植物多胺抗热机制及多胺转运蛋白的研究进展

多胺作为生理活性物质与植物耐热性关系紧密。多胺转运蛋白能够特异性介导多胺类物质跨膜运输。研究表明跨膜后的多胺类物质参与植物热胁迫早期反应中的分子调控过程,这对农作物耐高温及稳产高产有着重要意义。本研究对多胺合成途径、多胺作用机制、多胺的转运及多胺转运蛋白研究4个方面进行综述,为多胺及多胺转运蛋白的进一步研究和应用提供了理论依据。     

植物对磷饥饿的反应研究进展

磷是构成生命的重要元素之一,也是土壤中有效性最低的一种营养元素。我国是世界上最大的小麦生产国。但是我国耕地中有59%的土壤缺磷。农作物的产量常受到缺磷的影响而受损。土壤缺磷并不是土壤中总磷量低,而是土壤中可供植物直接吸收利用的有效态磷含量低。植物在磷饥饿时会发生各种各样的变化,以尽最大可能满足自身对磷的需求。植物对缺磷的反应是一个复杂的网络过程。大约有100多个基因参与了植物对缺磷的反应。其中主要的有磷转运蛋白基因、核糖核酸酶基因、磷酸酶基因等。植物在吸收外界的磷的过程中磷转运蛋白发挥了重要作用。植物磷转运蛋白基因按照序列相似性可以划分为H+/Pi共转运家族(Pht1家族)和Na+/Pi共转运家族(Pht2家族)。按照吸收动力学的标准可以分为高亲和力磷转运蛋白和低亲和力磷转运蛋白两种。磷饥饿时植物对磷吸收能力的增强的原因之一是增加了磷转运蛋白分子的合成数目。目前尽管人们对植物吸收磷的理解已经有了长足的进步,但是在植物对磷的具体调控机制、磷的跨液泡膜运输等重要方面仍然没有明确的结果。     

水稻Cd吸收、转运机理研究进展

综述水稻不同营养器官Cd吸收途径以及水稻根系Cd吸收、根系Cd外排、细胞壁Cd固定和液泡区室化作用、根系向地上部运输Cd等过程中参与Cd运输的各种转运蛋白功能的研究,并阐述影响水稻Cd吸收、转运的内在和外在因素,在此基础上提出问题和今后研究方向。     

植物对硫素的吸收、转运及利用的研究进展

本文旨在深入了解植物体对硫素的吸收方式及转运机制,归纳了近年来关于硫素对植物的重要性、植物缺硫的症状、植物对硫吸收和转运的机理,着重分析了硫酸盐的转运机制,硫酸盐进入植物体内经过活化、还原和半胱氨酸的合成过程,总结了国内外关于硫酸盐在植物体内部的变化、各种存在形式的利用机制,指出该领域仍存在的一些问题以及未来的研究侧重点,为相关研究奠定基础。     

SWEET转运蛋白家族的发现、结构及功能研究进展

植物细胞间溶质转运的质外体途径是植物溶质(K~+,Na~+,糖等)转运的重要方式,该途径通常需要有溶质外排以及吸收两种转运蛋白的协同作用。其中,糖外排转运蛋白(sugars will eventually be exported transporters,SWEETs)由于能够选择性吸收不同糖底物并在植物生理活动与发育过程中发挥重要功能,近年来受到广泛关注。研究发现:植物的SWEET蛋白是具有7个跨膜结构域的转运蛋白;SWEETs蛋白在蔗糖流出叶片的过程中发挥功能,可以促进糖类物质跨过细胞膜顺浓度梯度的扩散;还可以在病原菌侵染植物过程中被微生物劫持来为其生长提供糖分;SWEETs家族蛋白还参与花蜜的分泌从而促进传粉、参与花粉发育和花粉管生长;为菌根共生体提供营养等。有关SWEETs蛋白的功能及其结构的深入研究将植物的生长发育与基础代谢有机地联系在一起。     

植物中氮素利用及硝态氮转运蛋白的研究进展

硝态氮转运蛋白在植物吸收利用氮素方面发挥主要功能,植物生长发育过程中对氮素的吸收、转运和再利用都需要硝态氮转运蛋白参与调控。目前硝态氮转运蛋白主要分为四类:NRT1(NPF)、NRT2、SLAC/SLAH、CLC。硝态氮在植物吸收、代谢和基因表达方面是一种很重要的信号调控分子,硝态氮转运蛋白可作为植物的硝态氮受体。通过论述氮素代谢过程中硝态氮转运蛋白家族基因的功能和在拟南芥等作物中的研究现状,为作物的抗逆性研究和优良品种的培育提供参考。     

水稻磷酸盐转运蛋白Pht1家族研究进展

磷是高等植物生长发育所必需的大量元素之一,现有的研究表明植物磷酸盐转运蛋白介导了植物体内磷的吸收及转运。在低磷胁迫下,植物主要利用高亲和力磷吸收系统通过表皮细胞质膜从根围吸收磷元素。目前绝大部分克隆出来的磷酸盐转运蛋白基因都属于高亲和力的Pht1家族。概述了近年来水稻磷酸盐转运蛋白Pht1家族基因的表达调控机理和生物学特征,并对进一步研究做了展望。     

AM真菌改善植物磷营养吸收和转运机制的研究进展

旨在深入了解丛枝菌根(Arbuscular mycorrhizae,AM)真菌在植物吸收和转运磷元素方面的机制。本研究归纳了近年来关于AM真菌能够促使植物改善磷营养（如磷酸盐转运蛋白、磷酸酶基因等）相关的最新研究成果,着重分析了AM真菌的菌根吸收途径,总结了国内外关于AM真菌对水溶性无机磷、难溶性无机磷和有机磷等3种土壤磷存在形态下的利用机制。最后指出该领域仍存在的一些问题以及未来的研究侧重点。     

水稻磷信号途径研究进展

磷素是植物生长和发育所必需的大量元素之一。现在研究表明OsPHR2,OsSPX1,OsmiR399,OsPHO,OsIPS1,OsIPS2,OsSIZ1,pht1家族等基因与水稻磷吸收信号调控和磷转运有关。目前研究表明OsPHR2,OsSPX1与其在拟南芥中的同源基因功能相似,水稻超表达OsPHR2和干涉OsSPX1都有富集磷的表型。Pht1家族的大部分基因都属于高磷亲和力转运蛋白。此文概述了近年来水稻磷信号途径研究进展,并对进一步研究做了展望。     

植物硅转运蛋白的研究进展

在概括高等植物体内硅含量、形态、分布及作用等特征的基础上,分析了硅吸收部位、吸收机制以及水稻硅吸收突变体筛选的研究,详细综述了到目前为止在4种高等植物中发现的9种（其中水稻OsLsi1、OsLsi2、OsLsi6,玉米ZmLsi1、ZmLsi2、ZmLsi6,大麦HvLsi1和HvLsi2,南瓜CmLsi1）硅转运蛋白的吸收转运活性等特征,从植株水平上归纳了水稻、玉米和大麦体内多种硅转运蛋白分工合作的硅吸收转运机制。为了加深了解硅转运蛋白及其机理亟待拓宽研究对象。     

Molecular basis of Iron Biofortification in crop plants; A step towards sustainability

Iron is one of the most important micronutrients for crop plants due to its use in important physiological processes such as photosynthesis, mitochondrial respiration, metal homeostasis, and chlorophyll synthesis. Crop plants have adapted different strategies for uptake, transport, accumulation, and storage of iron in tissues and organs which later can be consumed by humans. Estimates indicate that about 2 billion people (33% of human population) are at risk of iron deficiency in which infants, children, and pregnant women are potentially compromised. Biofortification refers to the increase in concentration of micronutrients in edible parts of plants and understanding the pathways for iron accumulation in plants is necessary for breeding iron‐enriched crops. Iron‐biofortified crops are also one of the key factors in achieving multiple United Nations Sustainable Development goals. This review article covers different strategies of iron acquisition and transport in plants, its bioavailability, coping with the iron deficiency as a global perspective, the current status of iron biofortification, and how breeding future biofortified crops could be helpful in combating the said issue in a sustainable manner.     

Physiological effects of repeated foliar application of magnetite nanoparticles on maize plants

Iron is an essential micronutrient which is highly unavailable for plants in calcareous soils. Although the application of nanoparticles (NPs) to plants has been recently implemented, their long‐term effects have not been studied yet. The objective of this study was to investigate whether the treatment of maize plants with 100 ppm iron nanoparticles (Fe‐NPs) through their life cycle would affect the development of the second generation. The plants were treated with or without 100 ppm of Fe‐NPs and 100 ppm of Fe‐Ch, and their seeds were planted to obtain the second generation. The latter were again treated with or without Fe‐NPs and Fe‐Ch, and the results of two generations were compared. In the first generation, Fe‐NPs treatments improved maize photosynthesis and hydrogen peroxide (H₂O₂) scavenging capacity and lowered the rate of membrane lipid peroxidation, compared to the control and Fe‐Ch‐treated plants. The improvement of calcium, Fe²⁺, total iron and ferritin contents was more pronounced in Fe‐NPs treatments. However, the second progeny of Fe‐NPs‐treated plants showed less biomass, lower contents of chlorophyll, protein and calcium, and lower H₂O₂ scavenging capacity but higher amount of total iron content, compared with the control group and the first generation. In comparison, no adverse effects on growth parameters were observed in the plants which were treated with Fe‐Ch for two subsequent generations, while their total iron and ferritin contents were remarkable. Due to the adverse effects of Fe‐NPs in the second generation, more caution in its application for consecutive years is recommended.     

Studies on Iron Chlorosis of Sugar Cane (Saccharum officinarum L.) at Metahara, Ethiopia: Soil and Plant Characterisation and Efficiency of Different Iron Sources

In order to understand the nature and causes of chlorosis at Metahara Sugar Estate (8°53′N and 39°52′E) in Ethiopia, soil profile samples were collected from a ratoon field that exhibited chlorosis. From the same site, the first ratoon sugar cane leaf blades (+ 3) were sampled on the basis of the degree of chlorosis, and thus categorised into green, medium green, medium yellow and yellow. Soil sample analysis indicated that DTPA-extractable Fe, Mn and Cu were adequate for normal plant growth in spite of an increase in CaCO₃ content. Moreover, the chlorotic leaves contained higher iron content than the green ones. Consequently, it is concluded that iron chlorosis of sugar cane at Metahara could be due to physiological inactivation of iron in soils and the plant. A field experiment was also conducted using sugar cane variety CO-449 in order to select the most effective iron source to control iron chlorosis of the plant. The plots received the treatments of FeSO₄, EDDHA and DTPA at three different levels each as foliar sprays. The untreated plots were used as control. The chemicals were applied on the first ratoon 3 weeks after harvest, and repeated a week after the first spray. Twenty millable canes from the middle two rows were sampled at 12 months for yield and juice quality determinations. Iron sulphate spray at 15 kg ha^-1 increased cane length and commercial cane sugar by 33 and 44 % over the control, respectively. The highest cane yield was secured by spraying DTPA at 1.80 kg ha^-1 even though its recoverable sugar percentage was low. Not all sources of iron improved juice quality. Since FeSO₄ at 15 kg ha^-1 was equally effective as the 30 kg ha^-1 FeSO₄, applications, the need to consider other than the currently used rate in the Estate is timely and is very important.     

Using Electro slag Melting Process of Cast Molten Iron To Produce Ductile Cast Iron

This paper introduces experimental results of the ESM of cast iron in the laboratory and pilot plant based on predecessor's work by molten CaF 2-based slag systems containing MgO , CaO and RexOy. The results show that the desulfurization ,inclusion removal and gas elimination of the ESM have obvious effects on making iron liquid purified and producing high quality casting ,and indicate that the ESM of cast iron may essentially improve the traditional process of cast molten iron melting as a new technique for making high quality ductile cast iron.     

血红素铁的研究进展

缺铁性贫血是我国人群普遍存在的营养性疾病之一。虽然传统的补铁剂在日常生活中起到一定的治疗效果,但其副作用大、吸收率低,而血红素铁是一种生物态铁,可以直接被肠黏膜细胞吸收,生物利用率高,在国外已作为食品营养强化剂广为使用。就血红素铁的特性及研究进展加以综述。     

Pretreatment of Coke Oven Waste Water with Iron Scrap Method

Denitrification of Coke oven waste water is most biological.That COD/NH 3 N is too high is adverse to biological denitrification.Iron scrap method is used to pretreat coke oven wastewater in order to degrade COD.Coke oven wastewater is pretreated by iron scrap with ancillary material. A good result is got that the removal efficiency of COD cr of wastewater is 40% or so without regulating pH of wastewater and the solution is alkaline.The results show that the factors arragned in important order as the follows:the quantity of iron scrap,graphite,ancillary material A, treatment time,aeration time.The removal efficiency of COD does not lower ater the reactor has run about two months. The results are stable.     

The conception of moisture capacity for ironore and its application to granulation

The optimal water content added into the iron ore mixtures is of vital importance for improving granulation. A novel conception about moisture capacity of the iron ore, which means the maximum water content holding in the iron ore particles of unit mass, is proposed to develop a simple and accurate method. The related equipment and measuring procedure are also given. Five mixtures are selected for moisture capacity measuring, and the granulation experiments with the laboratory scale equipment are also carried out for the five mixtures with various water levels, and the permeability of the granules are also measured to get the optimal water content for each mixture. Comparing the optimal water content with the moisture capacity finds that the two parameters have a good positive relation, meaning that more water is necessary for the mixture with high moisture capacity to get a good permeability index. The relationship between the permeability index and particle size distribution is also discussed. It is found that the size of the granules increases with the increase of water content and the permeability of the burden first increases and then decreases with the increase of water content.     

铁的吸收与缺铁性贫血

铁是人体重要的微量元素。介绍了铁在人体内的分布情况和引起缺铁性贫血的原因,以及经常使用的铁强化剂,论述了影响铁吸收的因素和缺铁性贫血的病因,并列出了相应的治疗预防措施。     

石灰土壤中植物铁营养生理生化的研究进展

为了阐明石灰土中植物缺铁失绿的生理生化机理,综述了石灰土或重碳酸盐胁迫下植物对铁吸收和转运的研究进展。在石灰土壤中,由于存在CaCO3或MgCO3,它们与CO2和H2O反应形成过量的碳酸氢根离子（也叫重碳酸盐）,从而导致了石灰土中富含重碳酸盐。总结了重碳酸盐改变土壤pH,降低了土壤中铁的可利用性,从而限制了植物对土壤中铁的吸收;另一方面,植物在重碳酸盐胁迫下,诱导植物根系产生一系列的生理生化反应响应低铁生境,包括植物根系分泌相关的物质或质子到根际土壤酸化土壤,诱导根系铁还原酶基因表达从而增强铁还原酶活性,以及诱导铁转运体基因的表达等。石灰土壤中的存在大量的重碳酸盐,针对该土壤环境的特殊性,未来应加强以下几个方面的研究,（1）重点研究重碳酸盐对铁在植物组织之间的长距离运输的影响,挖掘重碳盐影响铁转运的分子机制;（2）植物细胞内的铁蛋白是否受到重碳酸盐的影响,仍然需要开展相关的研究;（3）进一步研究土壤中的微生物与重碳酸盐在植物胁迫中的作用。     

The Prespect by Using Poor Ore to Produce Sponge Iron

This paper summarizes the status that the coal-based rotary kiln using direct reduction technique to produce spouse iron in the world,introducing successful SL-RN process,investigatins the development presect by using poor ore to produce sponge iron.