Stem tissue phosphorus as an index of the phosphorus status of Banksia ericifolia L. f.

The effects of P fertilizer rate on shoot growth and the total P concentration of the whole shoot, new and mature leaves, symptom leaves and stems of Banksia ericifolia L. f., a P-sensitive species, were investigated in a six month greenhouse pot experiment. Shoot dry weight of plants growing in an Australian sedge peat, coarse sand and perlite potting mix (1:1:1) increased with up to 100 mg P L⁻¹ supplied as a six month controlled release P (0:18:0) fertilizer, but was reduced by toxicity at the highest application rate (200 mg P L⁻¹). Plants receiving this treatment developed chlorotic new and mature leaves. Leaf symptoms observed at rates of 60–100 mg P L⁻¹ were confined to old leaves and were related to the P concentration of the shoot. Growth was not affected at these rates. The P concentration of stems was strongly influenced by P supply. This tissue acted as a sink for excess P, helping to regulate the P concentration of leaves. The approximate range of P concentrations in stem tissue, associated with greater than 90% of maximum shoot dry weight, was 0.5–1.5 g P kg⁻¹ tissue dry weight. This was greater than that calculated for mature leaves (0.5–0.8 g kg⁻¹) or for whole shoots (0.5–1.2 g kg⁻¹). This wider range, and the capacity to store P in excess to requirement, makes the stem a better index tissue for plant P status than either leaves or whole shoots. This revised version was published online in June 2006 with corrections to the Cover Date.     

Alkylation reaction of phosphorus oxyacids.

Alkylation reactions of phosphorus oxyacids (i.e. phosphoric acid, phosphorous acid, hypophosphorous acid) were examined by means of several methods for the synthesis of the corresponding esters. These reactions were applied to the synthesis of oligonucleotide having phosphotriester bond or phosphonate diester bond.     

长期施肥对石灰性土壤磷素肥力的影响 Ⅰ.有机质、全磷和速效磷

在陕西关中黄土区连续23年进行了不同施肥、小麦玉米轮作定位试验,研究了0～100cm土层土壤有机质、全磷、速效磷含量变化.结果表明,长期单施化肥或有机肥与化肥且配施均可增加耕层(0～20cm)土壤有机质含量.长期施用厩肥并配施化肥处理对土壤总磷库及无机磷库、速效磷的贡献大于玉米秸秆处理.长期单施化肥可增加土壤全磷、无机磷和速效磷含量,增加幅度低于厩肥和休闲处理,与秸秆处理对全磷、速效磷含量的影响效应相近.23年的不同施肥处理,与无肥处理相比,其理土壤磷素增量在0～100cm土壤剖面中的分布特点是:全磷增量剖面分布可为3层———耕层(0～20cm)为显著累积层,20～60cm土层为微增-亏损层,60～100cm土层为轻度累积层.速效磷增量剖面分布趋势与全磷增量分布趋势基本相同,仅在60～100cm土层累积较弱.     

磷肥施用方式及类型对冬小麦产量和磷素吸收的影响

采用田间微区试验研究不同磷肥施用方式和种类对冬小麦生长和当季磷素吸收的影响.磷肥种类为磷酸二氢钙(MCP)和磷酸氢二铵(DAP),施用方式包括表面撒施,种子正下方5 cm条施,种子下方5 cm、偏3 cm条施,种子下方5 cm、偏10 cm条施,种子正下方20%土体混施5种.结果表明: 种子正下方5 cm条施对小麦的增产效果最高,其中磷酸二氢钙的产量达到7.63 t·hm^-2,磷酸氢二铵的产量达到7.99 t·hm^-2,分别较农民习惯撒施方式增产10.3%和10.7%.在5种施磷方式中,偏10 cm条施的小麦产量最低(6.60～6.77 t·hm^-2).种子正下方5 cm条施和20%土体混施处理的小麦总吸磷量均处于较高水平(34.4～35.6 kg·hm^-2),偏10 cm条施在小麦各生长阶段的吸磷量均显著低于其他施磷方式,但磷酸氢二铵偏10 cm条施的小麦总吸磷量较磷酸二氢钙高11.9%.表明将磷肥近距离集中施用于种子附近为该地区较为合理的施磷方式,在偏远距离条施下磷酸氢二铵对小麦的磷素吸收利用效果优于磷酸二氢钙.     

低磷胁迫下磷高效基因型大麦的根系形态特征

在根袋土培盆栽条件下,以磷高效基因型DH110+、DH147和低效基因型DH49大麦为试验材料,利用根系分析系统分析不同施磷(P₂O₅)水平(极低磷25 mg·kg^-1、低磷50 mg·kg^-1和正常磷75 mg·kg^-1)下,磷高效基因型大麦的根系形态特征及其与植株磷素吸收的关系.结果表明： 低磷胁迫显著降低大麦生物量和磷吸收量,其中磷高效基因型的生物量和磷吸收量在各施磷水平下分别为低效基因型的1.24～1.70和1.18～1.83倍;大麦的总根长、总根表面积、平均根系直径、不定根长及其根表面积、侧根长及其根表面积均随施磷水平的降低而显著降低,其中磷高效基因型大麦在各施磷水平下的总根长、总根表面积、比根长、侧根长及根表面积分别为低效基因型的1.46～2.06、1.12～1.51、1.35～1.72、1.69～2.42和1.40～1.78倍,而平均根系直径为低效基因型的70.6%～90.2%;主成分分析表明,平均根系直径、比根表面积和比根长受基因型差异的影响较为明显,是区分两类磷效率基因型大麦根系形态差异的主要指标;偏最小二乘回归分析表明,各施磷水平下,总根长、总根表面积对大麦植株磷素吸收贡献均较大,随施磷水平降低,不定根长、不定根表面积对大麦植株磷素吸收的贡献明显降低,而平均根系直径、比根长、侧根长及其根表面积的贡献明显增加.磷高效基因型大麦可通过维持侧根的生长、根细度和比根长的增加来适应低磷胁迫.     

不同磷源对磷高效利用野生大麦根际土壤磷组分的影响

在土培盆栽条件下,以野生大麦磷高效利用基因型IS-22-30、IS-22-25和低效基因型IS-07-07为材料,研究不施磷(CK)、无机磷(KH₂PO₄,Pi)、有机磷(phytate,Po)及二者混合(KH₂PO₄+phytate,Pi+Po)的方式施磷30 mg·kg^-1时,磷高效基因型野生大麦对磷素吸收利用能力及土壤磷组分特征.结果表明： Pi处理野生大麦干物质量和磷素积累量最大,Pi+Po处理其次,Po处理最小,均显著高于CK处理,且磷高效基因型物质生产和磷素吸收能力显著高于磷低效基因型.土壤有效磷在不同磷源处理间差异显著,Pi处理时含量最高,Pi+Po处理次之,且磷高效基因型野生大麦根际有效磷含量显著高于磷低效基因型.磷高效基因型野生大麦根际有效磷呈现亏缺现象,在Pi和Pi+Po处理时亏缺程度较大.根际与非根际土壤无机磷组分含量为Ca₁₀-P>O-P>Fe-P>Al-P>Ca₂-P>Ca₈-P,且其含量随着Pi的增加而增加.各磷源处理下,磷高效基因型野生大麦根际土壤Ca₂-P、Ca₈-P出现亏缺;Pi处理磷高效基因型野生大麦根际土壤Al-P、Fe-P出现富集.土壤中有机磷各组分含量为中活性有机磷>中稳性有机磷、高稳性有机磷>活性有机磷.野生大麦根际土壤活性有机磷和中活性有机磷呈现富集,其富集量在Pi处理时最大;中稳性有机磷和高稳性有机磷呈现亏缺.各磷源处理下,磷高效基因型野生大麦根际土壤活性有机磷含量显著高于磷低效基因型,中稳性有机磷和高稳性有机磷在基因型间差异不显著.Pi缺乏时,磷高效基因型野生大麦活化吸收Ca₂-P、Ca₈-P、Al-P和活性有机磷的能力较强.     

长期施肥对石灰性土壤磷素肥力的影响Ⅰ．有机质、全磷和速效磷

在陕西关中黄土区连续23年进行了不同施肥、小麦-玉米轮作定位试验。研究了0～100cm土层土壤有机质、全磷、速效磷含量变化．结果表明,长期单施化肥或有机肥与化肥且配施均可增加耕层(0～20cm)土壤有机质含量．长期施用厩肥并配施化肥处理对土壤总磷库及无机磷库、速效磷的贡献大于玉米秸秆处理．长期单施化肥可增加土壤全磷、无机磷和速效磷含量,增加幅度低于厩肥和休闲处理,与秸秆处理对全磷、速效磷含量的影响效应相近．23年的不同施肥处理,与无肥处理相比,其理土壤磷素增量在0～100cm土壤剖面中的分布特点是：全磷增量剖面分布可为3层——耕层(0～20cm)为显著累积层,20～60cm土层为微增一亏损层,60～100cm土层为轻度累积层．速效磷增量剖面分布趋势与全磷增量分布趋势基本相同,仅在60～100cm土层累积较弱．     

磷胁迫对不同种源枫香生长及氮、磷吸收利用率的影响

基于枫香(Liquidambar formosana)作为先锋树种的生态价值及南方红壤缺磷的现状,采用裂区设计,以不同磷水平模拟磷胁迫砂培处理枫香三叶期幼苗,研究7个种源枫香对磷水平的响应差异.结果表明：不同种源枫香间耐磷胁迫差异显著.随磷胁迫的加剧,各种源的生物量和氮、磷吸收量减少,而利用率增加.高磷处理条件下,南昌和宜兴种源枫香生物量和氮、磷吸收量较高,利用率较低,南丹种源枫香的氮、磷利用率较高,吸收量较低;低磷处理时,南昌和南丹种源枫香的磷吸收量、利用率和生物量均较高.说明高磷时,枫香高生物量种源呈高效吸收;而低磷时,则呈高效吸收和高效利用的特点.南昌种源是优良的耐磷胁迫种源,南丹种源次之;磷不是枫香的限制性养分因子.叶片Δ（N/P）、磷效率和生物量可作为确定枫香耐磷胁迫的指标.     

One pot conjugation of the polypeptides directed by phosphorus oxychloride.

A series of homopeptides and their conjugates were synthesized in one pot reaction in the presence of phosphorus oxychloride and the conjugate yield was structurally dependent. Menthol and benzylamine conjugated to the homopeptides quantitatively. Homopeptides when treated with diisopropyloxyphosphite (DIPPH) and NaClO yield the corresponding N-phosphoryl peptides. Electrospray ionization-mass spectrometry (ESI-MS)/MS was used to study the structure of peptide conjugates. This paper reports a simple method to synthesize the homopeptides and their conjugate derivatives and the fact that phosphoryl peptides could also be obtained by one pot reaction.     

Engineering microalgae for water phosphorus recovery to close the phosphorus cycle

As a finite and non-renewable resource, phosphorus (P) is essential to all life and crucial for crop growth and food production. The boosted agricultural use and associated loss of P to the aquatic environment are increasing environmental pollution, harming ecosystems, and threatening future global food security. Thus, recovering and reusing P from water bodies is urgently needed to close the P cycle. As a natural, eco-friendly, and sustainable reclamation strategy, microalgae-based biological P recovery is considered a promising solution. However, the low P-accumulation capacity and P-removal efficiency of algal bioreactors restrict its application. Herein, it is demonstrated that manipulating genes involved in cellular P accumulation and signalling could triple the Chlamydomonas P-storage capacity to ~7% of dry biomass, which is the highest P concentration in plants to date. Furthermore, the engineered algae could recover P from wastewater almost three times faster than the unengineered one, which could be directly used as a P fertilizer. Thus, engineering genes involved in cellular P accumulation and signalling in microalgae could be a promising strategy to enhance P uptake and accumulation, which have the potential to accelerate the application of algae for P recovery from the water body and closing the P cycle.     

Molecular analysis of the phosphorus starvation response in Trichodesmium spp.

The marine diazotroph Trichodesmium is a major contributor to primary production and nitrogen fixation in the tropical and subtropical oceans. These regions are often characterized by low phosphorus (P) concentrations, and P starvation of Trichodesmium could limit growth, and potentially constrain nitrogen fixation. To better understand how this genus responds to P starvation we examined four genes involved in P acquisition: two copies of a high-affinity phosphate binding protein ( pstS and sphX ) and two putative alkaline phosphatases ( phoA and phoX ). Sequence analysis of these genes among cultured species of Trichodesmium ( T. tenue, T. erythraeum, T. thiebautii and T. spiralis ) showed that they all are present and conserved within the genus. In T. erythraeum IMS101, the expression of sphX , phoA and phoX were sensitive to P supply whereas pstS was not. The induction of alkaline phosphatase activity corresponded with phoA and phoX expression, but enzyme activity persisted after the expression of these genes returned to basal levels. Additionally, nifH (nitrogenase reductase; involved in nitrogen fixation) expression was downregulated under P starvation conditions. These data highlight molecular level responses to low P and lay a foundation for better understanding the dynamics of Trichodesmium P physiology in low-P environments.     

配施磷细菌肥对复垦土壤细菌多样性及磷有效性的影响

为了解磷细菌肥对复垦土壤微生物群落结构变化特征和磷有效性的影响,本研究以连续配施磷细菌肥5年的定位试验为背景,利用16S rDNA基因序列测序方法对土壤细菌群落多样性进行分析,探讨土壤细菌群落与土壤Olsen-P、碱性磷酸酶的关系.试验共设对照、单施化肥、有机肥、有机肥化肥、化肥磷细菌肥、有机肥磷细菌肥和有机肥化肥磷细菌肥7个处理.结果表明: 复垦土壤中放线菌门和变形菌门菌群的相对丰度最大,分别为21.6％～32.2％和13.8％～28.9％.有机肥化肥磷细菌肥处理的OTU数和Chao1指数分别为809和26190,均属最高.磷细菌肥处理能提高土壤中放线菌门和变形菌门菌群的相对丰度,降低土壤中酸杆菌门、热袍菌门和硝化螺旋菌门菌群的相对丰度,对诺卡氏菌属、屈挠杆菌属有一定的促进作用.有机肥化肥磷细菌肥处理能够提高复垦土壤Olsen-P及碱性磷酸酶活性.复垦土壤变形菌门与Olsen-P、碱性磷酸酶的相关系数最高(0.900、0.955),在一定程度上可以作为土壤磷有效性的灵敏性指标.     

Histone F1. Purification and phosphorus content

1. Two minor protein fractions (B and C) were separated from histone F1 by chromatography on DEAE-cellulose. Fraction B was acidic. 2. Uptake of (32)P in vivo into histone F1 but not into fractions B and C was stimulated by partial hepatectomy. 3. It is suggested that partial hepatectomy causes an increase in the number of histone F1 molecules phosphorylated.