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The Japanese traditional fermented soybean or "natto", a cheap and nutrient-rich food, is very popular in Japan. The low-phytate (LP) soybeans exhibit higher mineral bioavailability; however, their use in preparing natto has not been reported. Therefore, in this study, characteristics and quality of natto prepared using LP soybean were investigated. The findings revealed a better color, lower stickiness, and lower hardness and taste of LP natto with lower phytate and higher inorganic phosphorus (Pi) concentrations than those in the normal-phytate (NP) natto. However, the Ca, Mg, and K concentrations were not significantly different between LP and NP natto, whereas the protein level in NP natto was slightly higher than that in LP natto. These findings indicate that the lower phytate content in LP natto than that in NP natto, could facilitate a higher bioavailability of P and other minerals. Moreover, the improved color and lower stickiness, in addition to lower hardness and taste of LP natto, imparted through improved manufacturing process could increase its acceptability overseas, thereby increasing its commercial value. These improved qualities of LP natto could contribute to improving human health as well as increasing sustainable food and nutrient security.

Declining rate of productivity and environmental sustainability is forcing growers to use organic manures as a source of nutrient supplement in maize farming. However, weed is a major constraint to maize production. A field study was carried out over two seasons to evaluate various integrated nutrient and weed management practices in hybrid maize. The treatment combinations comprised of supplementation of inorganic fertilizer (25% nitrogen) through bulky (Farmyard manure and vermicompost) and concentrated ( Brassicaceous seed meal (BSM) and neem cake (NC)) organic manures and different mode of weed management practices like chemical (atrazine 1000 g ha -1 ) and integrated approach (atrazine 1000 g ha -1 followed by mechanical weeding). Repeated supplementation of nitrogen through concentrated organic manures reduced the density and biomass accumulation of most dominant weed species, Anagalis arvensis by releasing allelochemicals into the soil. But organic manures had no significant impact on restricting the growth of bold seeded weeds like Vicia hirsuta and weed propagated through tubers i.e., Cyperus rotundus in maize. By restricting the weed growth and nutrient removal by most dominating weeds, application of BSM enhanced the growth and yield of maize crop. Repeated addition of organic manures (BSM) enhanced the maize grain yield by 19% over sole chemical fertilizer in the second year of study. Application of atrazine as pre-emergence (PRE) herbicide significantly reduced the density of A . arvensis , whereas integration of mechanical weeding following herbicide controlled those weeds which were not usually controlled with the application of atrazine. As a result, atrazine at PRE followed by mechanical weeding produced the highest maize grain yield 6.81 and 7.10 t/ha in the first year and second year of study, respectively.

Sodic-alkalinity is a more seriously limiting factor in agricultural productivity than salinity. Oat ( Avena nuda ) is a salt-tolerant crop species and is therefore useful in studying the physiological responses of cereals to alkalinity. We evaluated the differential effects of sodic-alkalinity on two naked oat lines, Caoyou1 and Yanke1. Seedlings of the two lines were exposed to 50 mM alkaline salt mixture of NaHCO 3 and Na 2 CO 3 (18:1 molar ratio; pH 8.5) for 2 weeks in a soil environment. Sodic-alkalinity exposure led the assimilation of abundant Na + at similar concentrations in the organs of both lines. However, Caoyou1 showed much stronger growth than Yanke1, exhibiting a higher dry weight, total leaf area, and shoot height under sodic-alkalinity. Further analysis showed that Caoyou1 was more sodic-alkalinity tolerance than Yanke1. This was firstly because of differences in the oxidative stress defense mechanisms in leaves of the two lines. Antioxidant enzyme activities were either slightly elevated (catalase (CAT), ascorbate peroxidase (APX), guaiacol peroxidase (GP), glutathione reductase (GR)) or unaltered (superoxide dismutase (SOD)) in Caoyou1 leaves, but some enzyme (SOD, GPOX, GR) activities were significantly reduced in Yanke1. An APX1 transcript levels significantly increased in Caoyou1 under sodic-alkalinity conditions compared with Yanke1, indicating its better antioxidant capacity. Secondly, the related parameters of Mg 2+ concentration, phosphoenolpyruvate carboxylase (PEPC) activity, and An PEPC transcript levels in the leaves showed significantly higher values in Caoyou1 compared with Yanke1. This demonstrated the effective utilization by Caoyou1 of accumulated HCO 3 - in the irreversible reaction from phosphoenolpyruvate to oxaloacetate to produce inorganic phosphorus, which was elevated in Caoyou1 leaves under alkalinity stress. Overall, the results demonstrated that the greater sodic-alkalinity tolerance of Caoyou1 is the result of: (1) maintained antioxidant enzyme activities; and (2) a higher capacity for the phosphoenolpyruvate to oxaloacetate reactions, as shown by the higher PEPC activity, Mg 2+ concentration, and total phosphorus concentration in its leaves, despite the lower soil pH.

Phytate is a storage form of phosphorus (P) in seeds and, when degraded, plays a vital role in seed germination. Low phytate content in grain seeds inhibits germination and seedling growth. Here, Low-phytate (LP) and normal-phytate (NP) soybean lines were grown in vermiculite to determine whether germination was affected by low phytate content. Growth, phytase activity, mineral concentration, and mineral extractability from the seedlings of NP and LP soybean lines were evaluated. Seedling growth did not differ significantly between NP and LP lines. Phytase and specific phytase activities at 11 days to 17 days after sowing were 1.3 to 2.6 folds greater in the NP line than in the LP line. The LP line hydrolyzed all the phytate 2 days earlier than the NP line. The concentration and extractability of minerals changed over time during germination, and the LP line had higher molar ratios of phytic acid to Ca, Mg, and K than the NP line. These results suggest that germination and growth of the seedlings are not affected by low phytate levels in seeds. We suggest that the LP line benefits from higher bioavailability of P and macro-minerals unlike the NP line.

Understanding the influence of the valuable "low-phytate" trait on soybean seedling growth, physiology, and biochemistry will facilitate its future exploitation. The aim was to elucidate the physiological and biochemical characteristics of low-phytate (LP) soybean at the seedling stage. To this end, seed P and mineral content and seedling dry weight, carbon (C) and nitrogen (N) accumulation, nitrogen fixation, and root and nodule phytase and phosphatase activity levels were measured at 21 d after sowing LP and normal-phytate (NP) soybean lines. Seedling dry weight, and C and N accumulation were 31%, 38% and 54% higher, respectively, in the LP line than the NP line. The total and specific nitrogen fixation levels in the LP nodules were 46% and 78% higher, respectively, than those in the NP nodules. The phytase, phosphatase, and specific phytase levels were 1.4-folds, 1.3-folds, and 1.3-folds higher, respectively, in the LP roots than the NP roots. The phosphatase and specific phosphatase levels in LP nodules were 1.5-folds and 1.3-folds higher, respectively, than those in the NP nodules. The mineral levels were substantially higher in the LP seeds and seedings than in those of the NP line. The HCl extractabilities of P, S, Fe, Cu and Mn were higher in the LP seeds than the NP seeds. These results indicate that the LP line presented with superior seedling growth and nitrogen fixation relative to the NP line. The LP line had relatively higher root phytase and root and nodule phosphatase activity levels than the NP line and could, therefore, be better suited and more readily adapt to low P conditions., Competing Interests: Declaration of competing interest The authors declare that they have no conflict of interest., (Copyright © 2020 Elsevier Masson SAS. All rights reserved.)

Sodic-alkalinity is a serious limiting factor in agricultural productivity. This study was conducted to examine the contribution of acclimation to the adaptation of rye ( Secale cereale ) to sodic-alkalinity. Effects of acclimation were determined in two sets of experiments: One experiment for mineral accumulation, antioxidative capacity, and other physiological parameters; and a vivo experiment for root Evan's Blue and Na + influx from medium to root. Being exposed to sodic-alkalinity, acclimation did not affect plant dry weight. However, acclimation significantly reduced Na + concentration and maintained a lower Na + /K + ratio in all the tissues, increased the Ca 2+ and Mg 2+ concentrations in the root tissues, and increased the water uptake ability in comparison to the non-acclimated plants. Acclimation increased the antioxidant capacity represented by the increased activities of the enzymes SOD, GR, CAT, and GPOX in the leaf tissues of acclimated plants in comparison to the non-acclimated plants. Moreover, acclimation increased the root cell viability inhibited the Na + influx to the root tissues in comparison to the non-acclimated plants. Together, these results suggest that rye can acclimate to sodic-alkalinity by increasing root cell viability, and therefore limited Na + influx to root tissues and increased water uptake and antioxidant capacities without any change in the plant growth.

Crop seed phosphorus (P) is primarily stored in the form of phytate, which is generally indigestible by monogastric animals. Low-phytate soybean lines have been developed to solve various problems related to seed phytate. There is little information available on the effects of P fertilization on productivity, physiological characteristics, and seed yield and quality in low-phytate soybeans. To address this knowledge gap, studies were conducted with a low-phytate line and two normal-phytate cultivars from western Japan when grown under high- and low-P fertilization. The whole plant dry weight, leaf photosynthesis, dinitrogen fixation, and nodule dry weight at the flowering stage were higher in the higher P application level, but were not different between the low-phytate line and normal-phytate cultivars. As expected, seed yield was higher in the higher level of P application for all lines. Notably, it was higher in the low-phytate line as compared with the normal-phytate cultivars at both levels of fertilizer P. The total P concentration in the seeds of the low-phytate line was the same as that of the normal-phytate cultivars, but the phytate P concentration in the low-phytate line was about 50% less than that of the normal-phytate cultivars. As a result the molar ratio of phytic acid to Zn, Fe, Mn, and Cu in seed were also significantly lower in the low-phytate line. From these results, it can be concluded that growth after germination, leaf photosynthesis, nitrogen fixation, yield and seed quality were not less in the low-phytate soybean line as compared with two unrelated normal-phytate cultivars currently grown in Japan, and that low-phytate soybeans may improve the bioavailability of microelements.

Although barley (Hordeum vulgare L.) is considered a salt tolerant crop species, productivity of barley is affected differently by ionic, osmotic, and oxidative stresses resulting from a salty rhizosphere. The current study was conducted to elucidate the mechanism of salt tolerance in two barley cultivars, Giza128 and Giza126. The two cultivars were exposed to 200 mM NaCl hydroponically for 12 days. Although both cultivars accumulated a large amount of Na + in their leaves with similar concentrations, the growth of Giza128 was much better than that of Giza126, as measured by maintaining a higher dry weight, relative growth rate, leaf area, and plant height. To ascertain the underlying mechanisms of this differential tolerance, first, the relative expression patterns of the genes encoding Na + /H + antiporters (NHX) and the associated proton pumps (V-PPase and V-ATPase) as well as the gene encoding the plasma membrane PM H + -ATPase were analyzed in leaf tissues. Salt stress induced higher HvNHX1 expression in Giza128 (3.3-fold) than in Giza126 (1.9-fold), whereas the expression of the other two genes, HvNHX2 and HvNHX3, showed no induction in either cultivar. The expression of HvHVP1 and HvHVA was higher in Giza128 (3.8- and 2.1-fold, respectively) than in Giza126 (1.6- and 1.1-fold, respectively). The expression of the PM H + -ATPase (ha1) gene was induced more in Giza128 (8.8-fold) than in Giza126 (1.8-fold). Second, the capacity for ROS detoxification was assessed using the oxidative stress biomarkers electrolyte leakage ratio (ELR) and the concentrations of malondialdehyde (MDA) and hydrogen peroxide (H 2 O 2 ), and these parameters sharply increased in Giza126 leaves by 66.5%, 42.8% and 50.0%, respectively, compared with those in Giza128 leaves. The antioxidant enzyme (CAT, APX, sPOD, GR, and SOD) activities were significantly elevated by salt treatment in Giza128 leaves, whereas in Giza126, these activities were not significantly altered. Overall, the results indicate that the superior salt tolerance of Giza128 is primarily the result of the ability to counter Na + -induced oxidative stress by increasing antioxidant enzyme levels and possibly by increasing vacuolar Na + sequestration and prevention of cellular K + leakage., (Copyright © 2018 Elsevier Masson SAS. All rights reserved.)

Ionic stress is one of the most important components of salinity and is brought about by excess Na + accumulation, especially in the aerial parts of plants. Since Na + interferes with K + homeostasis, and especially given its involvement in numerous metabolic processes, maintaining a balanced cytosolic Na + /K + ratio has become a key salinity tolerance mechanism. Achieving this homeostatic balance requires the activity of Na + and K + transporters and/or channels. The mechanism of Na + and K + uptake and translocation in glycophytes and halophytes is essentially the same, but glycophytes are more susceptible to ionic stress than halophytes. The transport mechanisms involve Na + and/or K + transporters and channels as well as non-selective cation channels. Thus, the question arises of whether the difference in salt tolerance between glycophytes and halophytes could be the result of differences in the proteins or in the expression of genes coding the transporters. The aim of this review is to seek answers to this question by examining the role of major Na + and K + transporters and channels in Na + and K + uptake, translocation and intracellular homeostasis in glycophytes. It turns out that these transporters and channels are equally important for the adaptation of glycophytes as they are for halophytes, but differential gene expression, structural differences in the proteins (single nucleotide substitutions, impacting affinity) and post-translational modifications (phosphorylation) account for the differences in their activity and hence the differences in tolerance between the two groups. Furthermore, lack of the ability to maintain stable plasma membrane (PM) potentials following Na + -induced depolarization is also crucial for salt stress tolerance. This stable membrane potential is sustained by the activity of Na + /H + antiporters such as SOS1 at the PM. Moreover, novel regulators of Na + and K + transport pathways including the Nax1 and Nax2 loci regulation of SOS1 expression and activity in the stele, and haem oxygenase involvement in stabilizing membrane potential by activating H + -ATPase activity, favorable for K + uptake through HAK/AKT1, have been shown and are discussed.

The present study sought to investigate the factors implicated in growth impairment of huckleberry (a leafy vegetable) under water stress conditions. To achieve this, seedlings of plant were subjected to control, mild stress and severe stress conditions for 30 days. Plant growth, plant water relation, gas exchange, oxidative stress damage, electrolyte leakage rate, mineral content and osmolyte accumulation were measured. Water deficit markedly decreased leaf, stem and root growth. Leaf photosynthetic rate was tremendously reduced by decrease in stomatal conductance under stress conditions. Malondialdehyde (MDA) content markedly increased under mild (82%) and severe (131%) stress conditions, while electrolyte leakage rate (ELR) increased by 59% under mild stress and 3-fold under severe stress. Mineral content in leafwas high in stressed plants, while proline content markedly increased under mild stress (12-fold) and severe stress (15-fold), with corresponding decrease in osmotic potential at full turgor and an increase in osmotic adjustment. These results suggest that maintenance of high mineral content and osmotic adjustment constitute important adaptations in huckleberry under water deficit conditions and that growth depression under drought stress would be mainly caused by increased electrolyte leakage resulting from membrane damage induced by oxidative stress.

Reduced Na(+) accumulation in the leaf blade is an important aspect of salinity tolerance and high affinity K(+) transporters (HKTs) are known to play a significant role in the process. Huckleberry and eggplant have previously been shown to display 'excluder' and 'includer' characteristics, respectively, under salt stress, but the underlying mechanisms have not been investigated. Here, we isolated the cDNA of the HKT homologs, Solanum scabrum HKT (SsHKT) from huckleberry and Solanum melongena HKT (SmHKT) from eggplant, and analyzed their expressions in different tissues under salt stress. SsHKT expression was markedly induced in the root (28-fold) and stem (7-fold), with a corresponding increase in Na(+) accumulation of 52% and 29%, respectively. Conversely, eggplant accumulated 60% total Na(+) in the leaf blade, with a lower SmHKT expression level in the root (3-fold). Huckleberry also maintained a higher K(+)/Na(+) ratio in the leaf blade compared to eggplant, due to the reduction of its Na(+) concentration and unaltered K(+) concentration. Functional analysis demonstrated that SsHKT-mediated Na(+) influx inhibited yeast growth under Na(+) stress, and that SsHKT did not complement the growth of the K(+) uptake-deficient CY162 strain under K(+)-limiting conditions. These results suggest that the Na(+) accumulation characteristics of both plants are caused by the differential expression of HKT genes, with SsHKT exerting a greater control over the ability of Na(+) to reach the leaf blade in huckleberry, than SmHKT does in eggplant., (Copyright © 2015 Elsevier Inc. All rights reserved.)

The potential benefits of the low phytic acid (lpa) seed trait for human and animal nutrition, and for phosphorus management in non-ruminant animal production, are well documented. However, in many cases the lpa trait is associated with impaired seed or plant performance, resulting in reduced yield. This has given rise to the perception that the lpa trait is tightly correlated with reduced yield in diverse crop species. Here we report a powerful test of this correlation. We measured grain yield in lines homozygous for each of six barley (Hordeum vulgare L.) lpa mutations that greatly differ in their seed phytic acid levels. Performance comparisons were between sibling wild-type and mutant lines obtained following backcrossing, and across two years in five Idaho (USA) locations that greatly differ in crop yield potential. We found that one lpa mutation (Hvlpa1-1) had no detectable effect on yield and a second (Hvlpa4-1) resulted in yield losses of only 3.5%, across all locations. When comparing yields in three relatively non-stressful production environments, at least three lpa mutations (Hvlpa1-1, Hvlpa3-1, and Hvlpa4-1) typically had yields similar to or within 5% of the wild-type sibling isoline. Therefore in the case of barley, lpa mutations can be readily identified that when simply incorporated into a cultivar result in adequately performing lines, even with no additional breeding for performance within the lpa line. In conclusion, while some barley lpa mutations do impact field performance, a substantial fraction appears to have little or no effect on yield.

Successful colonization is the initial step for plant-bacteria interactions; therefore, the development of strategies to improve adherence to plant surfaces is critically important for environmental bacteria. Biofilm formation is thought to be one such strategy for bacteria to establish stable colonization on inert and living surfaces. Although biofilms play potential roles in enabling persistent bacterial colonization, little attention has been paid to biofilms formed by plant-associated bacteria. In this study, we characterized the biofilm-forming ability of 6 species of bacteria from the family Pseudomonadaceae: Pseudomonas protegens, Pseudomonas fluorescens, Pseudomonas putida, Pseudomonas stutzeri, Pseudomonas mendocina, and Pseudomonas syringae. These strains exhibit different degrees of biofilm formation depending on incubation time and nutrient availability. Distinct preferences for growth media were observed, as biofilms were formed by P. protegens with rich nutrients and by P. fluorescens and P. putida with poor nutrients. Likewise, P. stutzeri did not form biofilms with rich nutrients but did form biofilms under nutrient-poor conditions. These observations indicate that particular components in media may influence biofilm formation. P. putida, one of the strains with high biofilm-forming ability, showed the highest ability for initial attachment, which may be mediated by the hydrophobicity of its cell surface. P. mendocina also has high ability for initial attachment, and this strain produces cell surface-attached extracellular polysaccharides that promote cell aggregation. Thus, each strain possesses different properties that facilitate biofilm formation. Shedding light on bacterial strategies for colonization via biofilm formation would enable a better understanding of plant-bacteria interactions.

Abiotic stressors, such as high salinity, greatly affect plant growth. In an attempt to explore the mechanisms underlying salinity tolerance, physiological parameters of two local Egyptian rice (Oryza sativa L.) cultivars, Sakha 102 and Egyptian Yasmine, were examined under 50 mM NaCl stress for 14 days. The results indicate that Egyptian Yasmine is relatively salt tolerant compared to Sakha 102, and this was evident in its higher dry mass production, lower leaf Na(+) levels, and enhanced water conservation under salt stress conditions. Moreover, Egyptian Yasmine exhibited lower Na(+)/K(+) ratios in all tissues examined under salinity stress. The ability to maintain such traits seemed to differ in the leaves and roots of Egyptian Yasmine, and the root K(+) content was much higher in Egyptian Yasmine than in Sakha 102. In order to understand the basis for these differences, we studied transcript levels of genes encoding Na(+) and K(+) transport proteins in different tissues. In response to salinity stress, Egyptian Yasmine showed induction of expression of some membrane transporter/channel genes that may contribute to Na(+) exclusion from the shoots (OsHKT1;5), limiting excess Na(+) entry into the roots (OsLti6b), K(+) uptake (OsAKT1), and reduced expression of a Na(+) transporter gene (OsHKT2;1). Therefore, the active regulation of genes related to Na(+) transport at the transcription level may be involved in salt tolerance mechanisms of Egyptian Yasmine, and these mechanisms offer the promise of improved salinity stress tolerance in local Egyptian rice genotypes., (Copyright © 2015 Elsevier Masson SAS. All rights reserved.)

Inositol hexaphosphate (Ins P6 or "phytic acid") typically accounts for 75 (± 10%) of seed total phosphorus (P). In some cases, genetic blocks in seed Ins P6 accumulation can also alter the distribution or total amount of seed P. In nonmutant barley (Hordeum vulgare L.) caryopses, ~80% of Ins P6 and total P accumulate in the aleurone layer, the outer layer of the endosperm, with the remainder in the germ. In barley low phytic acid 1-1 (Hvlpa1-1) seed, both endosperm Ins P6 and total P are reduced (~45% and ~25%, respectively), but germs are phenotypically wild type. This translates into a net reduction in whole-seed total P of ~15%. Nutrient culture studies demonstrate that the reduction in endosperm total P is not due to a reduction in the uptake of P into the maternal plant. Genetic tests (analyses of testcross and F2 seed) reveal that the Hvlpa1-1 genotype of the filial seed conditions the seed total P reduction; sibling seed in the same head of barley that differ in their Hvlpa1-1 genotype (heterozygous vs. homozygous recessive) differ in their total P (normal vs. reduced, respectively). Therefore, Hvlpa1 functions as a seed-specific or filial determinant of barley endosperm total P., (Published by Oxford University Press on behalf of the American Genetic Association 2014. This work is written by (a) US Government employee(s) and is in the public domain in the US.)

Background: The antileukemic activity of hot water extract of plant parts of some Japanese willow tree species grown at different levels of nitrogen were examined., Materials and Methods: Water extracts of willow leaves were prepared for this studies in different level of nitrogen nutrition., Results: The extracts obtained from the leaves and stem exhibited anti-leukemic activities prominently. The crude hot water extracts of the young growing parts including apex, matured leaves and stem, killed the blasts of acute myeloid leukemia (AML) cells, (HL60 and NB4) after 48h incubation, however, such desperation was far less in the root extract. Similar to the plant parts, response of extracts obtained from different willow species was not identical; the proportion of dead cells relative to whole cells of the culture medium ranged from 21% to 93% among the species. Leaf extracts obtained from the responsive willow species decreased the live cell percentage and increased the dead cell percentage at higher level of nitrogen nutrition. The mode of desperation of leaf extract treated AML cells in such species appeared to be cell apoptosis as shown by binding with fluorescein isothiocyanate (FITC) -labeled Annexin V., Conclusion: Differentiation of alive AML cells continued unabated and apoptosis was poor when extract of an unresponsive species added to the culture medium.

The potassium requirement of green house tomatoes is very high for vegetative growth and fruit production. Potassium deficiency in plants takes long time for expression of visible symptoms. The objective of this study is to detect the deficiency early during the vegetative growth and define the roles of aquaporin and K-channel transporters in the process of regulation of water status and source-sink relationship. The tomato plants were grown hydroponically inside green house of Hiroshima University, Japan and subjected to different levels of K in the rooting medium. Potassium deficiency stress decreased photosynthesis, expansion and transport of ¹⁴C assimilates of the source leaf, but the effects became evident only after diameter expansion of the growing stem (sink) was down-regulated. The depression of stem diameter expansion is assumed to be associated with the suppression of water supply more than photosynthate supply to the organ. The stem diameter expansion is parameterized by root water uptake and leaf transpiration rates. The application of aquaporin inhibitor (AgNO₃) decreased leaf water potential, stem expansion and root hydraulic conductance within minutes of application. Similar results were obtained for application of the K-channel inhibitors. These observations suggested a close relationship between stem diameter expansion and activities of aquaporins and K-channel transporters in roots. The deficiency of potassium might have reduced aquaporin activity, consequently suppressing root hydraulic conductance and water supply to the growing stem for diameter expansion and leaf for transpiration. We conclude that close coupling between aquaporins and K-channel transporters in water uptake of roots is responsible for regulation of stem diameter dynamics of green house tomato plants., (Copyright © 2010 Elsevier Ireland Ltd. All rights reserved.)

Ectoine is a common compatible solute in halophilic bacteria. Its biosynthesis originates from L-aspartate β-semialdehyde and requires three enzymes: L-2, 4-diaminobutyric acid aminotransferase (gene: ect B), L-2,4-diaminobutyric acid acetyl transferase (gene: ect A) and L-ectoine synthase (gene: ect C). Genetically engineered tomato plants expressing the three H. elongata genes (ectA, ectB, and ectC) generated showed no phenotypic abnormality. Expression of the ectoine biosynthetic genes was detected in the T3 transgenic plants by Northern blot analysis. The ectoine accumulating T3 plants were evaluated for salt tolerance by examining their photosynthestic activity, osmotic adjustment and carbon partitioning. Nuclear magnetic resonance (NMR) detected the accumulation of ectoine. The concentration of ectoine increased with increasing salinity. The transgenic lines showed higher activities of peroxidase, while the malondialdehyde (MDA) concentration was decreased under salinity stress condition. In addition, preservation of higher rates of photosynthesis and turgor values as compared to control was evident. Within a week of ( 13) CO 2 feeding, salt application led to increases in the partitioning of ( 13) C into roots at the expense of ( 13) C in the other plant parts. These results suggest that under saline conditions ectoine synthesis is promoted in the roots of transgenic plants, leading to an acceleration of sink activity for photosynthate in the roots. Subsequently, root function such as water uptake is improved, compared with wild-type plants. In this way, the photosynthetic rate is increased through enhancement of cell membrane stability in oxidative conditions under salt stress.

Barium (Ba)-induced phytotoxicity at 100, 1000, or 5000 microM Ba in soybean plants (Glycine max) was investigated under hydroponic culture conditions. Soybean growth and leaf photosynthetic activity were significantly inhibited by all three levels of Ba treatments. In the case of photosynthetic activity, 5000 microM Ba treatment shutdown stomatal opening and perturbed carbon fixation metabolism and translocation. However, 100 and 1000 microM Ba treatments shut down stomatal opening and inhibited carbon fixation, but without perturbation of leaf carbon fixation-related metabolism. Potassium (K) absorption by soybean roots was also reduced in all three Ba treatments. This decreased K absorption reduced K localization at guard cells. Barium accumulation in guard cells also inhibited K transport from epidermal cells to guard cells. This lack of K in guard cells resulted in stomatal closure. As a result of inhibition of K transport into guard cells and stomatal shutdown, photosynthetic activity and plant productivity were inhibited. Our experiment indicates that Ba has phytotoxic effects on soybean plants by inhibiting photosynthesis.

Tomato [Solanum lycopersicum (formerly Lycopersicon esculentum) L. cv. Momotarou] plants were grown hydroponically inside the greenhouse of Hiroshima University, Japan. The adverse effects of potassium (K) deficiency stress on the source-sink relationship during the early reproductive period was examined by withdrawing K from the rooting medium for a period of 21 d. Fruits and stem were the major sink organs for the carbon assimilates from the source. A simple non-destructive micro-morphometric technique was used to measure growth of these organs. The effect of K deficiency was studied on the apparent photosynthesis (source activity), leaf area, partitioning (13)C, sugar concentration, K content, and fruit and stem diameters of the plant. Compared with the control, K deficiency treatment severely decreased biomass of all organs. The treatment also depressed leaf photosynthesis and transport of (13)C assimilates, but the impact of stress on these activities became evident only after fruit and stem diameter expansions were down-regulated. These results suggested that K deficiency diminished sink activity in tomato plants prior to its effect on the source activity because of a direct effect on the water status of the former. The lack of demand in growth led to the accumulation of sugars in leaves and concomitant fall in photosynthetic activity. Since accumulation of K and sugars in the fruit was not affected, low K levels of the growing medium might not have affected the fruit quality. The micro-morphometric technique can be used as a reliable tool for monitoring K deficiency during fruiting of tomato. K deficiency directly hindered assimilate partitioning, and the symptoms were considered more detrimental compared with P deficiency.

Ectoine (1,4,5,6-tetrahydro-2-methyl-4-pyrimidinecarboxylic acid) biosynthetic genes (ect. ABC) from Halomonas elongata were introduced to tobacco plants using an Agrobacterium-mediated gene delivery system. The genes for ectoine biosynthesis were integrated in a stable manner into the tobacco genome and the corresponding transcripts were expressed. The concentration of ectoine under salt-stress conditions was higher in the roots than in leaves. A close relationship was found between stomatal conductance and the amount of transported nitrogen, suggesting that water transport through the xylem in the stem and transpiration may be involved in nitrogen transport to leaves. The data indicate that the turgor values of the ectoine transgenic lines increased with increasing salt concentration. The data revealed two ways in which ectoine enhanced salinity tolerance of tobacco plants. First, ectoine improved the maintenance of root function so that water is taken up consistently and supplied to shoots under saline conditions. Second, ectoine enhanced the nitrogen supply to leaves by increasing transpiration and by protecting Rubisco proteins from deleterious effects of salt, thereby improving the rate of photosynthesis.

A super-high-yielding rice (Oryza sativa L.) cultivar, Takanari, and a traditional japonica rice cultivar, Nakateshinsenbon, were grown under field conditions to compare partitioning of 13 C-labelled photosynthate to different plant organs during the period of reproductive development. The flag leaf and the two leaves immediately below it on the main culm were exposed individually to 13 CO 2 and the movement of the heavy carbon isotope to grains, hull, panicle branches and vegetative parts of plant was assessed. Also, the effect of a reduction of sink size on the partitioning of 13 C to different organs was studied by removing some of the primary branches of the panicle. 13 C taken up by the three leaves in the post-heading period, moved mostly to the grains and hull of the panicle. At this stage, the uppermost three leaves and the panicle consisted of a single source-sink unit. Partitioning of 13 C to the rest of the vegetative structures of the plant was minimal. In the case of Nakateshinsenbon, the flag leaf supplied most of the carbon assimilates for the grains and contributions from the other two leaves were much smaller. However, in Takanari, the contribution of 13 C to grains from the second leaf was equivalent to that of the flag leaf. In Takanari, removal of more than one third of the primary branches of the panicle significantly reduced partitioning from the third leaf of the culm, but partitioning from the flag leaf was not significantly changed. In contrast, branch removal treatment significantly depressed transport of carbon assimilates from the flag leaf in Nakateshinsenbon. The obligatory nature of the source-sink relationship in rice is discussed. It is concluded that in lower-yielding traditional rice, photosynthesis in the flag leaf supplies carbon assimilates to the developing grains. But in the super-yielding rice Takanari, the main source area is extended to include the two leaves below the flag leaf so as to sustain an extra large panicle. Even greater grain-filling is possible in super-yielding rice, if the source area is increased further.

To study the influence of genetic background on the transformation and regeneration of cultivated tomato plants, hairy root lines of tomato (Lycopersicon esculentum) were obtained by inoculating the hypocotyl explants of three tomato cultivars with the Agrobacterium rhizogenes strain DCAR-2, which harbors the pBI-121 binary vector. The Ri-T-DNA transformation into the plant DNA was confirmed by both of mikimopine and GUS assay analyses. The regeneration efficiency from hairy root explants was assessed. The data indicated that white embryonic calli were formed within two weeks in the presence of 2 mgl(-1) 2, 4-D plus 0.25 mgl(-1) kinetin. Adventitious shoots emerged from the embryonic callus in the presence of 1 mgl(-1) GA3 along with 0.5 mgl(-1) NAA. The regeneration frequency was higher in the cultivar UC-97, followed by Momotaro and then Edkawi. Molecular confirmation of the integration of the GUS gene into the hairy root-derived plants genomes was done via PCR using GUS-specific primers and also using Southern blotting analysis. Our data shows that regeneration is possible from hairy roots of the cultivated tomato and this system could be used to produce transgenic tomato plants expressing the genes present in Agrobacterium rhizogenes binary vectors.

Early diagnosis of water deficiency is essential to mitigate salt stress injury in plants. The effects of salt stress during the fruit growth stage on stem and fruit diameters of Japanese persimmon trees (Diospyrus kaki Thunb.) were measured by a micromorphometric technique under greenhouse conditions. This technique is less cumbersome and more precise in comparison to measurement of water potential in a small pressure chamber. The effect of stress was measured on photosynthetic rate, pre-dawn water potential, stomatal conductance, transpiration and Na + and K + contents of the stem and leaves. Salt stress was imposed by irrigating the plants with NaCl solution. Stem and fruit diameters of the plants given the control treatment started to decrease around 0600 h and reached a minimum at 1400 h. Salt stress did not change the diurnal pattern of response in stem and fruit diameter dynamics, but decreased the amplitude of the circadian rhythm by influencing both declining and recovery phases. The effect of salt stress on stem diameter appeared after 1 d of treatment, and on the third day in the fruit. Salt stress also reduced water potential, photosynthesis, transpiration and stomatal conductance, and increased concentrations of Na and K in the plant parts. Most of these effects were expressed after a lag period of 5 d of salt application. Utilization of micromorphometric techniques for early diagnosis of water deficiency in salt-prone environments is recommended based on results of this study.

The ability to synthesize and accumulate glycine betaine is wide-spread among angiosperms and is thought to contribute to salt and drought tolerance. In plants glycine betaine is synthesized by the two-step oxidation of choline via the intermediate betaine aldehyde, catalyzed by choline monooxygenase and betaine aldehyde dehydrogenase (BADH). Two sorghum (Sorghum bicolor) cDNA clones, BADH1 and BADH15, putatively encoding betaine aldehyde dehydrogenase were isolated and characterized. BADH1 is a truncated cDNA of 1391 bp. BADH15 is a full-length cDNA clone, 1812 bp in length, predicted to encode a protein of 53.6 kD. The predicted amino acid sequences of BADH1 and BADH15 share significant homology with other plant BADHs. The effects of water deficit on BADH mRNA expression, leaf water relations, and glycine betaine accumulation were investigated in leaves of preflowering sorghum plants. BADH1 and BADH15 mRNA were both induced by water deficit and their expression coincided with the observed glycine betaine accumulation. During the course of 17 d, the leaf water potential in stressed sorghum plants reached -2.3 MPa. In response to water deficit, glycine betaine levels increased 26-fold and proline levels increased 108-fold. In severely stressed plants, proline accounted for > 60% of the total free amino acid pool. Accumulation of these compatible solutes significantly contributed to osmotic potential and allowed a maximal osmotic adjustment of 0.405 MPa.

Pairs of homozygous near-isogenic glycinebetaine-containing (Bet1/Bet1) and -deficient (bet1/bet1) F8 lines of Zea mays L. (maize) were tested for differences in salt (150 mM NaCl or 127.25 mM NaCl plus 22.5 mM CaCl2) tolerance. The Bet1/Bet1 lines exhibited less shoot growth inhibition (as measured by dry matter accumulation, leaf area expansion rate and/or, plant height extension rate) under salinized conditions in comparison to their nearisogenic bet1/bet1 sister lines. These growth differences were associated with maintenance of a significantly higher leaf relative water content, a higher rate of carbon assimilation, and a greater turgor in Bet1/Bet1 lines than in bet1/bet1 lines under salinized conditions. These results strongly suggest that a single gene conferring glycinebetaine accumulation (and/or a tightly linked locus) plays a key role in osmotic adjustment in maize.

A series of near-isogenic glycinebetaine-containing and -deficient F8 pairs of Zea mays L. (maize) lines were developed. The pairs of lines differ for alternative alleles of a single locus; the wild-type allele conferring glycinebetaine accumulation is designated Bet1 and the mutant (recessive) allele is designated bet1. The near-isogenic lines were used to investigate whether glycinebetaine deficiency affects the pool size of the glycinebetaine precursor, choline, using a new method for glycinebetaine and choline determination: stable isotope dilution plasma desorption mass spectrometry. Glycinebetaine deficiency in maize was associated with a significant expansion of the free choline pool, but the difference in choline pool size was not equal to the difference in glycinebetaine pool size, suggesting that choline must down-regulate its own synthesis. Consistent with this, glycinebetaine deficiency was also associated with the accumulation of the choline precursor, serine. A randomly amplified polymorphic DNA marker was identified that detects the bet1 allele. In 62 F8 families tested the 10-mer primer 5'-GTCCTCGTAG produced a 1.2-kb polymerase chain reaction product only when DNA from Bet1/bet1 or bet1/bet1 lines was used as template. All 26 homozygous Bet1/Bet1 F8 families tested were null for this marker.