In plant tissue culture,callus,a group of pluripotent cells,can be induced from detached explants by phyto-hormones on callus-inducing medium(CIM),and then callus can differentiate into root or shoot tissues,respec-tively(Xu et al.2019;Zhai et al.2024).Therefore,cal-lus formation is thought to reflect a change in cell fate whereby differentiated somatic cells reacquire pluripo-tency(Xu et al.2019).
Geng ZhangPeipei LiuGuifang ZhangXiaomin YaoXinwei WangYueqian ZhangJinxing LinYaning CuiXiaojuan Li
Plants are aerobic organisms that rely on molecular oxygen for respiratory energy production.Hypoxic conditions,with oxygen levels ranging between 1%and 5%,usually limit aerobic respiration and affect plant growth and development.Here,we demonstrate that the hypoxic microenvironment induced by active cell proliferation during the two-step plant regeneration process intrinsically represses the regener-ation competence of the callus in Arabidopsis thaliana.We showed that hypoxia-repressed plant regener-ation is mediated by the RELATED TO APETALA2.12(RAP2.12)protein,a memberof the Ethylene Response Factor VIl(ERF-Vll)family.We found that the hypoxia-activated RAP2.12 protein promotes salicylic acid(SA)biosynthesis and defense responses,thereby inhibiting pluripotency acquisition and de novo shoot regeneration in calli.Molecular and genetic analyses revealed that RAP2.12 could bind directly to the SALICYLIC ACID INDUCTION DEFICIENT 2(SID2)gene promoter and activate SA biosynthesis,repressing plant regeneration possibly via a PLETHORA(PLT)-dependent pathway.Consistently,the rap2.12 mutant calli exhibits enhanced shoot regeneration,which is impaired by SA treatment.Taken together,these find-ings uncover that the cell proliferation-dependent hypoxic microenvironment reduces cellular pluripotency and plant regeneration through the RAP2.12-SID2 module.
Dohee KooHong Gil LeeSoon Hyung BaeKyounghee LeePil Joon Seo
Genetic transformation has been an effective technology for improving the agronomic traits of maize.However,it is highly reliant on the use of embryonic callus(EC)and shows a serious genotype dependence.In this study,we performed genomic sequencing for 80 core maize germplasms and constructed a high-density genomic variation map using our newly developed pipeline(MQ2Gpipe).Based on the induction rate of EC(REC),these inbred lines were categorized into three subpopulations.The low-REC germplasms displayed more abundant genetic diversity than the high-REC germplasms.By integrating a genome-wide selective signature screen and region-based association analysis,we revealed 95.23 Mb of selective regions and 43 REC-associated variants.These variants had phenotypic variance explained values ranging between 21.46 and 49.46%.In total,103 candidate genes were identified within the linkage disequilibrium regions of these REC-associated loci.These genes mainly participate in regulation of the cell cycle,regulation of cytokinesis,and other functions,among which MYB15 and EMB2745 were located within the previously reported QTL for EC induction.Numerous leaf area-associated variants with large effects were closely linked to several REC-related loci,implying a potential synergistic selection of REC and leaf size during modern maize breeding.
BACKGROUND The investigation of plant-based therapeutic agents in medicinal plants has revealed their presence in the extracts and provides the vision to formulate novel techniques for drug therapy.Vitex negundo(V.negundo),a perennial herb belonging to the Varbanaceae family,is extensively used in conventional medication.AIM To determine the existence of therapeutic components in leaf and callus extracts from wild V.negundo plants using gas chromatography-mass spectrometry(GCMS).METHODS In this study,we conducted GC-MS on wild plant leaf extracts and correlated the presence of constituents with those in callus extracts.Various growth regulators such as 6-benzylaminopurine(BAP),2,4-dichlorophenoxyacetic acid(2,4-D),α-naphthylacetic acid(NAA),and di-phenylurea(DPU)were added to plant leaves and in-vitro callus and grown on MS medium.RESULTS The results clearly indicated that the addition of BAP(2.0 mg/L),2,4-D(0.2 mg/mL),DPU(2.0 mg/L)and 2,4-D(0.2 mg/mL)in MS medium resulted in rapid callus development.The plant profile of Vitex extracts by GC-MS analysis showed that 24,10,and 14 bioactive constituents were detected in the methanolic extract of leaf,green callus and the methanolic extract of white loose callus,respectively.CONCLUSION Octadecadienoic acid,hexadecanoic acid and methyl ester were the major constituents in the leaf and callus methanolic extract.Octadecadienoic acid was the most common constituent in all samples.The maximum concentration of octadecadienoic acid in leaves,green callus and white loose callus was 21.93%,47.79%and 40.38%,respectively.These findings demonstrate that the concentration of octadecadienoic acid doubles in-vitro compared to in-vivo.In addition to octadecadienoic acid;butyric acid,benzene,1-methoxy-4-(1-propenyl),dospan,tridecanedialdehyde,methylcyclohexenylbutanol,chlorpyrifos,n-secondary terpene diester,anflunine and other important active compounds were also detected.All these components were only available in callus formed in-vitro.This study showed that the callus contained
