Phytohormone Profiling method for rice: effects of GA20ox mutation on the gibberellin content of japonica rice varieties

Gibberellins (GAs) are a very important group of phytohormones involved in seed germination, vegetative growth, flowering, and fruit development, being only 4 of the 136 known bioactives: GA1, GA3, GA4 and GA7. It has been evidenced that mutations in the OsGA20ox-2 gene produce rice (Oryza sativa) dwarf varieties, which were one of the main pillars of the green revolution. In this work two main objectives were proposed: (i) develop a rapid and broad phytohormone profiling method and (ii) to study the effects on the GA content of the GA20ox-2 mutation in several rice developmental stages using three varieties (tall variety, elite variety, mutated variety). A phytohormone extraction using an SPE step and HPLC-MS/MS detection using a QqQ instrument was determined which resulted in limits of detection (LOD) and limits of quantification (LOQ) for GAs that varied between 0.1-0.7 and 0.3-2.3 pg/g of rice sample respectively, allowing highly sensitive phytohormones detection in samples. Moreover, a good reproducibility was obtained for the GAs as relative standard deviations (RSD) for a 40 ng/mL pattern varied between 0.3-0.9%. Notoriously, GA1 was absent in the coleoptile and GA4 was the GA with higher content in the majority of developmental stages. We also observed a huge large content increment increase of the 4 bioactive GAs in the internode of the flag leaf of the mutated variety that allowinged it to attain reach the same height as the elite variety. Therefore, we provide a rapid and broad phytohormonal profiling method and evidence that the GA20ox-2 mutation is not the only factor generating dwarf varieties. To our knowledge, this is the first study that it has been reported such a high number of analyzed gibberellins at the same time in rice (Oryza sativa L. ssp. japonica)Oryza sativa japonica)

A novel aspect of essential oils: Coating seeds with thyme essential oil induces drought resistance in wheat

Coating seeds with biostimulants is among the promising approaches in crop production to increase crop tolerance to drought stress. In this study, we evaluated the potential of coating durum wheat seeds of the cultivar 'Karim' with thyme essential oil on enhancing seed germination and seedling growth, and on plant growth promotion and induction of drought resistance. Coated seeds were pre-germinated, grown in hydroponics, and grown in pots under controlled well-watered and progressive water/nutrient stress conditions. Seed coating with thyme oil increased germination rate and enhanced seedling growth development in hydroponics. In the pot experiment, thyme oil increased, when well watered, root and shoot development, chlorophyll, nitrogen balance index (NBI), abscisic acid (ABA), anthocyanins and flavonoids in leaves, decreased nitrogen isotope composition (δ15N) and increased carbon isotope composition (δ13C) of shoots. Increasing water/nutrient stress in control plants induced higher accumulation of ABA and anthocyanins coupled with a transient decrease in chlorophyll and NBI, a decrease in shoot and root development, the Normalized Difference Vegetation Index (NDVI), shoot C content, δ15N, and an increase in δ13C, revealing the avoidance strategy adopted by the cultivar. Thyme oil had the potential to enhance the avoidance strategy by inducing roots elongation, reducing the loss of shoot and roots dry matter and chlorophyll, maintaining balanced NBI, an decreasing anthocyanins, flavonoids, and δ13C via maintaining lower ABA-mediated-stomatal closure. Thyme oil increased shoot N content and δ15N indicating preferential uptake of the 15N enriched NH4+. Coating seeds with thyme oil is suggested as a promising alternative approach to improve plant's water and nutrient status and to enhance drought resistance

Exploring the potential of Meyerozyma guilliermondii on physiological performances and defense response against Fusarium Crown Rot on Durum Wheat

Coating seeds with bio-control agents is a potentially effective approach to reduce the usage of pesticides and fertilizers applied and protect the natural environment. This study evaluated the effect of seed coating with Meyerozyma guilliermondii, strain INAT (MT731365), on seed germination, plant growth and photosynthesis, and plant resistance against Fusarium culmorum, in durum wheat under controlled conditions. Compared to control plants, seed coating with M. guilliermondii promoted the wheat growth (shoot and roots length and biomass), and photosynthesis and transpiration traits (chlorophyll, ɸPSII, rates of photosynthesis and transpiration, etc.) together with higher nitrogen balance index (NBI) and lower flavonols and anthocyanins. At 21 days post infection with Fusarium, M. guilliermondii was found to reduce the disease incidence and the severity, with reduction rates reaching up to 31.2% and 30.4%, respectively, as well as to alleviate the disease damaging impact on photosynthesis and plant growth. This was associated with lower ABA, flavonols and anthocyanins, compared to infected control. A pivotal function of M. guilliermondii as an antagonist of F. culmorum and a growth promoter is discussed

An improved anther culture procedure for obtaining new commercial Mediterranean temperate japonica rice (Oryza sativa) genotypes

Rice is one of the greatest calorie supply for the world population, especially since its production is almost entirely destined to direct human consumption and its demand will increase along with the world population. There are efforts worldwide to increase rice yields by obtaining new improved and stabilized rice lines. The rice anther culture, a fast and cheap technique, allows to obtain double haploid lines in less than one year. We report its application with an improved protocol in four Mediterranean japonica rice genotypes at F2 generation. We performed a screening test for cold-pretreatment at 5.0±0.1°C and concluded that the optimum duration was 9 days as it produced the higher rate of anther-derived callus induction. This revised protocol was successfully applied to the four genotypes, obtaining good results in all the procedure's steps. At the end, more than 100 of double haploid green plants were generated. Moreover, 9 lines obtained from the anther culture procedure showed good qualities for the Spanish market at the growing, farming and grain production level during the field assays. Therefore, we report an improved anther culture procedure for obtaining double haploid lines from temperate japonica rice genotypes showing high commercialization expectance

A comprehensive study of the proteins involved in salinity stress response in roots and shoots of the FL478 genotype of rice (Oryza sativa L. ssp. indica)

Rice, a major staple, is the most salt-sensitive cereal. High salinity triggers several adaptive responses in rice to cope with osmotic and ionic stress at the physiological, cellular, and molecular levels. A major QTL for salinity tolerance, named Saltol, is present on chromosome 1 of Indian landraces such as Pokkali and Nona Bokra. The early proteomic and physiological responses to salinity in roots and shoots of FL478, an inbred rice line harboring the Saltol QTL, were characterized. Plantlets were cultured in hydroponic cultures with 100 mmol L−1 NaCl and evaluated at 6, 24, and 48 h. At the physiological level, root length significantly increased at 48 h, whereas shoot length was reduced. The Na+/K+ ratio was maintained at lower levels in shoots than in roots, suggesting that roots play a protective role. More than 2000 proteins were detected in both tissues. Roots showed a faster and more coordinated proteomic response than shoots, evident after only 6 h of treatment. These responses showed clear correspondence with those of proteins involved in transcription and translation. Maintenance of mitochondrial activity and amino acid metabolism in roots, and activation of stress-responsive proteins such as dehydrins and PLAT in shoots, may play a key role during the response of the plant to salinity stress. Proteomic and physiological responses showed that roots respond in a more highly adaptive manner than shoots to salinity stress, suggesting that this tissue is critical to the tolerance observed in cultivars harboring Saltol.This project has received funding from the European Union’s Horizon 2020 Research and Innovation Program under grant agreement No[678168]-NEURICE. The authors would also like to acknowledge the PFCHA Program of CONICYT for granting C.L. a BecasChile scholarship [72140224].Peer reviewe

A comprehensive study of the proteins involved in salinity stress response in roots and shoots of the FL478 genotype of rice (Oryza sativa L. ssp. indica)

Rice, a major staple, is the most salt-sensitive cereal. High salinity triggers several adaptive responses in rice to cope with osmotic and ionic stress at the physiological, cellular and molecular levels. A major QTL for salinity tolerance, named Saltol, is present on chromosome 1 of Indian landrace varieties such as Pokkali and Nona Bokra. In this study, we characterized the early proteomic and physiological responses to salinity in roots and shoots of FL478, an inbred rice line harboring the Saltol QTL. Plantlets were cultured in hydroponic cultures with 100 mM NaCl and evaluated at 6, 24 and 48 h. At the physiological level, root length significantly increased at 48 h, whereas shoot length was reduced. Moreover, the Na+/K+ ratio was maintained at lower levels in shoots compared to roots, suggesting that roots have a protective role. More than 2000 proteins were detected in both tissues. Roots showed a faster and more coordinated proteomic response than shoots, evident after only 6 h of treatment. These responses were markedly related with transcription- and translation-related proteins. Maintenance of the mitochondrial activity and the amino acids metabolisms in roots, and activation of stress-related proteins such ash dehydrins and PLAT in shoots may play a key role during the response of the plant to salinity stress. Finally, proteomic and physiological responses showed that roots respond in a highly adaptive manner to salinity stress compared to shoots, which suggests that this tissue is critical to the tolerance observed in varieties harbouring the Saltol region

Phytohormone Profiling method for rice: effects of GA20ox mutation on the gibberellin content of japonica rice varieties

Gibberellins (GAs) are a very important group of phytohormones involved in seed germination, vegetative growth, flowering, and fruit development, being only 4 of the 136 known bioactives: GA1, GA3, GA4 and GA7. It has been evidenced that mutations in the OsGA20ox-2 gene produce rice (Oryza sativa) dwarf varieties, which were one of the main pillars of the green revolution. In this work two main objectives were proposed: (i) develop a rapid and broad phytohormone profiling method and (ii) to study the effects on the GA content of the GA20ox-2 mutation in several rice developmental stages using three varieties (tall variety, elite variety, mutated variety). A phytohormone extraction using an SPE step and HPLC-MS/MS detection using a QqQ instrument was determined which resulted in limits of detection (LOD) and limits of quantification (LOQ) for GAs that varied between 0.1-0.7 and 0.3-2.3 pg/g of rice sample respectively, allowing highly sensitive phytohormones detection in samples. Moreover, a good reproducibility was obtained for the GAs as relative standard deviations (RSD) for a 40 ng/mL pattern varied between 0.3-0.9%. Notoriously, GA1 was absent in the coleoptile and GA4 was the GA with higher content in the majority of developmental stages. We also observed a huge large content increment increase of the 4 bioactive GAs in the internode of the flag leaf of the mutated variety that allowinged it to attain reach the same height as the elite variety. Therefore, we provide a rapid and broad phytohormonal profiling method and evidence that the GA20ox-2 mutation is not the only factor generating dwarf varieties. To our knowledge, this is the first study that it has been reported such a high number of analyzed gibberellins at the same time in rice (Oryza sativa L. ssp. japonica)Oryza sativa japonica)

Altered prefrontal cortex activity during working memory task in Bipolar Disorder: A functional Magnetic Resonance Imaging study in euthymic bipolar I and II patients

Working memory (WM) deficits are among the most frequently impaired cognitive domains in patients with Bipolar Disorder (BD), being considered promising cognitive endophenotype of the disorder. However, the related neurobiological correlates still deserve further investigation. The present study was aimed to explore whether dorsolateral prefrontal cortex (DLPFC) activity during WM processing was abnormal in euthymic bipolar patients and may represent a potential trait-related phenotype associated with the disorder. METHODS: Using 3 Tesla functional Magnetic Resonance Imaging (3T fMRI), we studied 28 euthymic bipolar patients (15 BDI and 13 BDII), and 27 healthy controls (HCs), matched for a series of socio-demographic variables, while performing the N-back task for WM assessment. RESULTS: We found that euthymic bipolar patients showed increased right middle frontal gyrus engagement compared with HCs (FWE-corrected p = 1 × 10(-3)), regardless of WM load, and in spite of similar WM behavioral performance between groups. In particular, BDI patients had greater BOLD signal change compared to HCs (post-hoc Tukey HSD, p = 1 × 10(-3)), while BDII patients expressed an intermediate pattern of activation between BDI patients and HCs. No other significant effects were detected in the corrected whole-brain analysis. LIMITATIONS: Sample size, cross-sectional assessment and potential influence of some clinical variables. CONCLUSIONS: Results provide direct evidence of a primary physiological abnormality in DLPFC function in BDI and II, even in the absence of behavioral differences with HCs. Such exaggerated fMRI response suggests inefficient WM processing in prefrontal circuitry, and further studies are warranted to investigate whether the dysfunction is related to the genetic risk for the disorder. Copyright © 2015 Elsevier B.V. All rights reserved