Strigolactones interact with other phytohormones to modulate plant root growth and development

Strigolactones(SLs),which are biosynthesized mainly in roots,modulate various aspects of plant growth and development.Here,we review recent research on the role of SLs and their cross-regulation with auxin,cytokinin,and ethylene in the modulation of root growth and development.Under nutrientsufficient conditions,SLs regulate the elongation of primary roots and inhibit adventitious root formation in eudicot plants.SLs promote the elongation of seminal roots and increase the number of adventitious roots in grass plants in the short term,while inhibiting lateral root development in both grass and eudicot plants.The effects of SLs on the elongation of root hairs are variable and depend on plant species,growth conditions,and SL concentration.Nitrogen or phosphate deficiency induces the accumulation of endogenous SLs,modulates root growth and development.Genetic analyses indicate cross-regulation of SLs with auxin,cytokinin,and ethylene in regulation of root growth and development.We discuss the implications of these studies and consider their potential for exploiting the components of SL signaling for the design of crop plants with more efficient soil-resource utilization.

Global Dynamic Molecular Profiling of Stomatal Lineage Cell Development by Single-Cell RNA Sequencing

The regulation of stomatal lineage cell development has been extensively investigated.However,a comprehensive characterization of this biological process based on single-cell transcriptome analysis has not yet been reported.In this study,we performed RNA sequencing on 12844 individual cells from the cotyledons of 5-day-old Arabidopsis seedlings.We identified 11 cell clusters corresponding mostly to cells at specific stomatal developmental stages using a series of marker genes.Comparative analysis of genes with the highest variable expression among these cell clusters revealed transcriptional networks that regulate development from meristemoid mother cells to guard mother cells.Examination of the developmental dynamics of marker genes via pseudo-time analysis revealed potential interactions between these genes.Collectively,our study opens the door for understanding how the identified novel marker genes participate in the regulation of stomatal lineage cell development.

Arabidopsis calcium-dependent protein kinase CPK28 is potentially involved in the response to osmotic stress

As calcium sensors, plant calcium-dependent protein kinases(CDPKs) play important roles in plants' responses to various abiotic stresses. Here, we report the functional characterization of CPK28, a member of the CDPK family in Arabidopsis, in response to osmotic stress.The cpk28 mutant, a loss-of-function mutant, exhibited an NaCl- and mannitol-sensitive phenotype in green cotyledons, while CPK28-overexpressing plants displayed stronger tolerance to NaCl and mannitol stresses than wildtype plants. Reverse transcriptase-polymerase chain reaction and beta-glucuronidase staining assays showed that NaCl and mannitol stresses induced CPK28. CPK28-overexpressing lines accumulated significantly more proline relative to wild-type plants and mutant plants under NaCl and mannitol stresses. Transient expression of CPK28-GFP in mesophyll cell protoplasts, as well as stable transgenic lines expressing CPK28-GFP, showed that CPK28 was localized in the plasma membrane. Expression levels of known stress-responsive genes were not significantly altered in the null mutant and overexpression lines,suggesting that CPK28 possibly mediated the stress response via the regulation of target proteins rather than via regulation at the level of transcription. Meanwhile, CPK28could autophosphorylate. Taken together, these data demonstrated that CPK28, a potential positive regulator, is involved in the response to osmotic stress in Arabidopsis.

理性设计拢牛儿物牛儿基焦磷酸合酶(GGPPS)能够显著增强模式植物烟草类胡萝卜合成及光合作用效率

植物品种培育的关键是寻找优良基因.通过理性设计对植物关键酶进行改造,有望为植物品种培有提供新的优良基因.NtGGPPSI是烟草类胡萝卜素合成途径的限速酶,ntggppsl突变体类胡萝卜含量显著降低.对NtGGPPS1进行理性设计,重塑酶与底物的结合口袋,构建单点饱和突变体文库.通过高通量的细菌颜色实验进行筛选,获.得5个可以显著提升酶活性的氨基酸位点,进一步对以上位点进行迭代组合突变获得酶活性最高的5突变体d-NtGGPPS1(V154A/1161L/F218Y/1209S/V233E).相对于NtGGPPSI,理性设计的d-NtGGPPSI可以将底物IPP和共同底物DMAPP转化为GGPP的效率提高约1995.5倍,能够将GPP或FPP转化产生GGPP的效率提高约25.9或16.7倍.将d-NtGGPPSI回补到ntggppsI突变体可以显著提升叶片类胡萝卜含量,生物量及光合作用效率.该研究表明理性设计GGPPS可以提升植物的产量和品质性状,并为未来通过理性设计获得植物优良基因提供新的突破口.

SRO1 regulates heavy metal mercury stress response in Arabidopsis thaliana

Heavy metals in the environment are harmful limiting factors for the normal growth and development of plants.Here,we isolated and identified an Arabidopsis thaliana T-DNA insertion mutant,named sro1-1,which showed a hyper-sensitive response to HgCl2.The SRO1protein contains a WWE domain that mediates proteinprotein interactions.Under HgCl2treatment,when compared with the wild-type plants,the growth of sro1-1 was repressed dramatically and the number of true leaves was reduced and etiolated.The electrolyte leakage rates showed that cell membrane integrity in sro1-1 was damaged more severely than in the wild type.DAB(3,5-diaminobenzidine)staining and confocal microscopy showed that Hg2?stress induced more hydrogen peroxide accumulation in sro1-1 than in the wild type.The qRT-PCR results indicated that the expression of some abiotic stress-induced genes,such as L-ascorbate peroxidase(APX1),was reduced under oxidative or Hg2?stress.Transgenic plants containing a GFP::SRO1 fusion protein showed that SRO1was localized in the nucleus of the cells.SRO1 was shown to be expressed in various tissues,and was most highly expressed in the vigorous tissues.Our results suggest thatSRO1 may play an important role in the stress response of A.thaliana to heavy metals.

Generation of the genetic mutant population for the screening and characterization of the mutants in response to drought in maize

The autonomous Mutator(Mu)transposon in maize(Zea mays L.)lines 115F,330I,and 715D were crossed with inbred lines B73,Mo17,97108,and H9-21,M1were self-pollinated to establish the Mu insertion-mutagenized M2seeds pool and The M2plants encompassed a large amount of biological variation relevant to improving agronomy traits by observed in the field.Next we statistically analyzed these candidate mutants.Under drought stress,we screened seedlings at 3-leaf stage by using the infrared thermography,and successfully got 108 droughtinsensitive and 121 drought-sensitive candidate mutants from more than 38,000 lines,which temperature were significant different with others.These candidate mutants were primarily analyzed by infrared thermography,chlorophyll fluorescence,leaf water losing,photosynthetic characteristics,content of soluble sugars,soluble protein,and proline assay.The selected mutants were cloned by MuTAIL–PCR methods.Here we provide the better genetic materials for research on maize breeding for drought tolerance.

Future challenges in understanding ROS in plant responses to abiotic stress

Plants must cope with a variety of environmental stresses.Most types of abiotic stresses,such as drought,salinity,flooding,heat and cold stress,disrupt the metabolic balance of cells,resulting in the enhanced production of reactive oxygen species(ROS).While being well-known as a toxic by-product,recent studies about ROS focus on their roles as signaling molecules.It has been reported that ROS functions in plant cell proliferation and cell expansion,root

Na_(2)CO_(3)-responsive Photosynthetic and ROS Scavenging Mechanisms in Chloroplasts of Alkaligrass Revealed by Phosphoproteomics

Alkali-salinity exerts severe osmotic,ionic,and high-p H stresses to plants.To understand the alkali-salinity responsive mechanisms underlying photosynthetic modulation and reactive oxygen species(ROS)homeostasis,physiological and diverse quantitative proteomics analyses of alkaligrass(Puccinellia tenuiflora)under Na_(2)CO_(3)stress were conducted.In addition,Western blot,real-time PCR,and transgenic techniques were applied to validate the proteomic results and test the functions of the Na_(2)CO_(3)-responsive proteins.A total of 104 and 102 Na_(2)CO_(3)-responsive proteins were identified in leaves and chloroplasts,respectively.In addition,84 Na_(2)CO_(3)-responsive phosphoproteins were identified,including 56 new phosphorylation sites in 56 phosphoproteins from chloroplasts,which are crucial for the regulation of photosynthesis,ion transport,signal transduction,and energy homeostasis.A full-length Pt FBA encoding an alkaligrass chloroplastic fructosebisphosphate aldolase(FBA)was overexpressed in wild-type cells of cyanobacterium Synechocystis sp.Strain PCC 6803,leading to enhanced Na_(2)CO_(3)tolerance.All these results indicate that thermal dissipation,state transition,cyclic electron transport,photorespiration,repair of photosystem(PS)Ⅱ,PSI activity,and ROS homeostasis were altered in response to Na_(2)CO_(3)stress,which help to improve our understanding of the Na_(2)CO_(3)-responsive mechanisms in halophytes.