Lateral root elongation in maize is related to auxin synthesis and transportation mediated by N metabolism under a mixed NO_(3)^(–) and NH_(4)^(+) supply

A mixed nitrate (NO_(3)^(–)) and ammonium (NH_(4)^(+)) supply can promote root growth in maize (Zea mays),however,the changes in root morphology and the related physiological mechanism under different N forms are still unclear.Here,maize seedlings were grown hydroponically with three N supplied in three different forms (NO_(3)^(–)only,75/25 NO_(3)^(–)/NH_(4)^(+)and NH_(4)^(+)only).Compared with sole NO_(3)^(–)or NH_(4)^(+),the mixed N supply increased the total root length of maize but did not affect the number of axial roots.The main reason was the increased total lateral root length,while the average lateral root (LR) length in each axle was only slightly increased.In addition,the average LR density of 2nd whorl crown root under mixed N was also increased.Compared with sole nitrate,mixed N could improve the N metabolism of roots (such as the N influx rate,nitrate reductase (NR) and glutamine synthase (GS)enzyme activities and total amino content of the roots).Experiments with exogenously added NR and GS inhibitors suggested that the increase in the average LR length under mixed N was related to the process of N assimilation,and whether the NR mediated NO synthesis participates in this process needs further exploration.Meanwhile,an investigation of the changes in root-shoot ratio and carbon (C) concentration showed that C transportation from shoots to roots may not be the key factor in mediating lateral root elongation,and the changes in the sugar concentration in roots further proved this conclusion.Furthermore,the synthesis and transportation of auxin in axial roots may play a key role in lateral root elongation,in which the expression of ZmPIN1B and ZmPIN9 may be involved in this pathway.This study preliminarily clarified the changes in root morphology and explored the possible physiological mechanism under a mixed N supply in maize,which may provide some theoretical basis for the cultivation of crop varieties with high N efficiency.

Effect of Jasmonic Acid on Lateral Root Formation in Rice Seedling

实验材料为水稻 (OryzasativaL .)栽培品种“IR8”(国际水稻所 8号 )及其少侧根突变体MT10。将 2d水稻幼苗种子根全部浸入 0 .0 16～ 5 0 μmol/L茉莉酸 (JA)溶液处理 2d ,结果表明JA显著抑制种子根的伸长 ,其抑制程度与JA浓度成正比。不高于 2 μmol/L的JA显著促进侧根的发生 ,每cm的侧根数目随浓度的增加而增加 ,最多可增加到原来的 16 8% (“IR8”)和 2 85 % (MT10 )。 10 μmol/L的JA仍促进处理过程中和处理后生成根区段的侧根数目的增加 ,但明显抑制处理前生成根区段侧根的发生 。

Effects of Nitrate on the Growth of Lateral Root and Nitrogen Absorption in Rice

Lateral root is primary organ for plant to explore and utilize soil nutrient efficiently. The development of lateral roots (LR) is controlled by both genetic factors and nutrient status in environment. To investigate the effects of nitrate (NO3-) on rice lateral root growth and nitrogen (N) uptake efficiency under upland condition, three treatments, including root-split culture and whole plant culture in N sufficient and deficient conditions, were used in a vermiculite culture experiment. Root-split treatment showed that the growth of lateral roots was stimulated by localized nitrate supply. However, in whole plant culture, elongation of lateral roots was induced by NO3- deficiency. The effects of NO3- on rice lateral root growth were genotype-dependent. Similar N concentration, soluble sugar concentration and N content in shoot were observed in both root-split treatment and whole plant culture under NO3- sufficient condition, suggesting that the nitrogen requirement for rice normal growth could be satisfied with only half of roots supplied with NO3-. In the root-split treatment, N uptake was positively correlated with the average of lateral root length (ALRL) in NO3--supplied side, suggesting that the ALRL is important for rice root N uptake in the environment where the nitrogen nutrient is limiting factor. No significant correlation was observed between N uptake and ALRL in whole plant culture under N sufficient condition, which implies that the length of lateral roots may not be the main factor to determine tire rice root N uptake in nutrient-rich zone. Morphological and metabolic evidence in this study provided some prospects for genetic improvement of root system characters to improve the efficiency of nutrient absorption in rice.

Exogenous strigolactones promote lateral root growth by reducing the endogenous auxin level in rapeseed

Strigolactones(SLs)are newly discovered plant hormones which regulate the normal development of different plant organs,especially root architecture.Lateral root formation of rapeseed seedlings before winter has great effects on the plant growth and seed yield.Here,we treated the seedlings of Zhongshuang 11(ZS11),an elite conventional rapeseed cultivar,with different concentrations of GR24(a synthetic analogue of strigolactones),and found that a low concentration(0.18μmol L–1)of GR24 could significantly increase the lateral root growth,shoot growth,and root/shoot ratio of seedlings.RNA-Seq analysis of lateral roots at 12 h,1 d,4 d,and 7 d after GR24 treatment showed that 2301,4626,1595,and 783 genes were significantly differentially expressed,respectively.Function enrichment analysis revealed that the plant hormone transduction pathway,tryptophan metabolism,and the phenylpropanoid biosynthesis pathway were over-represented.Moreover,transcription factors,including AP2/ERF,AUX/IAA,NAC,MYB,and WRKY,were up-regulated at 1 d after GR24 treatment.Metabolomics profiling further demonstrated that the amounts of various metabolites,such as indole-3-acetic acid(IAA)and cis-zeatin were drastically altered.In particular,the concentrations of endogenous IAA significantly decreased by 52.4 and 75.8%at 12 h and 1 d after GR24 treatment,respectively.Our study indicated that low concentrations of exogenous SLs could promote the lateral root growth of rapeseed through interaction with other phytohormones,which provides useful clues for the effects of SLs on root architecture and crop productivity.

MT 10 Mutant of Rice with Altered Lateral Root Initiation

Mutants with increased resistance to toxic anxin concentrations were first isolated in rice.The present report describes their isolation,genetics and physiological characterization.

Non-surgical management of dens invaginatus type IIIB in maxillary lateral incisor with three root canals and 6-year follow-up:A case report and review of literature

BACKGROUND The presence of dens invaginatus(DI)complicates treatment of any tooth,from diagnosis to access cavity and biomechanical preparation and obturation.Reports of successful non-surgical management of DI type IIIB in maxillary lateral incisor are rare.Here,we report such a case,with three root canals and a long follow-up.CASE SUMMARY A 13-year-old female patient presented with mild pain in the maxillary right lateral incisor(#7)for 10-15 d.On examination,the tooth was slightly rotated,with slight tenderness on percussion and grade I mobility but with no caries,pockets or restorations and non-vital pulp(via vitality tests).Radiographic examination revealed unusual configuration of the tooth’s root canals,with an enamel-lined invagination extending to the apex,suggesting the possibility of DI Oehler’s type IIIB and a periapical radiolucency.Widening the access cavity lingually revealed one distinct buccal orifice and two distinct palatal orifices;under higher magnification of a dental operating microscope(DOM),the mesio palatal and disto-palatal orifices were observed as connected by a C-shaped groove.The root canals were prepared with hand K-files following a step-back technique,and obturated using a combination technique of lateral condensation and vertical compaction.At the 6-year follow-up,the patient was asymptomatic,and the periapical radiography displayed significant healing around the apical end of the root.CONCLUSION Proper knowledge of unusual root canal anatomy is required in treating DI.Conventional methods of root canal treatment can successfully resolve such complex cases,facilitated by DOM and cone-beam computed tomography.

Review on Mutation in Lateral Root of Rice

Rice roots include seminal roots, adventitious roots, lateral roots and root hairs, At present, progresses in the research of rice roots have been achieved in many aspects, such as root morphology, root activity, root reaction to various environmental factors as a contribution of root growth and rice yield, the relationship between root growth and stems/leaves/flowers/rice, genetic laws of root characters, etc. However, there are very few researches on lateral root mutant. This paper reviewed progresses of the lateral root mutant of rice from the perspectives of phytomorphology to plant physiology and biochemistry to the gene mapping, consisting of mechanism of developing lateral root of rice, gene cloning and functional analysis of lateral root development, the relationship between auxin and lateral roots, agronomic traits of lateral roots mutant, structure and morphology of root hairs, gravity anomaly of root, redox metabolism and proteomics researches of the mutation in lateral root of rice.

imple Bioassay for PAMP-Triggered Immunity in Rice Seedlings Based on Lateral Root Growth Inhibition

Pathogen-associated molecular pattern(PAMP)-triggered immunity(PTI)is an essential layer of plant disease resistance.Robust bioassays for PTI are pre-required to dissect its molecular mechanism.In this study,we established that lateral root growth inhibition as a simple and robust measurement of PTI in rice seedlings.Specifically,flg22,a well-characterized PAMP from bacterial flagellin,was used to induce PTI in rice seedlings.While flg22 treatment induced PR gene expression and mitogen-activated protein kinase activation in the roots of rice seedlings to support the PTI triggered,this treatment substantially repressed lateral root growth,but it did not alter primary root growth.Moreover,treatments with chitin(i.e.,a fungal PAMP)and oligogalacturonides(i.e.,classical damage-associated molecular pattern)clearly inhibited the lateral root growth,although a priming step involving ulvan was required for the chitin treatment.The bioassay developed was applicable to various rice cultivars and wild species.Thus,lateral root growth inhibition represents a simple and reliable assay for studying PTI in rice plants.

A genome-wide association study of lateral root number for Asian cotton(Gossypium arboreum L.)

Background:The lateral root is one of the most important organs that constitute the root architecture system in plants.It can directly affect the contact area between plants and soil and plays an important role in plant structural support and nutrient absorption.Optimizing root architecture systems can greatly increase crop yields.This study was designed to identify the molecular markers and candidate genes associated with lateral root development in cotton and to evaluate correlations with yield and disease traits.Result:The number of lateral roots for 14-day old seedlings was recorded for 215 Gossypium arboreum accessions.A correlation analysis showed that the number of lateral roots positively correlates with the sympodial branch node and seed index traits,but negatively correlates with lint percentage.A Genome-wide association study(GWAS)identified 18 significant SNPs with 19 candidate genes associated with the lateral root number.Expression analysis identified three genes(FLA 12,WRKY29,and RBOHA)associated with lateral root development.Conclusion:GWAS an alysis identified key SNPs and candidate gen esfor lateral root number,a nd gen es of FLA 12,WRKY29,and RBOHA may play a pivotal role in lateral root development in Asian cotton.

Calcium Silicate Cements Application in Lateral Root Perforation Repair: A Case Report with 16-Month Follow-Up

Lateral root perforations are unfortunate procedures during endodontic treatment and often lead to tooth extraction. Conditioning factors such as time, size, location, inappropriate disinfection and sealing, are indispensable to achieve acceptable long-term outcomes. Calcium silicate cements are bioactive materials used for perforation repair. They can be set in moist environments such as blood, saliva and dentinal fluid making them a reliable material for clinical applications. This case report describes the treatment and repair after a 16-month follow-up of a lateral root perforation of the maxillary lateral incisor.

The glutamate receptor gene GLR3.3:A bridge of calciummediated root development in poplar

Poplar is one of the fastest-growing temperate trees in the world and is widely used in ornamental horticulture for shade.The root is essential for tree growth and development and its utilization potential is huge.Calcium(Ca),as a signaling molecule,is involved in the regulation of plant root development.However,the detailed underlying regulatory mechanism is elusive.In this study,we analyzed the morphological and transcriptomic variations of 84K poplar(Populus alba×P.glandulosa)in response to different calcium concentrations and found that low Ca^(2+)(1 mmol·L^(-1))promoted lateral root development,while deficiency(0.1 mmol·L^(-1)Ca^(2+))inhibited lateral root development.Co-expression analysis showed that Ca^(2+)channel glutamate receptors(GLRs)were present in various modules with significance for root development.Two GLR paralogous genes,PagGLR3.3a and Pag GLR3.3b,were mainly expressed in roots and up-regulated under Ca^(2+)deficiency.The CRISPR/Cas9-mediated signal gene(crispr-PagGLR3.3a,PagGLR3.3b)and double gene(crispr-PagGLR3.3ab)mutants presented more and longer lateral roots.Anatomical analysis showed that crispr-PagGLR3.3ab plants had more xylem cells and promoted the development of secondary vascular tissues.Further transcriptomic analysis suggested that knockout of PagGLR3.3a and PagGLR3.3b led to the up-regulation of several genes related to protein phosphorylation,auxin efflux,lignin and hemicellulose biosynthesis as well as transcriptional regulation,which might contribute to lateral root growth.This study not only provides novel insight into how the Ca^(2+)channels mediated root growth and development in trees,but also provides a directive breeding of new poplar species for biofuel and bioenergy production.

The MtRGF6 Peptide Differentially Regulates Root Development and Symbiotic Nodulation of Medicago truncatula and Lotus japonicus

Rhizobia induces nitrogen-fixing nodules in legumes used in agricultural production,providing a direct source of combined nitrogen to leguminous crops.Small peptides,such as CLAVATA3/EMBRYO SURROUNDING REGION peptides(CLE),are known to regulate the formation and development of nitrogen-fixing nodules in legumes.Root meristem growth factor(RGF)peptides from Medicago truncatula not only regulate root develop-ment but also modulate nodulation symbiosis with Sinorhizobium meliloti.However,the impact of RGF peptides from one leguminous species on the others remains unclear.In this study,we investigate the effects of the RGF family peptide MtRGF6p from M.truncatula on nodulation symbiosis and root development in Lotus japonicus.The MtRGF6 gene is predominantly expressed in the root nodules of M.truncatula and shows low identity with RGF homologous genes from L.japonicus.The gene promoter is active in the primordia of root nodules and lat-eral roots,as well as in young nodules and roots,and the meristem,infection,and nitrogen-fixing regions of the mature nodule.Chemically synthesized MtRGF6p promoted primary root growth in M.truncatula but sup-pressed the growth of L.japonicus primary roots.The peptide negatively affected the initiation of nodule primor-dia,the formation of infection threads,and nodulation in both legumes,with a low dosage showing effects on L.japonicus compared to M.truncatula.These results suggest that the MtRGF6 peptide from M.truncatula may serve as an inter-species signal affecting the root organ development of L.japonicus.

C-Root SP热牙胶充填技术用于根管治疗的临床疗效观察

目的观察C-Root SP热牙胶充填技术用于根管治疗的临床疗效。方法选取2022年12月至2023年9月湖南中医药大学口腔医学院收治的108例(108颗患牙)需行根管治疗的患者作为研究对象,按照随机数字表法分为对照组(54例,54颗患牙)与观察组(54例,54颗患牙)。对照组采用AH Plus热牙胶充填技术治疗,观察组采用C-Root SP热牙胶充填技术治疗。比较两组的根管充填质量、侧支根管充填率、疼痛程度及根尖周指数(PAI)。结果观察组侧支根管充填率高于对照组,术后视觉模拟评分法(VAS)评分低于对照组,术后PAI分级低于对照组,差异有统计学意义(P<0.05);两组根管恰填率比较,差异无统计学意义(P>0.05)。结论根管治疗中采用C-Root SP热牙胶充填技术可获得良好的根管充填质量,提高侧支根管充填率,降低疼痛程度,促进根尖周病变愈合。

C形根管充填治疗恒牙根尖周炎中采用热牙胶垂直加压法与iRoot SP冷侧压法的临床效果分析

目的分析C形根管充填治疗恒牙根尖周炎中采用热牙胶垂直加压法与iRoot SP冷侧压法的临床疗效。方法简单随机选择2019年6月—2021年12月烟台业达医院收治的60例恒牙根尖周炎患者作为研究对象,依据不同治疗方法分为两组,每组30例。两组患者均进行C形根管充填治疗,对照组采用热牙胶垂直加压法,观察组采用iRoot SP冷侧压法,比较两组患者临床疗效、填充效果、牙周指数。结果观察组治疗总有效率为100.00%(30/30),高于对照组的80.00%(24/30),差异有统计学意义(χ^(2)=4.630,P=0.031)。两组患者填充效果比较,差异无统计学意义(P>0.05)。治疗后10周,观察组出血指数、菌斑指数、牙龈指数、牙周袋深度均低于对照组,差异有统计学意义(P均<0.05)。结论在C形根管充填治疗恒牙根尖周炎患者中采用iRoot SP冷侧压法能提升临床疗效,改善牙周指数。

iRoot BP^(+Plus)和MTA修补根管侧穿的临床效果研究

纳入临床患牙83例,随机分为两组,分别使用生物陶瓷材料iRoot■BP^(+Plus)(A组,42例)和MTA(B组,41例)在显微镜下修补根管侧穿,A、B组初次封闭成功率分别为80.95%和58.54%(P<0.05)、1年后临床成功率分别为88.10%和75.61%(P>0.05)。CBCT显示两组材料在牙根管穿孔处均能诱导骨小梁形成。

iRoot SP冷侧压与热牙胶垂直加压对下颌第二磨牙根管充填的临床疗效对比

目的对比使用iRoot SP分别进行冷侧压与热牙胶垂直加压对下颌第二磨牙根管充填的临床疗效。方法选取2015-03—2016-03某院收治的行下颌第二磨牙根管充填治疗患者82例。按照随机数字表法分成观察组与对照组各41例。对照组采用iRoot SP热牙胶垂直加压进行根管充填,观察组采用iRoot SP冷侧压进行根管充填。分别对比两组患者下颌第二磨牙C形根管形态、根管充填效果、术后3个月疗效以及患者满意度。结果观察组C1型、C2型、C3型占比分别为14.63%(6/41)、58.54%(24/41)、24.39%(10/41),与对照组的12.20%(5/41)、56.10%(23/41)、29.27%(12/41)相比不明显,差异无统计学意义(均P>0.05)。观察组恰填、超填、欠填以及术后疼痛发生情况分别为85.37%(35/41)、7.32%(3/41)、7.32%(3/41)、4.88%(2/41),与对照组的87.80%(36/41)、9.76%(4/41)、2.44%(1/41)、7.32%(3/41)对比均不明显,差异无统计学意义(均P>0.05)。两组治疗3个月后的总有效率分别为95.12%(39/41)、92.68%(38/41),差异无统计学意义(P>0.05)。观察组患者满意度为97.56%(40/41),显著高于对照组的85.37%(35/41),差异有统计学意义(P<0.05)。结论使用iRoot SP进行冷侧压与热牙胶垂直加压技术对下颌第二磨牙C形根管充填的临床疗效相当,而iRoot SP冷侧压操作更为简便,患者满意度高。

MYB2 and MYB108 regulate lateral root development by interacting with LBD29 in Arabidopsis thaliana

AUXIN RESPONSE FACTOR 7(ARF7)-mediated auxin signaling plays a key role in lateral root(LR)development by regulating downstream LATERAL ORGAN BOUNDARIES DOMAIN(LBD)transcription factor genes,including LBD16,LBD18,and LBD29.LBD proteins are believed to regulate the transcription of downstream genes as homodimers or heterodimers.However,whether LBD29 forms dimers with other proteins to regulate LR development remains unknown.Here,we determined that the Arabidopsis thaliana(L.)Heynh.MYB transcription factors MYB2 and MYB108 interact with LBD29 and regulate auxin-induced LR development.Both MYB2 and MYB108 were induced by auxin in an ARF7-dependent manner.Disruption of MYB2 by fusion with an SRDX domain severely affected auxin-induced LR formation and the ability of LBD29 to induce LR development.By contrast,overexpression of MYB2 or MYB108 resulted in greater LR numbers,except in the lbd29 mutant background.These findings underscore the interdependence and importance of MYB2,MYB108,and LBD29 in regulating LR development.In addition,MYB2–LBD29 and MYB108–LBD29 complexes promoted the expression of CUTICLE DESTRUCTING FACTOR 1(CDEF1),a member of the GDSL(Gly-Asp-Ser-Leu)lipase/esterase family involved in LR development.In summary,this study identified MYB2–LBD29 and MYB108–LBD29 regulatory modules that act downstream of ARF7 and intricately control auxin-mediated LR development.

侧孢芽孢杆菌RT028及其代谢物对根结线虫的防效测定

通过盆栽试验模拟线虫高发地块的情况,研究了枯草芽孢杆菌RT028及其代谢物对根结线虫的防治效果。结果表明:在番茄幼苗期浇施枯草芽孢杆菌RT028及其代谢物可以有效抑制根结线虫的侵染,降低根结指数和根结数,减少损失。

热牙胶垂直加压根管充填与冷牙胶侧方加压根管充填治疗慢性牙髓炎患者的效果比较

目的:比较热牙胶垂直加压根管充填与冷牙胶侧方加压根管充填治疗慢性牙髓炎患者的效果。方法:选取2021年3月至2023年3月该院收治的100例慢性牙髓炎患者进行前瞻性研究,按照随机数字表法将其分为研究组与对照组各50例。对照组采用冷牙胶侧方加压根管充填治疗,研究组采用热牙胶垂直加压根管充填治疗,比较两组恰填率、血清超敏C反应蛋白(hs-CRP)水平、上颌第一磨牙咬合力和并发症发生率。结果:研究组恰填率为90.00%,高于对照组的74.00%,差异有统计学意义(P<0.05);治疗后2周,两组上颌第一磨牙咬合力高于治疗前,且研究组高于对照组,两组血清hs-CRP水平低于治疗前,且研究组低于对照组,差异均有统计学意义(P<0.05);两组并发症发生率比较,差异无统计学意义(P>0.05)。结论:热牙胶垂直加压根管充填治疗慢性牙髓炎患者可提高恰填率和上颌第一磨牙咬合力,以及降低血清hs-CRP水平,效果优于冷牙胶侧方加压根管充填治疗。

Constitutive expression of pathogen-inducible OsWRKY31 enhances disease resistance and affects root growth and auxin response in transgenic rice plants

WRKY transcription factors have many regulatory roles we isolated a rice WRKY gene （OsWRKY31） that is induced in response to biotic and abiotic stresses. In this study, by the rice blast fungus Magnaporthe grisea and auxin. This gene encodes a polypeptide of 211 amino-acid residues and belongs to a subgroup of the rice WRKY gene family that probably originated after the divergence of monocot and dicot plants. OsWRKY31 was found to be localized to the nucleus of onion epidermis cells to transiently express OsWRKY31-eGFP fusion protein. Analysis of OsWRKY31 and its mutants fused with a Gal4 DNA-binding domain indicated that OsWRKY31 has transactivation activity in yeast. Overexpression of the OsWRKY31 gene was found to enhance resistance against infection with M. grisea, and the transgenic lines exhibited reduced lateral root formation and elongation compared with wild-type and RNAi plants. The lines with overexpression showed constitutive expression of many defense-related genes, such as PBZI and OsSci2, as well as early auxin-response genes, such as OslAA4 and OsCrll genes. Furthermore, the plants with overexpression were less sensitive to exogenously supplied IBA, NAA and 2,4-1） at high concentrations, suggesting that overexpression of the OsWRKY31 gene might alter the auxin response or transport. These results also suggest that OsWRKY31 might be a common component in the signal transduction pathways of the auxin response and the defense response in rice.