el tiempo transcurrido desde el último riego. Las diferencias observadas explican los resultados obtenidos en los capítulos anteriores, y sugieren la existencia de procesos de aclimatación vinculados a la frecuencia de riego y a la disponibilidad hídrica. Las plantas bajo condiciones de baja disponibilidad hídrica se mostraron más aclimatadas al estrés hídrico que aquellas en condiciones de disponibilidad hídrica media. La frecuencia de riego afectó claramente la relación entre los parámetros de intercambio gaseoso a nivel de hoja, el estado hídrico de la planta y las condiciones atmosféricas, y junto con la cantidad de agua aplicada tuvo implicaciones en el desarrollo de mecanismos de aclimatación que afectaron a la respuesta fisiológica de la planta, afectando a la eficiencia del riego. ABSTRACT Water availability is one of the major factors that determine vineyard performance in many grape growing regions, so its implications have been widely studied before. However, for a given irrigation water amount, other aspects such as application frequency, or emitter spacing and flow rate (i.e., distribution pattern), may play a relevant role, but these factors have been scarcely studied. The aim of this work was to evaluate the agronomic and physiological implications of two irrigation frequencies (IrrF, every 2 and 4 days) and two water distribution patterns (DisP, 2 L h−1 emitters every 0.6 m vs. 4 L h−1 emitters every 1.2 m). The experiment was carried out during four consecutive seasons in a cv. Syrah vineyard with a clay soil in central Spain, and the two factors were evaluated under two water availability conditions (LOW WA: 20% of ETo and MEDIUM WA: 40% of ETo). The effect of irrigation frequency and water distribution pattern on the agronomical response of cv. Syrah was studied in Chapter 1. IrrF and DisP affected some aspects of vegetative development and yield components under both water availability conditions, although the effects observed were not the same every year. The effects were more evident for IrrF under low water availability and for DisP under medium water availability. Two out of the four years of the experiment, the change of irrigation frequency from 2 days to 4 days promoted an average yield increase of 20% for the LOW WA situation. Soil texture certainly conditioned the results obtained under LOW WA conditions, since high frequency irrigation implied applying small amounts of water that resulted in limited superficial water bulbs, which probably favored water evaporation. In Chapter 2, the effect of irrigation frequency and water distribution pattern on plant water status and leaf gas exchange was analyzed to explain the differences observed in the agronomical response. Concerning irrigation frequency, under LOW WA conditions, applying irrigation every 4 days, resulted in higher net assimilation rates and stomatal conductance than doing it every 2 days, supporting the hypothesis that the latter frequency resulted in a water use efficiency loss, probably due to higher evaporation as a consequence of the fact the wetted soil volume created was small and close to the surface. Under MEDIUM WA conditions, differences in leaf gas exchange were much smaller. At the beginning of the summer each irrigation frequency behaved better one of the measurements days, compensating at the end of the 4-day irrigation cycle. However, as the summer progressed and water deficit became higher, significant differences appeared only on ‘day 4’ of the irrigation cycle, when 2d plants behaved better than 4d plants. These physiological differences were smaller than under LOW WA conditions and apparently not sufficient to affect agronomical performance. Regarding water distribution pattern, the effect was less significant but the closest emitter spacing resulted in general terms in a higher leaf gas exchange, especially at midmorning. The effect was more noticeable for MEDIUM WA conditions. In Chapter 3, the relationships between leaf gas exchange and leaf water status and atmospheric demand were compared to explain the changes in the intensity of the physiological response observed in Chapter 2. No differences were found in the relationships for water distribution pattern, so only the effect of irrigation frequency was analyzed focusing on whether the plants have a different physiological response to changes in water status and atmospheric demand according to the time elapsed since the last irrigation. Differences observed in the relationships explained the results obtained in the previous chapters, and point at the occurrence of acclimation processes linked to irrigation frequency and to water availability. Plants under LOW WATER AVAILABILITY conditions seemed to be more acclimated to water stress than those under MEDIUM WATER AVAILABILITY conditions. Irrigation frequency clearly affected the relationship between leaf gas exchange parameters, plant water status and atmospheric conditions, and together with the amount of water applied had implications in the development of acclimation mechanisms that affected plant physiological response, thus affecting irrigation efficiency.

A homeobox gene with potential developmental control function in the meristem of the conifer Picea abies

Many homeobox genes control essential developmental processes in animals and plants. In this report, we describe the first cDNA corresponding to a homeobox gene isolated from a gymnosperm, the HBK1 gene from the conifer Picea abies (L.) Karst (Norway spruce). The sequence shows distinct similarities specifically to the KNOX (knotted-like homeobox) class of homeobox genes known from different angiosperm plants. The deduced amino acid sequence of HBK1 is strikingly similar within the homeodomain (84% identical) to the maize gene Knotted1 (Kn1), which acts to regulate cell differentiation in the shoot meristem. This similarity suggested that the phylogenetic association of HBK1 with the KNOX genes might be coupled to a conservation of gene function. In support of this suggestion, we have found HBK1 to be expressed in the apical meristem in the central population of nondifferentiated stem cells, but not in organ primordia developing at the flanks of the meristem. This pattern of expression is similar to that of Kn1 in the maize meristem. We show further that HBK1, when expressed ectopically in transgenic Arabidopsis plants, causes aberrations in leaf development that are similar to the effects of ectopic expression of angiosperm KNOX genes on Arabidopsis development. Taken together, these data suggest that HBK1 has a role, similar to the KNOX genes in angiosperms, in the control of cellular differentiation in the apical meristem of spruce. The data also indicate that KNOX-gene regulation of vegetative development is an ancient feature of seed plants that was present in the last common ancestor of conifers and angiosperms.

Phase identity of the maize leaf is determined after leaf initiation

The vegetative development of the maize shoot can be divided into juvenile and adult phases based on the types of leaves produced at different times in shoot development. Models for the regulation of phase change make explicit predictions about when the identity of these types of leaves is determined. To test these models, we examined the timing of leaf type determination in maize. Clones induced in transition leaf primordia demonstrated that the juvenile and adult regions of these leaves do not become clonally distinct until after the primordium is 700 μm in length, implying that these cell fates were undetermined at this stage of leaf development. Adult shoot apices were cultured in vitro to induce rejuvenation. We found that leaf primordia as large as 3 mm in length can be at least partially rejuvenated by this treatment, and the location of rejuvenated tissue is correlated with the maturation pattern of the leaf. The amount and distribution of juvenile tissue in rejuvenated leaves suggests that rejuvenation occurs nearly simultaneously in all leaf primordia. In vitro culture rejuvenated existing leaf primordia and the P0 primordium, but did not change the identity of subsequent primordia or the total number of leaves produced by the shoot. This result suggests that leaf identity can be regulated independently of the identity of the shoot apical meristem, and it implies that vegetative phase change is not initiated by a change in the identity of the shoot apical meristem.

CONTRIBUIÇÃO DOS ATRIBUTOS QUÍMICOS DO SOLO NO DESENVOLVIMENTO VEGETATIVO DO PARICÁ EM DIFERENTES SISTEMAS DE CULTIVO

Objetivou-se avaliar alguns componentes químicos de um Latossolo e a relação com o desenvolvimento vegetativo do paricá [ Schizolobium amazonicum (Huber ex Ducke)] em diferentes sistemas de cultivo em áreas de reflorestamento no município de Tailândia, nordeste paraense. Foram avaliados os sistemas PP [paricá x puerária ( Pueraria phaseoloides )], PA [paricá x acácia ( Acacia mangium )] e P (paricá monocultivo) conduzidos em 5 anos pela empresa G.M. Sufredini Industrial Ltda. e coletadas amostras de solos na profundidade de 0-20 cm para análise de pH, C e N totais, H+Al, P disponível, Ca, Mg, K e Al trocáveis e calculados os valores de C/N, SB, T, V e m. O desenvolvimento vegetativo do paricá foi avaliado pela sobrevivência, mortalidade e no número de plantas defeituosas além do DAP. Os resultados mostraram que houve o aumento no teor de nitrogênio do solo no tratamento PP; a baixa fertilidade do solo no tratamento PA, mas onde o paricá obteve a maior média em diâmetro (DAP = 16,64 cm) e a maior taxa de sobrevivência no tratamento P (90,63%). Conclui-se que a relação solo-planta nos sistemas paricá e puerária e paricá em monocultivo contribuiu para o estabelecimento dos indivíduos de paricá.

Characterization of the susceptibility of the vineyard of Château Margaux to the main fungal-like and diseases

Mestrado Vinifera Euromaster - Instituto Superior de Agronomia - UL

Rate and timing of vegetative growth, flowering and fruit development of Persoonia virgata (Proteaceae)

Persoonia virgata R. Br. is harvested from the wild in both its vegetative and flowering stages. There has been no systematic study published on the annual growth cycle and anecdotal reports are conflicting. The growth pattern, flowering and fruit development of P. virgata in its natural habitat was recorded monthly for two consecutive years. The main growth period occurred in late spring-mid-autumn (November-May) when the shrubs were producing little or no fruit. Very few open flowers were observed at the site over the 2 years, with only 6.7 and 12.7% of stems bearing open flowers in January and February 1996, respectively. A second study of flowering on container-grown shrubs showed that individual flowers were open for only 2-5 days, with individual stems taking 3-8.5 weeks to complete flowering. The main fruit growth period occurred from May to September, and in June and July 1996 the total fruit set per stem was 41.6 and 36.1%, respectively. The fruit took at least 6 months to develop during which vegetative growth was minimal. The harvesting of plants in the flowering or fruiting stages removes the annual seed crop, which may reduce regeneration of this obligate seed regenerator and threaten its survival after fire.

Interaction of temperature and vegetative flush maturity influences shoot structure and development of lychee (Litchi chinensis Sonn.)

Potted lychee trees (cv. Tai so) of varying vegetative flush maturity were grown under a range of temperature regimes and monitored for subsequent shoot structure and development. A combination of low temperature (15/17 or 18/13 degreesC day/night) and high vegetative flush maturity was necessary for floral initiation to occur, Exposure to high temperatures (28/23 degreesC) invariably resulted in the production of vegetative shoots, irrespective of flush maturity. Strong floral initiation was marked by the emergence of terminal particles and accompanying axillary particles. A decrea,;e in vegetative flush maturity or increase in temperature (e.g. 23/18 degreesC) resulted in a decrease in axillary shoot formation and the production of several intermediate shoot structures. These included leafy particles, stunted particles, partially emerged buds and non-emergent swollen buds, often produced on the same tree. At 23/18 degreesC, closer synchronisation of initial flush maturity was required for the production of a consistent shoot-type. Trees with synchronised mature flushes (I-2) at 23/18 degreesC resulted in the production of swollen terminal buds. Healthy trees were maintained in this state for at least 11 months. These results indicate that both temperature and flush maturity can influence subsequent shoot structure of lychee. In the absence of either a strong floral temperature (18/13 degreesC) or strong vegetative temperature (28/23 degreesC), slight differences in initial flush maturity have gteater impact on the type of emerging shoot formed. (C) 2002 Elsevier Science B.V. All rights reserved.

Vegetative and reproductive development of Costa Rican weedy rice compared with commercial rice (Oryza sativa)

The variability in the chronology of the vegetative and reproductive development of weedy rice complex has been little studied. However, a field trial was established to study the timing of growth stages of sixteen weedy rice morphotypes and five rice varieties of Costa Rica. Weedy rice presented a wide range of variation for all descriptors among and within morphotypes. Weedy rice was taller than the rice varieties during vegetative phase and showed a growth increase of 14-23 cm every two weeks. Six morphotypes emerged earlier than commercial rice varieties, but no differences where found between samples for the time required for starting tillering. Early emergence of weedy rice morphotypes was not associated with early flowering, thus no correlation was detected between the vegetative and reproductive phases. All weedy rice morphotypes reached anthesis and maturity earlier than the rice varieties. Nevertheless, varieties Setesa-9 and CR-5272 overlapped anthesis with eleven morphotypes and variety CR-4338 overlapped flowering with eight weedy rice morphotypes. In contrast, none of the morphotypes overlapped anthesis with varieties CR-1821 and CR-1113. The results obtained showed the competitive capacity of weedy rice and provided valuable information about flowering overlap between weedy rice morphotypes and rice varieties which will be useful in the design of gene flow studies among them.

Gibberellic acid in vegetative and reproductive development of Phalaenopsis orchid hybrid genus

O setor de floricultura movimenta cerca de um bilhão de dólares no Brasil e o desenvolvimento de técnicas direcionadas ao controle do florescimento é necessário. O presente trabalho avaliou a influência do ácido giberélico (GA3) no desenvolvimento vegetativo e reprodutivo de plantas jovens de Phalaenopsis FSNT 'Dai-Itigo', híbrido de coloração rósea. A aplicação do GA3 foi feita via pulverização foliar nas concentrações de 0, 125, 250, 500 e 1.000 mg L -1. O comprimento das folhas aumentou consideravelmente com o uso do GA3 em baixas concentrações, porém houve diminuição da largura foliar das plantas tratadas com esse fitorregulador. A aplicação do GA3 na concentração de 125 mg L -1 apresentou os melhores resultados para a promoção do florescimento e qualidade da floração deste híbrido de orquídea. Nesse tratamento, aproximadamente 50% das plantas pulverizadas apresentaram floração cerca de 6-12 meses antes da floração das plantas sem aplicação do fitorregulador. em conclusão, a qualidade da floração e das flores foi melhor no tratamento com 125 mg L -1 de GA3.

Systematic vegetative anatomy and ensiform leaf development in Xyris (Xyridaceae)

Ensiform leaf development in monocotyledons follows a broadly similar sequence in a wide range of relatively unrelated taxa, indicating a plastic developmental pattern, possibly associated with stressed environmental conditions, since Xyris species tend to grow in relatively damp but nutrient-poor environments. The bifacial leaf sheath surrounds the apex and the subadjacent primordium. A conical unifacial leaf tip 'Vorlauferspitze' is established at an early stage, followed by extension growth in the region behind it, generating a unifacial ensiform blade. Root and rhizome structure are also described in a systematic context, particularly in comparison with related taxa in Xyridaceae and other commelinoid monocotyledons, although information on these structure is relatively sparse.

Gibberellic acid in vegetative and reproductive development of Phalaenopsis orchid hybrid genus

The flower industry represents about one billion dollars in Brazil and the development of techniques aimed at flowering control is required. This study evaluated the influence of gibberellic acid (GA3) on the vegetative and reproductive development of young plants of Phalaenopsis FSNT 'Dai-Itigo' hybrid pink color. The application of GA3 was made by foliar sprays at concentrations of 0, 125, 250, 500 and 1,000 mg L -1. The length of leaves increased significantly when using GA3 at low concentrations, but leaf width decreased. The application of GA3 at 125 mg L -1 showed the best results for the promotion of flowering and flower quality of this orchid hybrid. In this treatment, about 50% of plants treated with GA3 flowered about 6-12 months before the plants that were non-treated with this plant growth regulator. The quality of flowering and flowers was best with 125 mg L -1 GA3.