Genome-wide identification of the CONSTANS-LIKE(COL)family and mechanism of fruit senescence regulation by PpCOL8 in sand pear(Pyrus pyrifolia)

Pyrus pyrifolia Nakai‘Whangkeumbae'is a sand pear fruit with excellent nutritional quality and taste.However,the industrial development of pear fruit is significantly limited by its short shelf life.Salicylic acid(SA),a well-known phytohormone,can delay fruit senescence and improve shelf life.However,the mechanism by which SA regulates CONSTANS-LIKE genes(COLs)during fruit senescence and the role of COL genes in mediating fruit senescence in sand pear are poorly understood.In this study,22 COL genes were identified in sand pear,including four COLs(Pp COL8,Pp COL9a,Pp COL9b,and Pp COL14)identified via transcriptome analysis and 18 COLs through genome-wide analysis.These COL genes were divided into three subgroups according to the structural domains of the COL protein.Pp COL8,with two B-box motifs and one CCT domain,belonged to the first subgroup.In contrast,the other three Pp COLs,Pp COL9a,Pp COL9b,and Pp COL14,with similar conserved protein domains and gene structures,were assigned to the third subgroup.The four COLs showed different expression patterns in pear tissues and were preferentially expressed at the early stage of fruit development.Moreover,the expression of Pp COL8 was inhibited by exogenous SA treatment,while SA up-regulated the expression of Pp COL9a and Pp COL9b.Interestingly,Pp COL8 interacts with Pp MADS,a MADS-box protein preferentially expressed in fruit,and SA up-regulated its expression.While the production of ethylene and the content of malondialdehyde(MDA)were increased in Pp COL8-overexpression sand pear fruit,the antioxidant enzyme(POD and SOD)activity and the expression of Pp POD1 and Pp SOD1 in the sand pear fruits were down-regulated,which showed that Pp COL8 promoted sand pear fruit senescence.In contrast,the corresponding changes were the opposite in Pp MADS-overexpression sand pear fruits,suggesting that Pp MADS delayed sand pear fruit senescence.The co-transformation of Pp COL8 and Pp MADS also delayed sand pear fruit senescence.The results of this study revealed that Pp COL8 can play a key role in pear fruit senescence by interacting with Pp MADS through the SA signaling pathway.

Insights into the dwarfing mechanism of pear(Pyrus betulaefolia) based on anatomical and structural analysis using X-ray scanning

The lack of a suitable rootstock to control scion growth has limited the development of high-density plantations in pear production, which is partly attributed to poor understanding of the dwarfing mechanism. In the present study, the rootstock of the dwarf-type pear (Pyrus betulaefolia)PY-9’ was identified and used as the material for anatomical analysis.PY-9’ grew to half the tree height of the normal cultivar Zhengdu’, along with fewer internodes and shorter length. Significant differences in growth rate betweenPY-9’ andZhengdu’ were detected at approximately 30 days after full bloom, which corresponded with the time of the greatest difference in water potential between the dwarf and normal cultivar.PY-9’ showed a higher photosynthetic rate thanZhengdu’. Anatomical analysis showed thatPY-9’ had higher area ratios of both phloem and xylem and more developed vascular tissues thanZhengdu’. The three-dimensional reconstructed skeleton of the xylem from X-ray computed tomography scanning revealed greater intervessel connectivity inZhengdu’ than inPY-9’, which could contribute to the more vigorous growth ofZhengdu’. This study thus provides the first comparison of the microstructural properties of xylem elements between a dwarfing-type and vigorous-type pear rootstock, providing new insights into the dwarfing mechanism in pear and facilitating breeding of dwarf pear rootstocks to increase crop productivity.

野生秋子梨(Pyrus ussuriensis Maxim)果实性状的遗传多样性

【目的】探讨野生秋子梨果实形态、香气物质及糖酸组分的遗传变异及遗传多样性,为野生秋子梨种质资源的保护与利用提供基本资料。【方法】以迁地保存圃的35个野生秋子梨实生株系的果实为试材,以‘小香水’梨、‘京白’梨和‘南果’梨3个秋子梨栽培品种为对照,测量果实的纵径、横径、果形指数(纵径/横径)及单果重,采用静态顶空和气相色谱-质谱联用、高效液相色谱技术,定性、定量分析果实的糖酸组分和香气物质。【结果】野生秋子梨各实生株系果实大小、香气成分总含量、各类香气成分种类数及其含量、主要香气成分分离比率与具体含量、各糖酸组分的含量、总糖以及总酸含量等均存在广泛的遗传变异,变异系数均在17%以上,各株系间差异明显,表现出丰富的遗传多样性;进一步与3个栽培品种比较发现,野生秋子梨的果实纵径、横径及单果重均小于3个栽培品种,但果形指数比较接近;野生秋子梨平均每个株系检测出41种香气成分,明显高于栽培品种的平均香气种类(25种);野生秋子梨平均香气成分含量为9.44μg·g-1,显著高于3个栽培品种的平均含量(5.71μg·g-1);野生秋子梨与栽培品种相比,含有酸类和烃衍生物类2类特有化合物,含有酯类等9类111种特有成分;野生秋子梨与3个栽培品种共检测出16种特征香气,其中1-己醇和己醛等8种化合物为野生秋子梨与3个栽培品种共有的特征香气,乙酸己酯和乙酸戊酯等8种特征香气为野生秋子梨特有;35个野生秋子梨实生株系和栽培品种中几乎均能检测出果糖、葡萄糖和蔗糖等3种糖组分以及苹果酸、酒石酸和柠檬酸等6种酸组分,且均以果糖和苹果酸含量最高;野生秋子梨中酒石酸及蔗糖含量明显高于栽培品种,其他糖酸组分、总糖及总酸含量最大值均高于3个栽培品种。【结论】野生秋子梨在果实形态、糖酸组分及香气成分上存在广泛的遗传变异,参试的35个实生株系间差异明显,遗传多样性极为丰富,并且含有酸类和烃衍生物类2类特有化合物和111种特有成分,进一步挖掘利用的潜力巨大。

Adaptive responses of Acer ginnala, Pyrus ussuriensis and Prunus davidiana seedlings to soil moisture stress

One-year-old seedlings of Amur maple (Acer ginnala Maxim), Ussurian pear (Pyrus ussuriensis Maxim) and David peach (Prunus davidiana Carr) were planted in pots in greenhouse and treated with four different soil moisture contents (75.0%, 61.1%, 46.4% and 35.4%). The results showed that net photosynthesis rate (NPR), transpiration rate (TR) and stomatal conductance (Sc) of seedlings of the three species decreased with the decease of soil moisture content, and Amur maple seedlings had the greatest change in those physiological indices, followed by Ussurian pear, David peach. Amur maple and Ussurian pear seedlings also presented a decrease tendency in water use efficiency (WUE) under lower soil moisture content, whereas this was reversed for David peach. Under water stress the biomass allocation to seedling root had a significant increase for all the experimental species. As to root/shoot ratio, Amur maple seedlings had the biggest increase, while David peach had the smallest increase. The leaf plasticity of Amur maple seedlings was greater, the leaf size and total leaf area decreased significantly as the stress was intensified. No significant change of leaf size and total leaf area was found in seedlings of Ussurian pear and David peach. It was concluded that Amur maple was more tolerant to soil moisture stress in comparison with David peach and Ussurian pear.

库尔勒香梨HB基因家族鉴定及其在越冬过程中的表达分析

【目的】HB家族转录因子具有调控植物器官发育和响应非生物及生物胁迫的功能。揭示库尔勒香梨HB基因家族成员在越冬过程中的表达模式及其调控机制,为深入研究库尔勒香梨HB家族基因的生物学功能提供理论基础。【方法】基于库尔勒香梨的全基因组数据库,利用生物信息学对HB基因家族成员进行鉴定,并对这些基因的系统发育、染色体定位、基因结构、启动子顺式作用元件及家族内共线性进行分析。同时,利用越冬转录组数据,对这些基因在越冬过程的差异表达模式进行分析。【结果】库尔勒香梨基因组中共鉴定出93个HB基因家族成员,分为8个亚家族。这些基因在17条染色体上不均匀分布,其编码的蛋白质在大小、相对分子质量和等电点等方面表现出显著多样性。顺式作用元件分析表明,大量的HB基因含有响应光(97.85%)、脱落酸(78.49%)、赤霉素(50.54%)、低温(41.94%)和干旱(54.84%)等环境应激的顺式作用元件。越冬适应性分析发现,39个HB基因在越冬过程中表现出显著的差异表达,其中23个基因在12月最冷期的表达量达到最高,暗示HB基因在低温应激下的适应性。【结论】93个PsHBs基因家族成员在越冬过程的不同时期,其表达模式存在差异。为深入理解HB基因在低温应激中的功能及其调控机制提供新见解,并为库尔勒香梨的遗传改良及环境适应性研究奠定基础。

杜梨(Pyrus betulifolia Bge.)多糖提取工艺及其清除自由基活性

通过L9(33)正交试验获得杜梨(Pyrus betulaefolia Bge.)多糖最佳提取工艺。在运用紫外光谱、红外光谱及高效液相色谱等方法研究杜梨多糖(PBP)理化性质的基础上,进一步评价了PBP对羟自由基(.OH)、超氧阴离子自由基(O2-.)和1,1-二苯基-2-苦基肼(DPPH)自由基的清除活性。结果表明,在料液比为1∶15,90℃下提取5h的最优条件下,PBP提取率达到18.65%。多角激光光散射仪分析表明,PBP分子质量为392.9kD。单糖组成分析表明,PBP是由阿拉伯糖、半乳糖醛酸、鼠李糖、半乳糖和葡萄糖组成,摩尔比为49.54∶28.68∶8.81∶8.45∶4.54。PBP不仅具有清除羟自由基和超氧阴离子自由基活性,对DPPH自由基的清除活性更强。

油红梨(Pyrus ussuriensis)果实后熟过程中香气成分的变化

通过顶空固相微萃取结合气相色谱质谱联用技术分析油红梨果实后熟不同时期挥发性组分。后熟0 d、5 d及10 d时分别检测出11、26和33种挥发性成分,主要为酯类、醛类、醇类及萜类物质。各种挥发性物质在不同的后熟时期种类及绝对含量均为升高的趋势,尤其是酯类组分的增加;35种挥发性组分中共检测出7种特征香气组分,分别为己醛、E-2-己烯醛、丁酸乙酯、2-甲基丁酸乙酯、己酸乙酯、乙酸己酯和庚酸乙酯,其中具有果香型特征的2-甲基丁酸乙酯、己酸乙酯及乙酸己酯对果实香气的贡献值较大;基于挥发性组分的差异,电子鼻能够很好的将不同时期的油红梨区分开来。

砂梨(Pyrus pyrifolia)过敏原蛋白基因(Ppmal)的克隆与表达分析

【目的】分离和克隆梨过敏原蛋白基因Ppmal(Gen Bank登录号为KP008110),探讨其在梨果实发育过程中的功能。【方法】以砂梨品种‘翠冠’[Pyrus pyrifolia(Burm.f.)Nakai]为试材,在盛花期后30 d对植株果柄进行涂抹赤霉素处理,利用同源克隆和RACE方法克隆目的基因全长序列,并通过实时荧光定量技术和半定量技术分析该基因在梨不同组织以及梨果实发育过程中的表达变化。【结果】Ppmal的全长是906 bp,含有480 bp的开放阅读框(ORF),编码159个氨基酸,预测的蛋白质相对分子质量为17.56 k D,等电点为5.62。生物信息学分析显示该基因没有信号肽序列,没有跨膜结构域,具亲水性。与其他物种的过敏原蛋白基因核苷酸序列同源性超过75%,与苹果和西洋梨编码的氨基酸序列同源性分别高达97.48%和96.23%,进化树分析表明该基因与苹果的进化关系最近。同时,定量结果显示经过赤霉素处理后的果实中该基因的表达量随着果实的生长发育呈现先降低后升高的趋势,并且具有组织差异表达的特点,其表达量在叶片中最大,其次是嫩叶,再次是花,枝条最低。【结论】获得梨Ppmal基因全长,对该基因在砂梨品种‘翠冠’发育过程中的表达分析显示,Ppmal受到赤霉素的调控,并在砂梨果实膨大期发生上调表达。

苹果梨（Pyrus Pyriforia （Burm） Nakai，cv．Pingguoli）果形畸变原因的探讨

本文研究了苹果梨果实畸变的原因，结果表明：果形偏斜与座果过多在生长期中互相挤压有关。果形严重畸变则是授粉不足或种子发育与生长不良的结果。这种变化在冬果梨的研究中也获得同样结果。对座果过多的果树可用疏花疏果的方法减少座果率。

玉露香梨组培快繁体系建立研究

【目的】针对梨品种间组培繁殖差异大、玉露香梨组培快繁体系也尚未建立的问题开展了相关研究,旨在建立玉露香梨的组培快繁技术体系,为深入开展玉露香梨的分子生物学研究和培育脱毒苗提供技术支撑。【方法】以玉露香梨(Pyrus bretschneideri‘Yuluxiang’)组培苗为试材,采用完全随机试验设计筛选影响继代增殖和生根的因素,如基本培养基及植物生长调节剂;设置暗培养和活性炭处理,对继代苗的生根条件进行优化。【结果】适宜玉露香梨组培苗继代增殖的培养基为MS+1.00 mg·L^(-1)6-BA+0.10 mg·L^(-1) NAA,繁殖系数为3.57,平均有效新梢数为1.17;适宜玉露香梨组培苗生根的培养基为1/2MS+2.00 mg·L^(-1) NAA,生根率为60.00%,生根条数为3.40。暗培养和活性炭处理均不适于玉露香梨组培苗生根,其中,暗培养0~20 d对玉露香生根无显著促进作用,且随暗培养时间延长,根部愈伤增大,茎尖枯死情况加重;活性炭对玉露香梨组培苗生根有显著抑制作用,低质量浓度活性炭(0.5 g·L^(-1))可促进地上部生长,高质量浓度活性炭(1.0~4.0 g·L^(-1))对地上部有明显抑制作用,部分组培苗的叶片出现褐化现象。移栽于温室60 d后,玉露香成活率为32.57%,植株生长良好。【结论】建立了玉露香梨组培快繁体系,筛选出适宜玉露香的继代增殖培养基、生根培养基及生根条件,并成功进行了玉露香梨生根苗的驯化移栽。

不同授粉方式下砀山酥梨早期受精生理特性与授粉效果分析

为探究不同授粉方式对砀山酥梨(Pyrus bretschneideri cv.Dangshansu)早期受精生理特性、果实动态发育和果实品质的影响,以人工授粉为对照、蜜蜂授粉为处理组,使用显微镜观察人工授粉和蜜蜂授粉后梨花花粉萌发差异,采用石蜡包埋子房切片观察子房发育差异,结合果实发育动态监测与果实品质检测,揭示2种授粉方式对梨树果实生长发育的影响。结果表明,相较于人工授粉,蜜蜂授粉后梨花花粉萌发较早,授粉后2 h已在柱头萌发,授粉后48 h到达花柱基部,椭圆型胚囊完整性更好。子房发育切片观察表明,相较于人工授粉,蜜蜂授粉后胚珠发育更快,且后期胚珠发育为种子数量更多。人工授粉和蜜蜂授粉的花序和花朵坐果率均可达到生产需要;蜜蜂授粉后,果实中苹果酸、柠檬酸和奎尼酸含量均极显著降低,葡萄糖、蔗糖和山梨醇含量均极显著升高,总酚含量显著升高。利用蜜蜂为梨树授粉,花粉萌发和到达子房基部的时间均早于人工授粉,还可以显著提升梨的果实品质。

Identification of Self-Incompatibility Genotypes in Some Sand Pears (Pyrus pyrifolia Nakai) by PCR-RFLP Analysis

The identification of self-incompatibility genotype （S-genotype） will be useful for selection of pollinizers and design of crossing in cultivar improvement of sand pear. This paper reported the identification of self-incompatibility genotypes of seven Chinese and two Japanese sand pear cultivars using PCR-RFLP analysis and S-RNase sequencing. The Sgenotypes of these cultivars were determined as follows： Huali 1 S1S3, Shounan S1S3, Xizilti S1S4, Qingxiang S3S7, Sanhua S2S7, Huangmi （Imamuranatsu） S1S6, Huali 2 S3S4, Baozhuli S7S33, Cangxixueli S5S15. S-RNase alleles （S1 to S9） in sand pear could be identified effectively by PCR-RFLP analysis.

Relationship Between Anthocyanin Biosynthesis and Related Enzymes Activity in Pyrus pyrifolia Mantianhong and Its Bud Sports Aoguan

The aim of this article is to study the relationship between biosynthesis of anthocyanin and activities of phenylalanine ammonia lyase （PAL）, chalcone ismoerase （CHI） enzymes in Pyrus pyrifolia. Changes in the level of anthocyanin and the activities of enzymes of anthocyanin biosynthesis including PAL, CHI were studied in the pericarp of Pyrus pyrifolia Aoguan and Mantianhong during the period of pigment formation. Bagging treatment was also carried out to manipulate the synthesis of anthocyanin and the activities of related enzymes during the period of pigment formation. The results demonstrated that the level of anthocyanin of Aoguan was higher than that of Mantianhong. However, the content of anthocyanins has the similar changing trend in Aoguan and Mantianhong, highest anthocyanin concentrations of two varieties appeared in immature fruit and faded toward harvest. Meanwhile, similar changing trends of activities of PAL and CHI were also observed in both varieties. Aoguan has a lower activity of PAL than Mantianhong, whereas activity of CHI in Aoguan was higher than that in Mantianhong. Activity of PAL decreased during the period of pigment formation and was apparently not limiting to color development, whereas CHI activity increased at the same period and was closely related to the synthesis of anthocyanin. The results of bagging treatment showed that bagging treatment inhibited the activity of CHI, as well as the synthesis of anthocyanin, whereas debagging enhanced both the activity of CHI and synthesis of anthocyanin. The activity of CHI in debagging Aoguan pericarp was higher than the untreated Aoguan. However, effect of bagging treatment toward PAL activity was not obvious. Anthocyanin of bagging treated Aoguan decreased toward harvest. The content of anthocyanin of Pyruspyrifolia increased at the beginning of fruit coloration period and decreased toward fruit harvest. Activity of PAL was apparently not limiting to color development, whereas CHI activity was closely related to the synthesis of anthocyanin. Debagging enhanced both the activity of CHI and anthocyanin synthesis. Bagging treatment also proved that degradation of anthocyanin was not induced only by light. Light appeared to have two opposing effects in pears： it is required for anthocyanin synthesis and also for apparently increasing red color loss through increased degradation of anthocyanin.

Cloning and Analysis of Full-Length cDNA of PumNPR1 Gene from Pyrus ussuriensis Maxim

The purpose of this study is to find a new gene resource for the researches of molecular breeding of Rosaceae plants disease-resistance. Pyrus ussuriensis Maxim is used as a starting material to clone the full-length cDNA of NPR1（nonexpressor of pathogenesis- related genes 1） which is a key regulator in SA （salicylic acid）-mediated systemic acquired resistance （SAR） by homologous cloning and RACE techniques. The length of the cDNA sequence was 1 767 bp, the ORF was 1 761 bp, it coded 586 amino acids, pi=5.58, the relative molecular weight was 65.009 ku, contained 19 kinds of amino acids, and had full BTB/POZ and ANK domains. Compared the homology of NPR1 gene in GenBank database, the homology with Pyrus pyrifolia, Arabidopsis thaliana, Nicotiana tabacum, Lycopersicon esculentum, Oryza sativa, Helianthus annuus were 98%, 62%, 68%, 65%, 57%, 63%. The homology offunctional area were 99%, 78%, 82%, 79%, 74%, 77%. This NPR1 gene was considered as homologic gene of Pyrus ussuriensis Maxim and named PumNPR1.

Isolation and Characterization of a Cinnamoyl CoA Reductase Gene(CCR) in Pear(Pyrus pyrifolia)

Pear is a popular and commercially important fresh fruit, and its texture is related to the presence of sclereid formatted by parenchyma cell with lignification in vascular plants. Previous studies have demonstrated that content of lignin may be regulated by cinnamoyl CoA reductase(CCR) in various plants. However, the function of CCR in pears remains very limited. In the present study, we isolated a cDNA encoding CCR(PpCCR, GenBank accession No. KF999958) and its promoter(proPpCCR) from Whangkeumbae pear to investigate the function of CCR in lignin biosynthesis. PpCCR-GFP expressed in rice mesophyll protoplast demonstrated that PpCCR-GFP was localized in the cytoplasm, indicating that CCR may function in cytoplasm without localization signals. In transgenic plants carrying PpCCR, we observed higher lignin content compared with that in wild type plants, further suggesting that PpCCR can affect the lignin contents through regulating lignin biosynthesis in Arabidopsis thaliana. More studies in other plants are needed to confirm our conclusion.

Integrative transcriptomic and metabolomic analyses reveal the flavonoid biosynthesis of Pyrus hopeiensis flowers under cold stress

Low temperature is among the most restrictive factors to limit the yield and distribution of pear. Pyrus hopeiensis is a valuable wild resource.PCA showed that P. hopeiensis had strong cold resistance. In this study, the mRNA and metabolome sequencing of P. hopeiensis flower organs exposed to different low temperatures were performed to identify changes of genes and metabolites in response to low-temperature stress. A total of 4 851 differentially expressed genes(DEGs) were identified. Trend analysis showed that these DEGs were significantly enriched in profiles 19, 18, 7, 14, 1, 4 and 11. And the KEGG enrichment analysis showed that the DEGs in profile 18 were significantly enriched in flavone and flavonol biosynthesis. Besides, the expressed trends as well as GO and KEGG functional enrichment analyses of DEGs under cold and freezing stress showed significantly difference. Analyses of flavonoid-related pathways indicated that flavonoid structural genes had undergone significant changes. Correlation analysis showed that b HLH and MYB TFs may affect flavonoid biosynthesis by regulating structural gene expression. And PhMYB308 and PhMYB330 were likely candidate repressors of flavonoid biosynthesis by binding to a specific site in bHLH proteins. In total, 92 differentially accumulated metabolites(DAMs) were identified in P. hopeiensis flowers including 12 flavonoids. WGCNA results showed that coral 1, pink and brown 4 modules were closely associated with flavonoids and 11 MYBs and 15 bHLHs among the three modules may activate or inhibit the expression of 23 structural genes of flavonoid biosynthesis. Taken together, the results of this study provided a theoretical basis for further exploration of the molecular mechanisms of flavonoid biosynthesis and cold resistance of P. hopeiensis flower organs and our findings laid a foundation for further molecular breeding in cold-resistant pear varieties.

Physiological Effects of Iron Deficiency on Pyrus pashia Buch-Ham

Pyrus pashia Buch-Ham, a wild specie was used to investigate the physiological effects of iron deficiency in culture solution. The result showed that Chla, Chlb, total chlorophyll content and photosynthesis rate(Pn) decreased sharply, and the decrease of Pn was prior to that of Chl content under the iron deficiency. The iron deficiency symptoms were visible when the iron concentration in culture medium was less than 25 μmol L-1. Peroxidase(POD) and catalase(CAT) activity in iron-deficient leaves declined significantly, and POD was more sensitive than CAT to Fe deficiency. However, the positive correlation between CAT activity and Chl content was more significant than that between POD activity and Chl content. The content of nutrient elements in Fe-deficient leaves, which changed irregularly, were higher than that in normal leaves. There were a most significant positive correlation between active Fe and Chl content, and between active Fe and Pn respectively. Therefore, active Fe could be useful physiological predicting index for diagnosis.

Identification and evolutionary characterization of SFBB genes in‘Yali’and its spontaneous self-compatible mutant‘Jinzhui’(Pyrus bretschneideri)

Pears carry a gametophytic self-incompatibility(SI)system.In this system,S-RNase is the SI pistil determinant,and S-locus F-box brothers(SFBBs)are candidate pollen determinants.However,compared with apple,fewer SFBB genes were identified from pear,possibly caused by the lack of economic and effective methods.Here,we used transcriptome sequencing on‘Yali’(Pyrus bretschneideri)to obtain sequence fragments of SFBB genes and then used polymerase chain reaction(PCR)to amplify the whole sequence of SFBB genes.Twenty-seven SFBB genes,including22 full-length and five nonfull-length SFBB genes,were identified in‘Yali’(P.bretschneideri).SFBBs linkage analysis by PCR-enzyme-linked immunoassay(ELISA)showed that 12 SFBB genes belong to the S21 locus,and 15 SFBB genes belong to the S34 locus.Phylogenetic analysis showed that SFBB genes from Pyrus were divided into 26 types,more than the original eight types.The intrahaplotypic divergence of SFBBs is high and comparable to the allelic diversity of S-RNase,which is consistent with a nonself-recognition SI system.In addition,the expression level of PbrSFBBs in‘Jinzhui’,the only known haploid pollen of a self-compatible mutant,was mostly approximately two times higher than in‘Yali’,which may be the reason for the self-compatible mutant.

The PcERF5 promotes anthocyanin biosynthesis in red-fleshed pear(Pyrus communis)through both activating and interacting with PcMYB transcription factors

As there is a strong interest in red-skinned pears,the molecular mechanism of anthocyanin regulation in red-skinned pears has been widely investigated;however,little is known about the molecular mechanism of anthocyanin regulation in red-fleshed pears due to limited availability of such germplasm,primarily found in European pears(Pyrus communis).In this study,based on transcriptomic analysis in red-fleshed and white-fleshed pears,we identified an ethylene response factor(ERF)from P.communis,PcERF5,of which expression level in fruit flesh was significantly correlated with anthocyanin content.We then verified the function of PcERF5 in regulating anthocyanin accumulation by genetic transformation in both pear skin and apple calli.PcERF5 regulated anthocyanin biosynthesis by different regulatory pathways.On the one hand,PcERF5 can activate the transcription of flavonoid biosynthetic genes(PcDFR,PcANS and PcUFGT)and two key transcription factors encoding genes PcMYB10 and PcMYB114.On the other hand,PcERF5 interacted with PcMYB10 to form the ERF5-MYB10 protein complex that enhanced the transcriptional activation of PcERF5 on its target genes.Our results suggested that PcERF5 functioned as a transcriptional activator in regulating anthocyanin biosynthesis,which provides new insights into the regulatory mechanism of anthocyanin biosynthesis.This new knowledge will provide guidance for molecular breeding of red-fleshed pear.

Advances in Origin,Evolution and Classification of Pyrus L.

China is not only one of the origin centers of Pyrus L.,but also the earliest birthplace of Pyrus L.in the world.This paper reviews the evolution of Pyrus L.from the aspects of leaf edge morphology,inflorescence and fruit type,and summarizes the research progress of classification and species distribution of Pyrus L.,which is of great significance for the protection,evaluation and utilization of germplasm resources.