ABA biosynthesis defective mutants reduce some free amino acids accumulation under drought stress in tomato leaves in comparison with Arabidopsis plants tissues

Fermentation in the technology of dry-cured meat products helps to create products with high sensory characteristics and an extended shelf life. The purpose of this work was to study how bacterial and enzyme preparations affected the accumulation of free amino acids in dry-cured meat products.
 The work considers how the preparation Iprovit-Lakmik based on the cultures L. plantarum, L. rhamnosus, L. casei, and Micrococcus varians acts on the accumulation of free amino acids during the ripening of dry-cured sausages, and how the bacterial preparation Iprovit-MKS based on the cultures Lactoba plantarum, L. rhamnosus, and Staphylococcus simulans and the enzyme preparation Protolad acts on proteolysis during the ripening of dry-cured whole-muscle products from pork and beef. Fermentation was carried out in a climatic chamber at a temperature required by the technological process of accelerated ripening of fermented sausages, using bacterial and enzyme preparations. The starter culture Iprovit-Lakmik was added in the amount 0.05% to the volume of the sausage mince prepared in accordance with the formulation of the dry-cured sausage Zhytomyrska. The preparations Protolad and Iprovit-MKS were added at the stage of injecting the balyk (cured fillet) Darnitsky. Samples with no preparations added were the controls. The amino acid composition of proteins was determined by ion-exchange chromatography on an automatic amino acid analyser Biotronik LC2000. The total content of free cyclic amino acids was determined by the Hull method, and that of acyclic amino acids by the Gomez method, using colourimetry.
 It has been found that after fermentation, each product had its own characteristics of the qualitative and quantitative accumulation of free amino acids. Adding the preparation Iprovit-Lakmik to raw meat allowed directed biochemical transformations with the formation of a significant amount of free amino acids, which exceeded the control by 115.86 mg/100 g of dry matter. The enzyme preparation Protolad has a positive effect on the chemical and physicochemical characteristics of salted products from pork and beef. It has been proved that its use activates the breakdown of muscle tissue proteins and increases the pool of free amino acids. In the test samples from pork and beef, the content of free amino acids increased, respectively, by 1.7 times and 3.4 times, and that of non-essential amino acids by 1.4 times and 1.3 times respectively, compared with the control. In the samples with the bacterial preparation Iprovit-MKS, the total amount of amino acids increased significantly: by 32% for beef balyk and by 20% for pork balyk.

Free amino acids in tea leaves are important chemical constituents that considerably influence the quality of tea, especially that of green tea. The present study was conducted to investigate the effects of the nutrients potassium, magnesium and sulphur on biomass production and amino acid accumulation in tea leaves in pot and field experiments. The results show that biomass production and the free amino acid contents in tea leaves increased considerably following the application of potassium and magnesium. Combined application of both nutrients produced the highest increment in free amino acids. The increased free amino acid content in tea leaves was accompanied by enhanced nitrate reductase activity. This indicates that potassium and magnesium application improved the nitrogen metabolism, leading to an increased synthesis of amino acids. A comparison between K2CO3 vs K2SO4 and MgO vs MgSO4 revealed significantly higher amino acid contents in tea leaves when both potassium and magnesium were applied in the sulphate form, indicating that not only potassium and magnesium but also sulphur plays an important role in the accumulation of amino acids in tea leaves. A pot experiment using KCl and K2SO4 was carried out in order to compare the two commercially available potassium fertiliser forms in their effect on biomass production and the content of free amino acids in tea leaves. The results showed no difference on biomass production between the two fertiliser forms. However, whereas KCl tentatively depressed nitrate reductase activity and hence the accumulation of free amino acids, K2SO4 significantly increased the contents of these quality promoting constituents of tea leaves. The role of fertiliser composition, detrimental effects of accompanying anions, eg Cl− and differences in nutrient availability (eg oxide≪sulphate form) and possible impact on soil chemistry as main reasons for the observations, being crucial aspects with regard to fertilisation of tea for good quality are discussed. © 1998 SCI.

The relationship between the nitrogen and the free amino acid content in Stratiotes aloides L. was investigated for 11 healthy stands in the Netherlands. In the shoots, the mean free asparagine and free arginine levels were strongly correlated with the mean total N concentrations and the ammonium concentrations in the water layer. The percentage of total N present as free amino acids varied from 5.4 % to 27.5 % between the stands. In the stands with the highest total N levels, up to 92 % of the nitrogen in the free-amino acid pool consisted of asparagine and arginine. The results reveal that the accumulation of these N-efficient free amino acids was caused by increased ammonium availability in the environment. The accumulation of specific free amino acids is regarded as an early indication for N-stress in still healthy S. aloides stands.

Proteolysis of chloroplast proteins is responsible for accumulation of free amino acids in dark-treated tea (Camellia sinensis) leaves

In this study, the effect of different planting combinations on the amino acid concentration in the pericarp of Zanthoxylum planispinum ‘dintanensis’ (hereafter referred to as Z. planispinum) was studied, and the response of amino acid concentration to soil factors was clarified. The aim of this study was to screen optimal planting combinations and provide a theoretical basis for improving pericarp quality. Five planting combinations of Z. planispinum in a karst rocky desertification area were selected as the research objects, and the concentration and accumulation of free amino acids in the pericarp of Z. planispinum were analyzed. Then, combined with existing soil quality data, the pericarp quality of Z. planispinum was comprehensively evaluated by principal component analysis, and the effect of soil factors on amino acid concentrations was clarified by redundancy analysis. The results are as follows: (1) except for arginine, serine, proline, alanine, tyrosine and cystine, the concentrations of other free amino acids significantly differed among the five planting combinations. In general, the planting combination has a great influence on the concentration of free amino acids in the pericarp of Z. planispinum, especially essential amino acids; (2) free amino acid concentration in the pericarp of Z. planispinum mostly increased in combination with Sophora tonkinensis Gagnep. (hereafter referred to as S. tonkinensis) and decreased in combination with Prunus salicina Lindl; (3) principal component analysis showed that the concentration of free amino acid in the pericarp of Z. planispinum was generally at a high level when combined with S. tonkinensis or Lonicera japonica Thunb. (hereafter referred to as L. japonica). Among them, the amino acids in the pericarp of Z. planispinum with S. tonkinensis were closer to the ideal protein standard of FAO/WHO; (4) soil-available potassium, available phosphorus, microbial biomass nitrogen, available calcium and microbial biomass phosphorus in soil factors had significant effects on amino acid concentration after a redundancy analysis. It can be seen that the available nutrients and soil microbial biomass contribute greatly to the amino acid concentration of the pericarp. According to the soil quality and the amino acid quality of the pericarp, planting with L. japonica can improve the amino acid quality of the pericarp of Z. planispinum, as well as selecting Z. planispinum + L. japonica as the optimal planting combination.

Drought is one of the most severe environmental stress factors limiting crop yield especially when occurring during anthesis and seed filling. This terminal drought is characterized by an excess production of the phytohormone abscisic acid (ABA) which plays an important role during seed development and dormancy. All the genes putatively involved in ABA biosynthesis and inactivation in barley were identified and their expression studied during plant ontogeny under standard and drought-stress conditions to learn more about ABA homeostasis and the possible mode of cross-talk between source and sink tissues. Out of 41 genes related to ABA biosynthesis and inactivation 19 were found to be differentially regulated under drought stress in both flag leaves and developing seed during seed filling. Transcripts of plastid-located enzymes are regulated similarly in flag leaf and seed under terminal drought whereas transcripts of cytosolic enzymes are differentially regulated in the two tissues. Detailed information on the expression of defined gene family members is supplemented by measurements of ABA and its degradation and conjugation products, respectively. Under drought stress, flag leaves in particular contain high concentrations of both ABA and the ABA degradation products phaseic acid (PA) and diphaseic acid (DPA); whereas, in seeds, besides ABA, DPA was mainly found. The measurements also revealed a positive correlation between ABA level and starch content in developing seeds for the following reasons: (i) genes of the ABA controlled SnRK2.6 and RCAR/PP2C-mediated signal transduction pathway to the ABF transcription factor HvABI5 are activated in the developing grain under drought, (ii) novel ABA- and dehydration-responsive cis-elements have been found in the promoters of key genes of starch biosynthesis (HvSUS1, HvAGP-L1) and degradation (HvBAM1) and these transcripts/activity are prominently induced in developing seeds during 12 and 16 DAF, (iii) spraying of fluridone (an ABA biosynthesis inhibitor) to drought-stressed plants results in severely impaired starch content and thousand grain weight of mature seeds.

The effects of Fe-deficiency and Mn-deficiency in macadamia leaves on the accumulation of free amino acids and total amino acids (free plus protein amino acids) were studied in water vs. sand culture. Leaves showing severe Fe-deficiency symptoms contained substantially higher concentrations of free histidine, aspartic acid, threonine, serine, glutamic acid, proline, alanine, valine, and tyrosine than analogous control leaves. The sum of the individual free amino acids were 177% higher in the Fe-deficient leaves than in the control leaves. Mn-deficient leaves, containing .0003% Mn, had significantly higher concentrations of free aspartic acid, threonine, glutamic acid, proline, alanine, valine, isoleucine, leucine, tryosine, and phenylalanine than analogous control leaves. The sum of the free amino acids in Mn-deficient leaves was 85% higher than in the analogous leaves from the control plants. In chlorotic Fe-deficient leaves the concentrations of total lysine, histidine, ammonia, arginine, aspartic acid, methionine, and leucine were significantly higher than in control leaves. Mn-deficient leaves contained significantly higher amounts of total lysine, histidine, ammonia, aspartic acid, threonine, serine, glutamic acid, proline, glycine, alanine, valine, methionine, isoleucine, leucine and phenylalanine than control leaves. The concentrations of free lysine, histidine, aspartic acid, glutamic acid, proline, alanine, and valine were higher in the leaves of plants grown in sand culture. The total ammonia, threonine, methionine, leucine, tyrosine, and phenylalanine were lower in the leaves of plants grown in water culture. Total arginine was higher in leaves from the sand culture. There were several significant interactions between treatments and culture media on the accumulation of free and total amino acids in the Fe- or Mn-deficient leaves.

Background and Aims Viticulture will be particularly affected by increasing drought and heat waves in the future. It is of interest to find traits that indicate stress before symptoms become apparent. We investigated whether the commonly used traits, proline and abscisic acid (ABA) biosynthesis, are suitable markers for heat, drought or combined stress and whether gene expression of key enzymes of ABA biosynthesis is regulated in grapevine leaves under these stress conditions. Methods and Results Plant growth and gas exchange were measured to evaluate plant reactions to increased temperature and water deficit. Proline and ABA concentration in leaf material was measured, respectively, photometrically and with GC/MS. Gene expression analysis of NCED1, NCED2 and P5CS was done by real-time quantitative reverse transcription-polymerase chain reaction. Drought stress had a stronger effect on growth, gas exchange, proline, and ABA biosynthesis than heat stress. An interaction between heat and drought stress was observed for gas exchange and for proline biosynthesis. Conclusions Proline concentration and gene expression of P5CS are good markers for combined stress. The concentration of ABA is a suitable marker for drought stress and might be a suitable marker for combined stress. Gene expression of NCED1 in leaves was a good marker for drought stress and might be a suitable marker for combined stress, whereas NCED2 was not suitable. Significance of the Study These results provide insight into the response of grapevines to heat, drought and combined stress and show the suitability of ABA and proline as stress markers.

Early repeat colonoscopy is associated with poor quality of the intial test

Drought stress is a major factor in turfgrass management; however, the underlying mechanisms of turfgrass drought tolerance are not well understood. This greenhouse study was designed to investigate proline and hormone responses to drought stress in two tall fescue [ Festuca arundinacea (Schreb.)] cultivars differing in drought tolerance. The two cultivars, Van Gogh (relatively drought-tolerant) and AST7002 (relatively drought-sensitive), were established and grown under either well-watered (maintaining 90% container capacity) or drought stress (≈26% container capacity) and then re-watered. Drought stress reduced turfgrass quality, relative leaf water content (LWC), leaf indole-3-acetic acid (IAA) and cytokinin zeatin riboside (ZR) content, and increased proline and abscisic acid (ABA) content. ‘Van Gogh’ had greater turfgrass quality rating, LWC, proline, ABA, and ZR content relative to ‘AST7002’ under drought stress conditions. At the end of drought stress, leaf proline, ZR, and ABA content were 32%, 43%, and 50% higher in ‘Van Gogh’ relative to ‘AST7002’, respectively. No cultivar difference was observed under well-watered conditions. The results of this study suggest that the proline, ABA, and ZR content are associated with drought tolerance. Selection and use of the cultivars with higher proline, ABA, and ZR content under drought stress may be a practical approach to improve tall fescue drought tolerance.

Transgenic lines of creeping bent grass were generated by Agrobacterium-mediated transformation with the VuNCED1 which was cloned from cow pea has a homology to 9-cis-epoxycarotenoid dioxygenase, which is supposed to be involved in abscisic acid (ABA) biosynthesis. ABA, a cleavage product of carotenoids, is involved in stress responses in plants. The limiting step of ABA biosynthesis in plants is presumably the cleavage of 9-cis-epoxycarotenoids, the first committed step of ABA biosynthesis. Molecular analyses of transgenic lines as performed by Southern hybridization genomic DNA-PCR revealed integration of the VuNCED1. Challenge studies performed with transgenic plants by exposure to salt stress (up to 10 dS m−1) and water stress (up to 75%) for 10 weeks, revealed that more than 50% of the transgenic plants could survive NaCl and drought stress whereas wild-type was not. ABA levels were measured under drought and normal conditions, endogenous ABA was dramatically increased by drought and NaCl stress in transgenic plants. These results indicate that it is possible to manipulate ABA levels in plants by over expressing the key regulatory gene in ABA biosynthesis and that stress tolerance can be improved by increasing ABA levels.

Gene expression in two contrasting hybrid clones of Eucalyptus camaldulensis x Eucalyptus urophylla grown under water deficit conditions

Tubers of the potato cultivars Pentland Dell and Record were stored for a period of up to 40 weeks at 5°C and 10°C over four consecutive storage seasons (1989–1990 to 1992–1993). Reconditioning treatments at 20°C were also performed at early, mid and late stages in storage. To assess the turnover of proteins during storage, tubers were analysed for free amino acid and soluble protein content. The net direction of nitrogen flow was dependent on the state of dormancy of the tuber and hence storage duration. An increase in free amino acid content commonly occurred during the latter part of storage, caused by an upturn of proteinase activity on the break of dormancy. This increased enzyme activity was probably due to de novosynthesis of proteinases, in particular of a 47 kDa aspartic proteinase which was purified to homogeneity and shown to have a marked substrate-specificity for endogenous tuber proteins such as patatin. The rate of protein turnover increased with storage temperature, although the net direction of nitrogen flow was temperature independent. However, when nitrogen flow exhibited a distinct direction, such as the protein breakdown in Pentland Dell during late storage, this was enhanced by higher temperatures. The accumulation of free amino acids in Pentland Dell at 10°C corresponded with a deterioration of processing quality that could not be accounted for by an upturn in reducing sugar content. Despite an excess of free amino acids with respect to reducing sugars, amino acids had a probable syn-ergistic influence on fry colour over the later stages of storage resulting in a darker colour per unit reducing sugar than in early storage. Reconditioning treatments were ineffective as a means of lowering the free amino acid pool size, these treatments operating solely through the decrease in reducing sugar content.

There was an accumulation of total free amino acids (calculated as the sum of the individual amino acids) in corollas from cut ‘Sonia’ roses ( Rosa hybrida ) stored at 2C (cold-stored flowers) but not in those kept at 20C (control flowers). In cold-stored flowers, senescence was retarded, as indicated by only a slight opening of the corolla and no subsequent petal abscission. Hence, there appeared to be no direct correlation between senescence of cut roses and accumulation of total amino acids in corollas; neither was there a relationship between individual or total free amino acids and protease activity in the corollas from either cold-stored or control flowers. Changes in the contents of all free amino acids, except alanine and lysine, were affected by cold storage. The effect on aspartic acid was statistically significant, but not spectacular. Cold storage delayed the decrease in contents of glutamic acid, asparagine, tyrosine, glycine, leucine, isoleucine and valine, and prevented accumulation of phenylalanine, proline, and histidine. We detected only one theoretically expected interconversion between two amino acids; i.e., glutamic acid to proline, that occurred in corollas from control flowers during the first 6 days of storage. We suggest that the patterns of changes in the contents of tyrosine, valine, isoleucine (or isoleucine plus leucine), and phenylalanine are not restricted to the cultivar Sonia.

Changes in the concentrations of free and total amino acids of several commercial <i>Vitis labruscana</i> musts during fermentation were examined by automated ion-exchange analysis. Except for proline, lysine, and glycine, there was a dramatic reduction in free amino acid content by the sixth day after yeast inoculation. At the end of the fermentation the concentration of the free amino acids had increased through yeast cellular autolysis but were still only between 2 and 30% of the initial must values. Proline was apparently not utilized by the yeast during fermentation. Except for proline, which averaged 16.4 mg/100 ml wine, all the free amino acids were less than 3 mg/100 ml in the final wine samples. Small amounts of β-alanine, ornithine, and citrulline were found, and cystathionine was detected at the end of the fermentations. Total amino acid concentrations determined from hydrolyzed wine samples showed trends similar to those of the free amino acids during fermentation. Next to proline, the most abundant of the total amino acids were glutamic acid, aspartic acid, lysine, and glycine. In contrast to proline, which existed mostly in the free form, those four amino acids were present primarily in protein and polypeptide form. Levels of protein and total nitrogen decreased initially and then increased during the later stages of the fermentation. An average of 26.1% of the total nitrogen in the wine at the end of fermentation was due to free amino acid nitrogen. Ammonia, apparently readily utilized by the yeast, decreased rapidly during fermentation. The patterns of change in amino acid composition observed during fermentation were similar to those found with vinifera varieties. The differences were primarily quantitative.