Morphological and Physiological Responses to Drought Stress of European Provenances of Scots Pine

Increased frequency and intensity of drought episodes as a consequence of current and predicted climatic changes require an understanding of the intra-specific variability in structural and physiological characteristics of forest trees. Adaptive plasticity and genotypic variability are considered two of the main processes by which trees can either be selected or can acclimate to changing conditions. We tested for the relative importance of genotypic variability, phenotypic plasticity and their interaction by comparing the growth and physiological performance of 15 provenances of Scots pine (Pinus sylvestris L.), under two contrasting irrigation regimes. Selected provenances representing the distribution range of the species in Anatolia, Turkey, were contrasted with seed sources spanning the range from Spain to the UK, in Europe. We found a strong latitudinal differentiation among the 15 provenances for survival after drought, largely the result of the higher mortality of some western and central European provenances. Differentiation in diameter and height growth was also clear with the worst provenance coming from Western Europe (UK). Among the Turkish provenances, the more extreme southern high-elevation populations showed greater survival and lower growth rates overall. Differences in growth and survival were related to differences in photosynthetic pigment and nutrient contents and in the photosynthetic efficiency of photosystem II. Plasticity was strongest for growth characters and pigment contents.WoSScopu

Bitkilerde Kuraklık Stresinin Etkileri Ve Dayanıklılık Mekanizmaları (Derleme)

Drought stress, one of the most common environmental limitations affecting growth and productivity of plants, causes many metabolic, mechanic and oxidative changes in plants. Drought induces a diverse set of physiological, biochemical and molecular responses in plants, which provide the ability of adaptation to limited environmental conditions, depending on intensity and periods of stress, interactive effects of the other stress types, development stage and genotype of plants.Bitkilerde, büyümeyi ve verimi etkileyen en yaygın çevresel streslerden biri olan kuraklık stresi, metabolik, mekanik ve oksidatif birçok değişikliğe neden olmaktadır. Kuraklık; stresin şiddetine, süresine, diğer stres türleri ile etkileşimlerine, strese maruz kalan bitkinin genotipine ve gelişim basamağına bağlı olarak, bitkilerde sınırlı çevresel koşullara adapte olmayı sağlayacak birçok fizyolojik, biyokimyasal ve moleküler cevabı indüklemektedir

PSII Photochemistry and Antioxidant Responses of a Chickpea Variety Exposed to Drought

The effect of drought on the chickpea variety ILC 3279 was investigated at the vegetative stage. After 20 days from sowing, the plants subjected to drought stress for 3, 5 and 7 days imposed by withholding water were permitted to recover by rewatering for 2 days after 3, 5 and 7 days of drought. Shoot elongation, leaf production, fresh and dry biomass reduced while MDA and proline accumulation increased with extended duration of stress. The plants stressed for 3 days exhibited a rapid drop in their relative and absolute water contents. The quantum efficiency of PSII open centres in the dark-adapted and light-saturated state, excitation energy trapping of PSII and electron transport rate decreased significantly from the 5th day to the end of the drought treatments. Plants drought-stressed for 7 days brought about a marked increase in non-photochemical energy dissipation and a marked decline in photochemical quenching. After rewatering all chlorophyll a fluorescence characteristics except for FM completely recovered and reached the control values. Under 5 and 7 days of drought, the anthocyanin content increased gradually while the total chlorophyll content of leaves declined compared to the controls. The total carotenoid content remained unchanged during the experiments. The antioxidant enzyme response to drought treatments was quite variable. The total SOD activity upregulated with increasing duration of stress. On the other hand, the total APX activity was significantly higher only on the 7th day while the total POD activity increased from the 5th day. Differences in the total GR activity of treated groups were not statistically significant compared to their controls throughout the treatments. The present results indicate that the chickpea variety ILC 3279 withstands severe drought with its upregulated protective mechanisms at the vegetative stage

Salt Pretreatment-Mediated Alleviation of Boron Toxicity in Safflower Cultivars: Growth, Boron Accumulation, Photochemical Activities, Antioxidant Defense Response

The study aims to elucidate alleviant effects of boron (B) toxicity by salt pretreatment (SP) on growth response, phytoremediation capacity, photosynthesis, and defense mechanisms in two safflower cultivars (Carthamus tinctorius L.; Dinçer and Remzibey-05). Eighteen-day-old plants were divided into two groups: SP (75 mM NaCl for 5 days) and/or B treatment (C, 2, 4, 6, and 8 mM B for 10 days). Depending on the applied B toxicity, B concentrations in roots and leaves of both cultivars, necrotic areas of leaves, ion leakage (RLR), and H2O2 synthesis increased, while shoot and root length as well as biomass, water, chlorophyll a+b, and carotenoid content decreased. In addition, chlorophyll a fluorescence results revealed that every stage of the light reactions of photosynthesis was adversely affected under B toxicity, resulting in decreases in performance indexes (PIABS and PITOT). However, the cultivars tended to induce the synthesis of anthocyanins and flavonoids and increase the activity of antioxidant enzymes (SOD, POD, APX, and GR) to detoxify reactive oxygen species (ROS) under B toxicity. SP mitigated the negative effects of toxic B on biomass, water and pigment content, membrane integrity, photosynthetic activity, and defense systems. Considering all results, Remzibey-05 was able to better overcome the biochemical and physiological changes that may be caused by B toxicity by more effectively rendering B harmless, although it accumulated more B than Dinçer

Effects of Water Deficit Induced by PEG and NaCl on Chickpea (Cicer arietinum L.) Cultivars and Lines at Early Seedling Stages

The effects of water deficit induced by different osmotic potential levels [0 (control), -0.4, -0.6 and -0.8 MPa] of PEG 6000 and NaCl treatments on chickpea (Cicer arietinum L.) cultivars and lines at germination and early growth stages by sampling on 4th and 8th days of incubation consisting of 4 days each of dark and subsequent 16 hours illumination. All of these treatments affected germination percentages of all genotypes but PEG was more effective in inhibition than NaCl at the MPa levels tested. The experimental studies showed that all of the genotypes tested could be classified as tolerant, moderately tolerant and sensitive ones. But the tolerance levels were not found to be correlated directly with MPa levels applied, as Canıtez and ILC-3279 were tolerant to PEG, but ILC-3279 was sensitive to NaCl treatment. Within this context the classification can be summarized as below: PEG tolerant (Canıtez and ILC-3279), moderately tolerant (AkN 87, FLIP 87-59C, Gökçe and Uzunlu), sensitive (AkN 290 and ER 99). NaCl tolerant (Uzunlu and FLIP 87-59C), moderately tolerant (Gökçe, Canıtez, AkN 290 and AkN 87) and sensitive (ER 99 and ILC-3279)

DOES SALT PRE-TREATMENT PROVIDE AMELIORATION EFFECT ON TOXIC BORON LEVELS IN TWO SUNFLOWER CULTIVARS?

Boron (B) is an essential micronutrient for plant growth and development such as photosynthesis and plasma membrane integrity, however its toxicity levels limit productivity throughout the world. This study was conducted to reveal whether the salt (NaCl) pre-treatment alleviate the adverse effects of increasing B concentrations on two sunflower (Helianthus annuus L., Tarsan-1018 and Sanbro) cultivars. On the 15th day after sowing, plants were divided into two groups, NaCl pre-treated (75 mM for 5 days) and/or B treated (2, 4 and 8 mM B for 10 days). The responses of the photosynthetic activities of two genotypes against the treatments was investigated by measuring polyphasic chlorophyll a fluorescence. Photochemical activity was decreased with increasing boron concentrations in both cultivars. PIabs and some JIP test parameters [PHI(D0), DI0/RC, FV/F0, TR0/RC, TR0/ABS] were changed significantly in both cultivars. In addition to that, the electron acceptor side of PSI [RE0/ET0, RE0/ABS] were negatively affected in only Sandro cultivar. Meanwhile, water content and, shoot and root growth were decreased in both cultivars, on the other hand membrane damage was increased with increasing B concentrations. These results indicated that the cultivars are adversely affected from increasing B concentrations. However, salt pre-treatment ameliorated the adverse effects of the B toxicity in both cultivars. Consequently, Tarsan-1018 protected photosynthetic apparatus, exhibiting better performance compared to Sanbro against B toxicity

Botanik Laboratuvarı El Kitabı

Bu kitap, Hacettepe Üniversitesi Fen Fakültesi Biyoloji Bölümünde iki dönem okutulmakta olan Genel Biyoloji dersleri kapsamında yeralan Botanik konuları ile ilgili laboratuvar çalışmalarını kapsamaktadır. Onüç bölümden oluşan bu eserde, Genel Biyoloji I ve Genel Biyoloji II derslerinde okutulan Botanik konularının akışına paralel olarak, bitki hücresi ve kısımları ile bitki doku ve organlarının morfolojik ve anatomik yapıları ayrı ayrı ele alınmıştır. Çeşitli bilgileri içeren bu laboratuvar kitabını hazırlarken temel konular seçilmiş ve metaryel olarak kolayca bulunabilen ve herkes tarafından kolayca tanınabilen bitki örnekleri tercih edilmiştir. Değişik bitkilerden gerek el ile gerekse mikrotom ile alınan kesitler incelenmiş ve konuyu en iyi açıklayan örnekler kitaba konmuştur. Bazı örneklerde daha ayrıntılı görüntüler sunabilmek için ilgili bölgeden uygun büyütmeler yapılmıştır. Her bölümün sonunda, öğrencilerimizn konu ile ilgili çizimleri yapabilmesi için uygulama sayfaları bırakılmış ve konunun daha iyi anlaşılmasını sağlayacak bazı sorular sorulmuştur. İlk baskısı 2005 yılında, Hacettepe Üniversitesi Basımevi tarafından yapılan bu eserin mevcut baskısı tükenmiştir. Eserde konuların ele alınışı, işleniş biçimi ve sırası, anlatım dilinin yalınlığı, verilen bitki örneklerinin seçimi, öğrenciler ve diğer okuyucular arasında oldukça beğeni kazanmıştır. Bu eserin, Biyoloji bölümlerinde eğitim yapan Lisans öğrencilerinden başka meslektaşlarımız, Biyoloji öğretmenleri ve Botanik konularına ilgi duyan tüm okuyucular için yararlı bir kaynak olacağını umuyoruz