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The salt overly sensitive (SOS) pathway is the only mechanism known for Na extrusion in plant cells. SOS pathway activation involves Ca-sensing proteins, such as calcineurin B-like (CBL) proteins, and CBL-interacting protein kinases (CIPKs). In this signalling mechanism, a transit increase in cytosolic Ca concentration triggered by Na accumulation is perceived by CBL (also known as SOS3). Afterward, SOS3 physically interacts with a CIPK (also known as SOS2), forming the SOS2/SOS3 complex, which can regulate the number downstream targets, controlling ionic homeostasis. For instance, the SOS2/SOS3 complex phosphorylates and activates the SOS1 plasmalemma protein, which is a Na/H antiporter that extrudes Na out of the cell. The CBL-CIPK networking system displays specificity, complexity and diversity, constituting a critical response against salt stress and other abiotic stresses. In a study reported in the journal Plant and Cell Physiology, we showed that NH induces the robust activation of transporters for Na homeostasis in root cells, especially the SOS1 antiporter and plasma membrane H-ATPase, differently than does NO. Despite some studies having shown that external NH ameliorates salt-induced effects on ionic homeostasis, there is no evidence that NH per se or some product of its assimilation is responsible for these responses. Here, we speculate about the signalling role behind glutamine in CBL-CIPK modulation, which could effectively activate the SOS pathway in NH-fed stressed plants.

-Information about the morphology, chemical composition and reserve mobilization is important in understanding the establishment of native and exotic species. The purpose of this study was to describe the morphology, chemical composition, and mobilization of reserves during germination of noni (Morinda citrifolia L.). Biometric and morphological analyzes were performed with 100 randomly selected dried seeds. Other seeds were treated with sulfuric acid PA and soaked in Petri dishes. Collected seeds of five different times of germination were used for cytochemical and chemical analysis. For cytochemical analysis, the cuts of 5 m were submitted to dyes TB at pH 4.0; XP at pH 2.5, reaction of PAS and Sudan IV. The seeds were crushed for chemical analysis with lipids, proteins and soluble sugars extraction that were determined gravimetrically, by the Bradford method and the Antrona method, respectively. The fatty acid composition of the dry seed was determined by gas chromatography. Noni seeds are albuminous and have a thick seed coat, rich in lignin. Lipid and protein bodies were observed inside the endosperm cells, representing 43.50% and 9.15% respectively, while the reservoir of soluble sugars was less than 5%. Linoleic acid was the most prevalent with 68.1%. The lipids were mobilized during germination, suffering a reduction of up to 38% of its total. Proteins, as well as lipids decreased by 25.78% during the germination period observed. The main reserves of noni seeds are lipids and proteins that are mobilized during germination to provide energy and matter to the developing embryo and synthesis of more complex compounds.Key words: Cytochemical. Lipids. Fatty acids. Proteins. Germination.RESUMO -Informações sobre as características morfológicas, a composição química e mobilização de reservas são fundamentais na compreensão do estabelecimento de espécies nativas e exóticas. O objetivo deste trabalho foi descrever a morfologia, a composição química e a mobilização das reservas durante a germinação das sementes de noni (Morinda citrifolia L.). As análises morfológica e biométrica foram feitas com 100 sementes secas escolhidas aleatoriamente. Para as análises citoquímica cortes de 5 µm foram submetidos aos corantes AT em pH 4,0; XP em pH 2,5; reação do PAS e Sudan IV. As determinações químicas para lipídeos, proteínas e açúcares solúveis foram realizadas por gravimetria, pelo método de Bradford e pelo método da Antrona, respectivamente. A composição de ácidos graxos da semente seca também foi determinada por cromatografia gasosa. As sementes de noni são albuminosas e apresentam um tegumento espesso, rico em lignina. Foram observados corpos lipídicos e protéicos nas células do endosperma, representando 43,50% e 9,15%, respectivamente, enquanto que as reservas de açúcares solúveis foram inferiores a 5%. O ácido linoléico foi o mais predominante com 68,1%. Os lipídeos foram mobilizados, sofrendo redução de até 38% do seu total. Como também as proteínas sofreram redução de 25,78% durante o tempo de germinação ...

The cowpea (Vigna unguiculata (L.) Walp) it is a leguminous widely cultivated in Northeast of Brazil. In the state of Ceara, its cultivation is performed mainly by family farms who make use of traditional varieties of good adaptation to the growing region. Thus, characterizing traditional varieties with characteristics of adaptation to regions with water shortage is essential for the production of food in the world, especially in semi-arid regions. In this sense, the objective was to evaluate the physiological and biochemical responses in three genotypes of cowpea, being two traditional varieties grown in Ceara (Sempre-Verde and Cabeça-de-Gato) and a genotype characterized as a standard of drought tolerance (Pingo-de-Ouro-1,2) under three water regimes: irrigated, moderate deficit and severe water deficit. The parameters evaluated were: gas exchange, chlorophyll a fluorescence, photosynthetic pigments, organic solutes (proline, total carbohydrates, reducing and non-reducing carbohydrates), starch and enzyme activity (APX, G-POD, CAT and SOD). The genotype Pingo-de-Ouro-1,2 confirmed its tolerance pattern in a water deficit condition, presenting greater water potential, higher photosynthetic rate, high levels of total carbohydrates and high accumulation of proline. Among the traditional varieties, the Cabeça-de-Gato presented superior photosynthesis to Sempre-Verde higher Electron Transport Rate (ETR), reflecting in a greater photochemical quenching (qP) and a greater accumulation of proline, indicating that this variety presents more pronounced adaptive characteristics for water restriction conditions, which is a common condition to the Brazilian semiarid.

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