Salt tolerance and salinity effects on plants: a review.

Elicitor signal transduction leading to production of plant secondary metabolites.

Flora of Turkey and the East Aegean Islands.

Phenolic secondary metabolites play an important role in plant-derived food quality, as they affect quality characteristics such as appearance, flavour and health-promoting properties. Their content in foods is affected by many factors that influence phenolic stability, biosynthesis and degradation. In terms of their biosynthesis the key enzyme phenylalanine ammonia-lyase (PAL) is especially relevant, as it can be induced by different stress (environmental) conditions. In addition, polyphenol oxidases (PPO) and peroxidases (POD) are the main enzymes responsible for quality loss due to phenolic degradation. The different factors affecting phenolic-related food quality are reviewed. These include internal (genetic) and environmental (agronomic) factors, technological treatments applied during postharvest storage of fruits and vegetables, as well as processing and storage of the processed products. The different strategies that are required to either maintain or enhance the phenolic-related quality of foods are critically reviewed. Genetic modification designed to decrease polyphenol oxidases or peroxidases is not always a feasible method, owing to side problems related to the growth and defence of the plant. Agronomic treatments can be used to enhance the phenolic content and pigmentation of fruits and vegetables, although the information available on this topic is very scarce and even contradictory. Some postharvest treatments (cold storage, controlled or modified atmospheres, etc) can also improve phenolic-related quality, as well as new processing methods such as irradiation (gamma, UV), high-field electric pulses, high hydrostatic pressures and microwaves. Les composes phenoliques, metabolites secondaires des plantes, jouent un role dans la qualite des fruits, au niveau de l'apparence, de la flaveur et des qualites nutritives. L'enzyme cle de leur biosynthese est la phenylalanine ammonium-lyase, regulee par les facteurs environnementaux. La polyphenol oxydase et la peroxydase sont responsables des degradations donc des pertes de qualite. Les differents facteurs internes (genetiques) et externes (agronomiques) affectant la qualite des produits vegetaux sont etudies. Les differentes mesures envisageables (modification genetique, traitements chimiques ou physiques apres recolte) pour modifier le contenu en compose phenoliques et donc la qualite des produits vegetaux sont etudies.

Phenolic compounds and related enzymes as determinants of quality in fruits and vegetables

The increasing frequency of dry periods in many regions of the world and the problems associated with salinity in irrigated areas frequently result in the consecutive occurrence of drought and salinity on cultivated land. Currently, 50% of all irrigation schemes are affected by salinity. Nutrient disturbances under both drought and salinity reduce plant growth by affecting the availability, transport, and partitioning of nutrients. However, drought and salinity can differentially affect the mineral nutrition of plants. Salinity may cause nutrient deficiencies or imbalances, due to the competition of Na+ and Cl– with nutrients such as K+, Ca2+, and NO. Drought, on the other hand, can affect nutrient uptake and impair acropetal translocation of some nutrients. Despite contradictory reports on the effects of nutrient supply on plant growth under saline or drought conditions, it is generally accepted that an increased nutrient supply will not improve plant growth when the nutrient is already present in sufficient amounts in the soil and when the drought or salt stress is severe. A better understanding of the role of mineral nutrients in plant resistance to drought and salinity will contribute to an improved fertilizer management in arid and semi-arid areas and in regions suffering from temporary drought. This paper reviews the current state of knowledge on plant nutrition under drought and salinity conditions. Specific topics include: (1) the effects of drought and salt stress on nutrient availability, uptake, transport, and accumulation in plants, (2) the interactions between nutrient supply and drought- or salt-stress response, and (3) means to increase nutrient availability under drought and salinity by breeding and molecular approaches.

https://mediatum.ub.tum.de/doc/1304727/file.pdf

Drought and salinity: A comparison of their effects on mineral nutrition of plants

Crops differ in their ability to grow under saline conditions and their responses are quite variable and not fully understood. This study was conducted to evaluate the root and shoot responses of tomato to salt stress conditions under different levels of phosphorus (P) nutrition. Tomato seedlings (cv Riogrande) were grown in 500 mL glass jars containing Hoagland's solutions which were salinized by four levels of NaCl salt (0,50,100, and 150 mM NaCl) and/or enriched with three P levels (0.5,1, and 2 mM P) making nine combination treatments. Plants were harvested at the vegetative growth stage and data were collected for root and shoot characteristics. The results indicate that increasing salinity stress was accompanied by significant reductions in shoot weight, plant height, number of leaves per plant, and a significant increase in leaf osmotic potential and peroxidase activity regardless of the level of P supplied. Both root length and root surface area per plant were decreased significantly unde...

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Tomato Root and Shoot Responses to Salt Stress Under Different levels of Phosphorus Nutrition

Micropropagation and accumulation of essential oils in wild sage (Salvia fruticosa Mill.)

Greenhouse experiment was conducted to evaluate the effect of arbuscular mycorrhizal fungi (AMF) on plant growth, and nutrient uptake in saline soils with different salt and phosphorus (P) levels. The following treatments were included in this experiment: (i) Soil A, with salt level of 16.6 dS m−1 and P level of 8.4 mg kg−1; (ii) Soil B, with salt level of 6.2 dS m−1 and P level of 17.5 mg kg−1; and (iii) Soil C, with salt level of 2.4 dS m−1 and P level of 6.5 mg kg−1. Soils received no (control) or 25 mg P kg−1 soil as triple super phosphate and were either not inoculated (control) or inoculated with a mixture of AM (AM1) and/or with Glomus intraradices (AM2). All pots were amended with 125 mg N kg−1 soil as ammonium sulfate. Barley (Hordeum vulgar L., cv. “ACSAD 6”) was grown for five weeks. Plants grown on highly saline soils were severely affected where the dry weight was significantly lower than plants growing on moderately and low saline soils. The tiller number and the plant height were a...

Effects of Arbuscular Mycorrhizal Fungi and Phosphorus Fertilization on Growth and Nutrient Uptake of Barley Grown on Soils with Different Levels of Salts

Physiological and biochemical responses of open-pollinated ‘Roma’ and dwarf F1 hybrid ‘Patio’ tomato (Lycopersicon esculentum Mill.) cultivars to in vitro induced salinity were examined in light of the possible contribution of ethylene to these symptoms. Salinity was induced by incorporating 0 (control), 50, 100, 150, or 200 mM NaCl into shoot culture media. Elevated salinity treatments significantly enhanced ethylene accumulation in the headspace and were accompanied by increased leaf epinasty in both cultivars. Growth, leaf cell sap osmolarity, leaf tissue viability and shoot soluble protein content were generally depressed with elevated salinity treatments, whereas electrolyte leakage, membrane injury, raffinose, and total sugars were concomitantly increased. Macronutrients N, P, K, Ca, Mg, and S decreased with elevated salinity in both cultivars and were accompanied by a significant increase in Na content and a sharp decrease in K/Na ratio. Tissue micronutrients, Fe, B, Zn, Mn, and Cu were generally decreased with elevated salinity especially at 100 mM or more. Incorporating ethylene inhibitors CoCl2 or NiCl2 at 5.0 or 10.0 mg/l into media supplemented with 100 mM NaCl significantly reduced ethylene accumulation in the headspace and prevented epinasty, but did not eliminate the negative impacts on growth and other physiological parameters caused by salinity treatment in either cultivar. Our results indicate that the increase in ethylene under salinity stress is not the primary factor contributing to salinity’s deleterious effect on tomato plant growth and physiology.

Rida A. Shibli

Papers

Tomato Root and Shoot Responses to Salt Stress Under Different levels of Phosphorus Nutrition

Micropropagation and accumulation of essential oils in wild sage (Salvia fruticosa Mill.)

Effects of Arbuscular Mycorrhizal Fungi and Phosphorus Fertilization on Growth and Nutrient Uptake of Barley Grown on Soils with Different Levels of Salts

Physiological and biochemical responses of tomato microshoots to induced salinity stress with associated ethylene accumulation

Growth and flowering of black iris (Iris nigricans Dinsm.) following treatment with plant growth regulators