The natural area of walnut in Central Asia includes the territory of Kyrgyzstan, Tajikistan and Uzbekistan. There the walnut has been grown since Oligocene times. The walnut forests in these countries are the centre of origin of walnut around the world. Walnut forests in Uzbekistan are widespread in an area of about 4000 hectares. They occupy areas with optimum forest growing conditions on slopes of mountains of Western Tien-Shan and Pamir-Alai at a height from 800 up to 2300 m above sea level. The Bostanlyk District of Tashkent Region is related to the zone of the densest concentration of walnut plantations. Surveys carried out in 2007-2009 in Uzbekistan walnut forests in a part of Western Tien-Shan territory showed that Juglans regia is widespread on ranges as separate, small populations on small river inflow and slopes of Ugam, Pskem, Chatkal. From the complex of investigated biomorphological attributes of trees, forms can be classified as related to breeding categories. From the study area selected trees in Charvak and Chatkal plots deserve special attention. Fruits of the surveyed trees showed a wide variability in size and shape as well as in the nutrient content. Oil, fatty acids, proteins, vitamin E were analysed. Several forms can be added as potential candidates for reproduction and establishment of a collection-mother production plantations and to become named cultivars.

Functioning of the antioxidant system in roots and leaves of Plantago major L. in water culture at the stage of 5–6 genuine leaves of the plants subjected to NaCl (100 mM) action for 96 h was investigated. This plant exhibited a pronounced organ specificity of antioxidant defense system functioning. The roots were characterized by high constitutive activities of superoxide dismutase and three forms of peroxidase, and a lower catalase activity. Constitutive level of polyamines in roots was higher than in leaves. In both leaves and roots during first 24 h, the polyamine content declined but spermidine remained to be a predominant polyamine. The analysis of differential expression of the genes encoding enzymes of polyamine biosynthesis demonstrated certain differences in these plant organs. The changes in expression of genes MET1, SPMS1 , and SPMS2 were observed in roots, whereas in leaves expression of MET1, SAMDC1, SPDS1 , and SPMS1 was altered. These changes are possibly one of the mechanisms responsible for the regulation of polyamine endogenous level under salinity. In contrast to leaves, in roots, the oxidative degradation of spermidine by polyamine oxidase can take part in the regulation of endogenous spermidine level. Taken together, these findings allowed us to conclude that, unlike leaves, the roots of P. major under salinity conditions possessed a higher activity of the antioxidant system protecting plants from injurious action of oxidative stress, thereby providing survival of this plant species under stress conditions.

Summary. The common ice plant ( Mesembryanthemum crystallinum L.) at-tained significance as a model organism for plant molecular biology studieson biochemical and physiological adaptation mechanisms, due to its extremestress tolerance, drought and high salinity resistance, and its ability to shiftfrom C3 photosynthesis to CAM in response to environmental stresses or aspart of its developmental programme. At present minor attention has beenpaid to elevated light and UV rays effects on ice plant metabolism and itsadaptation. Young ice plants have been exposed to 5 W m -2 UV-B light (3 to9 kJ m -2 d -1 UV-B BE ) for 10 – 30 min. On the next day leaves and roots havebeen collected, frozen and used for determination of total contents of osmolytes,chlorophyll, polyamines and free amino acid composition. A decrease in chlo-rophyll and net CO 2 assimilation gave evidence that ice plant had high sensi-tivity to UV-B irradiation. The absence of proline in leaves accompanied withother modifications in free amino acids composition in both leaves and roots,the slight stimulation of polyamine biosynthesis as well as the lack of cadav-erine in roots could be considered as indications for the damage of ice plantsdue to the poor metabolic adaptation to stress caused by UV-B irradiation.Our results suggest that ice plants have lower adaptive capacity to UV-B stressin comparison to drought and salinity. Data are discussed in relation to knownhypotheses for

In the seed, arginine, glutamate and alanine dominated cotyledonary free amino acid pool, whereas alanine was the main component of the embryo free amino acid pool. Seed germination resulted in marked changes in the metabolism of free amino acids present in cotyledons. In one month of seedlings subjected to nitrogen autotrophic growth, cotyledons were characterized by high concentrations of free arginine and citrulline. The relative high percentage of arginine and citrulline characterized not only the cotyledonary tissue, but all the tissues of one-month-old seedlings, especially the embryonic axis, tap root and stem. In these tissues, which have a nutrient storage function, the concentrations of citrulline and arginine made up about 80% of the total free amino acid, whereas in fine roots and leaves, characterized more as sink tissues, the relative percentages of citrulline and arginine were less than the 30%. In young walnut trees (2 years old), at spring regrowth, the concentration of free amino acids and in particular the concentrations of citrulline, arginine and proline present in woody tissues were dependent on the availability of nitrogen in soil, while the protein content of these tissues did not show significantly dependence. The xylem transport of free amino acids during a nitrogen autotrophic growth (germination) involved mainly citrulline. Its relative concentration in the xylem sap was greater than 50% of the total free amino acid translocated. Citrulline functions as a preferential compound by which nitrogen (amino acids) is translocated also during spring regrowth or after stress recovery; i.e. at all physiological stages where mobilization of nitrogen stored compounds occurs.

An unknown signal at 2.93 ppm in 1H-NMR spectra of rice, Oryza sativa, was assigned to the methyl groups of sulphur-methylmethionine (SMM), thereby devising a new method for the determination of this compound. Rice seedlings growing aerobically in the dark and in the light engaged for the synthesis of SMM an amount of Met corresponding to 23 and 8%, respectively, of the total seed reserves of this amino acid. In etiolated shoots, SMM reached 1.2 micromol g(-1) fresh weight, an unusually high level in vegetative tissues of wild-type plants. This is compared to a value of 0.4 micromol g(-1) fresh weight in green tissues. A decreased demand for Met during growth caused the higher accumulation of SMM in etiolated, rather than green, tissues. At the same time, dark seedlings were endowed with a readily utilizable and translocable alternative form of Met, as shown by retrieval of SMM from the coleoptile. The importance of methyl group storage in SMM is shown by comparison with choline and choline phosphate pools.

We investigated the composition of free amino acids in walnut (Juglans regia L.) seeds (embryo and cotyledons). We also examined xylem transport of free amino acids in young seedlings grown in the absence of external nutrients. A relatively high concentration of free alanine was found in seed tissue, whereas a relatively high concentration of citrulline was detected in young seedlings. Citrulline was the main free amino acid transported in the xylem to stem and leaves. The negligible presence of citrulline, a non-protein amino acid, in the kernel and its presence in high concentrations in all of the tissues of young seedlings, including cotyledons, embryonic axis, taproot and stem, suggest that citrulline is synthesized during walnut germination. We conclude that citrulline plays an important role in nitrogen translocation during walnut germination.

Few data on amino acid presence and composition in xylem sap of trees have been reported; the studies were mainly focused on the seasonal variation and the phenological stages of the trees. The aim of the present work has been to study the influence of water stresses, either drought and flooding, during the vegetative stage of walnut tree on the composition of amino acids in leaf sap. During the all vegetative season, July-September, in control trees well watered and with well drained soil, the amino acids composition remain without significant difference. In the leaf sap the concentration of amino acids ranged between 130-200 muM and it is 0.3 % only of total free amino acids in leaves. Glutamine account for about the 40-50% of the total amino acids. Glutamine has been reported to be the dominant one in the xylem of willow, poplar and black locust trees. During stress condition increase in concentration to the mM level for drought trees and over 10 mM for flooded one is the first evident effect. Glutamine remains one of the main component but the % increase in aspartate and glutamate in drought and of GABA in soil hypoxia stress are the main changes. After removing the stresses condition, the citrulline become one of main amino acids. The increase in leaf sap of free amino acids during the stress may be consequence of different causes: protein hydrolysis, synthesis or conversion. However, considering that few amino acids accounting for over 80% of the total, or more simple the release of free amino acids present in the cells, can occur.

Accumulation of amino acids was studied in rice roots of 3-day-old seedlings subjected for 48 h to anaerobic conditions. Alanine and Gaba were the main amino acids accumulated under anoxia. Their synthesis was strongly inhibited by MSX and AZA, inhibitors of glutamine synthetase and glutamate synthase. These activities increased after 8 h of anaerobic treatment and, by immunoprecipitation of 35S-labeled proteins, it was shown that glutamine synthetase and ferredoxin-dependent glutamate synthase were synthesized during the treatment. These findings indicate that the glutamine synthetase/glutamate synthase cycle play an important role in anaerobic amino acid accumulation.

Woody species vary in their ability to tolerate flooding. In sensitive plants when soil is flooded, the reduction of root nutrient and water uptake, due to root mortality or hypoxic root metabolism, are clearly observable on the foliage. The flood tolerance in woody species has been correlated with the capacity of the plants to produce adventitious roots to compensate the decay of original roots.Walnut (Juglans regia) tree is known to be very sensitive either to drought then to flooding. Of interest is the search of characters and parameters useful to select genotypes and/or phenotypes with the ability to survive in unfavorable conditions.Walnut trees, J. regia of different provenience, and interspecific hybrids J. regia x J. nigra and J. regia x J. major were subjected to waterlogging when full expansion leaves were reached. Physicochemical measures gave indication of decrease of net CO2 assimilation after 1 day of waterlogging in all genotypes tested. After 3 days, some J. regia varieties trees showed rapid desiccation and lost of all leaves and some plants clearly died. On other hand trees of a selected progeny of J. regia and of hybrids did not shown any visible apparent damaging symptoms till 10-12 days of anoxia stress treatment.Biochemical analyses of indole-acetic acid, abscisic acid, ethylene and ethanol content in leaves gave no significant difference between control and stress treated plants for the first two compounds, ethylene showed a rise of production that opposite the CO? assimilation. Ethanol, present in control plants, increased approaching the time of appearance of chlorosis and wilting of leaves.The data can confirm previous work that walnut trees have a low capacity to survive to soil anaerobiosis, but differences trough J. regia provenance and hybrid plants indicate the potentiality to select genotypes with more stress resistance capacity.

Rice, one of the few plant species adapted to growth in wetland conditions, is able to germinate in waterlogged soils promoting only the growth of a white coleoptile in order to reach the surface of the water, contact the atmosphere, and transfer oxygen to the seed, allowing subsequent growth of the radicle and leaf. In the anoxic cells of rice coleoptiles, an efficient alcoholic fermentation allows an elevated energy charge to be maintained. Significant RNA and protein syntheses including phosphorylation and glycosylation occur too. The cytoplasmic pH is maintained at a level far from acidosis. The anoxic growth of rice coleoptiles, essentially an elongation growth, is sustained by a high turgor pressure, with free amino acids and potassium as main components. Among the metabolic processes involved in the regulation of the elongation of rice coleoptiles, a crucial role is played by amino acid metabolism and the accumulation of putrescine, which is able to stimulate plasmalemma ATPase activity. Anaerobic elongation is also stimulated in the presence of 20% CO2 in the growth medium, inhibited by light and abscisic acid, unaffected by ethylene, and slightly promoted by auxin. The role of both metabolites and hormones along with environmental factors in maintaining cellular homeostasis and coleoptile elongation are reconsidered and discussed in Light of new data.

This paper describes the synthesis and the expression of the enzymes assimilating nitrogen and their regulation by exogenous nitrate in the anaerobic rice (Oryza sativa L.) coleoptile. Two nitrate reductases (NR, EC 1.6.6.1), nitrite reductase (NiR, EC 1.7.7.1), cytosolic and plastidic glutamine synthetase (GS, EC 6.3.1.2) and ferredoxin-dependent glutamate synthase (Fd-GOGAT, EC 1.4.7.1) were detected after immunoprecipitation with specific antibodies followed by SDS-PAGE. The Northern blot analysis revealed the presence of mRNA for NIR, cytosolic GS and Fd-GOGAT. The addition of exogenous nitrate increased the synthesis and the expression of all these proteins with the exception of the GS polypeptides. The role of these proteins in the rice coleoptile during the anaerobic germination is discussed.

The coleoptiles of rice seedlings germinated under water bubbled with nitrogen (anaerobic conditions) and placed to grow in a horizontal position by turning the growth jar 90 degrees, showed a fast gravitropic responsiveness. This process was inhibited by IAA at 0.1 mM. The decrease in the osmotic potential induced in rice coleoptiles by exogenous auxin and the role of auxin in the anaerobic elongation and gravitropic response of rice coleoptiles are discussed.

Synthesis and the polypeptide pattern of proteins and glycosylated proteins in excised roots and shoots of rice seedlings subjected to aerobic and anaerobic conditions were analyzed. In roots, the synthesis and glycosylation of proteins were more depressed by anoxia than in shoots. The synthesis of soluble proteins was, in both tissues, less inhibited by the anoxic stress than the synthesis of membrane proteins. On the contrary, the synthesis of glycosylated membrane proteins was less inhibited under anaerobic conditions than the soluble glycosylated proteins. Analysis of polypeptide patterns of proteins synthesized under nitrogen revealed some differences between root and shoot and a 35 kDa membrane glycoprotein was specifically detected in the shoots. The results are also discussed in relation to the capacity of rice shoots to undergo anaerobic growth.

In excised rice roots, anaerobic degradation of proteins gave rise to an increase of free-amino acids. Anoxic accumulation of alanine, γ-aminobutyric acid and proline was the consequence of the interconversion of glutamate, aspartate and amides. The shift in the composition of the amino acid pool appears to be caused by changes in keto acid levels. The role of reactions involved in amino acid interconversion and the physiological significance of these interconversions are considered and discussed.

Reggiani, R., Brambilla, I. and Bertani, A. 1985. Effect of exogenous nitrate on anaerobic metabolism in excised rice roots. I. Nitrate reduction and pyridine nucleotide pools.—J. exp. Bot. 36:1193-1199.

Excised rice roots grown on ammonium and nitrate media under aerobic and anaerobic conditions were compared. In air, differences between the two culture conditions were observed in the growth of the roots and in the pattern of newly synthesized proteins. Anaerobiosis completely blocked the growth of the roots and cancelled any difference in the polypeptide pattern of newly synthesized proteins. However, in anoxia there were substantial differences in the rate and type of fermentation carried out by the roots supplied with ammonium or nitrate.

Comparing nutrient translocation to the rice (Oryza sativa L. var. Arborio) shoot during anoxia with the aerobic situation, it was found that anoxia reduced the translocation of K+, phosphorus, Mg2+ and Ca2+ with progressive intensity; Ca2+ translocation was practically zero in the absence of oxygen. The translocation of K+ and phosphorus under anoxia was still considerable and contributed to the maintenance of a high osmotic potential while the blocking of Ca2+ translocation caused a decrease in its concentration in the anoxic coleoptile, possibly favouring high cell wall plasticity in that organ. As anoxia proceeded, amino acids, no longer employed in protein synthesis, accumulated in the coleoptile, reaching spectacular levels [51 mmol kg of tissue‐water)−1] and, after 48 h of anoxia, their contribution to the osmotic potential was 80% of that of K+, as against less than 20% in all aerobic treatments. Anoxia caused a reduction in soluble hexose concentrations which, however, were more than compensated osmotically by the accumulation of amino acids.