PbGIF1 promoting cell-proliferation in pear fruit is transcriptionally activated by Pb RR1

As a cell proliferation regulator involved in wide biological processes in plants,GRF-INTERACTING FACTOR(GIF)controls different tissues development.However,whether GIF participates in fruit development remains unclear.According to transcriptome data,we identified PbGIF1was highly expressed during fruit development in cytokinins induced parthenocarpy pear.In the present study,the biofunction of PbGIF1 was initially verified.Overexpression of PbGIF1 promoted fruit size of transgenic tomato.The size of flesh fruit was not affected by cell expansion but the cell proliferation was promoted by overexpressing Pb GIF1.The accelerated cell proliferation process was also observed in PbGIF1-overexpressed transgenic pear fruit calli.The transcriptional regulation of cytokinins on PbGIF1 was further confirmed by exogenous CPPU treatments in pear fruitlets.To investigate the underlying mechanism,the cytokinins-responded factor,PbRR1,was further focused on.The results of Yeast-one-hybrid assay suggested that PbRR1 can bind to the promoter sequence of PbGIF1.The transcriptional activation of PbRR1 on PbGIF1 was also confirmed by Dual-Luciferase assays.Taken together,the results showed that cytokinins control pear fruit development via the transcriptional activation of PbGIF1 by PbRR1.

拉盖尔–高斯光束在小尺度流场内的气动光学效应

为研究拉盖尔–高斯(LG)光束在经过由微小凸起造成的流场后的气动光学效应,采用二阶紧致差分对抛物型的复振幅微分方程进行求解,并使用四阶龙格库塔沿光束路径积分。比较了具有不同拓扑荷数的LG光束以及高斯光束在不同马赫数、不同攻角、不同海拔下的Strehl比(SR)以及成像偏移。仿真结果表明,在同样流场中,LG光束的拓扑荷数越大,相位稳定性越好且均优于高斯光束,但振幅稳定性越差,当且仅当径向指数为0,拓扑荷数为1时LG光束优于高斯光束。

Histological, hormonal and transcriptomic reveal the changes upon gibberellin-induced parthenocarpy in pear fruit

Phytohormones play crucial roles in fruit set regulation and development.Here,gibberellins(GA4+7),but not GA3,induced pear parthenocarpy.To systematically investigate the changes upon GA4+7 induced pear parthenocarpy,dynamic changes in histology,hormone and transcript levels were observed and identified in unpollinated,pollinated and GA4+7-treated ovaries.Mesocarp cells continued developing in both GA4+7-treated and pollinated ovaries.In unpollinated ovaries,mesocarp cells stopped developing 14 days after anthesis.During fruit set process,GA4+7,but not GA1+3,increased after pollination.Abscisic acid(ABA)accumulation was significantly repressed by GA4+7 or pollination,but under unpollinated conditions,ABA was produced in large quantities.Moreover,indole-3-acetic acid biosynthesis was not induced by GA4+7 or pollination treatments.Details of this GA–auxin–ABA cross-linked gene network were determined by a comparative transcriptome analysis.The indole-3-acetic acid transport-related genes,mainly auxin efflux carrier component genes,were induced in both GA4+7-treated and pollinated ovaries.ABA biosynthetic genes of the 9-cis-epoxycarotenoid dioxygenase family were repressed by GA4+7 and pollination.Moreover,directly related genes in the downstream parthenocarpy network involved in cell division and expansion(upregulated),and MADS-box family genes(downregulated),were also identified.Thus,a model of GA-induced hormonal balance and its effects on parthenocarpy were established.

Linkage map and QTL mapping of red flesh locus in apple using a R1R1×R6R6 population

The red flesh in apple fruit is a desired trait by consumers and it is associated to the anthocyanin content,which is mainly controlled by MdMYB10 with a R6 promoter.In this study,a high-density linkage group was constructed using the‘Fuji’x‘Red3’population which contained homozygous alleles R1R1 and R6R6,respectively.The linkage group consists of 7630 SNPs along 17 linkage groups,spanning 2270.21 cM,with an average density of 0.30 cM permarker.The cyanidin-3-galactoside concentration was used as the phenotypic data in QTL analysis.Moreover,one QTL peak which was flaked by two markers,marker2187260 to marker2173766,with LOD scores of 4.49 was detected.This QTL ranged from 0 to 40.79 cM on the top of linkage group(LG16).In addition one candidate molecular marker(marker2175442)in this QTL was identified,which was significant correlated with the flesh cyanidin-3-galactoside concentration.These genetic findings enrich the breeding basis of fruit flesh coloration in apple.

PbGA2ox8 induces vascular-related anthocyanin accumulation and contributes to red stripe formation on pear fruit

Fruit with stripes,which are generally longitudinal,can occur naturally,but the bioprocesses underlying this phenomenon are unclear.Previously,we observed an atypical anthocyanin distribution that caused red-striped fruit on the spontaneous pear bud sport“Red Zaosu”(Pyrus bretschneideri Rehd.).In this study,comparative transcriptome analysis of the sport and wild-type“Zaosu”revealed that this atypical anthocyanin accumulation was tightly correlated with abnormal overexpression of the gene-encoding gibberellin(GA)2-beta-dioxygenase 8,PbGA2ox8.Consistently,decreased methylation was also observed in the promoter region of PbGA2ox8 from“Red Zaosu”compared with“Zaosu”.Moreover,the GA levels in“Red Zaosu”seedlings were lower than those in“Zaosu”seedlings,and the application of exogenous GA4 reduced abnormal anthocyanin accumulation in“Red Zaosu”.Transient overexpression of PbGA2ox8 reduced the GA4 level and caused anthocyanin accumulation in pear fruit skin.Moreover,the presence of red stripes indicated anthocyanin accumulation in the hypanthial epidermal layer near vascular branches(VBs)in“Red Zaosu”.Transient overexpression of PbGA2ox8 resulting from vacuum infiltration induced anthocyanin accumulation preferentially in calcium-enriched areas near the vascular bundles in pear leaves.We propose a fruit-striping mechanism,in which the abnormal overexpression of PbGA2ox8 in“Red Zaosu”induces the formation of a longitudinal array of anthocyanin stripes near vascular bundles in fruit.

A bifunctional and recyclable catalyst:Amine and ionic liquid grafting on MOFs for the one-pot synthesis of N-aryl oxazolidin-2-ones

A bifunctional heterogeneous catalyst was designed and synthesized,denoted DMEDA/IL–NH2-MIL-101.The structure and physical-chemical characterization of DMEDA/IL–NH2-MIL-101 and its precursors were characterized by SEM,N2 adsorption-desorption,XPS,FT-IR,PXRD,elemental analysis,and TGA techniques.The date showed that the two catalytic components of N,N-dimethylethylenediamine(DMEDA)and 1-butyl-3-methylimidazolium bromide(BmimBr)were chemically immobilized in NH2-MIL-101 nanocages.The amine of DMEDA was grafted onto carrier NH2-MIL-101 by N–Cr coordinate covalent bonds and the ionic liquid of BmimBr(IL(Br-))was anchored in the NH2-MIL-101 nanocages by'ship-in-a-bottle'method,in which the amidogen of NH2-MIL-101 condensed with N,N-carbonyldiimidazole(CDI)firstly,and then alkylated with 1-bromo butane.This novel heterogeneous catalyst with two different active sites can efficiently catalyze the synthesis of N-aryl oxazolidin-2-ones from carbon dioxide(CO2),epoxides,and anilines in one-pot under mild solvent-free conditions.It not only showed good stability and recoverability after five cycles but also exhibited shape selectivity for the substrate due to the synergic catalysis of amine,ionic liquid,and NH2-MIL-101.This novel bifunctional material is a promising solid catalyst for the green synthesis of N-aryl oxazolidin-2-ones.

Apple SERRATE negatively mediates drought resistance by regulating MdMYB88 and MdMYB124 and microRNA biogenesis

The function of serrate(SE)in miRNA biogenesis in Arabidopsis is well elucidated,whereas its role in plant drought resistance is largely unknown.In this study,we report that MdSE acts as a negative regulator of apple(Malus×domestica)drought resistance by regulating the expression levels of MdMYB88 and MdMYB124 and miRNAs,including mdm-miR156,mdm-miR166,mdm-miR172,mdm-miR319,and mdm-miR399.MdSE interacts with MdMYB88 and MdMYB124,two positive regulators of apple drought resistance.MdSE decreases the transcript and protein levels of MdMYB88 and MdMYB124,which directly regulate the expression of MdNCED3,a key enzyme in abscisic acid(ABA)biosynthesis.Furthermore,MdSE is enriched in the same region of the MdNECD3 promoter where MdMYB88/MdMYB124 binds.Consistently,MdSE RNAi transgenic plants are more sensitive to ABA-induced stomatal closure,whereas MdSE OE plants are less sensitive.In addition,under drought stress,MdSE is responsible for the biogenesis of mdm-miR399,a negative regulator of drought resistance,and negatively regulates miRNAs,including mdm-miR156,mdm-miR166,mdm-miR172,and mdm-miR319,which are positive regulators of drought resistance.Taken together,by revealing the negative role of MdSE,our results broaden our understanding of the apple drought response and provide a candidate gene for apple drought improvement through molecular breeding.

CPPU may induce gibberellin-independent parthenocarpy associated with PbRR9 in‘Dangshansu’pear

Parthenocarpy is a valuable trait in self-incompatible plants,such as pear.N-(2-chloro-4-pyridyl)-N’-phenylurea(CPPU),a synthetic cytokinin analog,can induce parthenocarpy in pear(Pyrus spp.),but the mechanism of induction is unclear.To investigate the role of gibberellin in CPPU-induced parthenocarpy in pear,CPPU supplemented with paclobutrazol(PAC)was sprayed onto‘Dangshansu’pear.We found that the fruit set rate of pear treated with CPPU supplemented with PAC was identical to that in a CPPU-alone treatment group.In regard to cell development,CPPU mainly promoted hypanthium cell division and expansion,and PAC application had no influence on CPPU-induced cell development.RNA sequencing revealed that gibberellin 20 oxidase and gibberellin 3 oxidase genes were not differentially expressed following CPPU treatment.According to the analysis of fruit phytohormone content,the CPPU treatments did not induce gibberellin biosynthesis.These results suggest that CPPU-induced parthenocarpy may be gibberellin independent in‘Dangshansu’pear.After CPPU treatment,the indole acetic acid(IAA)content in fruit was significantly increased,and the abscisic acid(ABA)content was significantly decreased.Similarly,RNA sequencing revealed that many genes involved in the auxin and ABA pathways were significantly differentially expressed in the CPPU treatment groups;among them,indole-3-pyruvate monooxygenase(YUCCA)was significantly upregulated and 9-cis-epoxycarotenoid dioxygenase(NCED)was significantly downregulated.IAA and ABA may thus play important roles in CPPU-induced parthenocarpy.PbTwo-component response regulator9(PbRR9),PbYUCCA4,and PbNCED6 were then selected to further elucidate the mechanism of CPPU-induced parthenocarpy.A yeast one-hybrid assay indicated that PbRR9 can combine with the PbYUCCA4 and PbNCED6 promoters.Dual luciferase assays revealed that PbRR9 can promote and repress the activities of the PbYUCCA4 and PbNCED6 promoters,respectively.After the transient expression of PbRR9 in fruits,PbYUCCA4 expression was significantly upregulated,and PbNCED6 expression was significantly downregulated.This study uncovered a CPPU-induced parthenocarpy mechanism that is different from that in tomato.CPPU may upregulate PbYUCCA4 and downregulate PbNCED6 by upregulating PbRR9,thereby increasing IAA content and decreasing ABA content to ultimately induce parthenocarpy in‘Dangshansu’pear.However,because only a single time point was used and because‘botanical’and‘accessory’fruits have different structures,this conclusion is still preliminary.

PbEIL1 acts upstream of PbCysp1 to regulate ovule senescence in seedless pear

Numerous environmental and endogenous signals control the highly orchestrated and intricate process of plant senescence.Ethylene,a well-known inducer of senescence,has long been considered a key endogenous regulator of leaf and flower senescence,but the molecular mechanism of ethylene-induced ovule senescence has not yet been elucidated.In this study,we found that blockage of fertilization caused ovule abortion in the pear cultivar‘1913’.According to transcriptome and phytohormone content data,ethylene biosynthesis was activated by pollination.At the same time,ethylene overaccumulated in ovules,where cells were sensitive to ethylene signals in the absence of fertilization.We identified a transcription factor in the ethylene signal response,ethylene-insensitive 3-like(EIL1),as a likely participant in ovule senescence.Overexpression of PbEIL1 in tomato caused precocious onset of ovule senescence.We further found that EIL1 could directly bind to the promoter of the SENESCENCE-ASSOCIATED CYSTEINE PROTEINASE 1(PbCysp1)gene and act upstream of senescence.Yeast one-hybrid and dual-luciferase assays revealed the interaction of the transcription factor and the promoter DNA sequence and demonstrated that PbEIL1 enhanced the action of PbCysp1.Collectively,our results provide new insights into how ethylene promotes the progression of unfertilized ovule senescence.

中国公共政策扩散动力机制研究

公共政策扩散研究发端于西方并已取得长足的进步和发展。在我国,公共政策扩散现象亦越来越受到学界的重视。在公共政策扩散研究中,扩散的动力机制是中西方研究都关注的焦点。通过分析中西方的公共政策扩散动力机制并对其进行比较,论文试图回答'我国的公共政策扩散动力机制是什么'以及'与西方公共政策扩散动力机制有何区别'的问题。经过研究发现,我国特殊的政治体制造成了我国与西方国家不同的竞争动因,而我国不完善的政策诉求表达渠道和府际交流上的随意性为我国的公共政策扩散过程埋下了很大的隐患。这些都是我国未来公共政策扩散中需要改正和完善的地方。