Polyphenol Oxidase Inactivation by Microwave Oven and Its Effect on Phenolic Profile of Loquat (<i>Eriobotrya japonica</i>) Fruit

The objective of this research was investigated the effect of polyphenol oxidase microwave treatment on phenolic composition, antioxidant activity and microstructure of loquat fruit. Phenolic profile of methanolic extracts prepared from fresh, and microwave-treated samples were analyzed. Antioxidant activity was also evaluated by 2,2’-azinobis (3-ethylbenzothiazoline-6-sulfonic acid) (ABTS?+) and 1,1-diphenyl-2-picrylhydrazyl (DPPH+) methods. In addition, polyphenol oxidase inactivation was carried out using a response surface methodology to establish the optimal conditions of treatment. The phenolic content of fresh mesocarp was 311 ± 0.60 mg gallic acid equivalents (GAE)/100g dry weight (DW) and that of microwave-treated mesocarp was 1230 ± 0.36 mg GAE/100g DW. Total phenolic content of water/ methanol extract significantly increases after microwave treatment rather than methanolic extract of fresh loquat. Five glycoside phenolics were identified by HPLC-DAD-MS as 3-caffeoylquinic acid, 3-p-coumaroylquinic acid, 5-caffeoylquinic acid and quercetin-3-O-sambubioside. Methanolic extract of microwave-treated mesocarp showed higher antioxidant activity than that of fresh mesocarp. Thus, polyphenol oxidase inactivation by microwave energy preserved the integrity of phenolic compounds as well as antioxidant activity in mesocarp extracts prepared from loquat fruit. It was also noted that phenolics were more abundant in the microwaved samples than in the fresh samples.

Seed Germination Traits of Loquat (Eriobotrya japonica Lindl.) as Affected by Various Pre-Sowing Treatments (Cutting of Cotyledons, Removal of Perisperm, Moist Chilling and/or Exogenous Application of Gibberellin)

The purpose of this study was to investigate the effects of various presowing treatments on the germinability(final germination percentage)and germination rate of loquat seeds in order to increase seedling production in nurseries(applied research)as well as provide answers for important physiological issues related to loquat seeds and their seed coat(basic research).Three experiments were carried out with various pre-sowing treatments.These treatments included full or partial removal of seed coat(perisperm),partial cutting of cotyledons as well as moist chilling at 5℃ for 13 days and/or soaking the seeds in water or 250 ppm gibberellic acid(GA_(3))solution for 24 h.According to the results,cotyledons excision resulted in delayed germination,regardless of the presence or absence of the seed coat in comparison with the decoated seeds that demonstrated the highest germination rate amongst them.In addition,even the partial excision of seed coats affected positively both the germinability and the germination rate,compared to the control-intact seeds.Furthermore,control-intact seeds had a higher germination percentage when exposed to moist chilling independently of the application or not of gibberellin;while the combination of gibberellin application and moist chilling improved both the percentage and the rate of germination of decoated seeds.In conclusion,the role of perisperm(seed coat)in the germination procedure of loquat seeds seems to be important,indicating the existence of seed coat-imposed dormancy on loquat seeds.Finally,the existence of a mild endogenous embryo-dormancy on loquat is also discussed.

Selection and Validation of Reference Genes for Normalization of RT-qPCR Analysis in Developing or Abiotic-Stressed Tissues of Loquat (Eriobotrya japonica)

Loquat(Eriobotrya japonica Lindl.)is a subtropical evergreen fruit tree that produces fruits with abundant nutrients and medicinal components.Confirming suitable reference genes for a set of loquat samples before qRT-PCR experiments is essential for the accurate quantification of gene expression.In this study,eight candidate reference genes were selected from our previously published RNA-seq data,and primers for each candidate reference gene were designed and evaluated.The Cq values of the candidate reference genes were calculated by RT-qPCR in 31 different loquat samples,including 12 subgroups of developing or abiotic-stressed tissues.Different combinations of stable reference genes were screened according to a comprehensive rank,which was synthesized from the results of four algorithms,including the geNorm,NormFinder,BestKeeper andΔCt methods.The screened reference genes were verified by normalizing EjLGA1 in each subgroup.The obtained suitable combinations of reference genes for accurate normalization were GAPDH,EF1αand ACT for floral development;GAPDH,UBCE and ACT for fruit setting;EF1α,GAPDH and eIF2B for fruit ripening;ACT,EF1αand UBCE for leaves under heat stress;eIF2B,UBCE and EF1αfor leaves under freezing stress;EF1α,TUA and UBCE for leaves under salt stress;ACT,EF1αand eIF2B for immature pulp under freezing stress;ACT,UBCE and eIF2B for immature seeds under freezing stress;EF1α,eIF2B and UBCE for both immature pulp and seeds under freezing stress;UBCE,TUB and TUA for red-fleshed fruits under cold-storage stress;eIF2B,RPS3 and TUB for white-fleshed fruits under coldstorage stress;and eIF2B,UBCE and RPS3 for both red-and white-fleshed fruits under cold-storage stress.This study obtained different combinations of stable reference genes for accurate normalization in twelve subgroups of developing or abiotic-stressed tissues in loquat.To our knowledge,this is the first report to obtain stable reference genes for normalizing gene expression of abiotic-stressed tissues in E.japonica.The use of the three most stable reference genes could increase the reliability of future quantification experiments.

Effects of Lanthanum and Europium on Rooting of Plantlet Eriobotrya Japonica Lindl. in vitro

The effect of La 3+ and Eu 3+ on the rooting of Eriobotrya japonica Lindl. plantlet in vitro was studied with adding La 3+ and Eu 3+ to the rooted medium. The rooting rate, the number of root and the length of root were studied after transplanting 20 d. The activity of peroxidase, nitrate reductase and fresh weight of roots were determined after transplanting 44 d. The results show that the optimum concentration range of La 3+ (1.0～3.0 μmol·L -1), Eu 3+ (2.0～3.0 μmol·L -1) in the rooted medium can increase the rooting rate and the fresh weight of roots, and promote the length of root and raise the activities of peroxidase and nitrate reductase significantly. La 3+ has more effect in improving the rooting rate, root length and the activities of peroxidase and less effect in promoting root fresh weight and the activities of nitrate reductase than Eu 3+.

Occurrence, Prevention and Control of Cryphalus eriobotryae, a New Devastating Pest of Loquat

A devastating trunk beetle has been found in Baisha loquat in Dongshan Town, Wuzhong District, Suzhou City in recent years. It is iden-tified as a new insect species, Cryphalus eriobotryae, belonging to Scolytinae, Curculionidae, Coleoptera. So far, loquat is known as the unique host of C. eriobotryae, and trees of 20-30 years old or 3-4 years old are all attacked by the insect. Holes drilled by adults with the diameter of about0.8 mm and sores(ate by adults) with the diameter of 1 mm are found on bark and trunk of damaged trees. Three-dimensional channels in 3-4 layers are formed in cortex, which are filled with insect dung. The phloem turns black-brown in late stage, and loses transport function, resulting in plant death and a great impact on loquat production and industrial development. During the occurrence period of C. eriobotryae from April to November,the damaged trunks and branches should be sprayed with 48% chlorpyrifos EC or 5% imidacloprid EC 100 times dilution once every 10 d for con-tinuous 2-3 times, and various states of the insect could be killed. If the phloem is damaged in the early and middle stages and does not turn black and brown completely, the plant could grow new cortex to realize recovery.

Effects of Peracetic Acid(PAA) Combined with Calcium Treatments on Storage Quality of Loquat Fruit

[Objective] The paper was to evaluate effects of peracetic acid （PAA） combined with calcium treatments on storage quality of Ioquat fruits, so as to pro- vide practical techniques to solve the problems of postharvest rot and quality deteri- oration for Ioquat fruits. [Method] With Ioquat fruits of Qingzhong variety as materi- als, 0.2%, 0.4% and 0.8% PAA combined with 0.8% CaCI2 was used to soak Ioquat fruits for 4 min, 0.8% CaCl2 and water treatments were set as two controls; the fruits were dried and packaged by 0.02 mm PE bags, then stored under non-chilling low temperature of （7±1） ℃. The indicators related to storage quality of Ioquat fruits were randomly tested once every 3 d, and their variation situations were analyzed. [Result] Compared with two control treatments and 0.2% PAA, 0.8% PAA combined with calcium treatments, the treatment of 0.4% PAA combined with 0.8% CaCl2 could significantly inhibit rot index, weight loss rate, firmness and cell membrane permeability of Ioquat fruits during storage period, which could also effectively delay the reduction of titratable acid, vitamin C, soluble solid content and juice yield, and maintain respiration intensity of fruits at a low level; the appearance and flavor qual- ity of fruits were good after stored for 25 d. [Conclusion] 0.4% PAA combined with 0.8% CaCl2 treatment is an efficient, safe and economical practice technology in an- ti-corrosion and quality preservation for postharvest Ioquat fruits .

Preliminary Identification of Loquat Leaf Mould Pathogenic Fungus in Mengzi City of Yunnan Province

[Objective] The study aimed to investigate the Ioquat leaf mould disease in Mengzi City of Yunnan Province and lay the foundation for determination of effective prevention and control methods.[Method] Loquat leaf mould pathogenic fungus was isolated by tissue separation method and inoculated with conidial suspension.The pathogenicity of Ioquat leaf mould pathogen was verified by Koch＇s postulate.Under a microscope,mycelial morphology and conidial fructification were observed,spore sizes were measured,and Ioquat leaf mould pathogen was identified according to the morphological characteristics.[Result] Velvet-like,olive green fungal colonies were generated on PDA medium.Conidiophores erect,apex curved,dark brown,smooth,with obvious spore marks and no diaphragm,（33.0-152.8） μm×（2.6-4.0）μm.Cladosporium was brown or pale olive with spore marks,monocelled or with one diaphragm,（7.1-19.0） μm × （1.9-5.9） μm.Conidia concatenate （2-4）,oval or spherical,with no spore mark,light olive,monocelled,smooth,（2.1-9.4） μm × （1.2-2.6） μm.[Conclusion] Loquat leaf mold disease began to occur in the germination period of spring shoots and summer shoots and became serious in the germination period of autumn shoots.Sooty mold-like layer grew on both front and back surfaces and densely covered the whole leaves,thus seriously affecting the photosynthesis of plants.The pathogen was preliminarily identified as Cladosporium eriobotryae Pass.＆ Beltrani.

Gas exchange and water relations of young potted loquat cv.Algerie under progressive drought conditions

Relationships between plant water status and gas exchange parameters at increasing levels of water stress were determined in Algerie loquats which grown in 50 I pots. Changes in soil water content and stem water potential and their effects on stomatal conductance （Gs ） and net photosynthesis （Pn） rate were followed in control plants and in plants without irrigation until the latter reached near permanent wilting point and some leaf abscission took place. Then, the irrigation was restarted and the comparison repeated. Soil water content and stem water potential gradually diminished in response to drought reaching the minimum values of 0.9 mm and -5.0 MPa, respectively, 9 days after watering suspension. Compromised plant water status had drastic effects on Gs values that dropped by 97％ in the last day of the drought period. Pn was diminished by 80％ at the end of the drought period. The increasing levels of water stress did not cause a steady increase in leaf temperature in non-irrigated plants. Non-irrigated plants wilted and lost some leaves due to the severity of the water stress. However, all non-irrigated plants survived and reached similar Pn than control plants just a week after the irrigation was restarted, confirming drought tolerance of loquat and suggesting that photosynthesis machinery remained intact.

Removal of the main inflorescence to induce reflowering of loquat

Loquat(Eriobotrya japonica Lindl.)is an evergreen fruit tree species of the Rosaceae,and its unique flowering time greatly hinders its production.To explore the artificial regulation of loquat flowering time,we removed the main inflorescence(by cutting it)to induce reflowering.For different loquat tree cultivars with different stages,the inflorescence was removed by cutting the main floral axis at two alternative positions:the upper or the lower position beneath the inflorescence,and it was found that the proportion of reflowering resulting from removing the upper position of the main floral axis of yellow-flesh loquat cultivars during the full-bloom stage was the highest.In addition,compared with those of the normal-growing panicles,the number of flower buds and branch axes of the reflowering panicles decreased significantly after cutting.Importantly,these newly produced inflorescences flowered 2–4 months later than normal-growing inflorescences did,effectively prolonging both the flowering and fruiting time.In addition,qRT-PCR results showed that EjFT1,EjFT2,EjAP1–1 and EjAP1–2 were highly expressed in the floral axis.These findings highlighted a new method for extending the production cycle of loquat and provided a reference for the flowering regulation of loquat and other economically important fruit tree species.

腐植酸水溶肥对枇杷幼苗生长的影响

为研究叶面喷施腐植酸水溶肥对枇杷[Eriobotrya japonica(Thunb.)Lindl.]幼苗生长的影响,以大五星枇杷幼苗为材料,叶面喷施不同稀释浓度(700、1 000、1 300、1 600倍)的腐植酸水溶肥,以喷施等量清水为对照(CK),测定腐植酸水溶肥对枇杷幼苗生物量、光合色素含量和抗氧化酶活性的影响。结果表明,叶面喷施不同浓度的腐植酸水溶肥提高了枇杷幼苗茎杆和叶片生物量、光合色素含量,且均以稀释1 000倍效果最好。稀释1 000、1 300倍腐植酸水溶肥处理提高了枇杷幼苗过氧化氢酶(CAT)、过氧化物酶(POD)和超氧化物歧化酶(SOD)活性。枇杷幼苗茎杆、叶片生物量与叶绿素a、叶绿素b、类胡萝卜素含量、CAT活性、POD活性和SOD活性呈正相关。因此,叶面喷施腐植酸水溶肥能够促进枇杷幼苗生长,且以稀释1 000倍最佳。

千岛湖地区不同蜜蜂传粉对枇杷增产提质效果的评价

应用中华蜜蜂和意大利蜜蜂为浙江省千岛湖地区的枇杷传粉,评估2种蜜蜂传粉对枇杷果实品质和产量的影响。结果表明,枇杷花期不同时间2种蜜蜂访花密度差异较大,其中9:30~9:50时,中华蜜蜂的访花密度(10.35±2.15只/100朵花)显著大于意大利蜜蜂的访花密度(5.00±1.39只/100朵花)(P<0.05),其余时段2种蜂的访花密度差异不显著。经2种蜜蜂传粉的枇杷果实维生素C含量、总糖、糖酸比、单果重及果形指数等指标均显著优于隔离对照区的枇杷果实(P<0.05),在改善枇杷果实品质方面2种蜜蜂传粉效果基本一致。大田亩产量调查结果显示,中华蜜蜂传粉区的平均枇杷亩产量略高于意大利蜜蜂传粉区,但二者之间差异不显著(P>0.05)。本研究认为2种蜜蜂传粉均达到枇杷增产提质的效果,其中中华蜜蜂更适合为山区冬季开花的枇杷传粉。

低温胁迫下油菜素内酯对枇杷幼果生理特性的影响

对枇杷(Eriobotrya japonica LindL.)幼果使用0、0.5、1.0、1.5、2.0 mg/L外源油菜素内酯预处理后,于-3℃条件下低温处理24 h,研究低温胁迫下油菜素内酯对枇杷幼果相对电导率、抗氧化酶活性和渗透调节物质含量等生理指标的影响。结果表明,低温处理使枇杷幼果的相对电导率显著升高,冻害指数升高至90.5,但随油菜素内酯浓度的增加呈下降趋势;与0 mg/L相比,枇杷幼果的SOD、POD、CAT、APX酶活性和可溶性糖、可溶性蛋白质、脯氨酸含量在油菜素内酯的作用下得到不同程度的提高,并均与其相对电导率呈极显著负相关。这表明在低温胁迫下油菜素内酯可以通过调控抗氧化酶活性,提高渗透调节物质含量,增强枇杷幼果的耐寒性,并在油菜素内酯浓度为2.0 mg/L时枇杷幼果的耐寒性最佳。

大棚枇杷上木虱发生规律及5种杀虫剂的防治效果

浙江兰溪枇杷是农业农村部农产品地理标志产品,随着大棚设施普及,以木虱为主的害虫发生日益严重。在浙江省兰溪市大棚枇杷主产区调查大棚和露天枇杷上木虱的发生规律,比较不同地点木虱发生情况,并对大棚枇杷上木虱开展阿维菌素·双丙环虫酯干悬浮剂等5种药剂防控试验。结果表明,浙江省兰溪市女埠街道大棚枇杷上木虱若虫一年高发期3个,露天枇杷上木虱若虫一年高发期2个,其中大棚枇杷上木虱高发期相比露天早半个月左右。大棚和露天栽培的枇杷上木虱虫口发生量差异极显著(p<0.01),大棚枇杷上木虱平均虫量4.8头/枝,是露天的5.3倍;4个调查地点中女埠街道枇杷上木虱发生最重。75 g/L阿维菌素·双丙环虫酯干悬浮剂15 mL/667 m^(2)处理药后5、10、15 d的防效较高,分别为91.03%、90.88%和86.28%,显著高于5%阿维菌素微乳剂4000倍液,其药后15 d防效仅为46.34%。阿维菌素·双丙环虫酯防效好,使用安全,可在实际生产中推广应用。

枇杷PYL基因家族鉴定及表达分析

脱落酸(ABA)是调节植物生长发育与非生物胁迫的重要激素之一,ABA受体Pyrabactin Resistance 1(PYR)-like(PYL)于信号通路的顶端发挥核心调控作用,但枇杷Eriobotrya japonica的PYL基因家族尚未鉴定。本研究通过生物信息学分析鉴定出枇杷12个PYL基因家族成员,枇杷PYL蛋白分子量为10.47~29.12 kDa,且主要定位于细胞质。枇杷PYL基因家族成员分布在8条染色体上,进化树分析显示PYL基因家族包含三个亚家族,且枇杷EjPYL1与拟南芥AtPYL13亲缘关系较近。枇杷PYL蛋白含有1~6个motif,其中motif3为家族成员共有。枇杷PYL基因家族成员在物种内存在共线性,与拟南芥的物种间共线性有2对。顺式作用元件分析发现枇杷PYL基因启动子含有低温、干旱、光以及激素响应元件。枇杷幼果转录组分析表明,果肉和种子中EjPYL6和EjPYL8基因受低温诱导上调表达。该研究结果将为枇杷ABA信号转导途径的解析和抗冻新品种培育提供理论依据。

‘早钟6号’枇杷主要营养元素含量的年周期变化

‘早钟 6号’枇杷叶片中较高的N、P营养水平有利于花芽分化 ;叶片中营养元素含量次序为Ca >N >K >Mg >P ,花穗为K >N >Ca >Mg >P ,果实为K >N >Ca >P >Mg ;认为早钟 6号枇杷属喜Ca、喜K果树 ,生产上应重视Ca肥和K肥的施用 ;枇杷叶片营养分析采样以第一次夏梢叶片为宜 ,初步确定叶片营养诊断的采样适期为 9月。

镧、铕对白沙枇杷试管苗生根效应的研究

将不同浓度的La(NO3 ) 3 ,Eu(NO3 ) 3 加入白沙枇杷组培苗生根培养基中 ,2 0d后分别调查各处理的生根率、生根数 ,并记录根系生长动态 ;44d后切下各处理的根称重并测定其过氧化物酶及硝酸还原酶的活性。结果表明 ,白沙枇杷生根培养基 1/2MS +IBA 0 5 μmol·L- 1 中加入 1 0～ 3 0 μmol·L- 1 La (NO3 ) 3 ,2 0～ 3 0 μmol·L- 1 Eu(NO3 ) 3 均可显著提高其生根率、促进根的伸长生长和根重量的增加 ,增强根系过氧化物酶及硝酸还原酶的活性。但La(NO3 ) 3 和Eu(NO3 ) 3 对白沙枇杷组培苗生根效应有些差异 ,La(NO3 ) 3 对生根数、根长的增加作用及对过氧化物酶的激活作用比Eu(NO3 ) 3 显著 ,而Eu(NO3 ) 3 对根鲜重的增加、硝酸还原酶的激活作用比La(NO3 ) 3

枇杷叶中三萜类化学成分的研究

目的:研究枇杷叶的化学成分。方法:采用硅胶、ODS柱、制备薄层及制备液相法分离枇杷叶中的化学成分,运用化学和有机波谱分析方法确定化合物结构。结果:从枇杷叶中分离得到9个三萜类化合物,经鉴定分别为白桦脂酸甲酯(Ⅰ)、齐墩果酸(Ⅱ)、乌苏酸(Ⅲ)、2α-羟基齐墩果酸甲酯(Ⅳ)、科罗索酸甲酯(Ⅴ)、2α-羟基齐墩果酸(Ⅵ)、科罗索酸(Ⅶ)、委陵菜酸(Ⅷ)、蔷薇酸(Ⅸ)。结论:化合物Ⅰ、Ⅴ为首次从该植物及该属植物中分离得到。

6个枇杷品种对低温胁迫的生理响应及抗寒性评价

为探究枇杷对低温胁迫的生理响应,综合评价不同枇杷品种的抗寒能力,本研究以6个枇杷品种为试验材料,研究了低温胁迫对枇杷幼果种胚相对电导率、丙二醛、脯氨酸、可溶性糖和可溶性蛋白含量的变化。结果表明:随处理温度的降低,各枇杷品种幼果种胚相对电导率REC呈现"小?大?小"的"S"型曲线变化,结合Logistic方程得出不同枇杷品种种胚的半致死温度介于?4.759~?2.73℃之间,其中,WT(白肉芽变)幼果种胚的半致死温度最低,大五星幼果种胚的半致死温度最高;6个枇杷品种的脯氨酸(Pro)含量、丙二醛(MDA)含量随低温胁迫均呈现出先升高后降低的倒"V"型变化趋势,但增幅和达到峰值的时间点不同;可溶性糖和可溶性蛋白含量呈逐渐增加的趋势,均在?5℃时达到最大值;通过隶属函数综合分析,得出6个枇杷品种材料的抗寒能力表现为WT(白肉芽变)>冠玉>宁海白>龙泉5号>早钟6号>大五星。综上所述,WT(白肉芽变)对低温的胁迫具有较强的适应性,抗寒能力强;半致死温度LT50结合隶属函数法的综合评价能准确鉴定枇杷品种的抗寒性。本研究为枇杷抗寒种质的筛选及寻找提高抗寒性的新途径提供理论依据。

枇杷花研究及开发进展

我国枇杷产量占世界的70%,枇杷花资源非常丰富。枇杷花含有丰富的类黄酮、类胡萝卜素、齐墩果酸、熊果酸、苦杏仁苷等生物活性成分,具有十分重要的保健、营养价值和广阔的开发前景。从药理作用、生物活性成分研究等方面,综述了近年来枇杷花的研究进展,并对未来研究方向进行了分析评价。

枇杷果实发育过程中果肉质地与胞壁酶活性的变化

以果肉质地差异较大的白肉枇杷（Eriobotrya japonica Lindl.）＂白梨＂和黄肉枇杷＂解放钟＂为试材,探讨果实发育过程中胞壁酶活性变化与果肉质地形成的关系。结果表明,2个品种枇杷果实发育过程中多聚半乳糖醛酸酶（PG,EC 3.1.1.15）、果胶酯酶（PE,EC 3.1.1.11）与纤维素酶（Cx,EC 3.2.1.4）活性总体呈上升趋势,这3种酶活性在果实发育后期（即花后100~115 d）极显著高于前期并出现峰值。＂白梨＂枇杷PE,PG和Cx酶活性高于＂解放钟＂,果实发育前期,2个品种枇杷PE,PG和Cx酶活性差异较小;果实发育后期,＂白梨＂PE,PG和Cx酶活性显著或极显著高于＂解放钟＂。Cx,PG和PE与枇杷果肉质地形成密切相关,而β-半乳糖苷酶（EC 3.2.1.23）、α-葡萄糖苷酶（EC 3.2.1.20）、α-半乳糖苷酶（EC 3.2.1.22）、α-甘露糖苷酶（EC 3.2.1.24）等4种糖苷酶对＂白梨＂枇杷果实发育后期果肉软化起到一定的作用。