Advances in the study of auxin early response genes:Aux/IAA,GH3,and SAUR

Auxin plays a crucial role in all aspects of plant growth and development.Auxin can induce the rapid and efficient expression of some genes,which are named auxin early response genes(AERGs),mainly including the three families:auxin/indole-3-acetic acid(Aux/IAA),Gretchen Hagen 3(GH3),and small auxin-up RNA(SAUR).Aux/IAA encodes the Aux/IAA protein,which is a negative regulator of auxin response.Aux/IAA and auxin response factor(ARF)form a heterodimer and participate in a variety of physiological processes through classical or non-classical auxin signaling pathways.The GH3 encodes auxin amide synthetase,which catalyzes the binding of auxin to acyl-containing small molecule substrates(such as amino acids and jasmonic acid),and regulates plant growth and stresses by regulating auxin homeostasis.SAURs is a class of small auxin up-regulated RNAs.SAUR response to auxin is complex,and the process may occur at the transcriptional,post-transcriptional and protein levels.With the development of multi-omics,significant progress has been made in the study of Aux/IAA,GH3,and SAUR genes,but there are still many unknowns.This review offers insight into the characteristics of Aux/IAA,GH3,and SAUR gene families,and their roles in roots,hypocotyls,leaves,leaf inclinations,flowers,seed development,stress response,and phytohormone crosstalk,and provides clues for future research on phytohormone signaling and the molecular design breeding of crops.

Camellia sinensis CsMYB4a participates in regulation of stamen growth by interaction with auxin signaling transduction repressor CsAUX/IAA4

Subgroup 4(Sg4)members of the R2R3-MYB are generally known as negative regulators of the phenylpropanoid pathway in plants.Our previous research showed that a R2R3-MYB Sg4 member from Camellia sinensis(CsMYB4a)inhibits expression of some genes in the phenylpropanoid pathway,but its physiological function in the tea plant remained unknown.Here,CsMYB4a was found to be highly expressed in anther and filaments,and participated in regulating filament growth.Transcriptome analysis and exogenous auxin treatment showed that the target of CsMYB4a might be the auxin signal pathway.Auxin/indole-3-acetic acid 4(AUX/IAA4),a repressor in auxin signal transduction,was detected from a yeast two-hybrid screen using CsMYB4a as bait.Gene silencing assays showed that both CsIAA4 and CsMYB4a regulate filament growth.Tobacco plants overexpressing CsIAA4 were insensitive to exogenous a-NAA,consistent with overexpression of CsMYB4a.Protein-protein interaction experiments revealed that CsMYB4a interacts with N-terminal of CsIAA4 to prevent CsIAA4 degradation.Knock out of the endogenous NtIAA4 gene,a CsIAA4 homolog,in tobacco alleviated filament growth inhibition and a-NAA insensitivity in plants overexpressing CsMYB4a.All results strongly suggest that CsMYB4a works synergistically with CsIAA4 and participates in regulation of the auxin pathway in stamen.

Overexpression of auxin/indole-3-acetic acid gene MdIAA24 enhances Glomerella leaf spot resistance in apple(Malus domestica)

Auxin is throughout the entire life process of plants and is involved in the crosstalk with other hormones,yet its role in apple disease resistance remains unclear.In this study,we investigated the function of auxin/indole-3-acetic acid(IAA)gene Md IAA24 overexpression in enhancing apple resistance to Glomerella leaf spot(GLS)caused by Colletotrichum fructicola(Cf).Analysis revealed that,upon Cf infection,35S::Md IAA24 plants exhibited enhanced superoxide dismutase(SOD)and peroxidase(POD)activity,as well as a greater amount of glutathione(reduced form)and ascorbic acid accumulation,resulting in less H_(2)O_(2)and superoxide anion(O_(2)^(-))in apple leaves.Furthermore,35S::Md IAA24 plants produced more protocatechuic acid,proanthocyanidins B1,proanthocyanidins B2 and chlorogenic acid when infected with Cf.Following Cf infection,35S::Md IAA24 plants presented lower levels of IAA and jasmonic acid(JA),but higher levels of salicylic acid(SA),along with the expression of related genes.The overexpression of Md IAA24 was observed to enhance the activity of chitinase andβ-1,3-glucanase in Cfinfected leaves.The results indicated the ability of Md IAA24 to regulate the crosstalk between IAA,JA and SA,and to improve reactive oxygen species(ROS)scavenging and defense-related enzymes activity.This jointly contributed to GLS resistance in apple.

中国南瓜CmoAux/IAA基因的克隆和表达特征分析

在前期对中国南瓜败育雌蕊和正常雌蕊进行转录组分析发现,CmoAux/IAA基因可能参与了雌花发育,为进一步探究其生物学功能,利用同源序列克隆法从中国南瓜中克隆得到全长为600 bp的CmoAux/IAA基因,该基因编码199个氨基酸;保守结构域分析结果表明,其属于Aux/IAA家族,包含结构域Ⅰ、Ⅲ、Ⅳ;该蛋白无信号肽和跨膜结构。多序列比对和系统进化树分析结果显示,CmoAux/IAA氨基酸序列与印度南瓜XP_022986212.1的氨基酸序列、美洲南瓜XP_023513171.1的氨基酸序列亲缘关系较近,相似度高达98.01%、96.50%。拟南芥原生质体亚细胞定位结果显示,CmoAux/IAA蛋白定位于细胞核和细胞质。实时荧光定量结果显示,该基因具有组织表达特异性,主要在南瓜植株生长点及雌花柱头中表达,柱头中的相对表达量是雄蕊的137倍,在叶和根中不表达,其可能在植株生长点幼嫩组织分化或雌花发育过程中发挥着重要作用。

外源IAA对核桃内果皮生长发育的影响

【目的】探究生长素(IAA)对核桃内果皮发育的影响。【方法】采用不同质量浓度的IAA处理核桃,通过Wiesner法观察核桃内果皮木质素的沉积变化,并测定内果皮中木质素、纤维素、半纤维素和IAA含量,同时对IAA处理后第12天的样本进行高通量测序。【结果】与对照相比,低质量浓度IAA处理和高质量浓度IAA处理后内果皮木质素的积累存在显著差异,在处理后期,核桃内果皮部分硬化,仍存在内果皮缺失或不完整现象。木质素、纤维素和半纤维素含量整体呈上升趋势,最高分别可达30.55%、16.49%和17.23%,IAA含量整体呈上升趋势;通过RNA-seq分析,发现差异基因主要富集在植物激素信号转导和苯丙烷生物合成途径中,且随着IAA质量浓度的升高,部分与激素信号转导和苯丙烷生物合成相关的差异表达基因逐渐下调表达或不表达。【结论】IAA参与调控核桃内果皮的发育,影响内果皮木质素的积累,为后期研究核桃内果皮对外源生长素的响应提供参考依据。

外源IBA对无花果扦插苗抗氧化特性及IAA生物合成途径的影响

【目的】探讨适宜浓度吲哚丁酸(IBA)对无花果插穗生根萌芽、抗氧化性及生长素生物合成途径相关基因表达的影响,为其应用于无花果的育种、繁殖、推广和种植提供理论依据。【方法】以‘波姬红’无花果品种硬枝为插穗,观测不同质量浓度IBA(0,30,45,60,90 mg/L)处理下插穗生根性状、抗氧化特性,并对45 mg/L IBA处理及对照组的扦插枝条中段的腋芽进行转录组分析。【结果】(1)无花果插穗萌芽率和生根率在45 mg/L IBA处理时达到最大值,并与其他处理和对照差异显著。(2)随IBA浓度增加,插穗SOD和CAT活性先下降后上升,并均在45,60 mg/L IBA处理下显著低于对照,而POD活性无显著变化;各浓度IBA处理插穗中MDA和H2O2含量均显著高于对照,且45 mg/L IBA处理MDA显著低于其余处理。(3)45 mg/L IBA处理及对照组中共存在6 879个差异表达基因,KEGG富集显示有10个差异途径,GO富集分析表明生物学过程和分子功能为主要的生物学途径;与CAT、SOD相关的基因集中富集在过氧化物酶体通路上,POD相关基因则富集在苯丙烷生物合成通路中;IAA生物合成途径中代谢相关基因FcGH3显著上调表达,与信号转导相关基因FcAUX1、FcARG7和FcARF等显著下调表达。【结论】外源IBA处理会导致无花果插穗抗氧化酶和IAA生物合成途径中相关基因表达的差异变化,增强插穗抗逆性,促进插穗生根、萌芽、成苗,并以外源45 mg/L IBA促进效果最好。

外源ABA、ZR及IAA对甘薯脱毒苗生长及结薯的影响

以甘薯品种龙薯9号的脱毒试管苗为试验材料,采用盆栽基质培养、向根部营养液加入植物激素的处理方式,设置单因素试验,分别探究了0(CK)、0.7、7.0、14.0 mg/L的ABA与IAA,以及0(CK)、0.8、8.0、16.0 mg/L ZR对脱毒苗根生长发育及结薯的影响。结果表明:0.8 mg/L ZR处理的单株结薯数和单株薯重分别较CK提高2.25个和5.93 g;0.7 mg/L ABA处理的单株结薯数和单株薯重分别较CK提高2.00个和5.43 g;14 mg/L IAA处理可显著增加脱毒苗的根长和茎长。综上所述,在脱毒薯生产过程中,根部施加0.7 mg/L ABA或0.8 mg/L ZR均可显著增加脱毒苗的单株结薯数和单株薯重,根部添加14 mg/L IAA可显著促进脱毒苗根与茎的伸长。本试验结果可为脱毒种薯种苗高效生产提供技术支撑。

硬叶兜兰高产IAA菌株的筛选鉴定及其生物学特性研究

【目的】筛选鉴定硬叶兜兰根、叶内高产IAA菌株并对其进行生物学特性研究。【方法】采用组织分离法从根、叶中分离内生真菌,结合形态学和rDNA-ITS分子生物学进行鉴定;并运用Salkowski比色法比较分离菌株分泌IAA的能力;同时采用单因素法探究YD-16菌株最适生长条件。【结果】分离出的33株真菌经鉴定为8属12种,所有菌株表现出不同程度分泌IAA的能力,其中YD-16(Nemania cyclobalanopsina)在所有菌株中分泌量最高,该菌株在添加和不添加L-色氨酸的培养基中IAA的产量分别为(59.29±0.46)μg/mL和(17.36±0.09)μg/mL;YD-16菌株在中性培养基25℃恒温黑暗条件下培养,且氮源为蛋白胨、碳源为蔗糖和淀粉时菌丝生长最好。【结论】分离鉴定的内生真菌有8属12种,优势种为炭垫菌属真菌。其中,双座炭壳菌属、间座壳属、炭团菌属、黑孢属和炭角菌属是首次从硬叶兜兰中分离的真菌。YD-16菌株具有较高的分泌IAA的能力,其氮源偏好为蛋白胨,碳源偏好为蔗糖和淀粉,研究结果可为后续开展硬叶兜兰养分生理和资源保护提供科学依据。

深度学习驱动下IaaS云运维异常检测算法的研究进展

异常检测是IaaS云系统运维中的一个关键任务,通过早期预警和提前干预,可有效避免系统崩溃等严重事故的发生。但相较于传统数据中心,IaaS云系统具有较大规模的计算节点,节点拓扑复杂、监测数据量大、缺少标注信息等特点,为IaaS云运维异常检测带来新的挑战。从深度学习的技术框架出发,分析了异常检测问题面临的难点,调研总结了IaaS云系统下常见异常检测算法和相关技术。面向节点异常和系统异常两类典型问题,对深度学习驱动的解决方法进行调研:面向节点级别异常,重点调研了时间依赖的运维数据下由时序数据驱动的检测算法;面向系统级别异常,重点调研了网络拓扑建模下由图数据驱动的检测算法。最后,提出了数据驱动下IaaS云运维数据异常检测中的新问题与新挑战。

基于资源互补的IaaS云产品捆绑定价决策

随着市场竞争的日趋激烈,基础设施即服务(IaaS:Infrastructure as a Service)提供商要在竞争中胜出,很大程度上取决于其对产品的合理定价。考察一个拥有两种互补云计算资源的IaaS提供商,针对预留类产品的三种销售模式(单独销售、捆绑销售和混合销售),比较不同模式下的最优定价和IaaS提供商的利润情况。研究表明:(1)对于IaaS提供商而言,选择混合销售时利润最大,若其只能选择非混合销售,则当资源间互补性较强、且用户对捆绑折扣价格较为敏感时,选择捆绑销售,否则选择单独销售。(2)对于用户而言,捆绑产品用户最偏好捆绑销售,非捆绑产品用户最偏好混合销售。(3)灵敏度分析的结果表明,当资源间互补系数越小时,IaaS提供商的利润越大,混合销售的盈利优势越不明显。

2,4-D处理对欧李果实钙摄取的影响及与有机酸代谢和IAA的关系

为探究外源植物生长调节剂2,4-D处理对欧李(Cerasus humilis)果实发育成熟过程中钙素摄取能力的影响及与有机酸代谢、生长素(IAA)之间的关系,以内蒙古地区的低钙欧李MY-9果实为试材,以清水喷施作为对照,研究2,4-D处理对果实发育成熟过程中钙摄取能力和有机酸代谢及IAA的影响,并进行相关性分析。结果表明(:1)在摄钙速率方面,处理与对照果实的果胶钙、活性钙、总钙的摄钙速率变化规律相似,均表现为先升后降,处理后从硬核期到完熟期以上3种钙的摄取速率均显著高于对照;而水溶钙摄钙速率与其相反,表现为先降后升,果实发育后期显著高于对照。在摄钙活性方面,4种钙形态的变化规律相似,均表现为持续下降,处理后果实的摄钙活性均显著高于对照。在相对生长钙摄取量方面,4种钙形态的变化规律一致,均表现为先升后降,硬熟期和完熟期处理显著高于对照。(2)处理与对照果实中苹果酸脱氢酶(NAD-MDH)活性、苹果酸及有机酸含量随着果实发育成熟均呈上升趋势,苹果酸酶(NADP-ME)活性和柠檬酸含量均呈下降趋势,2,4-D处理可以不同程度提高果实中有机酸含量及相关酶活性。(3)处理与对照果实的IAA含量整体上均表现为先升后降,整个发育时期处理与对照均存在显著差异,2,4-D处理可显著提升欧李果实IAA含量。(4)相关性分析表明,水溶钙的摄钙速率和相对生长钙摄取量与NAD-MDH活性、苹果酸及有机酸含量均呈显著正相关,与IAA含量、NADP-ME活性及柠檬酸含量呈显著负相关;果胶钙、活性钙及总钙的摄钙活性与IAA含量、NADP-ME活性、柠檬酸含量呈显著正相关,与NAD-MDH活性、苹果酸及有机酸呈显著负相关;2,4-D处理提升了果实钙摄取能力与柠檬酸含量的相关性。综上所述,2,4-D处理可以提高欧李果实中钙摄取能力,提高有机酸代谢及IAA含量;欧李果实中钙摄取能力与有机酸代谢及IAA含量密切相关,随着NAD-MDH活性增强,苹果酸含量增加,有机酸含量增加,会提高水溶钙摄取能力,但会降低果胶钙、活性钙及总钙的摄取能力;而柠檬酸及IAA含量的增加会降低水溶钙摄取能力,提高果胶钙、活性钙及总钙摄取能力。2,4-D处理通过提高有机酸代谢及IAA含量调控果实钙摄取。

不同浓度IAA浸种对PEG模拟干旱胁迫下辣椒种子萌发的影响

为探究不同浓度IAA浸种后,干旱胁迫下辣椒种子萌发特性和早期幼苗的生长情况,对4个辣椒品种(6421、博辣9号、兴蔬曲美和兴蔬215)用浓度为0 mg/L、0.1 mg/L、1.0 mg/L和2.0 mg/L的IAA浸种处理,后用15%PEG-6000模拟干旱胁迫进行发芽试验,测定辣椒种子的发芽率、发芽势、发芽指数、根长、芽长和根冠比。结果表明,不同浓度IAA浸种及不同品种对干旱胁迫下辣椒种子萌发的性状指标存在显著差异。1 mg/L浓度处理对6421辣椒种子萌发和幼苗生长促进作用明显;0.1 mg/L浓度处理和1.0 mg/L浓度处理分别对博辣9号辣椒种子萌发和幼苗生长促进作用明显;2.0 mg/L浓度处理对兴蔬曲美辣椒种子萌发和幼苗生长促进作用明显,2.0 mg/L浓度处理和1.0 mg/L浓度处理分别对兴蔬215辣椒种子萌发和幼苗生长促进作用明显。

不同质量浓度的IAA、NAA处理对尤加利种子萌发的影响

为了探究不同质量浓度吲哚乙酸和萘乙酸对尤加利种子萌发的影响,设置0.3、3、30、120 mg·L^(-1)4种生长素质量浓度,浸种时间分别为1.5、3、4.5、6 h,分别对尤加利银元和尤加利蓝宝贝浸种处理,进行尤加利种子的发芽率、发芽势和相对发芽率的研究。试验结果表明,0.3~120 mg·L^(-1)质量浓度的IAA激素浸种处理两种尤加利种子,浸种时间为1.5~6 h,其发芽率和发芽势均优于对照组,对两种尤加利种子的萌发均表现为促进作用。NAA处理条件下,两种尤加利种子的发芽率和发芽势受激素质量浓度和浸种时间影响较大,表现为低质量浓度促进、高质量浓度抑制,浸种时间短促进、浸种时间长抑制的关系。

油茶果皮发育相关ARF-Aux/IAA互作分析

生长素在植物生长发育过程中发挥重要调控作用,ARF和Aux/IAA是生长素介导的信号转导通路中的关键调节因子。果皮厚度直接影响油茶的经济产量,不同种质的油茶果皮厚度具有明显的分化,为进一步研究油茶果皮厚度调控机制,通过转录组学和生物信息学系统分析油茶果皮转录组数据,筛选油茶果皮发育过程中可能存在相互作用的CoARF和CoIAA基因。结果表明,在油茶果皮转录组数据中共鉴定到19个CoARF和17个CoIAA基因,有10对CoARF-CoIAA(8个CoARF基因和6个CoIAA基因)的时空表达存在显著相关性,将其编码蛋白序列分别与拟南芥中的ARFs和IAAs构建系统进化树后发现,CoARF14、CoARF19和CoARF11与起转录抑制作用的AtARFS具有较近的亲缘关系。而CoARF6和CoARF10与起转录激活作用的AtARFS具有较近的亲缘关系。互作蛋白以拟南芥为参考进一步进行同源映射校验后,最终确定CoARF10-CoIAA5、CoARF6-CoIAA2和CoARF14-CoIAA12三对组合可能通过相互作用传递生长素信号参与调控油茶果皮发育。

糯高粱叶中IAA产生菌的分离筛选及其促植物生长作用

糯高粱是白酒酿造的重要原料,其生长过程需要大量的化学肥料,作为环境友好型肥料,微生物菌剂有很广阔的应用前景。为开发对糯高粱生长有促进生长功能的微生物菌剂,该研究以糯高粱叶片为材料,分离筛选具有植物生长激素吲哚乙酸(IAA)产生功能的微生物菌株,基于菌株的16S rDNA保守序列对菌株进行系统发育分析,确定菌株的分类学地位;通过菌悬液浸种处理,分析菌株对糯高粱种子萌发的影响;通过盆栽实验,分析菌株对高粱幼苗生长的影响。结果表明:(1)从糯高粱叶片中分离筛选得到4株具有产IAA功能的微生物菌株,分别编号为HY1-1、HY1-2、HY1-3和HY1-4。其中,IAA单位浓度产生量最高的菌株是HY1-1,为2.56 mol·L^(-1)。(2)运用贝叶斯推断树对菌株16S rDNA进行系统发育分析,结果显示这4株菌都属于枯草芽孢杆菌(Bacillus subtilis)。(3)HY1-1、HY1-2、HY1-3和HY1-4都能促进糯高粱种子萌发,与对照组相比,经菌悬液浸泡的糯高粱种子发芽率显著提高了40.04%~165.52%,其中促进效果最明显的是HY1-1,种子发芽率提高了165.52%。(4)选取HY1-1菌株做盆栽实验,在糯高粱幼苗根部接种HY1-130 d后,糯高粱幼苗的株高显著增加了29.17%、全磷含量显著增加了5.12%;糯高粱根际基质中速效氮显著增加了31.70%,有效磷显著增加了28.88%。综上认为,糯高粱叶内生菌HY1-1能够通过分泌植物生长激素IAA以及为植物提供营养元素等方式促进糯高粱植株的生长。该研究结果为进一步开发促糯高粱生长菌剂提供了种质资源。

Utilizing auxin dwarf genes to optimize seed yield and lodging resistance in rapeseed

Direct-seeding rapeseed production at high plant density raises the risk of lodging.We investigated the use of dwarf genes to improve rapeseed plant architecture to balance yield and lodging.Three genotypes with different plant architectures(dwarf sca^(HS5),semi-dwarf+/sca^(HS5),and tall ^(HS5))were evaluated under varying nitrogen rates(N1,N2,and N3:120,240,and 360 kg N ha^(-1))and plant densities(D1,D2,and D3:15,45,and 75 plants m^(-2))from 2019 to 2022.The results showed that increasing N rate positively influenced yield while decreasing lodging resistance in all genotypes.Increasing plant density(D2-D3)enhanced lodging resistance and yield in sca^(HS5) and+/sca^(HS5),but reduced yield in ^(HS5).Compared to the two parents,+/sca^(HS5) exhibited moderate expressions of IAA3,GH3.15,and SAUR30 in stems under N2D3,resulting in reduced plant height and increased compactness.Additionally,+/sca^(HS5) had a thicker silique layer than ^(HS5) by 14.7%,and it had a significant correlation between branch height/angle and yield.Increasing N rate led to increased lignin and pectin contents,while cellulose content decreased.Increasing plant density resulted in greater stem cellulose content and CSLA3/7 expression in sca^(HS5) and+/sca^(HS5),but decreased in ^(HS5).Compared to ^(HS5),+/sca^(HS5) exhibited higher expressions of ARAD1 and GAUT4,along with a 51.1%increase in pectin content,leading to improved lodging resistance under N2D3.Consequently,+/sca^(HS5) showed a 46.4%higher yield and 38.9%lodging resistance than ^(HS5) under N2D3,while sca^(HS5) demonstrated strong lodging resistance but lower yield potential.Overall,this study underscores the potential of utilizing auxin dwarf genes to optimize the trade-off between yield and lodging resistance in rapeseed and the possibility of maximizing yield potential by optimizing the plant architecture of+/sca^(HS5) through nitrogen reduction and dense planting.

Auxin-brassinosteroid crosstalk:Regulating rice plant architecture and grain shape

Rice(Oryza sativa)plant architecture and grain shape,which determine grain quality and yield,are modulatedby auxin and brassinosteroid via regulation of cell elongation and proliferation.We review the signaltransduction of these hormones and the crosstalk between their signals on the regulation of rice plantarchitecture and grain shape.

The role of the auxin-response genes MdGH3.1 and MdSAUR36 in bitter pit formation in apple

Apples often exhibit bitter pits in response to metabolic disorders during ripening and storage;however, the mechanisms underlying the bitter pit(BP) development remain unclear. Here, metabolome and transcriptome analyses were performed to investigate BP pulp of 'Fuji'. Two auxin-response genes, MdGH3.1 and MdSAUR36, were screened. Their expression as well as the auxin content in BP pulp were found to be higher than those in healthy pulp(P < 0.01). In the field, excess CO(NH2)2increased the incidence of BP. Moreover, the auxin content and MdGH3.1 expression increased in apples after nitrogen fertilization. On Day 30 before harvest, the two genes were transiently transferred to the fruit, and 20.69% and 23.21% of BP fruits were harvested. After 10 μmol·L-1auxin was infiltrated at low pressure into postharvest fruit, the increase in MdGH3.1 expression occurred earlier than that in MdSAUR36. MdGH3.1 increased the expression of MdSAUR36, but MdSAUR36 did not increase expression of MdGH3.1. Therefore, we suggest that MdGH3.1 acts upstream of MdSAUR36 during BP formation and that these genes induce BP formation by regulating auxin and phenylpropanoid biosynthesis.

Carbon Monoxide Modulates Auxin Transport and Nitric Oxide Signaling in Plants under Iron Deficiency Stress

Carbon monoxide(CO)and nitric oxide(NO)are signal molecules that enhance plant adaptation to environmental stimuli.Auxin is an essential phytohormone for plant growth and development.CO and NO play crucial roles in modulating the plant’s response to iron deficiency.Iron deficiency leads to an increase in the activity of heme oxygenase(HO)and the subsequent generation of CO.Additionally,it alters the polar subcellular distribution of Pin-Formed 1(PIN1)proteins,resulting in enhanced auxin transport.This alteration,in turn,leads to an increase in NO accumulation.Furthermore,iron deficiency enhances the activity of ferric chelate reductase(FCR),as well as the expression of the Fer-like iron deficiency-induced transcription factor 1(FIT)and the ferric reduction oxidase 2(FRO2)genes in plant roots.Overexpression of the long hypocotyl 1(HY1)gene,which encodes heme oxygenase,or the CO donor treatment resulted in enhanced basipetal auxin transport,higher FCR activity,and the expression of FIT and FRO2 genes under Fe deficiency.Here,a potential mechanism is proposed:CO and NO interact with auxin to address iron deficiency stress.CO alters auxin transport,enhancing its accumulation in roots and up-regulating key iron-related genes like FRO2 and IRT1.Elevated auxin levels affect NO signaling,leading to greater sensitivity in root development.This interplay promotes FCR activity,which is crucial for iron absorption.Together,these molecules enhance iron uptake and root growth,revealing a novel aspect of plant physiology in adapting to environmental stress.

Silencing of early auxin responsive genes MdGH3-2/12 reduces the resistance to Fusarium solani in apple

Apple replant disease(ARD)has led to severe yield and quality reduction in the apple industry.Fusarium solani(F.solani)has been identified as one of the main microbial pathogens responsible for ARD.Auxin(indole-3-acetic acid,IAA),an endogenous hormone in plants,is involved in almost all plant growth and development processes and plays a role in plant immunity against pathogens.Gretchen Hagen3(GH3)is one of the early/primary auxin response genes.The aim of this study was to evaluate the function of MdGH3-2 and MdGH3-12 in the defense response of F.solani by treating MdGH3-2/12 RNAi plants with F.solani.The results show that under F.solani infection,RNAi of MdGH3-2/12 inhibited plant biomass accumulation and exacerbated root damage.After inoculation with F.solani,MdGH3-2/12 RNAi inhibited the biosynthesis of acid-amido synthetase.This led to the inhibition of free IAA combining with amino acids,resulting in excessive free IAA accumulation.This excessive free IAA altered plant tissue structure,accelerated fungal hyphal invasion,reduced the activity of antioxidant enzymes(SOD,POD and CAT),increased the reactive oxygen species(ROS)level,and reduced total chlorophyll content and photosynthetic ability,while regulating the expression of PR-related genes including PR1,PR4,PR5 and PR8.It also changed the contents of plant hormones and amino acids,and ultimately reduced the resistance to F.solani.In conclusion,these results demonstrate that MdGH3-2 and MdGH3-12 play an important role in apple tolerance to F.solani and ARD.