杨梅属植物共生结瘤固氮研究进展

杨梅属35个种中有28个种能与Frankia放线菌共生结瘤固氮。根据有关文献从杨梅属植物共生固氮根瘤及其内生放线菌的形态结构、杨梅属植物根瘤内生放线菌的分类地位、杨梅属植物共生固氮放线菌的生理生化特性、环境条件对杨梅属植物根瘤共生固氮的影响以及分子生物学方法在杨梅属植物根瘤共生固氮放线菌中的应用等方面作了较为详细的阐述。     

中国杨梅资源及利用研究评述

杨梅属植物有60多个种,我国有6个种。综合有关文献归纳了我国6种杨梅种质资源的现状及地理分布,重点介绍了杨梅种的种质资源情况。全国现有杨梅栽培品种305个,单系120个,其中18个栽培品种通过了省级审定用于商业生产。由于杨梅具有重要的食用、药用、生态和观赏价值,经济效益、生态效益和社会效益兼备,开发潜力巨大。就杨梅果品开发、药用价值、工业原料、生态林果几方面探讨了杨梅资源的开发利用现状,重点介绍了杨梅的药用价值及活性成分。针对杨梅资源开发利用中存在的问题,提出加快杨梅医药产品的研制开发,充分利用杨梅生态效益,用于环境治理和生态重建的建议。     

不同修剪方式对杨梅矮化提质效应研究

以8 年生‘东魁’杨梅为材料，研究修剪的矮化提质效果。连续2 年进行大枝修剪(vertical branch pruning，VP)、精准修剪(precise pruning，PP)、大枝修剪+精准修剪(VP+PP)和“开天窗”常规修剪(pruning of open skylight，PO)，并以不修剪为对照(CK)。试验前后调查树体高度和冠幅，并测定株产量、果实品质（总糖、可滴定酸、Vc、总多酚、总黄酮等）和色差(L*、a*、b*、ho、C*)等。结果表明，对树冠控制能力的大小为VP+PP＞VP＞PP＞PO，其平均树高分别降低了63%、57%、55%和25%。平均株产量为VP+PP＞VP＞PP＞PO，产量分别提高了25%、20%、6%和-38%。对果实色泽改善以PP 和VP+PP 的效果最显著。调查L*和始熟期发现，近熟期L*越小成熟度越高。处理第2 年果实品质相比第1 年改善幅度增大，以单果重为例，处理第1 年VP+PP、PP、VP、PO的单果重分别提高了32.0%、30.3%、21.1%和8.7%，第2 年单果重分别提高了48.3%、44.9%、43.1%和8.9%；各处理的a*、ho和C*在处理第1 年无显著差异，第2 年出 现差异分离。综合分析，不同处理下杨梅的综合效益为VP+PP＞PP＞VP＞PO＞CK。     

杨梅基因组SSR引物的开发与应用

基于杨梅(Myrica rubar Sieb. et Zucc.)基因组序列信息,研究了1 431条scaffold中SSR位点的分布特点。共发掘到二至六核苷酸SSR位点43842个,分布在623条scaffold中,共有194种重复单元。二核苷酸SSR位点有36 383个,占总SSR的82.99%;AG/CT的出现频率最高,为55.70%,占总SSR位点的46.23%。三核苷酸SSR位点有6 115个,占总SSR的13.95%。四核苷酸SSR位点有827个,占1.89%。五核苷酸SSR位点为245个,占0.56%。六核苷酸SSR位点为272个,占0.62%。设计合成了59对基因组SSR引物,多态性分析显示,高度多态性引物26对,中度多态性引物为33对;将其应用于杨梅优株早鲜856及其他13个主栽品种的聚类分析,结果表明,上述引物在相似系数0.56处将14份杨梅材料分为两个群体,早鲜856与其他13个主栽品种在DNA水平上均存在差异,且与对照品种‘早色’的相似系数为0.86。     

杨梅叶枯病菌（Phomopsis myricina）生物学特性研究

杨梅叶枯病菌（Phomopsis myricina）生物学特性研究结果表明：该菌菌丝生长与分生孢子器形成最佳培养基为PSA+1‰酵母膏和PDA+1‰酵母膏。病菌能有效地利用多种碳源和氮源，但谷氨酸和精氨酸对病菌生长发育有抑制作用。菌丝生长和分生孢子器形成最适温度为20~25℃；最适pH值分别为6~8和7~9。紫外光处理有利于产孢。分生孢子萌发最适温度为20~30℃；最适pH值7~9；在相对湿度98%以上和水滴中孢子萌发率最高；不同营养对孢子萌发无显著影响。     

Effects of soil water availability on development of suberin lamellae in the endodermis and exodermis and on cortical cell wall thickening in red bayberry (Myrica rubra Sieb. et Zucc.) tree roots

The effects of soil water availability on suberin lamellae formation in the endodermis and exodermis and the occurrence of cell wall thickening in the cortex in red bayberry (Myrica rubra Sieb. et Zucc.) tree roots were examined during tissue aging. For several months, red bayberry trees were grown in small baskets under dry, normal, and waterlogged soil water conditions. Transverse sections of roots from 5 mm from the tip to the basal portion were stained with several staining solutions and the cell structure was observed. Root anatomical development was significantly changed by soil water conditions. The suberin lamellae in the endodermis formed later in plants grown under dry conditions than in those grown under waterlogged conditions. Cell wall thickening in the cortex near the endodermis was promoted by drought, but apparently not by waterlogged conditions.     

杨梅酸性转化酶基因cDNA分离及表达分析

杨梅果实富含蔗糖,酸性转化酶是蔗糖代谢关键酶,根据植物酸性转化酶基因保守区序列设计引物,提取杨梅叶片RNA,逆转录获得cDNA,以此为模板通过PCR技术扩增到长度为516bp的基因片段,克隆入pMD18-T载体中,命名为MrIVR1(GenBank:DQ339699)。测序及同源性检索表明,该基因推导氨基酸序列与君子兰、葡萄、草莓、胡萝卜等酸性转化酶基因氨基酸序列同源性为60%～69%。运用ClustalX软件对植物转化酶基因进行了系统树分析,结果显示,MrIVR1编码的蛋白质属于细胞壁酸性转化酶。半定量RT-PCR表达分析显示,MrIVR1基因在杨梅果实发育早期表达量最高,随着果实的发育表达量下降,在成熟果实中表达水平较低。     

早熟杨梅新品种‘早炭梅8801号’

 ‘早炭梅8801号’是从‘荸荠种’中选出的杨梅新品种。该品种6月10日果实开始成熟, 比荸荠种提早10～15 d, 果实比荸荠种早熟株系大17.86%, 树冠覆盖面积产量3.5 kg/m² , 可在生态环境较恶劣的低丘红壤区域作为多功能品种栽培。果实鲜食加工兼用, 适应性强, 高产稳产。     

Testing variability in pathogenicity of Phytophthora cinnamomi

Forty eight isolates of Phytophthora cinnamomi from various host plants in France (35 isolates) and in other countries were tested for pathogenicity. Seedlings of chestnut, northern red oak, pine and eucalyptus were infected by soil contamination. Taproots, stems and bark strips of plants of chestnut and different oak species were inoculated with mycelium agar disks. Results of the different experiments were in good agreement. All isolates appeared pathogenic to all the different test species but with variable levels of virulence. Isolates with consistent low or high level of virulence, which could be used as standards in further studies, were identified. Interaction between P. cinnamomi isolates and host plant species was significant in terms of lesion lengths. These interactions could not be related to host from which P. cinnamomi was isolated. Consistent with this, in Quercus rubra, the isolate-provenance interaction was not significant. This feature is encouraging for provenance screening for resistance to P. cinnamomi in this species. The variation in virulence was not related to other isolate characteristics (mating type, electrophoretic type, age).     

杨梅结瘤固氮特性研究*

研究４种土壤盆栽杨梅生长及结瘤固氮特性表明：花坛土有利于杨梅的生长和结瘤固氮，其生长量、结瘤量及根瘤固氮活性分别为３１．６８７ｇ／株、１．７８９ｇ／株和３．４２０μｍｏｌＣ２Ｎ４／（ｇ鲜瘤·ｈ）；红壤十砂（２：１混合）次之，在这种土壤上栽植的杨梅，其生长量略低于花坛土，结瘤量及根瘤固氮活性接近于花坛土；砂十花坛土（１０：１混合）居第三；红壤最差，仅为８。３２２ｇ／株、０．３３３ｇ／株和１．３１５μｍｏｌＣ２Ｈ４／（ｇ鲜瘤·ｈ）。红壤施用石灰（１５ｇ／盆）土壤ｐＨ为５．４～６．０时杨梅的生长量、结瘤量及根瘤固氮活性最高，分别为１８．５２４ｇ／株、１．１８２ｇ／株和２．５２４μｍｏｌＣ２Ｈ４／（ｇ鲜瘤·ｈ）；充足的水分有利于杨梅的生长和结瘤固氮，外套水盆以底部持续供水且底部渍水时杨梅的结瘤量、生长量和根瘤固氮活性均有提高，前者提高幅度较大，达３．５１９ｇ／株。杨梅根瘤固氮活性的季节动态和日变化是：一年中有两个活性高峰，分别在６～７月份和１０月份，１月份的固氮活性最低。一日中根瘤固氮活性以中午和夜间１２时最高。