Proline priming: An efficient strategy to mitigate salinity impact at early developmental stages of the oilseed halophyte Cakile maritima

Seed germination is a vital process, yet extremely sensitive to salinity. This is particularly true for coastal halophytes like the annual oilseed species Cakile maritima, which faces the simultaneous impact of wind, salt-spray and seawater inundations in its natural biotopes. At the early developmental stages, this may jeopardize seed germination, plant establishment capacity and hence its development and persistence. Osmopriming is a pre-sowing approach aiming to improve seedling emergence and establishment in adverse environments. Here, we investigate the effect of proline (at 0, 1, 5, and 20 mM) pre-treatment on salt tolerance of C. maritima at the juvenile stage under salinity (0, 100, and 200 mM NaCl). Proline seed priming enhanced the germination rate (28% to 92%) and promoted seedling establishment of C. maritima by stimulating α-amylase activity even at the highest salinity (+55 %). Besides, after transfer of non-germinated seeds on distilled water, salt impact was fully reversible. At the seedling stage, chlorophyll fluorescence parameters showed that this osmoticum increased the maximal quantum yield of PSII photochemistry (Fv/Fm) and the quantum yield of photochemical energy conversion [Y(II)]. In contrast, the quantum yield of nonregulated nonphotochemical energy dissipation [Y(NO)] and the quantum yield of regulated nonphotochemical energy dissipation [Y(NPQ)], which might be correlated to the mitigation of the salt deleterious effects on PSII. Proline and carbohydrate concentrations also increased following priming. Overall, our data provide strong arguments for using proline at low doses (1 and 5 mM) as a successful priming agent to alleviate salinity-induced adverse effect on plants

Splenogonadal Fusion Discovered by Testicular Torsion

Splenogonadal fusion, which is adherence of splenic tissue to gonads, is an uncommon congenital anomaly which mainly affects males. Herein, we report a case of splenogonadal fusion in a 20-month-old boy presenting with acute scrotal pain and inflammation. With the suspicion of left testicular torsion, an emergent left scrotal exploration was carried out. It revealed a necrotic left testicle along with a 360° rotation of the spermatic cord and three accessory structures in the lower pole of the testicle. Histology showed the presence of a splenic tissue. Splenogonadal fusion can present as an acute condition mimicking a testicular torsion. But, one should always bear in mind the possibility of this association. Splenogonadal fusion should be included in differential diagnosis of testicular mass to avoid unnecessary orchidectomy

Clonage et caractérisation électrophysiologique d’un transporteur HKT chez l’orge sauvage Hordeum maritimum

Clonage et caractérisation électrophysiologique d’un transporteur HKT chez l’orge sauvage Hordeum maritimum. Journées Internationales de Biotechnologie 2015 (Association Tunisienne de Biotechnologie

Clonage et caractérisation électrophysiologique d’un transporteur HKT chez l’orge sauvage Hordeum maritimum

Clonage et caractérisation électrophysiologique d’un transporteur HKT chez l’orge sauvage Hordeum maritimum. Journées Internationales de Biotechnologie 2015 (Association Tunisienne de Biotechnologie

The outward shaker channel OsK5.2 improves plant salt tolerance by contributing to control of both leaf transpiration and K+ secretion into xylem sap

Soil salinity constitutes a major environmental constraint to crop production worldwide. Leaf K+/Na+ homoeostasis, which involves regulation of transpiration, and thus of the xylem sap flow, and control of the ionic composition of the ascending sap, is a key determinant of plant salt tolerance. Here, we show, using a reverse genetics approach, that the outwardly rectifying K+-selective channel OsK5.2, which is involved in both K+ release from guard cells for stomatal closure in leaves and K+ secretion into the xylem sap in roots, is a strong determinant of rice salt tolerance (plant biomass production and shoot phenotype under saline constraint). OsK5.2 expression was upregulated in shoots from the onset of the saline treatment, and OsK5.2 activity in guard cells led to a fast decrease in transpirational water flow and, therefore, reduced Na+ translocation to shoots. In roots, upon saline treatment, OsK5.2 activity in xylem sap K+ loading was maintained, and even transiently increased, outperforming the negative effect on K+ translocation to shoots resulting from the reduction in xylem sap flow. Thus, the overall activity of OsK5.2 in shoots and roots, which both reduces Na+ translocation to shoots and benefits shoot K+ nutrition, strongly contributes to leaf K+/Na+ homoeostasis

Investigation of Na+ and K+ transport in halophytes: Functional analysis of the HmHKT2;1 transporter from Hordeum maritimum and expression under saline conditions

International audienceControl of K+ and Na+ transport plays a central role in plant adaptation to salinity. In the halophyte Hordeum maritimum, we have characterized a transporter gene, named HmHKT2;1, whose homologue HvHKT2;1 in cultivated barley, Hordeum vulgare, was known to give rise to increased salt tolerance when overexpressed. The encoded protein is strictly identical in two H. maritimum ecotypes, from two biotopes (Tunisian sebkhas) affected by different levels of salinity. These two ecotypes were found to display distinctive responses to salt stress in terms of biomass production, Na+ contents, K+ contents and K+ absorption efficiency. Electrophysiological analysis of HmHKT2;1 in Xenopus oocytes revealed distinctive properties when compared to HvHKT2;1 and other transporters from the same group, especially a much higher affinity for both Na+ and K+, and a Na+-K+ symporter behavior in a very broad range of Na+ and K+ concentrations, due to reduced K+ blockage of the transport pathway. Domain swapping experiments identified the region including the 5th transmembrane segment and the adjacent extracellular loop as playing a major role in the determination of the affinity for Na+ and the level of K+ blockage in these HKT2;1 transporters. Analysis (qRT-PCR) of HmHKT2;1 expression in the two ecotypes submitted to saline conditions revealed that the levels of HmHKT2;1 transcripts was maintained constant in the most salt tolerant ecotype while they decreased in the less tolerant one. Both the unique functional properties of HmHKT2;1 and the regulation of the expression of the encoding gene could contribute to H. maritimum adaptation to salinity