香蕉果实潜伏侵染真菌研究

通过埘海南省香蕉果实潜伏侵染病原真菌的研究表明,供试地区之间香蕉果实真菌带菌率没有显著差异,而香蕉果实不同发育时期的带菌率存在极显著差异,幼果带菌率最低,成熟期果实带菌率最高;香蕉果实不同部位的带菌率也存在极显著差异,轴部的带菌率最高,香蕉上部、中部、下部带菌率较低。在分离出的12种真菌中,有8种是潜伏侵染病原真菌,其中Colletotrichum musae为最主要潜伏侵染真菌,其次是Fusarium spp.、Botryodiplodia theobromae,另外还有Verticillium theobromae、Nigrorpora oryzae、Rhizopus stolonifer、Curvularia sp.和Pestalotiopsis sp.。     

杧果果实生长发育规律的研究

紫花着果后５０～６０天是果实生长的高峰期。随后生长速度减慢，果肉颜色从白转为淡黄，果核逐渐硬化。生长发育过程中有机物的变化主要是淀粉。着果后约６０天淀粉积累明显加快，９０天含量达最高（为５．６５％），以后明显下降。成熟期可溶性糖含量随淀粉下降而增高。有机酸含量亦在着果后６０天最高（为２．６２％），以后下降。结果表明，着果后６０天及９０天分别是果果实生长发育过程的生理转折期。     

黄河蜜甜瓜果实致病真菌潜伏侵染的时期与途径

黄河蜜甜瓜在从开花至成熟的整个生长发育过程中,均可受到链格孢(Alternaria alternata)和镰刀菌(Fusarium spp.)的侵染,并且随着果实体积的膨大,这2种病原菌的带菌率明显提高。在花期花瓣的潜伏侵染率最高,在发育期、网纹形成期潜伏侵染率明显升高,并且A.alternata的侵染率明显高于Fusarium spp.的侵染率,在成熟期Fusarium spp.的潜伏侵染率略有下降。     

蓝莓果实潜伏侵染病原真菌的分离与鉴定

以辽宁省蓝莓鲜果为试材,采用组织分离法分离潜伏侵染果实的病原真菌,通过形态学和分子生物学方法,对病原菌进行分类鉴定,研究了真菌的潜伏侵染状况,为指导蓝莓果实病害防治提供参考依据。结果表明:辽宁省蓝莓果实普遍存在真菌潜伏侵染现象,不同品种带菌率存在差异,‘M7’带菌率较高,"布里吉塔""爱国者""奥尼尔"和"南好"带菌率较低。从8个蓝莓品种中共分离鉴定出9种潜伏病原真菌,分别为互隔交链孢霉(Alternaria alternata)、细极链格孢菌(Alternaria tenuissima)、芽枝霉属(Cladosporiumsp.)、灰葡萄孢菌(Botrytis cinerea)、黑曲霉(Aspergillus niger)、嗜松青霉(Penicillium pinophilum)、茎点霉属(Phomasp.)、毛壳属(Chatetomiumsp.)和镰刀菌属(Fusariumsp.)。其中,互隔交链孢霉(Alternaria alternata)可在多个品种中分离,为蓝莓果实主要潜伏侵染病原真菌。另外,从蓝莓果实中分离到一株葡萄有孢汉逊酵母(Hanseniaspora uvarum),该酵母对互隔交链孢霉具有良好的抑制作用。     

BTH处理网纹甜瓜对两种真菌潜伏侵染率的影响

分别于网纹甜瓜开花前7 d、幼果期（花后14 d）、果实迅速膨大期（花后21 d）和网纹形成期（花后28 d）用100 mg·L^-1 BTH对植株进行1、2、3、4次喷洒,分析BTH处理后幼果期、膨大期、网纹形成期和成熟期果实内链格孢（Alternaria alternata）和镰刀菌（Fusarium sp.）潜伏侵染率的变化。结果表明：采前BTH处理可有效控制甜瓜果实内两种真菌的潜伏侵染。1、2、3、4次处理均降低了两种真菌的潜伏侵染率,2、3、4次处理的效果较好,在成熟期总潜伏侵染率均为对照的23.53 %。网纹形成期是两种真菌潜伏侵染的关键时期。采前BTH处理对潜伏于果实内的两种优势病原菌链格孢和镰刀菌的控制效果存在差异,且对果实顶部、中部的控制效果优于底部。     

ISSR分子标记与杧果果实生理性病害相关分析

从120条ISSR引物中筛选出9条引物,用以对20个杧果样品进行聚类分析.结果表明,杧果患果实生理性病害品种群体与ISSR分子标记聚类结果相吻合,可利用ISSR分子标记预测杧果果实生理性病害的发生,并作为杧果育种中早期筛选抗果实生理性病害品种的一种有效的辅助手段.     

黄河蜜甜瓜果实致病真菌潜伏侵染的时期与途径

黄河蜜甜瓜在从开花至成熟的整个生长发育过程中，均可受到链格孢(Alternaria alternata)和镰刀菌(Fusarium spp．)的侵染，并且随着果实体积的膨大，这2种病原菌的带菌率明显提高。在花期花瓣的潜伏侵染率最高，在发育期、网纹形成期潜伏侵染率明显升高，并且A．alternata的侵染率明显高于Fusarium spp．的侵染率，在成熟期Fusarium spp．的潜伏侵染率略有下降。     

不同套袋材料对红杧6号杧果果实品质的影响

研究了不同套袋材料对红杧6号杧果果实外观、果皮色素、果皮色泽及果实内在品质的影响。结果表明,采用白色单层袋套果后,青熟和完熟时,白色单层纸袋处理的叶绿素、类胡萝卜素质量分数较低,花青苷和类黄酮质量分数均较高,果皮亮度、色彩浓度和色度角均较高或最高,使果皮在青熟时呈紫红色,完熟时呈桃红色。白色单层袋套果后,果实的内在品质如维生素C、可溶性固形物、蔗糖、葡萄糖、果糖质量分数最高,内在品质最佳。外黄内黑复合纸袋果皮叶绿素、类胡萝卜素、花青苷、类黄酮质量分数均较低,果皮亮度、色彩浓度均最高,色度角最低,使果皮在青熟时呈浅黄色,完熟时呈橙黄色,但果实内在品质比白色单层袋差。因此,建议红杧6号杧果用白色单层纸袋进行套袋。     

杧果果实蝇及防治技术

杧果果实蝇在国内外杜果产区都有分布。属双翅目实蝇科，成虫产卵于成熟果实皮下，孵化后的幼虫在果内取食果肉，导致果实腐烂，不能食用。在云南省元江县杜果果实蝇对晚熟品种果实的危害为6％～15％，有的年份达20％以上。     

杧果果实响应1-MCP处理的数字基因表达谱分析

以‘台农1号’杧果为试材,用1–甲基环丙烯（1-MCP,1 μL · L-1）常温下处理12 h和未处理的果实为对照,通过数字基因表达谱（DGE）技术,寻找1-MCP处理对杧果贮藏影响的潜在关键基因。DGE数据分析结果表明,1-MCP处理与对照样品文库相比,共检测到7 350个差异表达基因。其功能主要涉及细胞壁代谢,激素调节,逆境胁迫应答,氧化损伤保护,能量代谢,蛋白质折叠,泛素化和蛋白酶体途径介导的细胞程序性死亡,成熟与衰老调控等。利用实时定量PCR（qRT-PCR）技术对DGE部分数据进行验证,检测了其中6个较有代表性的应答基因的差异表达。通过基因本体（Gene Ontology,GO）通路功能富集分析表明,1-MCP处理增加果实对逆境胁迫的抵抗能力,抑制物质和能量代谢,减少细胞内钙的流失并保护果实细胞。qRT-PCR技术数据支持RNA-Seq的检测结果。     

拮抗放线菌MY-4的分离、鉴定及其对果蔬病原菌的抑制作用

【目的】为了鉴定从沙糖橘果实表面分离得到的拮抗放线菌株MY-4,并确定该菌株对果蔬病原菌的拮抗作用,【方法】采用分析MY-4形态学、生理生化特性及16S rDNA序列相似性方法以确定其分类地位,并采用平板对峙培养法和生长速率法测定了其抑菌活性。【结果】结果显示,菌株MY-4为小白链霉菌(Streptomyces albulus Routien),菌株MY-4及其无菌发酵液对供试16种果蔬病原真菌均具有拮抗作用,其中菌株MY-4对香蕉炭疽病菌的拮抗作用最强,平板抑菌带宽度达17.08 mm,无菌发酵液对柑橘绿霉病菌的拮抗作用最强,菌丝生长抑制率高达98.82%,【结论】小白链霉菌菌株MY-4具有活性高、抑菌谱广的特点,有望继续研究开发成新的生防剂。     

内蒙古苹果树腐烂病病原菌鉴定

【目的】明确内蒙古地区引起苹果树腐烂病的病原种类。【方法】采用形态学结合分子生物学的方法,对内蒙古呼和浩特市周边果园的苹果腐烂病病菌进行分离、鉴定和致病力测定。【结果】从感病’金红’苹果树上分离到2株苹果腐烂病病菌,命名为QH1和QH2。QH1与QH2的致病力与分离自陕西杨凌的参照菌株YL1相同;菌落、分生孢子及子实体的形态特征均符合Cytospora属的特征;基于内转录间隔区、核糖体大亚基片段、转录延长因子和β微管蛋白4个基因的序列一致性和系统发育的分析证明,QH1属于Cytospora schulzer,QH2属于Cytospora mali。【结论】内蒙古呼和浩特地区苹果腐烂病病菌为C.schulzer和C.mali两种致病菌。     

72种中草药提取物对香蕉、杧果果实采后病害病原菌的抑菌活性

以9种分别来自香蕉、杧果采后病害的病原菌[Colletotrichum musae(Berk.et Curt.)Arx、Fusarium semitectum Berk.et Rav.、Verticillium theobromae(Turc.)Mason & Hughes、Cladosporium cladosporioides(Fre.)De Varies、Nigrospora oryzae(Berk et Br.)Petch、Colletotrichum gloeosporioides Penz、Botryodiplodia theobromae Pat.、Alternaria alternate(Fr.)Keissl.和Dothiorella dominicana Petr.& Cif.]为供试菌种,在中草药质量浓度相当于20mg/mL干药材的条件下,测定了41科72种中草药丙酮提取物对菌丝体生长的抑制作用。结果表明,供试的所有中草药提取物均有不同程度的抑菌作用,平均抑菌率为34.80%,其中,丁香对9种病原菌的抑菌率为100%,肉桂和大茴香的抑菌率大于90%,平均抑菌率大于50%的中草药提取物有16种,同一中草药对不同病原菌及不同中草药对同一病原菌的抑菌活性均存在差异。平均抑菌率大于90%的丁香、肉桂和大茴香对9种病原菌的EC50值为0.38～13.47mg/mL。     

杧果新品种——金桂香杧的选育

金桂香杧是从杧果实生繁育群体中选育出的新品种。果实肾状长椭圆形,平均单果质量260g,最大果质量330g,可溶性固形物18.5%,可食率74.8%,果肉橙黄色,质地较细致、细滑坚实、味清甜、香味浓郁,品质优。成熟果皮橙黄色,着色均匀,皮厚且紧密,抗炭疽病,耐贮运。植株生长势强,早实丰产,适应性强。成熟期7月上中旬,果实发育期115～130d。     

Multiple pre-harvest treatments with acibenzolar-S-methyl reduce latent infection and induce resistance in muskmelon fruit

Muskmelons (cv. Yindi) were sprayed with 100 mg a.i. L⁻¹ acibenzolar-S-methyl (ASM) four times at four different stages: flowering, the young fruit, the fruit enlarging period and the netting periods. Analyses were performed 1 week after each ASM treatment. Results showed that the incidence of total latent infection (caused by all observable fungi) and the incidence of relative latent infection (caused by Alternaria alternata or Fusarium spp.) were significantly lower in sprayed muskmelons than in the control fruit. Moreover, the reduction in the incidence of latent infection was greater with increased ASM treatments. The control of latent infection by ASM resulted in reduced incidence of postharvest decay and improved fruit appearance and firmness after 10 d of storage. In addition, the activities of peroxidase, phenylalanine ammonia lyase, β-1,3-glucanase and chitinase increased significantly in treated muskmelons. ASM treatments also contributed to the accumulation of phenolic compounds, lignin and flavonoids. Increases in defense-related enzyme activities and in particular metabolite levels were observed in plants with more ASM treatments. These results suggest that multiple ASM treatments could induce disease resistance in muskmelons and could be an ideal strategy for preventing latent infection in fruits.     

Expression of PPO and POD genes and contents of polyphenolic compounds in harvested mango fruits in relation to Benzothiadiazole-induced defense against anthracnose

Mango is susceptible to decay caused by pathogen infection during storage and transport. Chemical fungicides have been the major weapons against postharvest fungal diseases, but they have caused increasing public resistance. BTH does not have anti-microbial properties, but it induces systemic acquired resistance in plants. Here the relationship between BTH-induced disease resistance in harvested mango fruits and expression of PPO and POD genes, together with contents of total phenolic compounds (TPC), were investigated. BTH treatment reduced disease indices and lesion diameter. Compared with the control, BTH increased TPC, up-regulated gene expression and enhanced enzymes activities of PPO and POD during the latter period of storage life, suggesting that enhanced gene expression of PPO and POD played an important role in BTH-activated defense response of mango fruits and that the up-regulation of the two genes were related to the accumulation of TPC. This study also showed that BTH-induced resistance in harvested mango fruits could differ with varieties.     

Polyphenolic compounds and antioxidant properties in mango fruits

Fruit of eight mango genotypes were evaluated for antioxidant potential by several biochemical assays (DPPH, ABTS, ORAC, FRAP, SASR and MCC) and tested for their polyphenol composition and vitamin C contents. The significance analysis demonstrated that the antioxidant capacity of Tainong 1 fruits were significantly higher than that of other genotypes, which was about 2.1–6.3-fold higher than Guifei assayed in ABTS, DPPH, ORAC and FRAP methods. The total polyphenols and flavonoids contents showed a great variety amongst mango genotypes and highly correlation with the total antioxidant capacity. It is concluded that significant genotypic difference exists in the total antioxidant capacity of mango fruits. Both total polyphenols and flavonoids are major contributors to the total antioxidant capacity in mango fruit.     

杧果种质遗传多样性的RAPD分析

对杧果不同生态型、不同胚性、不同果形与果色的38份品种和1个近缘种—扁桃进行了RAPD分析,19个引物在39份种质中共扩增出223条带,其中多态性带为196条,多态性带的百分率为87.89%,表明品种间存在着广泛的遗传基础。利用UPGMA进行聚类分析,在相似性系数0.755的水平上将38个品种分成3组,该结果与传统上以胚型为依据进行品种类群划分比较吻合。发现了多个与胚性密切相关和1个与果皮颜色密切相关的RAPD标记,并就部分品种的系谱关系、胚性和果皮颜色的遗传进行了探讨。