16 research outputs found
Anthocyanins are Key Regulators of Drought Stress Tolerance in Tobacco
Abiotic stresses will be one of the major challenges for worldwide food supply in the near future. Therefore, it is important to understand the physiological mechanisms that mediate plant responses to abiotic stresses. When subjected to UV, salinity or drought stress, plants accumulate specialized metabolites that are often correlated with their ability to cope with the stress. Among them, anthocyanins are the most studied intermediates of the phenylpropanoid pathway. However, their role in plant response to abiotic stresses is still under discussion. To better understand the effects of anthocyanins on plant physiology and morphogenesis, and their implications on drought stress tolerance, we used transgenic tobacco plants (AN1), which over-accumulated anthocyanins in all tissues. AN1 plants showed an altered phenotype in terms of leaf gas exchanges, leaf morphology, anatomy and metabolic profile, which conferred them with a higher drought tolerance compared to the wild-type plants. These results provide important insights for understanding the functional reason for anthocyanin accumulation in plants under stress
Age- and season-dependent pattern of flavonol glycosides in Cabernet Sauvignon grapevine leaves
Flavonols play key roles in many plant defense mechanisms, consequently they are frequently investigated as stress sensitive factors in relation to several oxidative processes. It is well known that grapevine (Vitis vinifera L.) can synthesize various flavonol glycosides in the leaves, however, very little information is available regarding their distribution along the cane at different leaf levels. In this work, taking into consideration of leaf position, the main flavonol glycosides of a red grapevine cultivar (Cabernet Sauvignon) were profiled and quantified by HPLCâDAD analysis. It was found that amount of four flavonol glycosides, namely, quercetin-3-O-galactoside, quercetin-3-O-glucoside, kaempferol-3-O-glucoside and kaempferol-3-O-glucuronide decreased towards the shoot tip. Since leaf age also decreases towards the shoot tip, the obtained results suggest that these compounds continuously formed by leaf aging, resulting in their accumulation in the older leaves. In contrast, quercetin-3-O-glucuronide (predominant form) and quercetin-3-O-rutinoside were not accumulated significantly by aging. We also pointed out that grapevine boosted the flavonol biosynthesis in September, and flavonol profile differed significantly in the two seasons. Our results contribute to the better understanding of the role of flavonols in the antioxidant defense system of grapevine
Expression Analysis of Stress-Related genes involved in the response of Durum wheat to salinity and high light
The study of stress-related genes is critical to understand the molecular
mechanisms of stress tolerance in plants. Several studies have
demonstrated the important role of asparagine synthetase, glutamate
decarboxylase and Î1
-pyrroline-5-carboxylate synthase genes signalling
in response to environmental stresses. In order to investigate the
expression changes of these genes in durum wheat under salinity and
high light, a semi-quantitative RT-PCR analysis was performed. High
light increased the gene expression level of TdAsn1 alone (2.6 fold) and
in combination with salinity (2 fold) in comparison with the control at
low light. The isoforms TdAsn2 was expressed at low levels compared to
TdAsn1 and the transcript was present only in leaves in control conditions
or simultaneous stresses . A trend similar to that of TdAsn1 was observed
for P5CS expression. On the contrary, GAD expression was decreased
by salinity and high light (1.1 and 1.5-fold, respectively) and even more
under the two combined stresses (3.7 fold) compared to control. The
expression levels were compared to the respective enzymatic activities.
Our expression data confirmed the pivotal role of the studied genes in
the response to abiotic stresses in durum wheat