磷胁迫下蔗糖对水稻苗期根适应性和磷酸转运蛋白基因表达的影响

磷是植物生长和发育中最重要的必须元素之一。尽管土壤中磷资源很丰富,但大部分磷是以植物不能吸收利用的固定态和有机态存在,特别是以酸性土壤为主的南方稻田,水稻缺磷现象非常严重。理解和掌握水稻对低磷的适应机制有助于利用分子手段培育磷高效利用水稻品种。为阐明蔗糖提高水稻耐低磷的机制,本研究对水稻幼苗进行不同磷、糖处理,分析水稻幼苗在不同磷糖配比培养基中的根系结构、无机磷、酸性磷酸酶活性的变化,并利用定量RT-PCR技术分析水稻磷酸转运蛋白基因(OsPT)和酸性磷酸酶基因(OsSAP1)的表达。试验设2个磷浓度:无磷和85 mg·L?1KH2PO4,2个蔗糖浓度:无糖和3%蔗糖,正交设计。结果表明,在低磷胁迫时添加蔗糖,能使水稻幼苗的根总长度、总根数、根冠比显著增加,根分泌的酸性磷酸酶活性降低,但水稻体内的磷酸转运酶活性提高。11个与磷具有高度亲和力的磷酸转运酶的表达发生了改变,其中根优势表达的4个基因OsPT2、OsPT3、OsPT4、OsPT6对磷、糖的影响最为敏感,暗示了蔗糖是通过调节磷转运蛋白维持磷的吸收和平衡。增加根系的蔗糖分配能够提高水稻幼苗对磷胁迫的耐受性。     

Solubilization of inorganic phosphates and growth emergence of wheat as affected by Azotobacter chroococcum mutants

 Phosphate-solubilizing strains of A. chroococcum isolated from the wheat rhizosphere were evaluated for their ability to solubilize tricalcium phosphate (TCP), Mussoorie rock phosphate (MRP) and also for indole-acetic-acid (IAA) production. Strains were selected on the basis of the clearance zone on solid agar media of Pikovskaya and Jensen's media containing TCP, and phosphate solubilization in Jensen's liquid culture medium containing both TCP and MRP. Mutants of the best phosphate-solubilizing (TCP 1.52 μg ml^–1 MRP 0.19 μg ml^–1), IAA-producing A. chroococum strain P-4, were developed and screened for P solubilization and phytohormone production. Five mutants solubilized more P (in the range of 1.5–1.7 μg/ml^–1 of TCP and 0.19–0.22 μg ml^–1 of MRP) than the parent strains. In vitro growth emergence studies of three wheat varieties, viz. C-306, WH-542 and HD-2009, showed better performance with phosphate-solubilizing mutants than with the parent strain. Received: 15 October 1997     

烟草钾转运体基因NtHAK1的克隆及表达模式分析

采用RT-PCR的方法,结合3'RACE与5'RACE,从普通烟草(Nicotiana tabacum)品种K326中克隆出烟草K+转运体基因NtHAK1的全长cDNA序列.该序列长度为2016bp,编码378个氨基酸,其分子量为42.27kDa,等电点7.2.生物信息学分析表明,该蛋白具有6个跨膜区,含有K+转运蛋白...     

施磷对吊兰修复镉污染土壤及土壤酶活性的影响

选用吊兰进行室内盆栽,研究在Cd污染土壤中,施用不同剂量磷肥对吊兰生理指标、土壤酶活性等的影响,为合理施用磷肥,提高Cd污染土壤的植物修复效果提供参考依据。结果表明:吊兰在100mg/kg的Cd污染土壤中能正常生长,施P对吊兰的叶绿素、细胞膜透性、抗氧化酶活性影响显著(p0.01),表现为低浓度促进,高浓度抑制作用。当施磷量为200mg/kg时,叶绿素含量、CAT酶活性最大,外渗电导率和MDA含量最低,POD酶活性开始上升,说明施磷能使吊兰的细胞膜受害程度最低,抗氧化作用增强。同时,施P有利于改善Cd污染土壤的酶系统,对过氧化氢酶、脲酶的活性表现为低浓度促进、高浓度抑制,对蔗糖酶的活性表现相反,对磷酸酶的活性表现抑制作用;且200mg/kg的磷处理时,过氧化氢酶、脲酶的活性最高,蔗糖酶的活性最低。4种土壤酶活性均与P浓度呈高度相关性(p0.05),相关性为脲酶过氧化氢酶蔗糖酶磷酸酶。     

Investigation on Phosphate Solubilization Potential of Agricultural Soil Bacteria as Affected by Different Phosphorus Sources,Temperature, Salt,and pH

Ten phosphate-solubilizing bacterial strains belonging to genera Pseudomonas, Burkholderia, Enterobacter, Serratia, Klebsiella, and Aeromonas were tested for mineral phosphate solubilization activity in Pikovskaya's broth using different phosphate sources at four temperatures (15, 25, 35, and 45 ^οC). Dicalcium and tricalcium phosphate were solubilized more effectively (≥1000 mg L^?1) than ferric and rock phosphate (≥100 mg L^?1) and 35 °C was found to be the optimum temperature. Although Klebsiella and Aeromonas spp. are well known for their dinitrogen (N₂)–fixing ability, to the best of our knowledge, this is the first report of inorganic phosphate solubilization by Klebsiella terrigena and Aeromonas vaga. Interestingly, A. vaga BAM-77 is the most efficient strain at solubilizing inorganic phosphorus (P) even in the presence of 8% sodium chloride (NaCl) at pH 10. These findings indicate that all four strains are efficient P solubilizers under variable conditions of temperature, pH, and P source and thus can be recommended for P fertilization in different soils.     

Hydroponic experiment for identification of tolerance traits developed by rice Nagina 22 mutants to low-phosphorus in field condition

Development of phosphate (P)-deficiency tolerant rice cultivars is constrained by lack of suitable, reproducible, and consistent seedling stage screening methods in breeding programs. This study reports the screening and characterization of M5 mutants derived from an ethyl methane sulfonate treated population of rice cv. Nagina 22 (N22) in low-P field (soil Olsen P 1.94–2.01 mg kg^?1; alkaline Vertisol; pH 7.94) for high yield. The present study showed that seedling growth responses such as increase in root weight, root length, root/shoot weight, and dry weight in P-deficient medium can be taken as indices of low-P tolerance in mature plants in field. Total phosphorus content in seedlings showed an inverse relationship with total phosphorus content and low-P tolerance in mature plants in the field. But, phosphorus content in seeds and acid phosphatase activity in the seedling stage were positively correlated with survival and seed set in low-P field. In low-P field, plant height correlated most with yield per plant, and the number of productive tillers in mature plants was highly correlated with tiller number at vegetative stage. These mutants (NH776, NH710, and NH719) have agronomic importance because of their ability to grow and give higher yield than N22 in P-deficient field.     

提高供磷可缓解砷对番茄的胁迫作用

环境和食品中砷标准提高后,砷污染及其有关的食品安全问题更加受到广泛的关注。磷对植物吸收和累积砷的影响及其作用机制仍有很大争论。本文利用水培试验,研究了0.025~1.0 mmol L-1范围内7个供磷水平下50μmol L-1AsO43-胁迫对微型番茄生长、砷和磷的吸收及两个磷酸盐转运体基因(LePT1和LePT2)表达的影响。在0.025~0.4 mmol L-1的缺磷条件下,砷对番茄的生长有明显抑制作用。在缺磷状态下,增加磷供应能显著减少番茄体内砷的浓度。约58%的砷累积在番茄根部,根部砷的浓度较地上部高10倍以上。砷抑制番茄对磷的吸收只出现在严重缺磷(0.025~0.05 mmol L-1)条件下。此外,外界砷的存在对LePT1、LePT2基因的表达影响不显著。从本文的结果来看,番茄吸收过程中的磷砷相互作用在缺磷条件下更明显,提高供磷水平可降低番茄体内砷含量,缓解砷对番茄的胁迫作用。     

溶磷真菌的筛选及配施难溶态磷对土壤磷素有效性的影响

为研究溶磷真菌菌群对土壤磷素有效性的影响,首先在室内对3株不同种类溶磷真菌(1株属于被孢霉属Z1,1株为青霉属Z2,1株为黑曲霉Z3)的组合效应进行了研究,确定了最佳的菌株组合Z1+Z2+Z3,试验选用Z1、Z2、Z3组成菌群作为试验菌株;然后通过盆栽油菜试验研究溶磷真菌配施难溶态磷(磷酸三钙和磷矿粉)对土壤磷素有效性的影响。结果表明:溶磷真菌处理土壤有效磷、有机质、碱性磷酸酶、蔗糖酶含量和油菜产量分别比基质处理显著增加了60.00%,20.21%,56.45%,53.81%,14.38%,溶磷真菌配施难溶态磷上述各指标都高于单施溶磷真菌处理;单施溶磷真菌对土壤最大吸磷量的影响与基质无差异,溶磷真菌配施难溶态磷可以显著降低土壤最大吸磷量,溶磷真菌+磷酸三钙和溶磷真菌+磷矿粉处理土壤最大吸磷量比溶磷真菌处理显著减少158.7,47.6 mg/kg,溶磷真菌各处理土壤吸附常数都低于对应的基质处理,溶磷真菌可以降低土壤对磷的吸附。在土壤上溶磷真菌应与难溶态磷配合施用,对提高土壤磷素有效性有积极的作用。     

两株解磷细菌的解磷活性及作用机制研究

解磷细菌在增加土壤可溶性磷含量、提高磷肥利用效率方面具有重要作用。为选筛高效解磷菌、探讨其解磷机制,本文利用平板溶磷圈法筛选解磷细菌,采用钼锑抗比色法研究其解磷活性,苯磷酸二钠法研究其磷酸酶活性,利用薄层层析分析其产生的有机酸,根据生理生化特征和16S r RNA基因序列系统发育分析,确定其分类学地位。结果表明,菌株JXJ-11和JXJ-15对植酸钙的降解活性很强,3 d后培养液中可溶性磷浓度分别增加219 mg·L~(-1)和216 mg·L~(-1);对磷酸钙降解活性较弱,最高可溶性磷浓度仅为植酸钙的21.79%~30.37%;解磷细菌可分泌酸性、中性和碱性磷酸酶,降解不溶性磷,可能产生丙酸和琥珀酸等有机酸,降低培养液p H,增加可溶性磷浓度。两株细菌均为革兰氏阴性杆菌,无芽孢,产生硫化氢,其中菌株JXJ-11的16S rRNA基因序列与Sphingomonas melonis DAPP-PG 224T和S.aquatilis JSS7T相似性最高(99.79%),菌株JXJ-15的16S rRNA基因序列与Klebsiella pneumoniae subsp.pneumoniae DSM 30104T相似性最高(99.73%),根据以上信息,确定菌株JXJ-11和JXJ-15分别是鞘氨醇单胞菌属和克雷白氏杆菌属的成员。菌株JXJ-11和JXJ-15的解磷机制包括分泌有机酸和磷酸酶,其中JXJ-11在微生物磷肥研制方面具有潜在应用价值。     

Salinity effects on annual bedding plants in a peat‐perlite medium and solution culture

Annual vinca (Catharanthus roseus (L.) G. Don ‘Pink Carpet'), geranium (Pelargonium x hortorum L. H. Bailey ‘Jackpot'), and marigold (Tagetes erecta L. ‘First Lady') were grown in a sphagnum peat moss and perlite medium. Plants were irrigated with solutions of different salinity by the addition of 0.0, 1.0, 2.0, 4.0, and 8.0 g/1 of a NaCl and CaCl₂ mixture resulting in solution electrical conductivity (EC) values of about 1.3, 3.0, 4.5, 7.9, and 13.9 ds/m, respectively. In another experiment marigold and geranium were grown in solution culture containing the same salt mixture at 0.0, 1.0, 4.0, and 8.0 g/1 with EC values of 1.4, 3.0, 7.4, and 12.5 ds/m, respectively. All species showed some salinity tolerance up to 2.0 g/1 in peat‐perlite and 1.0 g/1 in solution culture as growth reductions were below 10% and no foliar injury occurred. Foliar injury occurred on marigold and geranium, but not annual vinca, at 4.0 and 8.0 g/1 in both growing media. On a concentration basis, recently mature leaves sampled from marigold grown in peat‐perlite contained more chloride (Cl) but less sodium (Na) than geranium and annual vinca. However results of the solution culture experiment showed that, with the exception of 1.0 g/1 treatment, geranium and marigold plants absorbed the same amount of Cl and Na when content was expressed on a mg/g dry weight basis. The low Na concentration in marigold leaves was a reflection of restricted translocation of Na from the roots to the shoots.     

EFFECTS OF CONVENTIONAL AND CONTROLLED RELEASE PHOSPHORUS FERTILIZER ON CROP EMERGENCE AND GROWTH RESPONSE UNDER CONTROLLED ENVIRONMENT CONDITIONS

A series of experiments on the effects of form and rate of seed row placed phosphorus (P) fertilizer were carried out under controlled environment conditions using flats of a P-deficient Brown Chernozemic soil from Saskatchewan, Canada. The experiments were conducted in the laboratory and growth chamber using rates of seed row placed granular P fertilizer up to 100 kg P₂O₅ ha^?1. Two forms of monoammonium phosphate fertilizer were compared: 1) conventional MAP granules and 2) controlled release phosphorus (CRP) fertilizer granules (Agrium Inc, Denver, CO, USA.) made with a polymer coating to slow the release of phosphate to soil solution. Six crops were utilized in the study to provide a range of commonly grown cereal, oilseed, pulse and forage crops in Western Canada: wheat (Triticum aestivum), canola (Brassica napus), mustard (Brassica juncea), flax (Linum usitatissimum), yellow pea (Pisum sativum) and alfalfa (Medicago sativum). Parameters measured were percentage of planted seeds that had emerged after two weeks, plant biomass yield, and plant P uptake after four weeks. Most of the crops tested showed no negative impact on emergence with seed row placed conventional P fertilizer at rates up to ～20 to 30 kg P₂O₅ ha^?1. Pea, flax and mustard tended to be most sensitive to injury from high rates of seed placed MAP while wheat was least sensitive. The controlled release phosphorus fertilizer (CRP) product greatly increased the tolerance of crops to high rates of seed row placed P, with rates of 80 kg P₂O₅ ha^?1 placed in the seed row producing no significant injury for most crops. This effect is attributed to the coating reducing the harmful salt effect that occurs when high rates of fertilizer are placed in the seed row in close proximity to the seed. Generally, a rate of 30 kg P₂O₅ ha^?1 was sufficient to produce maximum early season biomass yield and P uptake for both conventional MAP and CRP fertilizers. Large differences in early P availability were not evident between the conventional P and controlled released P fertilizer products.     

Cucumber performance is improved by inoculation with plant growth-promoting microorganisms

We investigated the effects of inoculation of Rhodobacter sphaeroides, Lactobacillus plantarum, and Saccharomyces cerevisiae on cucumber plant growth promotion and on the contents of plant hormones, amino acids, and mineral nutrients. We showed that treatment with all three bio-inoculants significantly increased the shoot length, root length, shoot fresh weight, shoot dry weight, and chlorophyll content, via secretion of indole acetic acid and/or organic acids. Inoculation with R. sphaeroides had more favorable effect on plant growth than did inoculation with L. plantarum or S. cerevisiae, by significantly enhancing the gibberellin and reducing the abscisic acid contents. The results of amino acid analysis revealed that inoculation with R. sphaeroides, L. plantarum, and S. cerevisiae generally increased the contents of 17 amino acids, namely, aspartic acid, threonine, serine, glutamic acid, glycine, alanine, cysteine, valine, methionine, isoleucine, leucine, tyrosine, phenylalanine, lysine, histidine, arginine, and proline. With the exception of cysteine, all these amino acids were present in higher concentrations in plants inoculated with R. sphaeroides than in control plants or in plants inoculated with L. plantarum and S. cerevisiae. Furthermore, inoculation with R. sphaeroides significantly increased the calcium, potassium, magnesium, and phosphate contents. Our results suggest that the use of R. sphaeroides, L. plantarum, and S. cerevisiae in agricultural fields can improve plant growth. Moreover, inoculation of cucumber plants with R. sphaeroides regulates plant functional metabolites, thereby promoting plant growth.     

A rice FRD3-like (OsFRDL1) gene is expressed in the cells involved in long-distance transport

We identified four putative AtFRD3-like genes (OsFRDL) in the rice genome that exhibited 39.1 to 56.7% amino acid sequence similarities to Arabidopsis FRD3. Of these, we cloned three OsFRDL genes from a cDNA library prepared from iron-deficient rice roots: OsFRDL1, OsFRDL2, and OsFRDL3. OsFRDL1 was expressed weakly in Fe-sufficient roots, and slight expression was induced in the roots of Fe-deficient plants. OsFRDL2 was expressed constitutively in both roots and leaves, and Fe deficiency reduced its expression in leaves. OsFRDL3 was expressed in leaves, but not in roots; Fe deficiency induced slight expression in leaves. An OsFRDL1-sGFP fusion protein was localized in the plasma membrane in onion epidermal cells. The promoter GUS analysis showed that OsFRDL1 was localized in the cells involved in long-distance transport, in both Fe-sufficient and Fe-deficient plants. Furthermore, OsFRDL1 expression was observed during the reproductive stage. These results suggest that OsFRDL1 is a transporter that resides in the plasma membrane of cells involved in long-distant transport.     

Phosphate solubilization by <Emphasis Type="Italic">Penicillium</Emphasis> spp. closely associated with wheat roots

In this study we found that Penicillium spp. exhibiting P-solubilizing activity are common both on and in the roots of wheat plants grown in southern Australian agricultural soils. From 2,500 segments of washed and surface-disinfested root pieces, 608 and 223 fungi were isolated on a selective medium, respectively. All isolates were screened for P solubilization on solid medium containing hydroxyapatite (HA); 47 isolates (5.7%) solubilized HA and were identified as isolates of Penicillium or its teleomorphs. These isolates were evaluated for solubilization of Idaho rock phosphate (RP) in liquid culture. Penicillium bilaiae strain RS7B-SD1 was the most effective, mobilizing 101.7 mg P l^–1 after 7 days. Other effective isolates included Penicillium simplicissimum (58.8 mg P l^–1), five strains of Penicillium griseofulvum (56.1–47.6 mg P l^–1), Talaromyces flavus (48.6 mg P l^–1) and two unidentified Penicillium spp. (50.7 and 50 mg P l^–1). A newly isolated strain of Penicillium radicum (KC1-SD1) mobilized 43.3 mg P l^–1. RP solubilization, biomass production and solution pH for P. bilaiae RS7B-SD1, P. radicum FRR4718 or Penicillium sp. 1 KC6-W2 was determined over time. P. bilaiae RS7B-SD1 solubilized the greatest amount of RP (112.7 mg P l^–1) and had the highest RP-solubilizing activity per unit of biomass produced (up to 603.2 g P l^–1 mg biomass^–1 at 7 days growth). This study has identified new isolates of Penicillium fungi with high mineral phosphate solubilizing activity. These fungi are being investigated for the ability to increase crop production on strong P-retaining soils in Australia.     

叶面喷施含Bacillus amyloliquefaciens SQR9 复合微生物液体肥料的肥效研究

研究叶面喷施含BacillusamyloliquefaciensSQR9复合微生物液体肥料在辣椒和白菜上的应用效果,以期开发出根际有益微生物新的应用模式和新的叶面肥产品。以辣椒和白菜为供试材料,设以下6个处理评估肥料效果:喷施清水处理(CK)、喷施与复合微生物液体肥料等养分的化肥处理(CF)、喷施含化肥+氨基酸+糖蜜的水溶肥处理(T1)、喷施含化肥+氨基酸+糖蜜+微量元素的水溶肥处理(T2)、喷施含化肥+氨基酸+糖蜜+SQR9的水溶肥处理(T3)和喷施含化肥+氨基酸+糖蜜+微量元素+SQR9的复合微生物液体肥料处理(T4)。盆栽试验结果表明,与其他5个处理(CK、CF、T1、T2、T3)相比,T4处理在各项促生指标上虽未全部达到显著性差异,但其更能够促进辣椒和白菜的生长,提高其生物学性状。可培养微生物数量上,新型含菌株SQR9复合微生物液体肥料的喷施,增加了叶际芽孢杆菌的数量;与喷施清水对照(CK)和与复合微生物液体肥料等养分的化肥处理(CF)相比,其他4个处理(T1、T2、T3、T4)对辣椒和白菜叶际可培养微生物数量影响更大,而喷施含Bacillus amyloliquefaciens SQR9复合微生物液体肥料(T4)的影响更为明显。叶面喷施含Bacillus amyloliquefaciens SQR9复合微生物液体肥料可有效促进辣椒和白菜的生长。     

Comparative Effect of Two Different Types of Phosphate on Cadmium Uptake by Radish (Raphanus sativa L.) Grown in Arable Soil Affected by Mine Activity

To evaluate the effect of type of phosphate (P) material on reducing soil cadmium (Cd) extractability and radish Cd uptake in the field, two different P materials, fused superphosphate (FSP) and dipotassium phosphate (K₂HPO₄), were applied at rates of 0, 33.5, 100.5, and 167.5 kg P ha^?1 before seeding radish (Raphanus sativa L.) in a Cd-contaminated soil. Plant-available Cd concentration in soil and total Cd uptake by radish increased with increasing FSP application but decreased with K₂HPO₄. The significant decrease in soil pH and negative charge of soil by FSP application led to an increase in bioavailable Cd fraction in soil and in Cd uptake by radish. However, K₂HPO₄ increased soil pH and negative charge of soil and decreased bioavailable Cd fractions. Soil pH and negative charge of soil played an important role in controlling Cd uptake by radish in soil to which phosphate was applied.     

Phosphate Solubilizing Ability and Phylogenetic Diversity of Bacteria from P-Rich Soils Around Dianchi Lake Drainage Area of China

The phylogenetic diversity of phosphate solubilizing bacteria(PSB)distributed in P-rich soils in the Dianchi Lake drainage area of China was characterized,and the tricalcium phosphate(TCP)solubilizing activities of isolated PSB were determined.Among 1 328 bacteria isolated from 100 P-rich soil samples,377 isolates(28.39%of the total)that exhibited TCP solubilization activity were taken as PSB.These PSB showed different abilities to solubilize TCP,with the concentrations of solubilized P in bacterial cultures varying from 33.48 to 69.63 mg L^-1.A total of 123 PSB isolates,with relatively high TCP solubilization activity(>54.00 mg L^-1),were submitted for restriction fragment length polymorphism(RFLP)analysis,which revealed 32 unique RFLP patterns.Based on these patterns,62 representative isolates,one to three from each RFLP pattern,were seffected for 16S rRNA sequencing.Phylogenetic analysis placed the 123 PSB into three bacterial phyla,namely Proteobacteria,Actinobacteria and Firmicutes.Members of Proteobacteria were the dominant PSB,where 107 isolates represented by 26 RFLP patterns were associated with the genera of Burkholderia,Pseudomonas,Acinetobacter,Enterobacter,Pantoea,Serratia,Klebsiella,Leclercia,Raoultella and Cedecea.Firmicutes were the subdominant group,in which 13 isolates were affiliated with the genera of Bacillus and Brevibacterium.The remaining 3 isolates were identified as three species of the genus Arthrobacter.This research extends the knowledge on PSB in P-rich soils and broadens the spectrum of PSB for the development of environmentally friendly biophosphate fertilizers.     

几株高效溶磷菌株对不同磷源溶磷活力的比较

在液体培养条件下，研究了4株溶磷菌株(Bmp5、Bmp6、Bmp7和Fmp9)对不同磷源溶解能力的差异并与荧光假单孢菌As1.867和巨大芽孢杆菌As1.223进行了比较，探讨了菌株组合培养对溶磷活力的影响。结果表明，4株菌株对磷酸钙、磷酸铝、磷酸氢钙溶解能力明显高于磷酸铁和卵磷脂。以磷酸钙为磷源时，Fmp9的溶磷量比As1.867和As1.223分别高出约92%和48%；而以磷酸铝为磷源时，As1.223的溶磷量明显高于其他菌株；在磷酸氢钙为磷源的条件下，Bmp6为优势菌株，溶磷量高达785.51mg/L。对比研究发现，Bmp5、Bmp6、Bmp7及Fmp9的优势磷源分别为卵磷脂、磷酸氢钙、磷酸铝和磷酸钙。组合培养表明，Bmp5+Fmp9和Bmp6+Fmp9较单株菌的溶磷量有所增加，为较好的组合。试验得到的溶磷微生物配方已经应用于生物复合肥料的研究，并进行了盆栽实验，得到了较好的效果。该研究可为土壤生物肥料工业的微生物学研究提供借鉴。