Serdal Sakcali

Boron induced expression of some stress-related genes in tomato

Boron (B) is a potential environmental toxicant for plants under excessive conditions. To understand the molecular stress response involved in high B exposure, we focused on the transcript accumulation of three stress-related genes: Hsp90, MT2 and GR1. Transcript accumulations were determined on B-stressed tomato plants by using a quantitative real-time PCR technique. Tomato seedlings were exposed to B ranging from 80 to 5120 μM for 24 h in nutrient solution. Root and shoot transcript accumulations were assessed. Results showed that the genes were over-expressed in B-stressed tomato. The highest relative fold change value was measured on GR1 for both root and shoot (8-10 and 30-34-fold increases, respectively), indicating the activation of the oxidative stress enzyme to tolerate B-stress as an early response. The activation of these genes could be a protection mechanism against to B stress.

Boron and Plants

Boron is found naturally in the earth’s crust in the oxidized form as borax and colemanite, particularly in the oceans, sedimentary rocks, coal, shale, and some soils. It is never found in the elemental form in nature possessing a complex chemistry similar to that of silicon, with properties switching between metals and non-metals. Boron has become an important and strategic element in terms of developing technologies. It is released into the environment mainly through the weathering of rocks, volatilization from oceans, geothermal steam, burning of agricultural refuse and fuel wood, power generators (coal/oil combustion), glass industry, household use of boron-containing products (including soaps and detergents), borax mining and processing, leaching from treated wood and paper, chemical plants, and sewage/sludge disposal, but a major proportion originates from the weathering of rocks. Boron is regarded as an essential element for human beings, animals and plants. Boron occurs in soils at concentrations ranging from 10 to 300 mg kg−1 depending on the type of soil, amount of organic matter, and amount of rainfall. The treatments lead to significant increases in the productivity of some plants but in certain cases a decrease is seen as the boron level increases with the boron content of irrigation water, in particular on the soils with a heavy texture, high CaCO3 and clay content. Lack of boron in plants results in necrosis but excess amounts are said to produce poisonous effects. Turkey produces more than 60% of the world’s borax, with important boron reserves located in Susurluk, Bigadic and Sindirgi regions of Balikesir, Kestelek-Bursa, Emet-Kutahya, the largest reserves occur in Kirka-Eskisehir. Therefore, there is a naturally occurring high level of boron in the ground waters in some of these areas due to the excess amounts of boron given out to the environment during washing and purification processes which result in the pollution of cultivated areas. An attempt will be made here to present an overview of the plant diversity on the boron contaminated soils in Turkey, effects of different concentrations of boron on the germination ability of some plants and possible candidates for phytomining of the soils showing boron toxicity symptoms.

Halophyte plant diversity in the Irano-Turanian phytogeographical region of Turkey

Irano-Turanian phytogeographical region includes the central, east and southeast Anatolian geographical divisions of Turkey. The region is characterized by a continental type of climate with very cold winters and hot summers. Precipitation in the form of a heavy snowfall is seen usually in winter and rains are common in spring and autumn. However, the southeast experiences a steppe climate with very hot summers, severe aridity and evaporation. The area of saline and degraded soils in the region is increasing. The factors responsible for this are over-irrigation practices, and salt accumulation due to evaporation. In the region, 137 halophytic taxa belonging to 88 genera and 34 families are found. The genera Salsola, Chenopodium, Limonium, Alhagi and Allium include the highest number of taxa. Phytogeographically 80.29% of these taxa are Irano-Turanian and 13.14% are common. The number of endemic taxa is around 42. For a management of the saline-alkaline habitats sound information on plant diversity, vegetation cover, habitat types, and locations of species communities is needed, together with land cover maps, to follow the habitat deterioration and its causes. The present study will thus help in the determination of site quality.

An overview of the possiblities for wastewater utilization for agriculture in Turkey

Treated municipal wastewater and sewage sludge are an important source of water for irrigation in arid and semiarid regions. It may also serve as a promising source of plant nutrients and organic material that has a potential to increase soil productivity under arid conditions. Utilization of treated wastewaters for agricultural irrigation, in addition to being a low-cost available water source, also minimizes effluent disposal problems and hence environmental contamination, and reduces the need for the input of chemical fertilizers. Disadvantages of the application of treated effluents for agricultural irrigation involve the potential for human health problems, groundwater contamination, and the need for continued follow up and control. As of now, treated wastewater in Turkey is discharged to streams and seas, and is not reused for agriculture irrigation. Environmental considerations and the predicted increase in water shortage make effluent irrigation a national priority. Recent field and pot studies de...

Effects of Temperature and Salinity on Germination and Seedling Growth of Daucus carota cv. nantes and Capsicum annuum cv. sivri and Flooding on Capsicum annuum cv. sivri

The germination and seedling growth of Daucus carota cv. nantes and Capsicum annuum cv. sivri were investigated under stress conditions. D. carrota seeds germinated well in the dark at 20°C (92%) but in the light germination was only 54%. The germination in dark at 20%C was 92%, 84% and 80% at 0.1%, 0.5% and 1% salt (NaCl) solutions, as the concentration increased germination decreased and length of radicle and plumule also got reduced. Germination was 90% at 0.1% NaCl + 10 ppm GA3 and 43% at 2% NaCl +10 ppm GA3. The seeds of C. annuumcv. sivri germinated well at constant temperatures of 15°C (83%), 20°C (100%), and 30°C (88%). The germination was 100% in the seeds placed in distilled water and left at 20°C, but it was delayed or inhibited when salt solutions were applied to these seeds. An application of growth regulators showed that GA3 was stimulatory under saline conditions, However plant survival was low at 2% and 3% salt conditions as compared to 0.5% and 1% salt solutions. C. annuumcv. sivri did not show salt tolerance. When 4 weeks old seedlings of C. annuumwere subjected to fl ooding using tap water, the performance of seedlings was better on unfl ooded soils. The plants survived under short periods of fl ooding but growth was poor, however, under longer periods of fl ooding the mortality increased and plants became sensitive.