Distinctive phytohormonal and metabolic profiles of Arabidopsis thaliana and Eutrema salsugineum under similar soil drying

Main conclusions: Arabidopsis and Eutrema show similar stomatal sensitivity to drying soil. In Arabidopsis, larger metabolic adjustments than in Eutrema occurred, with considerable differences in the phytohormonal responses of the two species. Although plants respond to soil drying via a series of concurrent physiological and molecular events, drought tolerance differs greatly within the plant kingdom. While Eutrema salsugineum (formerly Thellungiella salsuginea) is regarded as more stress tolerant than its close relative Arabidopsis thaliana, their responses to soil water deficit have not previously been directly compared. To ensure a similar rate of soil drying for the two species, daily soil water depletion was controlled to 5–10% of the soil water content. While partial stomatal closure occurred earlier in Arabidopsis (Day 4) than Eutrema (from Day 6 onwards), thereafter both species showed similar stomatal sensitivity to drying soil. However, both targeted and untargeted metabolite analysis revealed greater response to drought in Arabidopsis than Eutrema. Early peaks in foliar phytohormone concentrations and different sugar profiles between species were accompanied by opposing patterns in the bioactive cytokinin profiles. Untargeted analysis showed greater metabolic adjustment in Arabidopsis with more statistically significant changes in both early and severe drought stress. The distinct metabolic responses of each species during early drought, which occurred prior to leaf water status declining, seemed independent of later stomatal closure in response to drought. The two species also showed distinct water usage, with earlier reduction in water consumption in Eutrema (Day 3) than Arabidopsis (Day 6), likely reflecting temporal differences in growth responses. We propose Arabidopsis as a promising model to evaluate the mechanisms responsible for stress-induced growth inhibition under the mild/moderate soil drying that crop plants are typically exposed to

L'Albinisme oculocutané au Maghreb, à propos de 15 observations en Algérie, Maroc et Tunisie

Nous rapportons l¿étude clinique , biologique et moléculaire de 15 sujets atteints d¿Albinisme OculoCutané (AOC) appartenant à 14 familles originaires de Tunisie (2 cas), d¿Algérie (5 cas) et du Maroc (8 cas) dont 2 proviennent de couples mixtes : Maroc/Algérie et Maroc/France. La consanguinité est présente dans 11 familles et elle a pu être précisée dans 10 cas par le coefficient de consanguinité F= 1/16,1/32 et 1/64 . La recherche des mutations du gène de la tyrosinase caractéristique de l¿AOCIA ou IB a pu être réalisée chez 9 sujets. .Dans 3 cas seulement des mutations faux sens ont été identifiées : 1 mutation homozygote (Y327C) chez un garçon marocain de phénotype AOCIA, 2 mutations hétérozygotes chez un garçon franco-marocain de phénotype AOCIB (V275F/R403S) et chez un garçon algérien de phénotype AOCIA (H404P/ ?)