Holm oak decline is determined by shifts in fine root phenotypic plasticity in response to belowground stress

Climate change and pathogen outbreaks are the two major causes of decline in Mediterranean holm oak trees (Quercus ilex L. subsp. ballota (Desf.) Samp.). Crown-level changes in response to these stressful conditions have been widely documented but the responses of the root systems remain unexplored. The effects of environmental stress over roots and its potential role during the declining process need to be evaluated. We aimed to study how key morphological and architectural root parameters and nonstructural carbohydrates of roots are affected along a holm oak health gradient (i.e. within healthy, susceptible and declining trees). Holm oaks with different health statuses had different soil resource-uptake strategies. While healthy and susceptible trees showed a conservative resource-uptake strategy independently of soil nutrient availability, declining trees optimized soil resource acquisition by increasing the phenotypic plasticity of their fine root system. This increase in fine root phenotypic plasticity in declining holm oaks represents an energy-consuming strategy promoted to cope with the stress and at the expense of foliage maintenance. Our study describes a potential feedback loop resulting from strong unprecedented belowground stress that ultimately may lead to poor adaptation and tree death in the Spanish dehesa.This research was mainly funded by the Spanish Government through the IBERYCA project (CGL2017-84723-P), its associated FPI scholarship BES-2014-067971 (ME-V) and SMARTSOIL (PID2020-113244GB-C21). It was further supported by the BC3 María de Maeztu excellence accreditation (MDM-2017-0714; the Spanish Government) and by the BERC 2018–2021 and the UPV/EHU-GV IT-1018-16 programme (Basque Government). Additionally, this research was further supported through the ‘Juan de la Cierva programme’ (MV; IJCI-2017-34640; the Spanish Government) and one project funded by the Romanian Ministry of Research, Innovation and Digitization through UEFISCDI (A-MH; REASONING, PN-III-P1-1.1-TE-2019-1099)

Short-Term Exposure to High Atmospheric Vapor Pressure Deficit (VPD) Severely Impacts Durum Wheat Carbon and Nitrogen Metabolism in the Absence of Edaphic Water Stress

Low atmospheric relative humidity (RH) accompanied by elevated air temperature and decreased precipitation are environmental challenges that wheat production will face in future decades. These changes to the atmosphere are causing increases in air vapor pressure deficit (VPD) and low soil water availability during certain periods of the wheat-growing season. The main objective of this study was to analyze the physiological, metabolic, and transcriptional response of carbon (C) and nitrogen (N) metabolism of wheat (Triticum durum cv. Sula) to increases in VPD and soil water stress conditions, either alone or in combination. Plants were first grown in well-watered conditions and near-ambient temperature and RH in temperature-gradient greenhouses until anthesis, and they were then subjected to two different water regimes well-watered (WW) and water-stressed (WS), i.e., watered at 50% of the control for one week, followed by two VPD levels (low, 1.01/0.36 KPa and high, 2.27/0.62 KPa; day/night) for five additional days. Both VPD and soil water content had an important impact on water status and the plant physiological apparatus. While high VPD and water stress-induced stomatal closure affected photosynthetic rates, in the case of plants watered at 50%, high VPD also caused a direct impairment of the RuBisCO large subunit, RuBisCO activase and the electron transport rate. Regarding N metabolism, the gene expression, nitrite reductase (NIR) and transport levels detected in young leaves, as well as determinations of the δ15N and amino acid profiles (arginine, leucine, tryptophan, aspartic acid, and serine) indicated activation of N metabolism and final transport of nitrate to leaves and photosynthesizing cells. On the other hand, under low VPD conditions, a positive effect was only observed on gene expression related to the final step of nitrate supply to photosynthesizing cells, whereas the amount of 15N supplied to the roots that reached the leaves decreased. Such an effect would suggest an impaired N remobilization from other organs to young leaves under water stress conditions and low VPD.This work was supported by the Spanish Innovation and Universities Ministry (AGL2016-79868-R; 427 PCIN-2017-007) and the Basque Country Government consolidated group program (IT-932-16)

Analysis of the effect of temperature on yield components and starch concentration in tritordeum and wheat

Resumen del trabajo presentado en el II Simposio Español de Fisiología y Mejora de Cereales, celebrado en Córdoba (España), los días 6 y 7 de marzo de 2019Cereal production is highly dependent on environmental conditions. Elevated temperature is a key factor currently affecting crop yield and grain quality. Tritordeum is fertile amphiploid derived from the crosses between Hordeum chilense, and Triticum durum (tetraploid or hexaploid). This cereal has been described to display important grain nutritional properties. One high yielded bread wheat genotype (Togano) and four tritordeum lines (HTC15432, HT435, HT621, Bulel T1) were selected for this study. Bulel T1 is the commercial tritordeum line, HTC15432 is a new line with high yield and both HT435, HT621 were selected for their high lutein content. These plants were grown in greenhouses under two temperature levels (ambient temperature, Tambient versus elevated temperature, Tambient +4ºC) in order to test the impact of temperature increase on crop productivity and nutritional traits. Together with the agronomic characterization (aboveground biomass, grain yield, kernel number/plant, spike number/plant, thousand kernel weight (TKW) and harvest index (HI), starch, C/N % and protein concentration were determined in grains. Grain yield analyses showed that temperature effect on crop production varied depending on the analysed variety. While HT15432, yield decreased, HT435 production significantly increased. In other cases, no significant effects were observed

Functional traits of field-droughted contrasting rice genotypes reveal multiple independent genomic adaptations and metabolic responses

Drought is the most critical environmental stress limiting crop productivity and yield. Rice is one of the top leading food crops worldwide and modern rice varieties are notably drought-sensitive due to their high-water requirements. Generating drought-resilient varieties and fine-tuning their yield performance are time-consuming tasks that could be achieved by exploiting the genetic diversity expressed by the wild ancestors of current-day crop species. We conducted a large-scale field experiment, imposing pre-flowering and post-flowering water shortages on 20 Oryza genotypes. Using detailed agro-physiological, isotopomics, and metabolite characterization of different Asian and African rice accessions, we shed light on the evolutionary biases that have evolved into the spectrum of strategies used to adapt to drought and have added to the rice knowledge base. We find that relevant decreases in photosynthetic rates (linked with stomatal opening) that differed between genotypes. We also identified genotypic differences in core C and N metabolism, and central metabolic pathways, highlighting the possible mechanisms of drought tolerance. Additionally, data suggest strong genetic associations of several amino acids that are significantly enriched during drought. We provide strong evidence of the distinctiveness of agro-physiological and metabolic pathway behaviors to drought across the use of diverse germplasm resources. Also, the resulting data provide insight into the wide variety of germplasm responses triggered by drought.This work was supported by grants JPMJSC16C5 from EIG CONCERT–Japan under the Strategic International Collaborative Research Program by the JST SICORP and PCIN-2017-007 from the Spanish Science, by Innovation and Universities Ministry (Acciones de programación conjunta Internacional). A Grant for Promotion of KAAB Projects (Niigata University, Japan) from the Ministry of Education, Culture, Sports, Science, and Technology is also acknowledged

Rapid phenotyping tools applied to the prediction of wheat grain yield and quality traits of Navarra: A multi-local study

Resumen del trabajo presentado en el II Simposio Español de Fisiología y Mejora de Cereales, celebrado en Córdoba (España), los días 6 y 7 de marzo de 2019The general objective of the present study was to analyze the correlation between different rapid phenotyping tools and production parameters in the two most cultivated bread wheat varieties in Navarra (Camargo and Marcopolo). In the present study, 17 parcels in Navarre distributed in the north, center and south of the community were analyzed. During the months of May and June, in vivo measures were carried out with SPAD equipment, GreenSeeker and infrared thermometer. Parallel to these measurements, samples of flag and second leaves were taken. Upon reaching the maturity period, samples of mature grain were taken and the yield of the crops was quantified. With the aforementioned samples, the following parameters were quantified: d13C, d15N, C/N, alveographic parameters, gliadins and glutenins

Impact of water availability in quinoa (cv. Vikinga) yield and quality traits

Trabajo presentado a la XXIII Reunión Bianual de la Sociedad Española de Fisiología Vegetal y al XVI Congreso Hispano-Luso de Fisiología Vegetal, celebrados en Pamplona (España) del 26 al 28 de junio de 2019

Photosynthetic metabolism under stressful growth conditions as a bases for crop breeding and yield improvement

23 Pags.- 4 Figs. © 2020 by the authors. Licensee MDPI, Basel, Switzerland. This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY) license.Increased periods of water shortage and higher temperatures, together with a reduction in nutrient availability, have been proposed as major factors that negatively impact plant development. Photosynthetic CO2 assimilation is the basis of crop production for animal and human food, and for this reason, it has been selected as a primary target for crop phenotyping/breeding studies. Within this context, knowledge of the mechanisms involved in the response and acclimation of photosynthetic CO2 assimilation to multiple changing environmental conditions (including nutrients, water availability, and rising temperature) is a matter of great concern for the understanding of plant behavior under stress conditions, and for the development of new strategies and tools for enhancing plant growth in the future. The current review aims to analyze, from a multi-perspective approach (ranging across breeding, gas exchange, genomics, etc.) the impact of changing environmental conditions on the performance of the photosynthetic apparatus and, consequently, plant growth.This work was supported by the Spanish Innovation and Universities Ministry (AGL2016-79868-R; PCIN-2017-007).Peer reviewe

Short-Term Exposure to High Atmospheric Vapor Pressure Deficit (VPD) Severely Impacts Durum Wheat Carbon and Nitrogen Metabolism in the Absence of Edaphic Water Stress

Low atmospheric relative humidity (RH) accompanied by elevated air temperature and decreased precipitation are environmental challenges that wheat production will face in future decades. These changes to the atmosphere are causing increases in air vapor pressure deficit (VPD) and low soil water availability during certain periods of the wheat-growing season. The main objective of this study was to analyze the physiological, metabolic, and transcriptional response of carbon (C) and nitrogen (N) metabolism of wheat (Triticum durum cv. Sula) to increases in VPD and soil water stress conditions, either alone or in combination. Plants were first grown in well-watered conditions and near-ambient temperature and RH in temperature-gradient greenhouses until anthesis, and they were then subjected to two different water regimes well-watered (WW) and water-stressed (WS), i.e., watered at 50% of the control for one week, followed by two VPD levels (low, 1.01/0.36 KPa and high, 2.27/0.62 KPa; day/night) for five additional days. Both VPD and soil water content had an important impact on water status and the plant physiological apparatus. While high VPD and water stress-induced stomatal closure affected photosynthetic rates, in the case of plants watered at 50%, high VPD also caused a direct impairment of the RuBisCO large subunit, RuBisCO activase and the electron transport rate. Regarding N metabolism, the gene expression, nitrite reductase (NIR) and transport levels detected in young leaves, as well as determinations of the δ15N and amino acid profiles (arginine, leucine, tryptophan, aspartic acid, and serine) indicated activation of N metabolism and final transport of nitrate to leaves and photosynthesizing cells. On the other hand, under low VPD conditions, a positive effect was only observed on gene expression related to the final step of nitrate supply to photosynthesizing cells, whereas the amount of 15N supplied to the roots that reached the leaves decreased. Such an effect would suggest an impaired N remobilization from other organs to young leaves under water stress conditions and low VPD.This work was supported by the Spanish Innovation and Universities Ministry (AGL2016-79868-R; 427 PCIN-2017-007) and the Basque Country Government consolidated group program (IT-932-16).Peer reviewe