OsbZIP72 Is Involved in Transcriptional Gene-Regulation Pathway of Abscisic Acid Signal Transduction by Activating Rice High-Affinity Potassium Transporter OsHKT1;1

We created CRISPR-Cas9 knock-out and overexpressing OsbZIP72 transgenic rice plants to gain a better understanding of the role and molecular mechanism of OsbZIP72 gene in stress tolerance,which has remained largely elusive.OsbZIP72 was expressed and integrated into rice transgenic plant genomes,and the OsbZIP72 transcript in overexpression lines was elicited by salinity,abscisic acid(ABA)and drought stresses.OsbZIP72 overexpressing plants showed higher tolerance to drought and salinity stresses,while knock-out transgenic lines showed higher sensitivity to these stresses.The differentially expressed genes(DEGs)from RNA-sequencing data encompassed several abiotic stress genes,and the functional classification of these DEGs demonstrated the robust transcriptome diversity in OsbZIP72.Yeast one-hybrid,along with luciferase assay,indicated that OsbZIP72 acted as a transcriptional initiator.Remarkably,electrophoresis mobility assay revealed that OsbZIP72 bound directly to the ABAresponsive element in the OsHKT1;1 promoter region and activated its transcription.Overall,our findings revealed that OsbZIP72 can act as a transcriptional modulator with the ability to induce the expression of OsHKT1;1 in response to environmental stress through an ABA-dependent regulatory pathway,indicating that OsbZIP72 can play a crucial role in the ABA-mediated salt and drought tolerance pathway in rice.

Analgesic effect of intrathecal bumetanide is accompanied by changes in spinal sodium-potassium-chloride co-transporter 1 and potassium-chloride co-transporter 2 expression in a rat model of incisional pain

Accumulating evidence has demonstrated that the sodium-potassium-chloride co-transporter 1 and potassium-chloride co-transporter 2 have a role in the modulation of pain transmission at the spinal level through chloride regulation in the pain pathway and by effecting neuronal excitability and pain sensitization. The present study aimed to investigate the analgesic effect of the speciifc sodium-potassium-chloride co-transporter 1 inhibitor bumetanide, and the change in spinal sodium-potassium-chloride co-transporter 1 and potassium-chloride co-transporter 2 expression in a rat model of incisional pain. Results showed that intrathecal bumetanide could decrease cumulative pain scores, and could increase thermal and mechanical pain thresholds in a rat model of incisional pain. Sodium-potassium-chloride co-transporter 1 expression in-creased in neurons from dorsal root ganglion and the deep laminae of the ipsilateral dorsal horn following incision. By contrast, potassium-chloride co-transporter 2 expression decreased in neurons of the deep laminae from the ipsilateral dorsal horn. These ifndings suggest that spinal sodium-potassium-chloride co-transporter 1 expression was up-regulated and spinal potassi-um-chloride co-transporter 2 expression was down-regulated following incision. Intrathecal bumetanide has analgesic effects on incisional pain through inhibition of sodium-potassi-um-chloride co-transporter 1.

Influences of external nutrient conditions on the transcript levels of a nitrate transporter gene in Skeletonema costatum

To verify the feasibility of high-affinity nitrate transporter gene （Nrt2） as an indicator of nitrogen status, changes in the transcript levels of transcripts associated with phosphate starvation and different nitrate concentrations were studied using real-time quantitative reverse-transcription PCR （QRT-PCR） technology in batch cultures of Skeletonema costatum. The results show that compared with P-replete condition, P starvation could reduce the Nrt2 transcript levels apparently. Nrt2 transcript levels had a significant negative linear correlation with nitrate concentrations below 40 pmol/L. The results of 48 h short-term incubation experiment under different nitrate concentrations confirmed this correlation, and the following regression equation is built： y = -3.305x ＋ 98.95, R2 = 0.988, where x represents nitrate concentrations （〈40 btmol/L） and y represents the Nrt2 transcript levels.

Potassium nutrition of maize:Uptake,transport,utilization,and role in stress tolerance

Potassium(K) is an essential macronutrient for plant growth and development and influences yield and quality of agricultural crops.Maize(Zea mays) is one of the most widely distributed crops worldwide.In China,although maize consumes a large amount of K fertilizer,the K uptake/utilization efficiency(KUE)of maize cultivars is relatively low.Elucidation of KUE mechanisms and development of maize cultivars with higher KUE are needed.Maize KUE is determined by K+uptake,transport,and remobilization,which depend on a variety of K+channels and transporters.We review basic information about K+channels and transporters in maize,their functions and regulation,and the roles of K+in nitrogen transport,sugar transport,and salt tolerance.We discuss challenges and prospects for maize KUE improvement.

Potassium transporter OsHAK9 regulates seed germination under salt stress by preventing gibberellin degradation through mediating OsGA2ox7 in rice

Soil salinity has a major impact on rice seed germination,severely limiting rice production.Herein,a rice germination defective mutant under salt stress(gdss)was identified by using chemical mutagenesis.The GDSS gene was detected via MutMap and shown to encode potassium transporter OsHAK9.Phenotypic analysis of complementation and mutant lines demonstrated that OsHAK9 was an essential regulator responsible for seed germination under salt stress.OsHAK9 is highly expressed in germinating seed embryos.Ion contents and non-invasive micro-test technology results showed that OsHAK9 restricted K^(+)efflux in salt-exposed germinating seeds for the balance of K^(+)/Na^(+).Disruption of OsHAK9 significantly reduced gibberellin 4(GA4)levels,and the germination defective phenotype of oshak9a was partly rescued by exogenous GA_(3)treatment under salt stress.RNA sequencing(RNA-seq)and real-time quantitative polymerase chain reaction analysis demonstrated that the disruption of OsHAK9 improved the GA-deactivated gene OsGA2ox7 expression in germinating seeds under salt stress,and the expression of OsGA2ox7 was significantly inhibited by salt stress.Null mutants of OsGA2ox7 created using clustered,regularly interspaced,short palindromic repeat(CRISPR)/CRISPR-associated nuclease 9 approach displayed a dramatically increased seed germination ability under salt stress.Overall,our results highlight that OsHAK9 regulates seed germination performance under salt stress involving preventing GA degradation by mediating OsGA2ox7,which provides a novel clue about the relationship between GA and OsHAKs in rice.

Migration-associated secretion of melanoma inhibitory activity at the cell rear is supported by KCa3.1 potassium channels

Malignant melanoma, characterized by invasive local growth and early formation of metastases, is the most aggressive type of skin cancer. Melanoma inhibitory activity （MIA）, secreted by malignant melanoma cells, interacts with the cell adhesion receptors, integrins a4131 and 05131, facilitating cell detachment and promoting formation of me- tastases. In the present study, we demonstrate that MIA secretion is confined to the rear end of migrating cells, while in non-migrating cells MIA accumulates in the actin cortex. MIA protein takes a conventional secretory pathway including coat protein complex I （COPI）- and coat protein complex II （COPII）-dependent protein transport to the cell periphery, where its final release depends on intracellular Ca2＋ ions. Interestingly, the Ca2＋-activated K＋-channel, subfamily N, member 4 （KCa3.1）, known to be active at the rear end of migrating cells, was found to support MIA secretion. Secretion was diminished by the specific KCa3.1 channel inhibitor TRAM-34 and by expression of dominant- negative mutants of the channel. In summary, we have elucidated the migration-associated transport of MIA protein to the cell rear and also disclosed a new mechanism by which KCa3.1 potassium channels promote cell migration.

Identification of the HAK gene family reveals their critical response to potassium regulation during adventitious root formation in apple rootstock

Adventitious root formation is a bottleneck during vegetative proliferation.Potassium(K^(+))is an essential macronutrient for plants.K^(+)accumulation from the soil and its distribution to the different plant organs is mediated by K^(+)transporters named K^(+)transporter(KT),K^(+)uptake(KUP),or high-affinity K^(+)(HAK).This study aimed to identify members of the HAK gene family in apples and to characterize the effects of K^(+)supply on adventitious root formation and on the expression of HAK genes and the genes that putatively control auxin transport,signaling,and cell fate during adventitious root formation.In this study,34 HAK genes(MdHAKs)were identified in the apple(Malus×domestica‘Golden Delicious’)genome.A phylogenetic analysis divided MdHAKs into four clusters(Ⅰ,Ⅱ,Ⅲ,andⅣ),comprising 16,1,4,and 13 genes,respectively.The syntenic relationships revealed that 62.5%of the total MdHAK genes arise from genomic duplication events.Chromosome location,domain structure,motif analysis,and physico-chemical characteristics were subsequently investigated.Furthermore,the application of K^(+)indicated the emergence of adventitious roots at 8 d and produced more adventitious roots at 16 d than the K^(+)-free control(CK)treatment.In addition,various MdHAKs showed root-specific expression in B9 apple rootstock stem cuttings and enhanced expression during the initiation and emergence stages of adventitious root formation in response to K^(+)treatment.Additionally,K^(+)treatment enhanced the expression levels of MdPIN1,MdPIN2,and MdAUX1.Further data indicated that a higher expression of MdWOX11,MdLBD16,and MdLBD29 and of cell cycle-related genes contributed to the auxin-stimulated adventitious root formation in response to K^(+).

Potassium sulphate induces resistance of rice against the rootknot nematode Meloidogyne graminicola

Potassium(K),an important nutrient element,can improve the stress resistance/tolerance of crops.The application of K in resisting plant-parasitic nematodes shows that the K treatment can reduce the occurrence of nematode diseases and increase crop yield.However,data on K_(2)SO_(4)induced rice resistance against the root-knot nematode Meloidogyne graminicola are still lacking.In this work,K_(2)SO_(4)treatment reduced galls and nematodes in rice plants and delayed the development of nematodes.Rather than affecting the attractiveness of roots to nematodes and the morphological phenotype of giant cells at feeding sites,such an effect is achieved by rapidly priming hydrogen peroxide(H_(2)O_(2))accumulation and increasing callose deposition.Meanwhile,galls and nematodes in rice roots were more in the potassium channel OsAKT11 and transporter OsHAK5 gene-deficient plants than in wild-type,while the K_(2)SO_(4)-induced resistance showed weaker in the defective plants.In addition,during the process of nematode infection,the expression of jasmonic acid(JA)/ethylene(ET)/brassinolide(BR)signaling pathway-related genes and pathogenesis-related(PR)genes OsPR1 a/OsPR1 b was up-regulated in rice after K_(2)SO_(4)treatment.In conclusion,K_(2)SO_(4)induced rice resistance against M.graminicola.The mechanism of inducing resistance was to prime the basal defense and required the participation of the K^(+)channel and transporter in rice.These laid a foundation for further study on the mechanism of rice defense against nematodes and the rational use of potassium fertilizer on improving rice resistance against nematodes in the field.

SbHKT1;4, a member of the high‐affinity potassium transporter gene family from Sorghum bicolor, functions to maintain optimal Na^+/K^+ balance under Na^+ stress

In halophytic plants, the high-affinity potassium transporter HKT gene family can selectively uptake K＋ in the presence of toxic concentrations of Na＋. This has so far not been well examined in glycophytic crops. Here, we report the characterization of SbHKTI;4, a member of the HKT gene family from Sorghum bicolor. Upon Na＋ stress, SbHKT1;4 expression was more strongly upregulated in salt-tolerant sorghum accession, correlating with a better balanced Na＋/ K＋ ratio and enhanced plant growth. Heterogeneous expression analyses in mutants of Saccharomyces cerevisiae and Arabidopsis thaliana indicated that overexpressing SbHKT1;4 resulted in hypersensitivity to Na＋ stress, and such hypersensitivity could be alleviated with the supply of elevated levels of K＋, implicating that SbHKT1;4 may mediate K＋ uptake in the presence of excessive Na＋. Further electrophysiological evidence demonstrated that SbHKT1;4 could transport Na＋ and K＋ when expressed in Xenopus laevis oocytes. The relevance of the finding that SbHKTI;4 functions to maintain optimal Na＋/K＋ balance under Na＋ stress to the breeding of salt-tolerant glycophytic crops is discussed.

杨树KT、HAK、KUP基因家族鉴定及钾肥处理对杨树生长的影响

KT、HAK、KUP基因家族是植物进行K^(+)转运的最大蛋白系统。以毛果杨(Populus trichocarpa Torr.&Gray)全基因组数据为基础,利用生物信息学方法对杨树KT、HAK、KUP家族进行了全基因组鉴定,并在毛果杨全基因组中鉴定出20个KT、HAK、KUP家族成员。理化性质预测分析表明:KT、HAK、KUP基因家族成员均为疏水性蛋白,等电点在5.30~9.16;亚细胞定位预测显示家族成员蛋白集中在细胞质膜上。应用拟南芥和杨树构建系统进化树显示,KT、HAK、KUP基因家族可分为5个亚家族。基因结构及基序(motif)分析表明,KT、HAK、KUP基因进化过程相对保守。顺式作用元件分析表明,KT、HAK、KUP基因家族成员含有诸多与激素、逆境胁迫的响应元件。杨树不同钾离子浓度处理下,植株的净生长情况呈现了显著的差异,说明钾元素对杨树生长影响较大。

Regulating ion transport behaviors toward dendrite-free potassium metal batteries:recent advances and perspectives

With abundant potassium resources and high capacity,potassium metal batteries(PMBs)present a compelling option for the next generation of energy storage technology.However,PMBs suffer from an unstable anode interface caused by uncontrolled dendrite growth,which results in unsatisfactory cyclability and safety concerns.Extensive investigations suggest that significant progress has been made in enhancing the interfacial stability of PMBs.The various effective strategies for stabilizing interfaces can ultimately be attributed to the regulation of the sluggish ion transfer kinetics and irregular deposition,i.e.,the arrangement of ion transport behaviors at the interface.Rational modulation of ions transport rate and ions deposition directions makes it possible to obtain a dendrite-free and smooth deposition plane.Herein,the influencing factors and action mechanism of K^(+)interface transport behaviors are discussed to understand the nature of material design for constructing stable anode interfaces,including regulating the solvation and desolvation structures,accelerating K^(+)transport kinetics and controlling K^(+)deposition direction.In addition,the deficiencies and prospects of the research on electrolyte,separators and designed electrode involved in the manufacturing and testing and ion transport process of PMBs are discussed.This review is expected to provide some possible directions for constructing dendrite-free interfaces in advanced PMBs-related research and offer significant insights for prospective experimental research and commercial applications.

Membrane Transporters for Nitrogen,Phosphate and Potassium Uptake in Plants

Nitrogen, phosphorous and potassium are essential nutrients for plant growth and development. However, their contents in soils are limited so that crop production needs to invest a lot for fertilizer supply. To explore the genetic potentialities of crops （or plants） for their nutrient utilization efficiency has been an important research task for many years, in fact, a number of evidences have revealed that plants, during their evolution, have developed many morphological, physiological, biochemical and molecular adaptation mechanisms for acquiring nitrate, phosphate and potassium under stress conditions. Recent discoveries of many transporters and channels for nitrate, phosphate and potassium uptake have opened up opportunities to study the molecular regulatory mechanisms for acquisition of these nutrients. This review aims to briefly discuss the genes and gene families for these transporters and channels, in addition, the functions and regulation of some important transporters and channels are particularly emphasized.

Molecular evolution and functional divergence of HAK potassium transporter gene family in rice(Oryza sativa L.)

The high-affinity K＋ （HAK） transporter gene family is the largest family in plant that functions as potassium transporter and is important for various aspects of plant life. In the present study, we identified 27 members of this family in rice genome. The phylogenetic tree divided the land plant HAK transporter proteins into 6 distinct groups. Although the main characteristic of this family was established before the origin of seed plants, they also showed some differences between the members of non-seed and seed plants. The HAK genes in rice were found to have expanded in lineage-specific manner after the split of monocots and dicots, and both segmental duplication events and tandem duplication events contributed to the expansion of this family. Functional divergence analysis for this family provided statistical evidence for shifted evolutionary rate after gene duplication. Further analysis indicated that both point mutant with positive selection and gene conversion events contributed to the evolution of this family in rice.

Gene Structure and Expression of the High-affinity Nitrate Transport System in Rice Roots

Rice has a preference for uptake of ammonium over nitrate and can use ammonium-N efficiently. Consequently, transporters mediating ammonium uptake have been extensively studied, but nitrate transporters have been largely ignored. Recently, some reports have shown that rice also has high capacity to acquire nitrate from growth medium, so understanding the nitrate transport system in rice roots is very important for improving N use efficiency in rice. The present study Identified four putative NRT2 and two putative NAR2 genes that encode components of the high-affinity nitrate transport system （HATS） in the rice （Oryza sativa L. subsp, japonica cv. Nipponbare） genome. OsNRT2.1 and OsNRT2.2 share an Identical coding region sequence, and their deduced proteins are closely related to those from mono-cotyledonous plants. The two NAR2 proteins are closely related to those from mono-cotyledonous plants as well. However, OsNRT2.3 and OsNRT2.4 are more closely related to Arabidopsis NRT2 proteins. Relative quantitative reverse trsnscription-polymerase chain reaction analysis showed that all of the six genes were rapidly upregulated and then downrsgulated in the roots of N-starved rice plants after they were re-supplied with 0.2 mM nitrate, but the response to nitrate differed among gene members. The results from phylogenetic tree, gene structure and expression analysis implied the divergent roles for the Individual members of the rice NRT2 and NAR2 families. High-affinity nitrate influx rates associated with nitrate induction in rice roots were investigated and were found to be regulated by external pH. Compared with the nitrate influx rates at pH 6.5, alkaline pH （pH 8.0） inhibited nitrate influx, and acidic pH （pH 5.0） enhanced the nitrate influx in 1 h nitrate induced roots, but did not significantly affect that in 4 to 8 h nitrate induced roots.

Regulation of the High-Affinity Nitrate Transport System in Wheat Roots by Exogenous Abscisic Acid and Glutamine

Nitrate is a major nitrogen （N） source for most crops. Nitrate uptake by root cells is a key step of nitrogen metabolism and has been widely studied at the physiological and molecular levels. Understanding how nitrate uptake is regulated will help us engineer crops with improved nitrate uptake efficiency. The present study investigated the regulation of the high-affinity nitrate transport system （HATS） by exogenous abscisic acid （ABA） and glutamine （Gin） in wheat （Triticum aestivum L.） roots. Wheat seedlings grown in nutrient solution containing 2 mmol/L nitrate as the only nitrogen source for 2weeks were deprived of N for 4d and were then transferred to nutrient solution containing 50 μmol/L ABA, and 1 mmol/L Gin in the presence or absence of 2 mmol/L nitrate for 0, 0.5, 1, 2, 4, and 8 h. Treated wheat plants were then divided into two groups. One group of plants was used to investigate the mRNA levels of the HATS components NRT2 and NAR2 genes in roots through semi-quantitative RT-PCR approach, and the other set of plants were used to measure high-affinity nitrate influx rates in a nutrient solution containing 0.2 mmol/L ^15N-labeled nitrate. The results showed that exogenous ABA induced the expression of the TaNRT2.1, TaNRT2.2, TaNRT2.3, TaNAR2.1, and TaNAR2.2 genes in roots when nitrate was not present in the nutrient solution, but did not further enhance the induction of these genes by nitrate. Glutamine, which has been shown to inhibit the expression of NRT2 genes when nitrate is present in the growth media, did not inhibit this induction. When Gin was supplied to a nitrate-free nutrient solution, the expression of these five genes in roots was induced. These results imply that the inhibition by Gin of NRT2 expression occurs only when nitrate is present in the growth media. Although exogenous ABA and Gin induced HATS genes in the roots of wheat, they did not induce nitrate influx.

黄瓜HAK基因家族的鉴定与生物信息学分析

为了深入研究黄瓜K^(+)转运蛋白基因家族KUP/HAK/KT的相关功能,本研究通过全基因组分析技术等生物信息学手段鉴定CsHAK家族成员,分析其进化关系、基因结构,蛋白质三级结构、顺式作用元件及共线性关系。结果发现,黄瓜基因组共有15个CsHAK基因,不均匀分布在黄瓜染色体chr1、chr3、chr4、chr5、chr7上,亚细胞定位预测发现CsHAK基因位于细胞质膜;CsHAK基因家族可分为3个亚家族,大部分家族成员包含12个保守基序和K_trans保守功能结构域,基因启动子区所含元件与激素调节、光响应、胁迫密切相关;CsHAK家族成员之间发生2个串联重复事件,Ks/Ka值均小于1,表明其进化受纯化选择作用。研究结果为进一步深入挖掘CsHAKs在黄瓜生长发育及逆境胁迫响应中的功能及作用机制提供了理论基础。

The Potassium Transporter OsHAK5 Alters Rice Architecture via ATP-Dependent Transmembrane Auxin Fluxes

Plant HAK/KUP/KT family members function as plasma membrane(PM)H^(+)/K^(+)symporters and may modulate chemiosmotically-driven polar auxin transport(PAT).Here,we show that inactivation of OsHAK5,a rice K^(+)transporter gene,decreased rootward and shootward PAT,tiller number,and the length of both lateral roots and root hairs,while OsHAK5 overexpression increased PAT,tiller number,and root hair length,irrespective of the K^(+)supply.Inhibitors of ATP-binding-cassette type-B transporters,NPA and BUM,abolished the OsHAK5-overexpression effect on PAT.The mechanistic basis of these changes included the OsHAK5-mediated decrease of transmembrane potential(depolarization),increase of extracellular pH,and increase of PM-ATPase activity.These findings highlight the dual roles of OsHAK5 in altering cellular chemiosmotic gradients(generated continuously by PM H^(+)-ATPase)and regulating ATP-dependent auxin transport.Both functions may underlie the prominent effect of OsHAK5 on rice architecture,which may be exploited in the future to increase crop yield via genetic manipulations.

烟草钾吸收和转运机理及钾含量提高措施研究进展

钾是烟草体内重要的矿质营养元素,与烟叶品质密切相关。烟叶钾含量偏低是我国烟叶与国际优质烟叶品质差异的主要原因之一。鉴于此,从钾对烟草生长发育的作用、烟草钾吸收和转运机理、烟叶钾含量的主要影响因素及烟叶钾含量提高措施4个方面进行综述,主要概述了烟草对钾吸收和转运机理的相关研究,归纳了近年来提高烟叶钾含量的相关措施,主要包括培育高钾基因型品种、应用耐低钾基因型品种、优化施肥方式、增施有机肥、采取物理调控措施和应用化学调控措施,以期为提高烟叶钾含量和改善烟叶品质提供参考。

施锌对小麦开花后氮、磷、钾、锌积累和运转的影响

为明确大田条件下施锌对小麦地上部器官氮、磷、钾、锌的积累量和转移量的影响,2001～2002年开展了田间试验.试验以专用强筋小麦（8901-11）和普通小麦（4185）两个冬小麦品种为材料,包括4个施锌水平（分别为施ZnSO4·7H2O 0、11.25、22.5和33.75 kg/hm^2）.结果表明,各器官中Zn的含量变化在4.14～54.18 mg/kg,刚开花时及灌浆前期的含量以子粒＞穗壳＞叶片＞茎秆,至接近成熟时则以子粒＞叶片＞穗壳＞茎秆.每生产100kg小麦子粒需要吸收Zn的范围在4.40～5.20g之间.小麦成熟时吸收的Zn约为N或K2O的1/800～1/700,为P2O5的1/500～1/300.施锌后小麦各器官氮、磷、钾、锌的积累量及开花后向子粒的运转量增加,但施锌过多,这些营养元素的吸收、积累和运转反而受到抑制.4185开花前吸收氮和磷的能力较强,而8901-11开花后吸收氮和磷的能力较强;而吸收钾和锌的能力与吸收氮和磷的情况相反.8901-11氮、磷、钾、锌的积累量基本随施锌量增加而提高,以施硫酸锌22.5～33.75 kg/hm^2的积累量最高;而4185以施硫酸锌11.25 kg/hm^2的积累量最高.因此,在施用大量元素的基础上,普通小麦以施硫酸锌11.25 kg/hm^2为宜,而强筋小麦以施硫酸锌22.5～33.75 kg/hm^2为宜.

钾营养对甘薯某些生理特性和产量形成的影响

田间试验结果表明 ,适量供钾可增加甘薯功能叶和块根中的ATP含量 ,增加块根中的脱落酸 (ABA)含量 ;提高叶片中可溶性碳水化合物的装载效率和块根中可溶性碳水化合物的卸载效率 ,促进碳水化合物由叶片向块根的运输 ;增加块根中的淀粉含量 ,提高块根干重与单株干重的比率 ,促进块根迅速膨大 。