NaCl stress is one of the most serious forms of salt stress. Prohexadione–calcium (EA) is a plant growth regulator, and gibberellin (GA) is a plant hormone that regulates various plant developmental processes. In this experiment, Guanghong 3 and Huang Huazhan served as experimental rice (Overza sativa L.) varieties to study the effects of EA and GA on the growth of rice seedlings. The results revealed that NaCl treatment significantly inhibited plant growth and destroyed the balance of the carbon metabolism. The inhibition effect of NaCl stress on the growth and physiological metabolism of rice seedlings was alleviated by EA and GA, but the effects of EA and GA were slightly different. Compared with the NaCl treatment, the EA and GA treatments significantly increased the net photosynthetic rate, stem base width, and dry matter accumulation but had opposite effects on the plant height, with the GA treatment significantly increasing the plant height of rice seedlings. The EA treatment was superior to the GA treatment in improving the metabolic pathway efficiency of sucrose and starch in the leaves of rice seedlings. The soluble sugar content, sucrose content, fructose content, sucrose synthase activity, sucrose phosphate synthase activity, α-amylase activity, β-amylase activity, and starch phosphorylase activity increased with increasing NaCl stress time, and the changes in the starch content and acid invertase activity were the opposite. The max/min values were reached on the 13th day of NaCl stress.

Abiotic stress caused by soil salinization remains a major global challenge that threatens and severely impacts crop growth, causing yield reduction worldwide. In this study, we aim to investigate the damage of salt stress on the leaf physiology of two varieties of rice (Huanghuazhan, HHZ, and Xiangliangyou900, XLY900) and the regulatory mechanism of Hemin to maintain seedling growth under the imposed stress. Rice leaves were sprayed with 5.0 mmolL-1 Hemin or 25.0 mmolL-1 ZnPP (Zinc protoporphyrin IX) at the three leaf and one heart stage, followed by an imposed salt stress treatment regime (50.0 mmolL-1 sodium chloride (NaCl)). The findings revealed that NaCl stress increased antioxidant enzymes activities and decreased the content of nonenzymatic antioxidants such as ascorbate (AsA) and glutathione (GSH). Furthermore, the content of osmoregulatory substances like soluble proteins and proline was raised. Moreover, salt stress increased reactive oxygen species (ROS) content in the leaves of the two varieties. However, spraying with Hemin increased the activities of antioxidants such as superoxide dismutase (SOD), peroxidase (POD), and catalase (CAT) and accelerated AsA-GSH cycling to remove excess ROS. In summary, Hemin reduced the effect of salt stress on the physiological characteristics of rice leaves due to improved antioxidant defense mechanisms that impeded lipid peroxidation. Thus, Hemin was demonstrated to lessen the damage caused by salt stress.

Prohexadione calcium (EA) and gibberellin (GA) are two different types of plant growth regulators that have different effects on the regulation of plant development. The objective of this study was to evaluate the impacts of EA and GA on rice plant growth, development and morph-physiological traits in two rice varieties: ‘Huang Huazhan’ and ‘Guang Hong 3’. At the three-leaf seedling stage, the plants were treated with 50 mM NaCl 24 h after foliar application of EA (100 mg·L−1) and GA (1 mg·L−1). Data on morphological indexes, osmotic regulators and antioxidant activities were compared with the treatment of EA and GA on the 4th, 7th, 10th and 13th days after NaCl stress. Our data analysis showed that NaCl stress inhibited the leaf area growth of rice seedlings, altered the microstructure and disrupted the antioxidant system, ion uptake and transport balance. The significant increase in malondialdehyde (MDA) content and superoxide anion production rate (O2·¯) indicated that NaCl stress caused a severe oxidative stress response to rice seedlings. Treatment with EA and GA activated the antioxidant system under NaCl stress, significantly elevated superoxide dismutase (SOD), peroxidase (POD) and catalase (CAT) activities and suppressed the increase in MDA content and the O2·¯ production rate. Under NaCl stress, EA and GA treatments improved the osmoregulatory balance, significantly increased soluble protein and proline contents and maintained lower Na+/K+ levels. EA and GA treatments significantly increased the K+ and Ca2+ contents, thereby maintaining ionic balance, which was favorable for maintaining the growth of rice seedlings. In this study, moth plant growth regulators maintained the growth and development of rice seedlings under NaCl stress by inducing an increase in osmoregulation and antioxidant levels, reducing the degree of membrane damage and regulating the selective uptake of ions by rice seedlings. Current findings also clarified that foliar application of EA was more effective than GA in three-leaf seedlings by enhancing the morph-physiological and antioxidant parameters under NaCl stress.

Abstract Background IBAK, as a plant growth regulator, has broad application prospects in improving crop resistance to abiotic stress. Results In this study, the regulation mechanism of IBAK on rice was revealed by physiology and transcriptomics by spraying 80 mg·L−1 IBAK solution on rice leaves at the early jointing stage under salt stress. The results showed that spraying IBAK solution on leaves under salt stress could significantly increase K+ content, decrease Na+ content, increase net photosynthetic rate (Pn), and increase the activity of catalase (CAT) and the contents of glutathione (GSH) and soluble protein in rice leaves. Using IBAK under salt stress increased the expression of plant hormone signal transduction pathway-related genes LOC4332548 and LOC4330957, which may help rice to more effectively sense and respond to plant hormone signals and enhance resistance to salt stress. In addition, the photosynthesis pathway-related genes LOC4339270, LOC4327150, and LOC4346326 were upregulated after using IBAK under salt stress, and the upregulation of these genes may be beneficial to improve the efficiency of photosynthesis and increase the photosynthetic capacity of rice. Regarding starch and sucrose metabolism pathway, spraying IBAK on leaves could promote the expression of sucrose synthesis-related gene LOC4347800 and increase the expression of starch synthesis-related genes LOC4330709 and LOC4343010 under salt stress. Finally, IBAK spraying resulted in the upregulation of multiple 50 S and 30 S ribosomal protein genes in the ribosome pathway, which may increase protein synthesis, help maintain cell function, and promote rice growth and development. Conclusion The results of this study revealed the mechanism of IBAK mediating resistance to salt stress in rice.

It is widely known that salt stress restricts rice growth and productivity severely. However, little information is available regarding the stage of rice seedlings subjected to the Heme oxygenase 1 (HO-1) inducer, Hemin. This study aimed to investigate the effects of salt stress on two rice varieties (Huanghuazhan and Xiangliangyou 900) and the effect of Hemin in promoting photosynthesis, carbohydrate metabolism, and key enzymes under salt-stress conditions. At the stage of three leaves and one heart, Huanghuazhan (HHZ) and Xiangliangyou 900 (XLY900) were sprayed with 5 μmol·L −1 Hemin and then subjected to 50 mM NaCl stress. The results showed that NaCl stress decreased the contents of chlorophyll a, chlorophyll b, and carotenoids. Furthermore, the net photosynthetic rate ( P n ) decreased remarkably and the starch content was also lowered. However, NaCl treatment enhanced the concentration of sucrose and soluble sugar, simultaneously enhancing the sucrose metabolism. Nevertheless, the foliar spraying of exogenous Hemin mediated the increase in fructose and starch content, along with the activities of key enzymes’ soluble acid invertase (SAInv), basic/neutral invertase (A/N-Inv), and sucrose synthase (SS) in rice leaves under NaCl stress. The sucrose phosphate synthase (SPS) in leaves decreased significantly, and the fructose accumulation in leaves increased. Hemin also mediated the increase of starch content and the α-amylase, total amylase, and starch phosphorylase (SP) activities under NaCl stress. Under stress conditions, the application of the Heme oxygenase 1 (HO-1) inhibitor, ZnPP failed to alleviate the damage to rice seedlings by NaCl stress. The ZnPP treatment showed similar tendency to the NaCl treatment on pigment content, gas exchange parameters and carbon metabolism related products and enzymes. However, ZnPP decreased carotenoids, fructose, starch content and enzyme activities related to starch metabolism. The regulation effect of Hemin on HuangHuaZhan was better than XiangLiangYou 900. These results indicate that Hemin improved the effects of salt stress on the photosynthesis and physiological characteristics of rice leaves as a result of enhanced carbohydrate metabolism. Thus, Hemin could alleviate the damage caused by salt stress to a certain extent.

BACKGROUND:Salt stress is one of the key factors limiting rice production. Alginate oligosaccharides (AOS) enhance plant stress resistance. However, the molecular mechanism underlying salt tolerance in rice induced by AOS remains unclear. FL478, which is a salt-tolerant indica recombinant inbred line and IR29, a salt-sensitive rice cultivar, were used to comprehensively analyze the effects of AOS sprayed on leaves in terms of transcriptomic and metabolite profiles of rice seedlings under salt stress.RESULTS:In this experiment, exogenous application of AOS increased SOD, CAT and APX activities, as well as GSH and ASA levels to reduce the damage to leaf membrane, increased rice stem diameter, the number of root tips, aboveground and subterranean biomass, and improved rice salt tolerance. Comparative transcriptomic analyses showed that the regulation of AOS combined with salt treatment induced the differential expression of 305 and 1030 genes in FL478 and IR29. The expressed genes enriched in KEGG pathway analysis were associated with antioxidant levels, photosynthesis, cell wall synthesis, and signal transduction. The genes associated with light-trapping proteins and RLCK receptor cytoplasmic kinases, including CBA, LHCB, and Lhcp genes, were fregulated in response to salt stress. Treatment with AOS combined with salt induced the differential expression of 22 and 50 metabolites in FL478 and IR29. These metabolites were mainly related to the metabolism of amino and nucleotide sugars, tryptophan, histidine, and β -alanine. The abundance of metabolites associated with antioxidant activity, such as 6-hydroxymelatonin, wedelolactone and L-histidine increased significantly. Combined transcriptomic and metabolomic analyses revealed that dehydroascorbic acid in the glutathione and ascorbic acid cycles plays a vital role in salt tolerance mediated by AOS.CONCLUSION:AOS activate signal transduction, regulate photosynthesis, cell wall formation, and multiple antioxidant pathways in response to salt stress. This study provides a molecular basis for the alleviation of salt stress-induced damage by AOS in rice.

Salt stress affects crop quality and reduces crop yields, and growth regulators enhance salt tolerance of crop plants. In this report, we examined the effects of prohexadione-calcium (Pro-Ca) on improving rice (Oryza sativa L.) growth and tillering under salt stress. We found that NaCl stress inhibited the growth of two rice varieties and increased malondialdehyde (MDA) levels, electrolyte leakage, and the activities of the antioxidant enzymes. Foliar application of Pro-Ca reduced seedling height and increased stem base width and lodging resistance of rice. Further analyses showed that Pro-Ca application reduced MDA content, electrolyte leakage, and membrane damage in rice leaves under NaCl stress. Pro-Ca enhanced the net photosynthetic rate (Pn), stomatal conductance (Gs), and intercellular CO2 concentration (Ci) of rice seedlings, while increasing the activities of superoxide dismutase (SOD), catalase (CAT), peroxidase (POD), and ascorbic acid peroxidase (APX) at the tillering stage under salt stress. Overall, Pro-Ca improves salt tolerance of rice seedlings at the tillering stage by enhancing lodging resistance, reducing membrane damages, and enhancing photosynthesis and antioxidant capacities of rice seedlings.

Prohexadione-calcium (Pro-Ca) has been proved to play an important role in releasing abiotic stress in plants. However, there is still a lack of research on the mechanism of Pro-Ca alleviating salt stress in rice. To explore the protective effects of Pro-Ca on rice seedlings under salt stress, we investigated the effect of exogenous Pro-Ca on rice seedling under salt stress by conducting the following three treatment experiments: CK (control), S (50 mmol·L −1 NaCl saline solution) and S + Pro-Ca (50 mmol·L −1 NaCl saline solution + 100 mg·L −1 Pro-Ca). The results indicated that Pro-Ca modulated the expression of antioxidant enzyme-related genes (such as SOD2 , PXMP2 , MPV17 , E1 . 11 . 1 . 7 ). Spraying Pro-Ca under salt stress significantly increased in ascorbate peroxidase, superoxide dismutase, and peroxidase activity by 84.2%, 75.2%, and 3.5% as compared to the salt treatment, as demonstrated by an example of a 24-hour treatment. Malondialdehyde level in Pro-Ca was also dramatically decreased by 5.8%. Moreover, spraying Pro-Ca under salt stress regulated the expression of photosynthesis genes (such as PsbS , PsbD ) and chlorophyll metabolism genes ( heml , PPD ). Compared to salt stress treatment, spraying Pro-Ca under salt stress significantly increased in net photosynthetic rate by 167.2%. In addition, when rice shoots were sprayed with Pro-Ca under salt stress, the Na + concentration was considerably reduced by 17.1% compared to salt treatment. In conclusion, Pro-Ca regulates antioxidant mechanisms and photosynthesis to aid in the growth of rice seedlings under salt stress.

Salt stress inhibits crop quality and yields, and growth regulators are used to enhance salt tolerance of crops. Here, we report the effect of prohexadione-calcium (Pro-Ca) on rice tillering under salt stress. The results showed the malondialdehyde (MDA) levels and electrolyte leakage in leaves were increased as well as the expression of the antioxidant enzymes was induced under salt stress. Foliar application of Pro-Ca reduced seedling height, increased the stem base width, improved the lodging resistance of rice, decreased MDA content and electrolyte leakage, and alleviated the membrane damage of rice under salt stress. Exogenous Pro-Ca also increased the net photosynthetic rate (Pn) and the stomatal conductance (Gs) of rice, decreased the intercellular CO 2 concentration (Ci), and increased the activities of superoxide dismutase (SOD), catalase (CAT), peroxidase (POD), and ascorbate peroxidase (APX) of rice at the tillering stage under salt stress. In conclusion, Pro-Ca improved the salt tolerance of rice at the tillering stage by enhancing the lodging resistance of rice, alleviating cell membrane damage of leaves caused by NaCl stress, and enhancing photosynthesis and antioxidant capacity. Effect of Pro-Ca on rice at the tillering stage under 0.3% NaCl stress was discussed, which provided a theoretical basis for revealing physiological changes at the rice tillering stage.

Waterlogging is a major limiting factor in global crop production and seriously endangers growth and yield improvement in low-lying, rainfed regions. Soybean is an important economic crop affected by waterlogging stress. The current study investigates the effects of waterlogging stress on the leaf physiology and yield of two soybean varieties (Kenfeng 14, waterlogging-tolerant and Kenfeng 16, waterlogging-sensitive) and the mitigation effect of uniconazole (S3307) in promoting growth and productivity under waterlogging conditions. The results showed that waterlogging stress increased antioxidant enzyme activity and decreased the contents of non-enzymatic antioxidants such as AsA and GSH. Furthermore, the content of MDA and H2O2 increased significantly, indicating oxidative stress and O2-· production rate also improved, and the increase in the waterlogging-sensitive variety Kenfeng 16 was greater than that of the waterlogging-tolerant variety Kenfeng 14. Spraying S3307, however, increased the activities of antioxidants such as SOD, POD, CAT, and APX. GR, MDHAR, and DHAR increased the content of non-enzymatic antioxidants, effectively inhibited the increase of MDA, H2O2 content, and O2-· production rate, and alleviated the loss of yield factors caused by waterlogging stress. The waterlogging-tolerant variety Kenfeng 14 recovered better than the waterlogging-sensitive variety Kenfeng 16. In summary, S3307 ameliorated the effects of waterlogging stress on the physiological characteristics of soybean leaves and improved yield as a result of improved antioxidant defense mechanisms that impeded lipid peroxidation. Thus, S3307 could decelerate the damages caused by waterlogging stress to some extent.

为明确外源调环酸钙(Pro-Ca)缓解大豆幼苗盐碱胁迫的机理,以大豆'合丰50'为试验材料,研究在110 mmol·L-1复合盐碱胁迫下,叶面喷施100 mg·L-1 Pro-Ca对大豆幼苗生长、光合特性、抗氧化代谢、AsA-GSH循环以及渗透调节的影响.结果表明:盐碱胁迫显著抑制大豆幼苗生长,降低了净光合速率(Pn)、叶绿素、可溶性蛋白、可溶性糖、蔗糖和淀粉含量;增加了过氧化氢酶(CAT)活性以及脯氨酸、活性氧(ROS)、丙二醛(MDA)和电解质渗漏率积累;与盐碱处理相比,喷施Pro-Ca能够改善大豆幼苗地上部和根系生长,提高叶绿素a、叶绿素b、类胡萝卜素和总叶绿素含量,维持较高的Pn,促进蔗糖、果糖和淀粉的积累;显著上调叶片6种抗氧化酶(SOD、POD、CAT、GR、MDHAR和DHAR)活性、2种非酶抗氧化剂(AsA和GSH)水平和脯氨酸含量;而电解质渗漏率、O2·-产生速率以及MDA和H2O2含量显著降低.综上所述,调环酸钙通过调节抗氧化酶活性和AsA-GSH循环系统、增加渗透溶质积累、降低ROS损伤来提高大豆幼苗对盐碱胁迫的耐性.

[目的]研究苗期淹水胁迫对小豆抗逆生理和产量的影响以及外源脱落酸(abscisic acid,ABA)缓解胁迫的效应,为探明小豆对淹水胁迫的应激生理机制及外源ABA的应用效果提供理论依据.[方法]盆栽条件下,以龙小豆4号和天津红小豆品种为试验材料,于苗期进行预喷施外源ABA并连续淹水处理5d,研究淹水胁迫对小豆根系活性氧(ROS)物质积累、膜脂过氧化伤害、抗氧化系统和产量的影响,以及外源ABA的缓解作用.[结果]幼苗期淹水胁迫引起小豆根系H2O2和MDA含量、脯氨酸、可溶性糖和可溶性蛋白含量显著提高,SOD、POD和CAT活性显著提高,淹水处理5d导致龙小豆4号单盆产量显著下降6.18％ ～ 8.40％,天津红显著下降4.97％ ～9.91％.叶面喷施ABA可有效提高小豆根系脯氨酸、可溶性糖和可溶性蛋白含量,显著降低H2 O2和MDA含量,能够显著提高SOD、POD和CAT活性并降低SOD/POD的比值,喷施ABA使龙小豆4号在淹水3d时产量显著提高1.50％ ～6.05％,使天津红在淹水4d时产量显著提高3.00％～4.46％.[结论]本试验条件下,淹水胁迫引起小豆根系H2O2积累和膜脂过氧化加剧,诱导保护酶活性及渗透调节物质含量增加以抵御胁迫,淹水胁迫最终导致产量下降.外源ABA可在一定程度上提高保护酶活性和渗透调节物质含量,提高抗氧化能力,减缓淹水胁迫危害,相对提高小豆产量.

为了研究吲哚丁酸钾(IBA-K)在减轻干旱对大豆根系的伤害中的作用,以垦丰16(干旱敏感型)和合丰50(耐旱型)为材料,采用盆栽法研究IBA-K拌种对两个品种大豆在正常供水、干旱和复水条件下根系形态建成及生理代谢的影响.结果表明,与正常供水相比,干旱胁迫抑制了大豆根系的生长发育,而IBA-K处理后,大豆根系干物质积累量、形态建成、抗氧化酶活性和渗透调节物质含量在不同土壤水分条件下均高于其干旱对照,膜受损程度减轻.IBA-K处理下,大豆根系SOD活性、POD活性、可溶性糖和脯氨酸含量在干旱条件下均显著高于其干旱对照;MDA含量、相对电导率显著低于其干旱对照.IBA-K处理下的两个品种大豆根表面积、根平均直径、根体积、POD活性和CAT活性在复水条件下分别高于其干旱对照,均未达到显著性差异.复水后,IBA-K处理下的垦丰16根干重和总根长分别较其干旱对照显著增加了3.13％和24.51％,合丰50根干重和总根长较其干旱对照未达到显著性差异.IBA-K处理下的合丰50相对电导率和MDA含量分别较其干旱对照显著降低11.80％和15.09％,SOD活性和可溶性糖含量分别较其干旱对照显著增加14.90％和3.94％,垦丰16相对电导率、MDA含量、SOD活性和可溶性糖含量较其干旱对照未达到显著性差异.IBA-K处理下的两个品种大豆根系脯氨酸含量分别较其干旱对照显著增加了10.62％和10.70％.IBA-K处理和不同土壤水分处理对两个品种大豆根系形态和生理指标存在显著或极显著影响,二者间的交互作用无明显调控作用.综上,IBA-K通过提高根系干物质积累量、抗氧化酶活性和渗透调节物质含量,降低MDA含量和相对电导率,减轻干旱胁迫对苗期大豆根系的伤害.

为研究不同时期高氮施肥对大豆干物质积累、光合生理特性及产量的影响,以大豆品种"垦丰16"和"合丰50"为试验材料,进行大田试验.于播种前施尿素(71.1 kg·hm-2)为N0处理和于大豆V2、V6、R1、R2和R4期施尿素(每次施尿素125.1 kg·hm-2)为N1处理,并于R1～R6期进行取样,对不同时期高氮施肥下大豆干物质积累、光合特性和产量及产量构成因素进行测定和分析.结果表明,N1处理能有效促进大豆R1～R6期干物质的积累;显著增加"垦丰16"叶片R1和R2期蔗糖含量,R1、R3、R5和R6期果糖含量,R3～R6期可溶性糖含量,R3和R6期淀粉含量;显著增加"合丰50"叶片R1和R3期蔗糖含量,R1、R2、R3和R5期果糖含量,R2、R4和R5期淀粉含量和R2～R6期可溶性糖含量.与N0处理相比,N1处理明显提高两大豆品种的叶面积指数,显著增加"垦丰16"叶片SPA D值,增幅为5.48％,显著增加"合丰50"叶片气孔导度和蒸腾速率,增幅分别为35.14％和32.95％.与N0处理相比,N1处理均增加了R8期两品种单株荚数、单株粒数、百粒重和产量,其中,"垦丰16",N1处理较N0处理分别增加9.09％、6.86％、11.01％和16.67％;"合丰50",N1处理较N0处理分别增加4.92％、6.04％、11.87％和16.52％.综上所述,不同时期高氮施肥可促进大豆干物质积累,促进碳代谢产物的合成,提高R6期叶片SPA D值、叶面积指数及光合能力,最终使大豆获得高产.

为探究苗期（V1期）淹水胁迫对大豆生理特性和显微结构的影响及烯效唑(S 3307 )的缓解效应,以‘垦丰14’为材料,于V1期进行叶面喷施S 3307 ,并于喷药后5d进行淹水处理,对淹水胁迫下大豆叶片和根系生理特性、下胚轴显微结构及S 3307 的调控效应进行了测定和分析。结果表明,淹水胁迫会增加大豆下胚轴通气组织数量,随淹水胁迫时间延长,通气组织面积逐渐增大;S 3307 能提高大豆对淹水逆境的适应性,增加通气组织数量和通气组织的面积,以应对淹水胁迫对植株造成的缺氧胁迫。与对照（CK）相比,淹水胁迫会增加叶片和根系中活性氧（ROS）和丙二醛（MDA）含量,并随胁迫时间延长而逐渐升高。在淹水胁迫前期会诱导酶促抗氧化防御系统活性的增强,引起渗透调节物质含量的增加,随胁迫时间延长,抗氧化酶活性和渗透调节物质含量均呈下降趋势。S 3307 可促进叶片和根系中抗氧化酶活性的提高,抑制ROS和MDA含量的过量积累,并始终维持较高的渗透调节物质含量,减缓淹水胁迫造成的损伤。

为探讨调环酸钙(Pro-Ca)对盐碱胁迫下大豆(Glycine max)根系生长的缓解作用,以大豆品种合丰50(耐盐)和垦丰16(盐敏感)为试验材料,研究叶面喷施100 mg·L-1 Pro-Ca对盐碱胁迫下大豆根系生长特性、活性氧代谢、抗氧化酶活性和渗透调节物质含量的影响.结果表明,外源喷施Pro-Ca均能不同程度缓解盐碱胁迫对合丰50和垦丰16根系生长的抑制,两品种根长、根鲜重和根干重分别增加了11.2％和23.6％、3.2％和19.8％、38.0％和37.6％;上调了盐碱胁迫下大豆根系超氧化物歧化酶(SOD)、过氧化物酶(POD)、过氧化氢酶(CAT)和抗坏血酸过氧化物酶(APX)活性以及抗坏血酸(AsA)和谷胱甘肽(GSH)水平;抑制了 O2·-和H2O2积累,降低了丙二醛(MDA)含量和电解质渗漏率(EL);促进了渗透调节物质积累,合丰50和垦丰16大豆根系的可溶性糖、可溶性蛋白和脯氨酸含量分别增加了 5.1％～7.8％和6.2％～28.0％、6.6％～17.8％和3.8％～10.3％、19.1％～31.9％和6.9％～27.8％.主成分分析表明外源喷施Pro-Ca对耐盐品种合丰50和盐敏感品种垦丰16根系均具有较好的调控效果.综上所述,外源喷施Pro-Ca可通过增强根系抗氧酶活性、渗透调节能力以及降低膜脂过氧化来增强大豆根系的耐盐碱能力.本研究初步阐明了 Pro-Ca缓解大豆根系盐碱胁迫伤害的生理生化机制,为进一步从分子水平揭示其作用机制提供了理论依据.

[目的]研究淹水胁迫对初花期(R1)大豆叶片抗坏血酸-谷胱甘肽(AsA-GSH)循环的影响及烯效唑(uniconazole,S3307)的调控效应,为提高大豆耐涝性及烯效唑的应用提供理论依据.[方法]2019年在黑龙江八一农垦大学国家杂粮工程技术研究中心盆栽场,以耐涝品种垦丰14和涝渍敏感品种垦丰16为试验材料,进行盆栽试验.待植株生长至R1期时叶片喷施S3307(浓度为50 mg·L-1,喷施量为225 L·hm-2),喷施5 d后开始淹水胁迫处理,分别于淹水后0 d(R1+5)、5 d(R1+10)和恢复正常水分处理5 d(R1+15)后进行取样,以2个品种大豆正常水分管理为对照组(CK)、淹水胁迫处理(W)和淹水胁迫处理+S3307(W+S)为处理组,分别采用分光光度计法对各项生理指标进行测定,研究淹水胁迫对大豆叶片膜脂过氧化程度(MDA)、活性氧(ROS)和AsA-GSH循环系统中非酶抗氧化剂(AsA、DHA、GSH和GSSG)和关键酶(APX、GR、MDHAR和DHAR)的影响及S3307的缓解效应.[结果]R1期,淹水胁迫R1+5时,与CK相比,喷施S3307降低了垦丰14和垦丰16叶片内MDA、O2-产生速率和H2O2含量,同时提高了AsA-GSH循环中非酶抗氧化剂和关键酶含量,以维持ROS平衡,促进2种大豆品种的生长发育.淹水胁迫R1+10时,W处理增加了垦丰14和垦丰162个大豆品种叶片内MDA含量,分别较CK显著增加40.02％和37.53％,并加速了ROS(O2-和H2O2)的积累,淹水胁迫下2个品种O2-产生速率分别较CK显著增加60.29％和27.77％,H2O2含量分别较CK显著增加49.45％和43.40％,且涝渍敏感品种垦丰16的受害程度大于耐涝品种垦丰14,同时,在淹水胁迫下,2个品种叶片内的抗氧化物质和关键酶活性均有所提高,以适应淹水胁迫所产生的应激反应.叶面喷施S3307后,W+S处理可进一步提高2个大豆品种淹水胁迫下抗氧化物质(AsA、GSH)、氧化还原物质(DHA、GSSG)及总抗坏血酸(AsA+DHA)和总谷胱甘肽(GSH+GSSG)含量,并提高抗氧化酶(APX、GR、MDHAR、DHAR)活性,降低叶片MDA含量,抑制ROS积累,减少淹水胁迫对膜系统造成的伤害.恢复正常水分处理5 d(R1+15)后,2个品种W处理的上述指标均有所降低,但W+S处理能维持大豆叶片内较高的抗氧化酶活性和抗氧化物质含量,加速清除MDA和ROS的过度积累,促进淹水胁迫下大豆叶片内AsA-GSH循环运转,进而促进大豆品种叶片恢复至正常状态.[结论]淹水胁迫对大豆叶片膜脂过氧化程度、ROS积累及AsA-GSH循环中关键酶活性和非酶抗氧化剂具有不同程度的影响,喷施S3307可在一定程度上提高关键酶活性,提高抗氧化能力,减缓淹水胁迫所造成的危害.

Soil salinization has become a global problem and seriously endangers crop growth and yield improvement. In the present study, soybean (Hefeng 50) seedlings were used as test materials to study the mitigation effect of foliar spraying of different plant growth regulators (PGRs) [50 mg L−1 indole-3-butyric acid potassium salt (IBAK), 50 mg L−1 chitosan oligosaccharide (COS), 2 mg L−1 abscisic acid (ABA), 30 mg L−1 5-aminolevulinic acid (ALA), and 1.2 mg L−1 brassinolide (BR)] on oxidative stress caused by the mixed Saline–Alkali concentration of 110 mmol L−1. The results showed that the application of PGRs promoted the growth of Saline–Alkali stressed plants, where the maximum increase in shoot FW was treated with COS, and in root FW, root length, root surface area, and root volume were obtained with the IBAK treatment. Treatments ABA, ALA, and BR had higher net photosynthetic rates, and the chlorophyll content was considerably increased under COS and BR treatments compared with Saline–Alkali treatment. Moreover, PGRs markedly enhanced the activities of antioxidant enzymes, the concentration of ascorbate (AsA), glutathione (GSH), proline, soluble protein, soluble sugar, sucrose, and starch, and the ratios of AsA/DHA and GSH/GSSG, but reduced the concentration of malondialdehyde (MDA), electrolyte leakage (EL), hydrogen peroxide (H2O2), and superoxide radical (O2·−) in soybean seedlings compared with Saline–Alkali treatment. The principal component analysis revealed that the ranking of PGRs enhancing Saline–Alkali tolerance of soybean seedlings was BR > IBAK > ABA > COS > ALA, and the most effective treatment was BR, which may be assigned to more vigorous antioxidant defense and osmotic adjustment.

Objective: To investigate microRNA (miRNA) expression profiles in the seminal plasma of nonobstructive azoospermia (NOA) patients with different histopathologic patterns and evaluate potential noninvasive diagnostic biomarkers of NOA. Design: Sequencing and validation using quantitative reverse transcription polymerase chain reaction (qRT-PCR). Setting: Reproductive center and research institute. Patient(s): Thirteen patients with NOA (7 Sertoli cell-only syndrome [SCOS] and 6 hypospermatogenesis to spermatogenesis arrest [SA]) and 7 normal fertile controls for sequencing, six samples per group for validation; 54 patients with NOA (27 SCOS and 27 SA) and 19 normal fertile controls for large-sample qRT-PCR analysis. Intervention(s): None. Main Outcome Measure(s): MicroRNA expression profiles in the seminal plasma of patients with NOA with different histopathologic patterns were assessed using high-throughput sequencing and validated using qRT-PCR. Result(s): There were 78 overexpressed and 132 underexpressed miRNAs in patients with SCOS and 32 up-regulated and 90 down-regulated miRNAs in patients with SA compared with fertile men with normozoospermia. Two down-regulated and one up-regulated miRNA were validated using qRT-PCR, which indicated that the qRT-PCR and sequencing results were basically consistent. Hsa-miR-34c-5p expression was significantly lower in the seminal plasma of patients with NOA than normal fertile controls. The area under the receiver operating characteristic curve(AUC) for hsa-miR-34c-5p was 0.979 and 0.987 in the seminal plasma of patients with SA and patients with SCOS, respectively, compared with normal fertile controls. The AUC was 0.799 for hsa-miR-34c-5p in the seminal plasma between patients with SA and patients with SCOS. Kyoto Encyclopedia of Genes and Genomes pathway enrichment analysis of differentially expressed miRNA target genes revealed that the Notch signaling pathway was one of the most abundant signaling pathways. The expression of Hes5, an effector of the Notch signaling pathway, was significantly higher in the seminal plasma of patients with NOA than normal fertile controls. Conclusion(s): MicroRNA expression profiles in seminal plasma were altered in patients with NOA compared with normal fertile controls. The profiles differed in patients with NOA with different pathologic patterns. We speculate that miR-34c-5p in seminal plasma could be a potential noninvasive biomarker to diagnose patients with NOA and distinguish different pathologic types of NOA. The Notch signaling pathway may be involved in the pathogenesis of NOA. ((C) 2020 by American Society for Reproductive Medicine.)

为探究吲哚丁酸钾(IBA-K)对苗期大豆生长发育的影响,以大豆品种垦丰16和合丰50为试验材料,研究吲哚丁酸钾包衣剂量分别为0(CK),20,40,80,160和320 mg·kg-1时,对苗期大豆叶片生长发育及生理代谢的调控效应.结果表明:与对照相比,不同剂量IBA-K包衣处理时苗期大豆地上部形态建成、光合作用、保护酶活性及渗透调节物质含量均有不同程度的提高,除株高外,均在IBA-K浓度为80 mg·kg-1时达到最大值,且显著高于对照.垦丰16株高在IBA-K浓度为20和160 mg·kg-1时达到最大,较对照均增加了 10.78％;SOD活性在IBA-K浓度为80 mg·kg-1时较其对照增加了 4.81％.合丰50的株高和SOD活性在80 mg·kg-1时达到最大,较对照显著增加了 27.78％和8.83％.IBA-K处理下的垦丰16和合丰50 VPD分别较对照显著降低了 17.24％和23.74％、MDA含量分别较对照显著降低了 38.11％和46.44％.综上分析表明,采用80 mg·kg-1IBA-K进行种子包衣处理时,对促进大豆苗期生长,提高大豆苗期的光合能力,增强大豆叶片抗氧化酶活性,降低MDA含量,提高渗透调节物质含量的效果最佳.