Effects of Ocean Acidification on Nitrogen Metabolism of Skeletonema costatum

Ocean acidification(OA),caused by the rising concentration of atmospheric CO_(2),leads to changes in the marine carbonate system.This,in turn,affects the physiological processes of phytoplankton.In response to increased pCO_(2) levels,marine microalgae modulate their physiological responses to meet their energy and metabolic requirements.Nitrogen metabolism is a critical metabolic pathway,directly affecting the growth and reproductive capacity of marine microorganisms.Understanding the molecular mechanisms that regulate nitrogen metabolism in microalgae under OA conditions is therefore crucial.This study aimed to investi-gate how OA affects the expression profiles of key genes in the nitrogen metabolic pathway of the marine diatom Skeletonema costatum.Our findings indicate that OA upregulates key genes involved in the nitrogen metabolic pathway,specifically those related to nitrate assimilation and glutamate metabolism.Moreover,pCO_(2) has been identified as the predominant factor affecting the expression of these genes,with a more significant impact than pH variations in S.costatum.This research not only advances our understanding of the adaptive mechanisms of S.costatum in response to OA but also provides essential data for predicting the ecological consequences of OA on marine diatoms.

Effects ofγ-aminobutyric Acid on Nitrogen Metabolism in Roots and Leaves of Cold-stressed Rice(Oryza sativa L.)During Early Vegetative Growth

Cold stress adversely affects rice growth,particularly at the early vegetative growth stage.In higher plants,nitrogen metabolism plays a central role in amino acid metabolism,plant defense mechanisms and productivity.This report investigated the effects of cold stress and supplementalγ-aminobutyric acid(GABA)under cold stress on nitrogen metabolism in rice seedlings.Cold stress resulted in a greater increase in the transformation to NH_(4)^(+)by nitrate reductase(NR)in roots,it further resulted in lower levels of NO_(3)^(-)content in roots,weakened glutamine glutamate(GOGAT/GS)pathway and elevated glutamate dehydrogenase(GDH)pathway of rice seedlings.Whereas,compared with cold stress,supplementation of GABA(2.5 mmol·L^(-1))could increase relative water content(79.43%)and biomass(34.15%)of rice seedlings.GABA could act as an amplifier of stress signal conduction/transduction to increase NR activity and promote NO_(3)^(-)assimilation in leaves.In addition,GABA elicited the Ca^(2+)signaling pathway which could promote the GDH pathway and GABA shunt,increase the activities of GS and GDH,and the expression of OsGAD2 and OsGDH family.The GABA might increase the ratio of the Glu family and avoid NH4+toxicity in order to raise the concentration of organic compounds and alleviate the harmful consequences of cold stress.Based on these observations,this study proposed that GABA mediated cold tolerance in rice seedlings by activating Ca^(2+)burst and subsequent crosstalk among Ca^(2+)signaling,GDH pathway and GABA shunt.

Influences of Nitrogen Level on Carbon Metabolism of Spring Maize

[Objective]To study the effect of supplies of nitrogen level on spring maize leaf blade carbon metabolism.[Method]In this experiment,field trail and biochemistry analysis were used to study the effect of the diference-nitrogen level on the content of chlorophyl and carboxylase activity of RuBP and PEP in the leaf of spring maize during main growing period.[Result]Applying proper amount of N could keep relative higher content of chlorophyl and higher activity of carboxylase of RuBP and PEP in the leaf of spring maize,insufficient or excessive（N 400 kg/hm^2） of nitrogenous fertilizer has the adverse effect.[Conclusion]In this experiment,applying 300 kg/hm^2 amount of N could keep relative higher content of chlorophyl and higher activity of carboxylase of RuBP and PEP in the leaf of spring maize during main growing period.It was important to strengthens the leaf blade photosynthesis ability,promote the yield formation and postpone the decline of leaf blade.

Effect of RPlys on Digestive Metabolism of Nitrogen in Sheep

[Objective] The aim was to study the effect of RPlys on digestive metabolism of nitrogen in sheep.[Method] The contribution of RPlys for nitrogen residual in sheep was researched by digestive metabolism test.[Result] The results showed that adding RPlys decreased excretion of urine nitrogen （P0.05） and had no significant effect on excretion of fecal nitrogen （P0.05）,and precipitation coefficient of nitrogen was increased （P0.05）.[Conclusion] RPlys is propitious to the aggradations of nitrogen in sheep.

Effects of Postponing N Application on Metabolism,Absorption and Utilization of Nitrogen of Summer Maize in SuperHigh Yield Region

[Objective] The aim was to explore effects of application postponing of N fertilizer and the mechanism of yield increase in order to provide references for N fertilizer application in a rational way. [Method] In a super-high yielded region of summer maize, field experiment was conducted to research effects of N fertilizer postponing on key enzymes of N metabolism, yield of maize and N fertilizer use. [Result] After application of N fertilizer was postponed, NR, SPS and GS activities of ear-leaf of summer maize increased by 11.99%-34.87%, 8.25%-10.64% and 10.00%- 16.81% on the 28^th d of silking; content of soluble sugar in leaves enhanced signifi- cantly and accumulated nitrogen increased by 5.00%-9.74% in mature stage. The postponing fertilization of ＂30% of fertilizer in seedling stage＋30% of fertilizer in flare- opening stage＋40% of fertilizer in silking stage meets N demands of summer maize in late growth period. Compared with conventional fertilization, the maize yield, agro- nomic efficiency and use of N fertilizer all improved by 5.05%, 1.75 kg/kg and 6.87%, respectively, after application postponed. [Conclusion] Application postponing of N fertilizer maintains activity of NR, GS and SPS higher and coordinates metabolism of C and N in late growth period, to further improve yield of maize.

Effects of Irrigation on Nitrogen Metabolism and Yield of Strong Gluten Wheat

[Objective] The aim was to provide reference for the field irrigation management of high yield and quality cultivation of strong gluten wheat.[Method]Under field conditions,the effects of irrigation times on nitrogen metabolism and yield of strong gluten wheat cultivar zhengmai 9023 were studied.[Result]The results indicated that NR activity,Chlorophyll and nitrogen content in flag leaf increased with irrigation times,and the irrigation treatment had obvious advantages during middle filling stage.Grain protein content showed ＂V＂ type change with grain filling going on,and protein content decreased when irrigation times going on.There was significant difference among treatments during early stage of grain filling,and the difference became smaller in the late grain filling stage.The grain yield and protein yield increased but the protein content decreased with increasing of irrigation times.[Conclusion] Increasing irrigation times properly could improve grain yield and protein yield per unit area,but reduce the grain protein content.

Effects of Cadmium Stress on Key Enzymes Involved in Nitrogen Metabolism and Nitrogen,Phosphorus, Potassium Accumulation of Different Varieties of Rice

In this study, the pot experiment was used to explore the differences of activity of key enzymes involved in N metabolism and NPK accumulation under Cd stress during the til iering stage of differen varieties of rice. The results showed that：Cd stress could increase the NPK concentration of different rice type in the til ering stage, while Shen-Liangyou 5867,Yongyou 5550 and Wu-Yunjing 27 showed the highest amplification respectively. Morever, Cd stress can also contribute to the ac-tivity of NR,GS,GOGAT increasing.A s for NR,the Cd stress significantly contribute to NR activity increasing of Huang-Huazhan and Yongyou 538 but is not significant for Wu-Yunjing 27, Shen-Liangyou 5867 and Yongyou 5550, however, the difference among them is not obvious.However, for the activity of GS , Cd stress promote the GS activity. Huang-Huazhan and Wu-Yunjing 27 with low activity in Cd normal level are the most sensitive. Meanwhile the difference between two treatment is the most significant. To the contrary, restrain the GS activity of Shen-Liangyou 5867, Yongy-ou 5550 and the difference is not significant. And under Cd stress, either difference reached significant in GS activity. Cd stress also improve the activity of GOGAT, Wu-Yunjing 27 showed the highest inprovement which showed the lowest GOGAT activity under Cd normal level. Cd stress on rice growth and development of ad-verse, make its lower seed setting rate, 1 000 grain weight decreased, resulting in different degrees of reduction of output of rice.

Effects of Aeration on Root Physiology and Nitrogen Metabolism in Rice

In order to clarify the effects of aeration on root nitrogen metabolism in rice seedlings,rice cultivars Guodao 6 （indica） and Xiushui 09 （japonica） were investigated for root growth,the activities of glutamine synthetase （GS）,glutamic acid-pyruvic acid transaminase （GPT） and glutamic acid oxaloacetate transaminase （GOT）,the nitrate （NO 3-N） concertration,the contents of free amino acids and soluble sugar in root under hydroponics with continuous aeration treatment.The results showed that rice seedlings grown in oxygenation solutions had higher root dry matter,longer root length,stronger root activity and larger root absorption area compared with the control.In addition,the contents of soluble sugar,root vigor and the activities of GS,GOT and GPT in the aeration solutions were higher than those in the control.The results also indicated that the activities of enzymes involved in root nitrogen metabolism of Xiushui 09 were enhanced by aeration,however,there was no significant influence on root nitrogen metabolism of Guodao 6,which suggested that effect of oxygenation on rice root nitrogen metabolism might be genotype-specific.

High Temperature at Grain-filling Stage Affects Nitrogen Metabolism Enzyme Activities in Grains and Grain Nutritional Quality in Rice

Rice plants would more frequently suffer from high temperature (HT) stress at the grain-filling stage in future. A japonica rice variety Koshihikari and an indica rice variety IR72 were used to study the effect of high temperature on dynamic changes of glutamine synthetase (GS) activity, glutamate synthase (GOGAT) activity, glutamic oxalo-acetic transminase (GOT) activity, glutamate pyruvate transminase (GPT) activity in grains and grain nutritional quality at the grain-filling stage. Under HT, the activities of GOGAT, GOT, GPT and soluble protein content in grains significantly increased, whereas GS activity significantly decreased at the grain-filling stage. In addition to the increase of protein and amino acids contents, it was suggested that GOGAT, GOT and GPT in grains played important roles in nitrogen metabolism at the grain-filling stage. Since the decrease of GS activity in grains did not influence the accumulations of amino acids and protein, it is implied that GS might not be the key enzyme in regulating glutamine content in grains.

Effects of lanthanum(Ⅲ) on nitrogen metabolism of soybean seedlings under elevated UV-B radiation

The hydroponic culture experiments of soybean bean seedlings were conducted to investigate the effect of lanthanum （La） on nitrogen metabolism under two different levels of elevated UV-B radiation （UV-B, 280-320 nm）. The whole process of nitrogen metabolism involves uptake and transport of nitrate, nitrate assimilation, ammonium assimilation, amino acid biosynthesis, and protein synthesis. Compared with the control, UV-B radiation with the intensity of low level 0.15 W/m^2 and high level 0.45 W/m^2 significantly affected the whole nitrogen metabolism in soybean seedlings （p 〈 0.05）. It restricted uptake and transport of NO3^-, inhibited activity of some key nitrogen-metabolism-related enzymes, such as： nitrate reductase （NR） to the nitrate reduction, glutamine systhetase （GS） and glutamine synthase （GOGAT） to the ammonia assimilation, while it increased the content of free amino acids and decreased that of soluble protein as well. The damage effect of high level of UV-B radiation on nitrogen metabolism was greater than that of low level. And UV-B radiation promoted the activity of the anti-adversity enzyme glutamate dehydrogenase （GDH）, which reduced the toxicity of excess ammonia in plant. After pretreatment with the optimum concentration of La （20 mg/L）, La could increase the activity of NR, GS, GOGAT, and GDH, and ammonia assimilation, but decrease nitrate and ammonia accumulation. In conclusion, La could relieve the damage effect of UV-B radiation on plant by regulating nitrogen metabolism process, and its alleviating effect under low level was better than that under the high one.

Weakened carbon and nitrogen metabolisms under post-silking heat stress reduce the yield and dry matter accumulation in waxy maize

Post-silking high temperature is one of the abiotic factors that affects waxy maize(Zea mays L. sinensis Kulesh) growth in southern China. We conducted a pot trial in 2016–2017 to study the effects of post-silking daytime heat stress(35°C) on the activities of enzymes involved in leaf carbon and nitrogen metabolisms and leaf reactive oxygen species(ROS) and water contents. This study could improve our understanding on dry matter accumulation and translocation and grain yield production. Results indicated that decreased grain number and weight under heat stress led to yield loss, which decreased by 20.8 and 20.0% in 2016 and 2017, respectively. High temperature reduced post-silking dry matter accumulation(16.1 and 29.5% in 2016 and 2017, respectively) and promoted translocation of pre-silking photoassimilates stored in vegetative organs, especially in leaf. The lower leaf water content and chlorophyll SPAD value, and higher ROS(H2O2 and O2^-·) content under heat stress conditions indicated accelerated senescent rate. The weak activities of phosphoenolpyruvate carboxylase(PEPCase), Ribulose-1,5-bisphosphate carboxylase(Ru BPCase), nitrate reductase(NR), and glutamine synthase(GS) indicated that leaf carbon and nitrogen metabolisms were suppressed when the plants suffered from a high temperature during grain filling. Correlation analysis results indicated that the reduced grain yield was mainly caused by the decreased leaf water content, weakened NR activity, and increased H2O2 content. The increased accumulation of grain weight and post-silking dry matter and the reduced translocation amount in leaf was mainly due to the increased chlorophyll SPAD value and NR activity. Reduced PEPCase and Ru BPCase activities did not affect dry matter accumulation and translocation and grain yield. In conclusion, post-silking heat stress down-regulated the leaf NR and GS activities, increased the leafwater loss rate, increased ROS generation, and induced pre-silking carbohydrate translocation. However, it reduced the post-silking direct photoassimilate deposition, ultimately, leading to grain yield loss.

Effects of Uniconazole on Nitrogen Metabolism and Grain Protein Content of Rice

The effects of uniconazole by soaking seeds and spraying leaves at booting stage with different concentrations （0, 20 and 40 mg/kg） on the nitrogen metabolism of flag leaf and grains after flowering, and rice grain protein content and yield were studied with hybrid rice combination Shanyou 63. Under uniconazole treatment, the soluble protein content in flag leaf was increased in early and middle period of grain filling, but this content was nearly the same as or even lower than that of control at maturity; Glutamine synthetase activity in superior and inferior grains and non-protein nitrogen content in superior grains at early stage of grain development were promoted, and moreover, the transforming speed from non-protein nitrogen to protein nitrogen was accelerated; Non-protein nitrogen content was lower than that of control at maturity, but protein nitrogen content at each stage was higher than those of control; Protein nitrogen content in superior and inferior grains and protein nitrogen absolutely accumulative content in a grain both were enhanced and protein content and yield in rice grain were raised. The application of uniconazole by soaking seeds and spraying leaves raised crude protein content by an average of 7.2% and 8.3%, and protein yield by an average of 13.1% and 13.4%, respectively.

Effect of Water Stress and Foliar Boron Application on Seed Protein, Oil, Fatty Acids, and Nitrogen Metabolism in Soybean

Effects of water stress and foliar boron (FB) application on soybean (Glycine max (L) Merr.) seed composition and nitrogen metabolism have not been well investigated. Therefore, the objective of this study was to investigate the effects of water stress and FB on seed protein, oil, fatty acids, nitrate reductase activity (NRA), and nitrogenase activity (NA). A repeated greenhouse experiment was conducted where one set of soybean plants were subjected to water stress (WS), and the other set was watered (W). Foliar boron (B) was applied at rate of 0.45 kg·ha-1. Treatments were watered-plants with no FB (W), watered-plants with FB (WB), water-stress plants with no FB (WS), and water-stress plants with FB (WSB). The results showed that seed protein and oil percentage were significantly (P 15N/ 14N and 13C/12C natural abundance were altered between watered-and watered-stressed plants. These results suggest that water stress and FB can influence seed composition, and nitrogen metabolism, and 15N/14N and 13C/12C ratios, reflecting environmental and metabolic changes in carbon and nitrogen fixation pathways. Lack of B translocation from leaves to seed under water stress may suggest a possible mechanism of limited B translocation under water stress. These findings may be beneficial to breeders to select for B translocation efficiency under drought conditions. Altered 15N/14N and 13C/12C under water stress can be used as a tool to select for drought tolerance using N and C isotopes in the breeding programs.

Effect of Nitrogenous Fertilizer Treatment on Mineral Metabolism in Grazing Yaks

To assess the impact of N fertilization on contents of mineral elements in herbage and the effect of increased forage S on the copper metabolism of grazing yaks, study was conducted during the summer grazing season （2005, 2006, and 2007）. Pasture replicates （20 ha; n=3 per treatment） received the same fertilizer treatment in each growing season, consisting of i） 90 kg N ha^-1 from quickly available nitrogen, ii） 90 kg N ha^-1 from ammonium nitrate, iii） 90 kg N ha^-1 from ammonium sulfate, and iv） control （no fertilizer）. Forage sampling was collected at 60 days intervals following fertilization （10 samples per pasture） for Cu, Mo, Mn, Se, Fe, Zn, Ca, and P. To determine the effect of fertilizer treatment on mineral metabolism in grazing yaks, liver and blood samples were collected at the start and end of the study period in 2005, 2006, and 2007. Ammonium sulfate fertilization increased （P 〈 0.01） forage S concentration. Plant tissue N concentrations were increased by N fertilization, regardless of source in 2005, 2006, and 2007. Yaks grazing S fertilization pastures had lower （P〈0.05） liver and blood Cu concentrations at the end of the study period in 2005, 2006, and 2007, compared with urea, ammonium nitrate, and control. Nominal increases in forage in vitro organic matter digestibility were realized by fertilization, regardless of N source in each year.

The effects of phenolic acid on nitrogen metabolism in Populus 3 euramericana ‘Neva’

The declines in soil fertility and productivity in continuously cropped poplar plantations axe related to phenolic acid accumulation in the soil. Nitrogen is a vital life element for poplar and whether the accumulation of phenolic acid could influence nitrogen metabolism in poplar and thereby hinder continuous cropping is not clear. In this study, poplar cuttings of Populus × euramericana ‘Neva＇ were potted in vermiculite, and phenolic acids at three concentrations （032, 0.5X and 1.0X） were added according to the actual content （1.0X） in the soil of a second-generation poplar plantation. Each treatment had eight replicates. We measured gas exchange parameters and the activities of key enzymes related to nitrogen metabolism in the leaves. Leaf photosynthetic parameters varied with the concentration of phenolic acids. The net photosynthetic rate （PN） significantly decreased with increasing phenolic acid concentration, and non-stomatal factors might have been the primary limitation for PN- The activities of nitrate reductase （NR）, glutamine synthetase （GS） and glutamate synthase （GOGAT）, as well as the contents of nitrate nitrogen, ammonium nitrogen, and total nitrogen in the leaves decreased with increasing phenolic acid concentration. This was significantly and positively related to PN （P 〈 0.05）. The low concentration of phe- nolic acids mainly affected the transformation process of NO3- to NO2-, while the high concentration of phenolic acids affected both processes, where NO3- was transferred to NO2- and NH4＋ was transferred to glutamine （Gln）. Overall, phenolic acid had significant inhibitory effects on the photosynthetic productivity of Populus x euramericana ＇Neva＇. This was probably due to its influence on the activities of nitrogen assimilation enzymes, which reduced the amount of amino acids that were translated into protein and enzymes. Improving the absorption and utilization of nitrogen by plants could help to overcome the problems caused by continuous cropping.

Photosynthetic Characteristics and Antioxidative Metabolism of Flag Leaves in Responses to Nitrogen Application During Grain Filling of Field-Grown Wheat

A two-factorial experiment was conducted with two wheat cultivars, SN1391 （large spike and large grain） and GC8901 （multiple spike and medium grain）, and two nitrogen （N） application rates （12 and 24 g N m^-2）, to investigate the responses of photosynthetic characteristics and antioxidative metabolism to nitrogen rates in flag leaves of field-grown wheat during grain filling. The results showed that the content of N and chlorophyll （Chl） in wheat flag leaves decreased after anthesis and the net photosynthetic rate （Pn）, effective quantum yield of PS Ⅱ （Фps n）, efficiency of excitation capture by open PS Ⅱ reaction centers （Fv′/Fm′）, and photochemical quenching coefficient （qp） began to decrease at 14 days after anthesis. However, the maximal efficiency of PS Ⅱ photochemistry （Fv/Fm） decreased slightly until the late period of senescence and the nonphotochemical quenching coefficient （NPQ） increased during flag leaves＇ senescence, As a result, a conflict came into being between absorption and utilization to light energy in flag leaves during senescence, which might accelerate the senescence of flag leaves. Compared with GC8901, the lower plant population of SN1391 during grain filling was helpful to maintain the higher content of photosynthetic pigment, activity of PS II, and Pn in flag leaves during senescence, The delayed decrease in antioxidative enzyme activity and the lower degree of membrane lipid peroxidation in the senescing leaves of SN1391 were beneficial to protect the photosynthetic apparatus, which lead to the prolonged duration of CO2 assimilation. With the increase of N application, the Chl content of SN1391 flag leaves and the efficiency of excitation captured by open PS Ⅱ centers increased. At the same time, the thermal dissipation in SN1391 flag leaves at high N （HN） treatment decreased and Фps Ⅱ improved greatly, which were favorable to the increase of Pn. The SOD, POD, CAT and APX activities in the flag leaves of SN1391 increased markedly at HN treatment, indicating that these enzymes could clean more active oxygen and decrease the degree of membrane lipid peroxidation. In this way, the ability of SN1391 to protect photosynthetic apparatus was improved with the increase of N. In the HN treatment, the decreased activity of PS Ⅱ and increased thermal dissipation resulted in the decline of Pn in flag leaves of GC8901. Meanwhile, the decreased antioxidative enzyme activities and the increased degree of membrane lipid peroxidation had indirect and unfavorable influences on CO2 assimilation. This implied that the conflict between absorption and utilization to energy in senescing leaves was an important reason which induced and accelerated the senescence of wheat leaves in the field. The photosynthetic characteristics and antioxidative metabolism of flag leaves during grain filling were markedly different among wheat cultivars. The effects of nitrogen rate on the photosynthetic and senescent characteristics of flag leaves also varied with wheat cultivars.

Plant growth and metabolism of exotic and native Crotalaria species for mine land rehabilitation in the Amazon

Despite its enormous benefits,mining is respon-sible for intense changes to vegetation and soil properties.Thus,after extraction,it is necessary to rehabilitate the mined areas,creating better conditions for the establishment of plant species which is challenging.This study evaluated mineral and organic fertilization on the growth,and carbon and nitrogen(N)metabolism of two Crotalaria species[Cro-talaria spectabilis(exotic species)and Crotalaria maypu-rensis(native species from Carajás Mineral Province(CMP)]established on a waste pile from an iron mine in CMP.A control(without fertilizer application)and six fertilization mixtures were tested(i=NPK;ii=NPK+micronutrients;iii=NPK+micronutrients+organic compost;iv=PK;v=PK+micronutrients;vi=PK+micronutrients+organic compost).Fertilization contributed to increased growth of both species,and treatments with NPK and micronutrients had the best results(up to 257%cf.controls),while organic fertilization did not show differences.Exotic Crotalaria had a greater number of nodules,higher nodule dry mass,chlorophyll a and b contents and showed free ammonium as the predominant N form,reflecting greater increments in biomass compared to native species.Although having lower growth,the use of this native species in the rehabilitation of mining areas should be considered,mainly because it has good development and meets current government legislation as an opportunity to restore local biodiversity.

Dynamics of Bt cotton Cry1Ac protein content under an alternating high temperature regime and effects on nitrogen metabolism

This study was conducted to investigate the effects of alternating high temperature on CrylAc protein content on Bt cotton cultivars Sikang 1 （SK-1, a conventional cultivar） and Sikang 3 （SK-3, a hybrid cultivar）. In 2011 and 2012, cotton plants were subjected to high temperature treatments ranging from 32 to 40℃ in climate chambers to investigate the effects of high temperature on boll shell insecticidal protein expression. The experiments showed that significant decline of the boll shell insecticidal protein was detected at temperatures higher than 38℃ after 24 h. Based on the results, the cotton plants were treated with the threshold temperature of 38℃ from 6：00 a.m. to 6：00 p.m. followed by a normal temperature of 27℃ during the remaining night hours （DH/NN） in 2012 and 2013. These treatments were conducted at peak boll growth stage for both cultivars in study periods of 0, 4, 7, and 10 d. Temperature treatment of 32℃ from 6：00 a.m. to 6：00 p.m. and 27℃ in the remaining hours was set as control. The results showed that, compared with the control, after the DH/NN stress treatment applied for 7 d, the boll shell CrylAc protein content level was significantly decreased by 19.1 and 17.5% for SK-1 and by 15.3 and 13.7% for SK-3 in 2012 and 2013, respectively. Further analysis of nitrogen metabolic physiology under DH/NN showed that the soluble protein content and the glutamic pyruvic transaminase （GPT） activities decreased slightly after 4 d, and then decreased sharply after 7 d. The free amino acid content and the protease content increased sharply after 7 d. The changes in SK-1 were greater than those in SK-3. These results suggest that under DH/NN stress, boll shell CrylAc protein content decline was delayed. Reduced protein synthesis and increased protein degradation in the boll shell decreased protein content, including Bt protein, which may reduce resistance to the cotton bollworm.

Influence of N, P, Fe Nutrients Availability on Nitrogen Metabolism-Relevant Genes Expression in Skeletonema marinoi

Nitrogen(N), Phosphorus(P), and Iron(Fe) are essential elements for cellular structure and metabolism. In addition to dissolved inorganic nitrogen(DIN), phytoplankton is able to utilize dissolved organic nitrogen(DON). There is general consensus that both bacteria and higher plants nitrogen metabolism is affected by phosphate availability; this was also found to be true in coccolithophorid. Iron affects the structure and function of ecosystems through its effects on nitrogen metabolism. However, it is unclear how these nutrients affect Skeletonema marinoi's nitrogen metabolism. Here, using RT-qPCR, we investigate effects of N, P, and Fe on S. marinoi's nitrogen metabolism and nitrate reductase activity. These results illuminate that in S. marinoi, various nutrients have direct regulation on these genes expression at the molecular level. The varying degree of responses for these genes expression with differing N sources may act to increase the efficiency of nutrient capture when nitrate is limited. Suitable gene expression occurs at a N/P ratio of 16, which represents the atomic N/P ratio of phytoplankton cells and N/P concentrations in ocean; thus, nitrogen metabolism gene expression should be regulated by the existing N/P ratios in the phytoplankton's internal and external environment. Fe concentration has a direct and significant effect on nitrogen metabolism by regulating gene expression and nitrate reductase activity. Gene expression profiles identified in S. marinoi provide a foundation for understanding molecular mechanisms behind diatom nitrogen metabolism with changing N, P, and Fe nutrients allowing a basic understanding of how diatom growth is affected by nutrient utilization.

Integration of root architecture,root nitrogen metabolism,and photosynthesis of‘Hanfu’apple trees under the cross-talk between glucose and IAA

Sugars and auxin have important effects on almost all phases of plant life cycle,which are so fundamental to plants and regulate similar processes.However,little is known about the effect of cross-talk between glucose and indole-3-acetic acid(IAA)on growth and development of apple trees.To examine the potential roles of glucose and IAA in root architecture,root nitrogen(N)metabolism and photosynthetic capacity in‘Hanfu’(Malus domestica),a total of five treatments was established:single application of glucose,IAA,and auxin polar transport inhibitor(2,3,5-triiodobenzoic acid,TIBA),combined application of glucose with TIBA and that of glucose with IAA.The combined application of glucose with IAA improved root topology system and endogenous IAA content by altering the mRNA levels of several genes involved in root growth,auxin transport and biosynthesis.Moreover,the increased N metabolism enzyme activities and levels of genes expression related to N in roots may suggest higher rates of transformation of nitrate(NO3--N)into amino acids application of glucose and IAA.Contrarily,single application of TIBA decreased the expression levels of auxin transport gene,hindered root growth and decreased endogenous IAA content.Glucose combined with TIBA application effectively attenuated TIBA-induced reductions in root topology structure,photosynthesis and N metabolism activity,and mRNA expression levels involved in auxin biosynthesis and transport.Taken together,glucose application probably changes the expression level of auxin synthesis and transport genes,and induce the allocation of endogenous IAA in root,and thus improves root architecture and N metabolism of root in soil with deficit carbon.