Molecular cloning,identification,and chromosomal localization of two MADS box genes in peach(Prunus persica)

MADS box proteins play an important role in floral development. To find genes involved in the floral transition of Prunus species, cDNAs for two MADS box genes, PpMADS1 and PpMADSIO, were cloned using degenerate primers and 5＇- and T-RACE based on the sequence database of P. persiea and P. duleis. The full length of PpMADS1 cDNA is 1,071 bp containing an open reading frame （ORF） of 717 bp and coding for a polypeptide of 238 amino acid residues. The full length of PpMADSIO cDNA is 937 bp containing an ORF of 633 bp and coding for a polypeptide of 210 amino acid residues. Sequence comparison revealed that PpMADS1 and PpMADSIO were highly homologous to genes API and PI in Arabidopsis, respectively. Phylogenetic analysis indicated that PpMADS1 belongs to the euAP1 clade of class A, and PpMADSIO is a member of GLO/PI clade of class B. RT-PCR analysis showed that PpMADS1 was expressed in sepal, petal, carpel, and fruit, which was slightly different from the expression pattern ofAPl; PpMADS10 was expressed in petal and stamen, which shared the same expression pattern as PI. Using selective mapping strategy, PpMADSI was assigned onto the Binl：50 on the G1 linkage group between the markers MCO44 and TSA2, and PpMADSIO onto the Bin1：73 on the same linkage group between the markers Lap- 1 and FGA8. Our results provided the basis for further dissection of the two MADS box gene function.

Effects of nitrogen content on growth and hydraulic characteristics of peach(Prunus persica L.) seedlings under different soil moisture conditions

A pot experiment was conducted to investigate the effects of nitrogen content [Nl （no fertilizer）, N2 （0.15 g.kg-l）, and N3 （0.3 g.kg 1）] on the growth and the hydraulic characteristics of peach seedlings under different soil moisture conditions （Wl, W2 and W3, in which the soil water content was 45% to 55%, 60% to 70%, and 75% to 80% of the field water capacity, respectively） by using a specialized high pressure flow meter with a root chamber and a coupling, which was connected to plant organs. Leaf area and leaf hydraulic conductivity （KL） increased significantly in the seedlings because of increased soil moisture and N content. KL increased with leaf area. A linear correlation was documented between KL and leaf area. KL was higher in the morning and began to decline sharply after 16：00, at which KL declined after an initial increase. Soil moisture and N content enhanced shoot （Ks） and root （Kr） hydraulic conductivities, thereby improving the low soil moisture condition to a large extent. Ks and Kr of the seedlings were reduced by 32% and 27% respectively in N~, and by 14.7% and 9.4%, respectively in N2, and both in Wb compared with the control treatment. N3 had no significant effect on Ks and Kr under similar conditions. Linear negative correlations were observed between Kr and the excised root diameter as well as between Ks and the shoot stem diameter. The shoot-to-root ratio increased with in- crease in N content. The shoot-to-root ratio in N3 was increased by 14.37%, compared with N1 in W1 as well as by 12% and 4.39% in Wz and W3, respectively. Knowledge of the effects of soil moisture and N fertilizer on hydraulic characteristics and growth is important. Our results provide basic guidelines for the implementation of water-saving irrigation and fertilization management of nursery stock.

Novel in silico EST-SSR markers and bioinformatic approaches to detect genetic variation among peach(Prunus persica L.)germplasm

Because there are thousands of peach cultivars,cultivar classification is a critical step before starting a breeding project.Various molecular markers such as simple sequence repeats(SSRs)can be used.In this study,67 polymorphic primers produced 302 bands.Higher values for SI index(1.903)suggested higher genetic variability in the genotype under investigation.Mean values for observed alleles(Na),expected heterozygosity(He),effective alleles(Ne),Nei’s information index(h),and polymorphic information content(PIC)were 4.5,0.83,5.45,0.83,and 0.81,respectively.The dendrogram constructed based on Jaccard’s similarity coefficients outlined four distinct clusters in the entire germplasm.In addition,an analysis of molecular variance(AMOVA)showed that70.68%of the total variation was due to within-population variation,while 29.32%was due to variation among populations.According to this research,all primers were successfully used for the peach accessions.The EST-SSR markers should be useful in peach breeding programs and other research.

桃(Prunus persica(L.) Batsch.)品种核心种质的构建与评价

为构建桃品种核心种质,通过对56份桃（Prunus persica（L.） Batsch.）初级核心种质的形态农艺性状数据（MOR）和SSR等位基因数据的分析,研究了不同聚类取样方法和完全随机取样方法下9种取样比例的遗传多样性指数、保留比例及各频率段等位基因的丢失比例。结果表明：聚类取样的方法优于完全随机取样,并以在80%的取样比例下MOR结合SSR数据聚类取样的效果最好,利用此方案构建的桃品种核心种质共包括45份材料,该核心种质的基因遗传多样性指数最高,保留了初级核心种质100%的形态农艺性状和96.6%的SSR等位基因,在出现频率低于0.05的等位基因中共丢失了2个等位变异,保留了出现频率在0.05-0.10的所有等位基因;利用6个数量性状对所构建的核心种质的代表性检测表明所构建的核心种质很好地代表558份桃原始种质的遗传变异。

Effects of Weak Light on the Ultrastructural Variations of Phloem Tissues in Source Leaves of Three-Year-Old Nectarine Trees(Prunus persica L.var. nectarina Ait.)

Leaves from three_year_old solar greenhouse nectarine trees ( Prunus persica L. var. nectarina Ait. “Zao Hong Yan”) were used as materials in this study. It was the first time that the ultrastructural characteristics of phloem tissues of source leaves were observed and compared in normal and weak light intensities using the transmission electron microscopy. Results showed that the average diameters of companion cells (CC) and sieve elements (SE) of all kinds of veins were bigger in normal than that in weak light intensity, indicating that light could influence the cell development and growth. Dense cytoplasm with abundant mitochondria, endoplasmic reticulums, multivesicular bodies, vesicles and plastids were observed in normal light intensity. On the contrary, CC with small vacuolar structures and few mitochondrias, endoplasmic reticulums were shown in weak light. Misalignment of grana thylakoid margins of nectarine leaves also was seen in weak light. The sieve pores of SEs were obstructed in weak light. Chloroplasts with numerous starch grains and few mitochondrias were noticed in the mesophyll cell (MES) surrounding the bundle sheath in weak light. The storage of starch grains appeared to result from an unbalance between photosynthate production and export of photosynthates. This observation provided a strong support to the point that most leaves export the most of assimilates in the light time. Plasmodesmal densities between SE/CC, CC/PP (phloem parenchyma cell), PP/PP and PP/BSC (bundle_sheath cell) decreased in weak light. Plasmodesmata were observed between CC/SE (NS) (nacreous_walled sieve element), PP/BSC in branch veins in normal light intensity, but not in weak light. Thus apoplasmic pathway may be the main mode of transport of assimilates in weak light, however symplasmic pathway may be the main mode of transport of assimilates in normal light intensity. These results demonstrated that the solar greenhouse nectarine trees could be adapted to the weak light via the ultrastructure variation of phloem tissues of the source leaves.

Study on SSR Markers Linked to Flesh Color around the Stone of Prunus persica(L.) Batsch

[Objective] This study aimed to select SSR molecular markers linked to flesh color around the stone of Prunus persica （L.） Batsch. [Method] P. persica （L.） Batsch varieties Chongyanghong and Yanhong were used as parents to construct F1 orthogonal group. A total of 138 FI individuals were selected as experimental materi- als for construction of color around the stone gene pool （B1） and non-color around the stone gene pool （B2） by using bulked segregant analysis （BSA） method, molec- ular markers linked to the flesh color around the stone of P. persica （L.） Batsch were selected with SSR molecular marker technology. [Result] After selection with 256 pairs of SSR primers, three pairs of molecular markers linked to the gene con- trolling flesh color around the stone of P. persica （L.） Batsch were selected （UDP96- 003, ch04g09 and UDP97-402）. In addition, genetic distances between the three molecular markers and the gene controlling flesh color around the stone of P. persi- ca （L.） Batsch were calculated, which were 16.7, 10.1 and 17.0 cM, respectively. [Conclusion] This study laid the foundation for further selection of co-dominant molecular markers with closer genetic distance.

The Potential Efficacy of Glycyrrhizic Acid and Its Nanostructure Against Brown Rot of Peach fruits

Production of peaches(Prunus persica(L.)Batsch)for both local market and export is increasing each year in Egypt.Brown rot disease,caused by Monilinia laxa and Monilinia fructigena,is considered one of the most important postharvest rots affecting peaches in Egypt and economic losses are increasing.Antifungal activity of glycyrrhizic acid nanoparticles(GA-NPs)and glycyrrhizic acid(GA)at 0.2 and 0.4 mmol/L was investigated as a control for both these brown rot pathogens on peach fruits in both in vitro and in vivo studies.In the in vitro studies,GA-NPs were the most effective as shown by the ability to decrease linear growth of both brown rot pathogens in potato dextrose agar(PDA)amended with 0.4 mmol/L GA-NPs.Micrographs of M.fructigena exposed to 0.4 mmol/LGA showed mycelial deformations,nodule formation,detachment of the cell wall,shrinkage and inhomogeneous cytoplasmic materials with large vacuoles.Mycelium of M.laxa exposed to 0.4 mmol/LGA-NPs resulted in thinner and distorted hyphae,nodule formation,cell wall thinning,and swellings.The GANPs and GA treatments improved fruit quality by maintaining firmness and total soluble solids(TSS).GA-NPs were more effective in decreasing decay incidence than their bulk material.The 0.4 mmol/L GA-NPs completely inhibited the disease on naturally infected peach fruits for both seasons of 2018 and 2019.Furthermore,0.4 mmol/L GA-NPs reduced the disease incidence in inoculated fruits by 95(M.laxa)and 88%(M.fructigena)in 2018 season and 96(M.laxa)and 85%(M.fructigena)in 2019 season.In conclusion,GA-NPs could enhance the resistance of peaches against brown rot caused by M.laxa and M.fructigena.

Identification and expression analysis of chlorogenic acid biosynthesis key gene PpHCT in peach

Shikimic acid/quinic acid hydroxy cinnamyl transferase(HCT)is one of the key enzymes in the phenylpropanoid pathway.However,the role of the HCT gene in chlorogenic acid(CGA)biosynthesis in peach fruit remains unclear.For this,we identified the accumulation pattern of CGA in four peach cultivars,cloned and characterized 11 PpHCT gene members,and further analyzed the expression patterns of these PpHCT genes during fruit development.The contents of CGAs in the four peach cultivars all exhibited a trend of increasing and then decreasing during the fruit growth and development.Moreover,the contents of CGAs in the peel and flesh were tissue-specific.Gene structure analysis indicated that the PpHCT genes were highly conserved,containing two exons and one intron.The protein structure analysis demonstrated that the PpHCT proteins contained two conserved motifs(HXXXD,DFGWG)and a transferase domain(PF02458),which belonged to the BAHD acyltransferase family.The cis-acting element analysis suggested that the promoters of PpHCT genes contained many light-related,hormone-related,stress-related,tissue-specific,and circadian-related elements,and they could participate in a variety of biological processes.Phylogenetic analysis showed that the HCT proteins of peach were closely related to the HCT proteins of plum and had a close evolutionary relationship.The qRT-PCR analysis indicated that the expression levels of PpHCT1 and PpHCT2 showed an opposite trend to the accumulation of CGA,whereas the expression levels of PpHCT4,PpHCT5,PpHCT7,PpHCT8,and PpHCT11 demonstrated the same trend as CGA accumulation.It was worth noting that only PpHCT4 and PpHCT5 were highly expressed in the two high-CGA cultivars but showed low levels of expression in the two low-CGA cultivars.Therefore,it was hypothesized that these two genes might be key genes to the synthesis of CGA in peach fruit.Those findings provide a theoretical basis for further study on the biological functions of the HCT gene and help to reveal the molecular mechanism of CGA.

Molecular Identification and Cultivar Fingerprints of Prunus persica (L.) Batsch Germplasms

[Objective] The aim was to study the molecular identification and cultivar fingerprints of Prunus persica (L.) Batsch germplasms.[Method] Sixty peach genotypes,representing China common local cultivars and European samples were screened by microsatellites (simple sequence repeats,SSRs) and Inter-Simple Sequence Repeat (ISSR) markers.[Result] 26 reproducible bands were amplified by Nine SSR primers,and 24 of which were polymorphic; 236 bands were amplified by 30 ISSR primers,and 113 of which were polymorphic.31 genotypes were discriminated with 1-3 distinct polymorphic bands generated from the primers ISSR and SSR.Seven cultivar-specific ISSR fragments and two SSR unique alleles obtained from this study were available to be converted into Sequence Characterized Amplified Region (SCAR) markers.The genetic similarity coefficient (GS) estimated from these molecular data averaged were 0.939 (ranged from 0.856 to 0.983) for ISSR and 0.646 (ranged from 0.240 to 1.000) for SSR,respectively.The combined grouping association indicated that most local Chinese peach cultivars and exotic accessions were clustered together.This could be related to the mode of introduction and maintenance of the peach cultivars involving limited foundation germplasm,exchange of cultivars between plantations,and periodic development of new recombinant cultivars following sexual reproduction.[Conclusion] The results obtained in this work would help to improve the conservation,molecular identification and management of peach germplasm in breeding.

Relationships Between the Distribution of Relative Canopy Light Intensity and the Peach Yield and Quality

The aim of the present experiment was to study the relationship between the distribution of relative light intensity in canopy and yield and quality of Wanmi peach. The optimum relative canopy light intensity was judged to be 36.3% for high quality peaches, when canopy volumes of Wanmi peach trees with a relative light intensity 〈 30% accounted for 7.7 and 47.9% of the total canopy volume in June and September, respectively. The canopy volume with a relative light intensity 〉 80% was 27.7 and 3.1% of the total canopy volume in June and September, respectively. Peach canopies were divided into 0.5 m × 0.5 m × 0.5 m cubes, with the relative light intensity being measured at different positions of the canopy during the growing season. Yield and fruit quality were also measured at these positions at harvest. The results showed that the relative light intensity decreased gradually from outside to inside and from top to bottom of the tree canopy. Fruit were mainly distributed in the upper and middle portions of the canopy, 1.5-3.0 m above ground. Regression results showed that single fruit weight and soluble solid content were positively related to relative light intensity.

Effects of Different Storage Methods on the Fruit Quality and Physiological Changes in Yihong Honey Peach

Taking Yihong,the main cultivar of mid-ripening honey peaches(Prunus persica)in Hunan,as material,this study explored the effects of different storage methods on the fruit quality and physiological changes in Yihong honey peach by the combination of polyethylene film packaging with low-temperature storage.The results showed that the weight loss rate of packaged storage at normal temperature(T1)was significantly lower than that of unpackaged storage at normal temperature(CK),but there was no significant difference in other indicators.In the middle of storage,the respiration rate and ethylene release of packaged storage at 0℃(T3)were extremely significantly lower or significantly lower than those of unpackaged storage at 0℃(T2),packaged storage at 0℃after cold adapting at 8℃for 5 d(T4),and packaged storage in a fluctuating temperature range of 0~3.5℃(T5).After storage,the structure of the middle lamella in the cell wall of T3 was compact and uniform,and the mitochondrial structure was complete,while the cell walls and mitochondria of T4 and T5 were severely deformed and disintegrated.The activities of antioxidant enzymes peroxidase(POD)and superoxide dismutase(SOD)of T3 was significantly higher than those of T4 and T5,and the content of malondialdehyde(MDA)and polyphenol oxidase(PPO)of T3 was also the lowest.Therefore,0°C packaged storage can effectively delay the senescence of Yihong honey peach and prolong its freshness period.

Effects of Nitric Oxide and Exogenous Ethylene Treatments on Ethylene Biosynthesis in Feicheng Peach

The effects of nitric oxide （NO） and exogenous ethylene on ethylene biosynthesis in harvested Feicheng peaches were studied. The antagonistic actions between NO and exogenous ethylene was also investigated. The Feicheng peaches were fumigated with 10μL L^-1 NO, 1 000 μL L^-1 ethylene, or 10 μL L^-1 NO plus 1 000 μL L^-1 ethylene for 3 h. The results suggested that application of exogenous ethylene promoted the biosynthesis of endogenous ethylene in peach fruit. The treatment with NO remarkably inhibited the biosynthesis of ethylene by significantly reducing the activities of ACC synthase （ACS） and ACC oxidase （ACO）. Ethylene biosynthesis in the fruits treated with both NO and exogenous ethylene was lower than that in fruits treated with exogenous ethylene alone but higher than that in fruits treated with NO alone, suggesting that there were antagonistic actions between NO and exogenous ethylene. NO could inhibit the biosynthesis of ethylene and the catalysis of exogenous ethylene during ethylene biosynthesis in peach fruits.

Effect and Functional Mechanism of the Action of Exogenous Gibberellin on Flowering of Peach

This study was conducted to assess the effect of gibberellin and its possible mechanism of action on peach flower formation. At flower induction, 100 mg L^-1 of gibberellic acid 3 （GA3） was sprayed on the leaves of peach [Prunus persica （L.） Batsch.] cv. Bayuecui. Using anatomy, immunohistochemistry, and semi-quantitation, the in situ distribution of GAs and the expression of the key genes involved in peach flower formation in the apical meristem were studied during flowering differentiation. The results showed that induction of flowering in the Bayuecui peach occurred prior to 10 July in Beijing, China. Flower induction and further differentiation of the peach flower organs were significantly inhibited by leaf-spraying of GA3 at a concentration of 100 mg L^-1 during the induction stage. The flowering rate was only 11.67% after treatment. The distribution of GA1 in the apical meristem varied during the process of flower bud differentiation. From 13 June to 25 July, the GA1 signal from control plants was detected mainly in the vascular bundles at the base of the flower buds. No GA1 signal was detected in the apical meristem. After treatment with GA3, the distribution was similar to that of the control from 13 June to 3 July. On 13 July, a GA1 signal was detected in the apical meristem accompanied by an increase in the GA1 signal in the vascular bundles at the base of the flower buds. The GA1 signal weakened significantly in both the vascular bundles and the apical meristem on 25 July. The expression of the genes PpLEAFY and MADS6 in flower buds could be detected only on 10 October in the GA3-treated plants. The critical period for flower induction of Bayuecui peach in Beijing was in early July, during which time, leaf-spraying with 100 mg L-1 GA3 could effectively inhibit flower induction and further differentiation of the flower buds. GA1 in the gibberellin family was the suppressor for flower induction in peach. Its action was affected by the stage of flower bud differentiation. Expression of the key genes PpLEAFY and MADS6 involved in flower formation was inhibited by GA3 treatment.

PpWRKY4通过影响PpCCD4表达调控桃果实类胡萝卜素积累

【目的】克隆桃PpWRKY4基因,探究其在桃果实类胡萝卜素代谢过程中的调控机制。【方法】以白肉桃中油桃14号果实为材料,分析了其果实中类胡萝卜素含量变化趋势,克隆桃中PpWRKY4基因,对其进行生物信息学和表达分析。通过亚细胞定位、酵母单杂交技术和双荧光素酶试验确定PpWRKY4对PpCCD4的调控机制。【结果】随着中油桃14号果实成熟,PpCCD4基因表达量逐渐升高,类胡萝卜素含量(w,后同)由1.97μg·g^(-1)降至0.68μg·g^(-1)。PpWRKY4基因CDS区共1764 bp,编码587个氨基酸,蛋白分子质量为64.06 ku,等电点为6.00;通过氨基酸序列比对,其包含两个WRKY保守基序,为Ⅰ类WRKY蛋白。PpWRKY4基因在桃果实发育前期高表达,后期表达量较低,与PpCCD4表达趋势相反。亚细胞定位结果表明PpWRKY4定位在细胞核。酵母单杂交技术和LUC试验表明PpWRKY4通过结合PpCCD4启动子抑制其表达。【结论】PpWRKY4通过负调控PpCCD4表达进而调控桃果实类胡萝卜素降解,研究结果为进一步解析桃果实类胡萝卜素积累分子机制提供理论基础。

八种植物生长调节剂在桃果实上的残留及膳食摄入风险评估

植物生长调节剂已广泛应用于中国桃生产中,但在桃树上已登记的植物生长调节剂产品仅多效唑·甲哌鎓,且中国无桃果实中植物生长调节剂最大残留限量标准,由于登记的植物生长调节剂产品少,缺少安全间隔期、用药间隔期等信息,可能会导致盲目用药,增加残留与膳食风险。为明确中国桃主产区桃果实中植物生长调节剂残留现状,本研究采集中国13个桃主产区420份样品,针对8种植物生长调节剂开展残留情况调查与慢性膳食摄入风险评估,并对不同产地、不同时间残留情况进行分析。结果表明,中国桃主产区果实样品中植物生长调节剂残留检出率达到71.4%,8种植物生长调节剂检出率分别为多效唑60.0%、矮壮素21.7%、胺鲜酯8.1%、复硝酚钠6.7%、赤霉素5.0%、噻苯隆1.0%、氯吡脲1.0%、烯效唑0.7%。样品总体残留检出率较高,慢性膳食摄入风险为0.001 0%~0.360 8%,对一般人群为“无不可接受风险”。中国桃不同主产区、不同时间桃果实中植物生长调节剂残留种类与残留量差异较大,南方地区应重视露地栽培桃树7月份的多效唑的使用,北方地区应关注设施栽培桃树5月份的植物生长调节剂的使用。建议农业技术推广人员根据地域、栽培模式、环境气候的差别,指导种植户科学使用植物生长调节剂。为保障中国居民膳食安全,应尽快制定桃果实中植物生长调节剂最大残留限量标准。

甘肃桃(Prunus kansuensis)雌雄配子体发育规律及遗传特性的研究

为了了解甘肃桃的早花性与其花芽分化的关系及早花性的遗传能力,以甘肃桃1号(甘肃桃)(Prunus kan-suensis)、96-7(普通桃)(P.persica)、甘肃桃1号×96-7的杂种一代群体(20株)为试材,对材料的生物学特性和花芽分化解剖结构进行了研究。结果表明,1)通过对叶、花、果形态特征观察发现,甘肃桃1号×96-7杂种群体的表现性状趋向甘肃桃1号。2)甘肃桃1号在落叶前形成雄配子体,具有花粉的早熟性。3)杂种群体花芽分化始期及花芽分化特性也趋向于母本甘肃桃1号。

HPLC法测定不同产地桃仁中苦杏仁苷的含量

目的:建立不同产地桃仁中苦杏仁苷含量的高效液相测定方法,测定不同产地桃仁药材中苦杏仁苷的含量。方法:色谱柱HypersilBDS C18(250mm×4.6mm,5μm),流动相为乙腈-水(17∶83)。结果:苦杏仁苷在4.94～80μg/mL范围内线性关系良好,r=0.9996,平均回收率为99.87%,RSD=1.01%。含量测定结果表明,不同产地桃仁药材中苦杏仁苷含量存在差异。结论:该方法简便快捷,准确灵敏,重复性好,可用于桃仁药材的质量控制。

不同方法测定桃树抗寒性关系研究

以生产中抗寒性表现较强、中等、较弱的3个桃品种为试材,应用电解质渗透法(EL)和电阻抗图谱法(EIS)研究了不同时期枝条抗寒性和未经冷冻处理枝条EIS参数的变化,并对未经冷冻处理枝条EIS参数、冷冻处理枝条EIS参数测定的半致死温度与EL测定的半致死温度的关系进行了统计分析。结果表明:未经冷冻处理3个桃品种的胞外电阻率(r_e)和胞内电阻率(r_i)均随着外界温度的降低而升高,随着外界温度的升高而降低;弛豫时间(τ)与r_(e)、r_(i)变化趋势相反;通过对4个电阻抗参数与EL测定的半致死温度统计分析得出,EIS(r_(i))是最佳参数,其相关系数为-0.828,通径系数为-7.385,线性回归方程为y=-4.063 9x+4.333 8,R^(2)=0.686。EL和EIS参数法测定3个桃品种的抗寒性与生产上抗寒性强弱表现一致;通过对2种方法统计分析得出,EL与EIS 4个参数法测定抗寒性均呈极显著正相关,其中弛豫时间法相关系数、通径系数和决定系数均最高,因此,弛豫时间是预测冷冻处理桃树枝条抗寒性的适宜参数。

毛桃11-21的SFB/SLF基因全长克隆与分析

为进一步明确桃自交亲和性机制,对毛桃11-21的SFB/SLF基因进行全长克隆,共克隆得到2条SFB序列和1条SLF序列。SFB/SLF基因与其他李属F-box基因的核苷酸序列和氨基酸序列都具有较高的同源性。序列分析发现,试验克隆的2个SFB基因序列由于核苷酸片段插入或者序列异常导致翻译提前终止,因此氨基酸序列异常,其中Pp SFB2更是缺失了C端的V2,HVa和HVb。毛桃11-21的Pp SLF1基因能正常翻译,没有提前终止,该基因编码的蛋白序列具有典型李属F-box蛋白结构,与其他李属果树氨基酸序列具有较高的一致性,而与梨属果树氨基酸同源性较低。系统进化分析表明,桃SFB基因与李和杏的同源性较高,而3个桃SFB基因间的同源性较低。李属SLF基因与梨属果树的亲缘关系则较远,而桃SLF基因与其他李属果树关系也较远。

Simple Sequence Repeat Analysis of Genetic Diversity in Primary Core Collection of Peach(Prunus persica)

In this study, the genetic diversity of 51 cultivars in the primary core collection of peach （Prunus persica （L.） Batsch） was evaluated by using simple sequence repeats （SSRs）. The phylogenetic relationships and the evolutionary history among different cultivars were determined on the basis of SSR data. Twenty-two polymorphic SSR primer pairs were selected, and a total of 111 alleles were identified in the 51 cultivars, with an average of 5 alleles per locus. According to traditional Chinese classification of peach cultivars, the 51 cultivars in the peach primary core collection belong to six variety groups. The SSR analysis revealed that the levels of the genetic diversity within each variety group were ranked as Sweet peach 〉 Crisp peach 〉 Flat peach 〉 Nectarine 〉 Honey Peach 〉 Yellow fleshed peach. The genetic diversity among the Chinese cultivars was higher than that among the introduced cultivars. Cluster analysis by the unweighted pair group method with arithmetic averaging （UPGMA） placed the 51 cultivars into five linkage clusters. Cultivar members from the same variety group were distributed in different UPGMA clusters and some members from different variety groups were placed under the same cluster. Different variety groups could not be differentiated in accordance with SSR markers. The SSR analysis revealed rich genetic diversity in the peach primary core collection, representative of genetic resources of peach.