Explorando el potencial bioestimulante del alga invasora Rugulopterix okamurae en vid

Trabajo presentado en las IV Jornadas del Grupo de Viticultura de la Sociedad Española de Ciencias Hortícolas, celebradas en Pamplona (España), del 26 al 28 de octubre de 202

Microarray analysis and scale-free gene networks identify candidate regulators in drought-stressed roots of loblolly pine (P. taeda L.)

<p>Abstract</p> <p>Background</p> <p>Global transcriptional analysis of loblolly pine (<it>Pinus taeda </it>L.) is challenging due to limited molecular tools. PtGen2, a 26,496 feature cDNA microarray, was fabricated and used to assess drought-induced gene expression in loblolly pine propagule roots. Statistical analysis of differential expression and weighted gene correlation network analysis were used to identify drought-responsive genes and further characterize the molecular basis of drought tolerance in loblolly pine.</p> <p>Results</p> <p>Microarrays were used to interrogate root cDNA populations obtained from 12 genotype × treatment combinations (four genotypes, three watering regimes). Comparison of drought-stressed roots with roots from the control treatment identified 2445 genes displaying at least a 1.5-fold expression difference (false discovery rate = 0.01). Genes commonly associated with drought response in pine and other plant species, as well as a number of abiotic and biotic stress-related genes, were up-regulated in drought-stressed roots. Only 76 genes were identified as differentially expressed in drought-recovered roots, indicating that the transcript population can return to the pre-drought state within 48 hours. Gene correlation analysis predicts a scale-free network topology and identifies eleven co-expression modules that ranged in size from 34 to 938 members. Network topological parameters identified a number of central nodes (hubs) including those with significant homology (E-values ≤ 2 × 10^-30) to 9-cis-epoxycarotenoid dioxygenase, zeatin O-glucosyltransferase, and ABA-responsive protein. Identified hubs also include genes that have been associated previously with osmotic stress, phytohormones, enzymes that detoxify reactive oxygen species, and several genes of unknown function.</p> <p>Conclusion</p> <p>PtGen2 was used to evaluate transcriptome responses in loblolly pine and was leveraged to identify 2445 differentially expressed genes responding to severe drought stress in roots. Many of the genes identified are known to be up-regulated in response to osmotic stress in pine and other plant species and encode proteins involved in both signal transduction and stress tolerance. Gene expression levels returned to control values within a 48-hour recovery period in all but 76 transcripts. Correlation network analysis indicates a scale-free network topology for the pine root transcriptome and identifies central nodes that may serve as drivers of drought-responsive transcriptome dynamics in the roots of loblolly pine.</p

Strategies in the use of light energy by Genipa spruceana Steyerm seedlings subjected to flooding

In an attempt to elucidate strategies in the use of light energy by G. spruceana seedlings subjected to flooding, we investigated the capacity of light capture and use of light energy by G. spruceana in three growing conditions: 1- absence of flooding (SA), 2- partially flooded (PA) and 3- totally flooded (TA). Destructive and non-destructive measurements, such as specific leaf area, chloroplast pigment (chlorophyll and carotenoids) content and fluorescence analyses, were made at regular intervals over a period of 90 days. All parameters decreased in seedlings subjected to flooding. Plants of treatment TA dropped all of their leaves after 30 days of complete submergence. Chloroplast pigment content differed between treatments SA and TA after 30 days from the start of the experiment; whereas SA and PA plants only differed for this variable after 90 days. Plants subjected to flooding (PA and TA) exhibited high dissipation of photochemical de-excitation (DIo/ABS), indicating a limited efficiency of light energy use. This fact was proven by the performance index (PI ABS) only in analyses after 90 days, and no significant difference was verified for PI ABS among treatments up to 30 days. Therefore, considering that G. spruceana seedlings subjected to flooding reduced the chloroplast pigment content more quickly than PI ABS, we suggest that the light energetic flux in G. spruceana seedlings subjected to flooding, in the beginning, is more restricted to a decrease in the structures that captures light (reduction chlorophyll pigment content) than how the photosynthetic apparatus functions (alterations in photochemical efficiency of photosystem II).Na tentativa de elucidar estratégias de utilização da energia luminosa em plantas jovens de Genipa spruceana Steyerm submetidas ao alagamento, nós investigamos a capacidade de captura e uso de energia luminosa em G. spruceana sob três condições de crescimento1- ausência de alagamento (SA), 2- plantas parcialmente alagadas (PA) e 3- plantas totalmente alagadas (TA). Medidas de área foliar específica, teores de pigmentos cloroplastídicos e fluorescência da clorofila a foram feitas em intervalos regulares no período de 90 dias. Todos os parâmetros analisados diminuíram em condições de alagamento (PA e TA). Aos 30 dias, as plantas no tratamento TA sofreram abscisão foliar. Os teores dos pigmentos cloroplastídicos (clorofilas e carotenóides) entre os tratamentos SA e TA diferiram aos 30 dias. Ao passo que, somente foi possível verificar diferenças entre os tratamentos SA e PA aos 90 dias. As plantas submetidas ao alagamento (PA e TA) exibiram alta dissipação de energia de excitação (DIo/ABS) indicando limitada eficiência na utilização da energia luminosa. Este fato foi comprovado pelos resultados do índice de desempenho (PI ABS) somente ao fim do período experimental (90 dias). Mas, não foi verificado diferença para PI ABS entre os tratamentos aos 30 dias. Portanto, considerando que G. spruceana submetidas ao tratamento TA reduziram seus teores de clorofilas mais rapidamente do que decrescem seus PI ABS, sugere-se que o fluxo de energia luminosa em plântulas de G. spruceana sob alagamento total, no início, é mais restringido pelo decréscimo na estrutura de captura de luz (diminuição dos pigmentos cloroplastídicos) do que no funcionamento do aparato fotossintético (alterações na eficiência fotoquímica do fotossistema II)

EFFETTO DELL’ALTA CO2 SULL’AZIONE DELL’ACIDO LIPOICO IN CVS DI ORZO DIVERSAMENTE SENSIBILI ALLA SALINITA’

Lo stress salino costituisce per l’agricoltura mondiale forse uno dei più importanti stress abiotici. L’alta salinità è un fenomeno che può essere aggravato dalla siccità e/o da pratiche agricole come l’irrigazione con acqua di scarsa qualità. L’alto contenuto di sali causa uno squilibrio nel bilanciamento cellulare ionico che dà luogo a tossicità da ioni e stress osmotico. Insieme a questi fatti, la concentrazione atmosferica di CO2 sta continuamente crescendo e si prevede che entro la fine del 21° secolo raggiungerà il livello di 700 ppm. Sebbene ci siano evidenze che l’elevata CO2 aiuti la crescita e lo sviluppo delle piante, questi effetti positivi sono soggetti all’influenza di altre limitazioni ambientali. In condizioni di alta salinità l’ingresso di CO2 nelle foglie è ridotto in seguito alla chiusura stomatica e di conseguenza risulta depresso il rapporto pCO2/pO2 del cloroplasto con conseguente accumulo del potere fotoriducente e la maggiore produzione di specie reattive dell’ossigeno (ROS). In condizioni di elevata CO2 esiste un gradiente di concentrazione più alto tra l’interno e l’esterno della foglia e questo permette di far diffondere ulteriore CO2 all’interno della foglia. L’accresciuto rapporto pCO2/pO2 in corrispondenza dei siti di fotoriduzione può accrescere l’utilizzazione del NADPH e ridurre la formazione di ROS. L’orzo costituisce una delle specie maggiormente coltivate in tutto il mondo ed è, tra i cereali, una delle colture maggiormente tolleranti la salinità, sebbene differenze tra le varie cv. di orzo possono essere osservate. Dal momento che la salinità provoca uno stress ossidativo e che sembra che l’elevata CO2 possa alleviare gli effetti negativi dello stress riducendo la formazione delle ROS, con il presente lavoro ci proponiamo di studiare che cosa può accadere se si verificano entrambe le condizioni. A tale scopo sono state prese in considerazioni due cv. di orzo diversamente sensibili alla salinità (Alpha ed Iranis). Le piante di orzo sono state sottoposte per 14 giorni a quattro trattamenti con concentrazioni saline crescenti( 0, 80, 160 e 240 mM NaCl) e due livelli di CO2 (350 e 700 ppm). In particolare sono state eseguite misure di lisciviaggio, perossidazione lipidica e del contenuto degli antiossidanti ascorbato, glutatione ed acido lipoico. La salinità induceva uno stress ossidativo nelle foglie di orzo causando danni alle membrane come mostrato dal maggiore lisciviaggio dei soluti e dalla aumentata perossidazione lipidica. Questi incrementi erano meno accentuati nella cv. Iranis che si mostrava quella più tollerante la salinità. Questi effetti negativi erano inoltre mitigati dal trattamento con elevata CO2. La migliore resistenza della cv. Iranis era probabilmente ottenuta perché possiede costitutivamente più alti livelli di acido lipoico, l’antiossidante universale che può rigenerare l’ascorbato ed il glutatione. In condizioni di alta CO2 l’acido lipoico era presente prevalentemente come forma ridotta

Changes in environmental CO2 concentration can modify Rhizobium-soybean specificity and condition plant fitness and productivity

Over the past 10 years, it has been demonstrated in the literature that legume responses to elevated [CO2], whether positive, negative, or null, are in part dependent on the Rhizobium species and genotypes that establish symbiosis with the plant. However, all the strains used in these past experiments were isolated in field conditions at ambient [CO2]. We studied for first time the fitness response of soybean inoculated with a Rhizobium strain that has been previously isolated from nodules of plants grown at elevated [CO2] in field conditions at a FACE site. In experiments developed in controlled growth chambers, and in the field under ambient [CO2], the plants inoculated with the strain isolated at elevated [CO2] showed similar response as plants without inoculation. We hypothesize that deficient nodulation may be associated with a change in root exudates caused by the change in [CO2]. This study showed that the strains isolated in nodules at elevated [CO2] are not capable of properly nodulating soybean plants grown at ambient [CO2] and that the origin of strains do not ensure the performance of plants under the same conditions. However, more research is needed in order to understand how changes in environmental conditions can affect the symbiotic relationship and ultimately how we can improve plant fitness in a changeable world.A. Sanz-Sáez was the recipient of a post-doctoral fellowship granted by the Education, Linguistic Policy, and Education Department of the Basque Country, Spain. This research was financially supported by the following grant: GRUPO GobiernoVasco-IT1022-16.Peer reviewe