海南火龙果细菌性腐烂病的病原鉴定及田间药剂筛选

细菌性腐烂病是近年在海南火龙果上普遍发生的一种病害。为有效防治该病害,阻止其进一步扩散和蔓延,本研究从临高县东英镇采集病样多份,经病原分离、形态和分子鉴定、致病性测定以及田间药效试验,对其进行了病原鉴定和田间药剂的筛选。结果表明:代表菌株Huo30能产生黄色素,使火龙果致病,与成团泛菌(Pantoea agglomerans)相似性100%,为火龙果细菌性腐烂病的病原菌。4种药剂中,53.8%氢氧化铜WG1000倍液和47%春雷·王酮WP600倍液处理的防效最好,分别为71.05%和69.93%,与另外两个处理的防效差异显著;72%农用链霉素SP5000倍液处理的防效一般,在供试浓度下防效为65.14%;而2%春雷霉素AS600倍液处理对该细菌病害的防效最差,仅为63.31%。本研究结果为海南火龙果的防治提供了重要的理论依据。     

火龙果溃疡病菌实时荧光定量PCR内参基因的筛选

火龙果溃疡病是由火龙果溃疡病菌引起的重要真菌病害,近年来在世界火龙果产区的爆发严重影响了火龙果产业的发展。为研究火龙果溃疡病菌响应逆境胁迫的基因表达和功能,需要筛选火龙果溃疡病菌在各种条件下表达稳定的内参基因。以火龙果溃疡病菌菌株LJ02为研究对象,以在马铃薯葡萄糖液体培养基（PDW）培养的菌丝体为对照组,以在LB培养基培养的菌丝体和分别在添加过氧化氢、吡唑醚菌酯和苯醚甲环唑的PDW培养的菌丝体为处理组。利用实时荧光定量PCR技术以及内参基因稳定性评估软件（geNorm、NormFinder、Bestkeeper和RefFinder）,评估18个候选内参基因（CYT1、SDH2＿1、TBCC、SUI1、RPL19、PPH、ATP5B、UBE2＿16、RPL13、UBE2＿2、PRS17、SUCLA2、ATP5A、TUB1＿2、ACT1、EFTU、EF1A和GAPDH）的表达稳定性。结果显示,火龙果溃疡病菌的18个候选基因在上述培养条件下的Ct值介于14.80-24.66之间,表达水平适中;稳定性最高的内参基因是CYT1,其次为SUI1,GAPDH和ACT1的稳定性最差;最少使用2个内参...     

火龙果果皮中可溶性膳食纤维的提取方法

火龙果(Hylocereus undulatus)果皮可以作为一种优良的膳食纤维来源,且其膳食纤维具有良好的理化性能。为提高火龙果果皮的综合利用水平,该研究以火龙果果皮为原料,首先采用纤维素酶水解法对火龙果果皮中的可溶性膳食纤维进行提取,然后采用单因素试验和响应面法优化酶提取工艺。结果表明,纤维素酶法提取火龙果果皮中可溶性膳食纤维的优化工艺条件为:纤维素酶浓度0.54%,酶解温度50°C,pH5.2。在此条件下,可溶性膳食纤维的提取率可达19.81%;膳食纤维的持水力为31.25 g·g~(–1),溶胀性为29.11 m L·g~(–1)。     

外源GA_3浸种处理促进火龙果种子发芽

火龙果种子播种育苗存在着种子发芽慢、发芽不整齐、发芽率低及幼苗细弱等问题。为了探讨提高火龙果种子发芽速度、发芽率和种子活力的方法,本试验以白肉火龙果(Hylocereus undatus Brit.t Rose)种子为材料,采用4个不同浓度(100mg/L,200mg/L,300mg/L和400mg/L)外源GA3对种子进行浸种处理,在适宜的光、温、水、气条件下催芽,通过对种子发芽势、发芽率、发芽指数、幼苗鲜重和活力指数的测定,研究不同浓度外源GA3浸种处理对火龙果种子发芽的影响,不处理为对照。结果表明,不同浓度外源GA3浸种处理对火龙果种子的发芽势、发芽率和种子活力均有明显的促进作用,其中400mg/L处理效果最好,300mg/L处理次之,再次是200mg/L、100mg/L,对照最差。本文的研究结果,将为火龙果种子播种育苗及育种工作提供科学理论依据。     

有机肥和套种对干热区火龙果土壤微生物特性和产量、品质的影响

为探明施用有机肥和套种对红心火龙果(Hylocereus costaricensis)种植的优势机理,以干热区红心火龙果园为研究对象,探索有机肥施用量(F₀:0 t·hm^-2和F₂₀:20 t·hm^-2)和套种方式(MP:单种火龙果,IP:火龙果套种花生(Arachis hypogaea)和IS:火龙果套种大豆(Glycine max))对土壤微生物数量、微生物生物量、酶活性以及红心火龙果产量、品质的影响,并分析产量、品质与土壤微生物特性之间的关系。结果表明：与F₀处理相比,F₂₀处理显著增加土壤细菌、真菌、放线菌数量和微生物生物量碳、氮、磷,增加土壤蔗糖酶、脲酶、酸性磷酸酶和过氧化氢酶活性,提高红心火龙果产量和品质。在F₀和F₂₀条件下,相比于MP处理,IP和IS处理明显增加土壤微生物数量、微生物生物量氮以及蔗糖酶和脲酶活性;而IP和IS处理仅在F₂₀条件下显著提高土壤微生物生物量碳、磷和...     

响应面法优化火龙果茎甾醇的提取及纯化工艺研究

以火龙果茎为原料,研究火龙果茎甾醇的提取及精制工艺.利用响应面分析法对火龙果茎甾醇超声提取工艺进行优化.结果表明:超声波辅助提取火龙果茎甾醇的最佳工艺条件为提取时间57 min、超声功率143 W、液料比12∶1 (mL/g)、温度53℃,甾醇得率为2.693％‰.通过正交试验确定火龙果茎甾醇精制的最佳条件为:液料比为4∶1(mL/mg),结晶初始温度为55℃,养品时间为18h,此条件下火龙果茎甾醇的纯度达到87.6％.     

火龙果汁发酵饮品的研制

火龙果不但营养丰富而且具有一定的保健功能。本试验以新鲜的红皮白肉型火龙果果实的榨汁为原料,分别对发酵工艺条件、蔗糖添加量、柠檬酸用量、稳定剂用量等条件进行了研究,通过单因素试验和正交试验,得到火龙果汁发酵饮料的最佳工艺配方。采用该工艺配方制备的发酵饮料澄清透明,具有清新的果香和淡淡的醇香,酸甜可口,口感顺滑。     

性激素对大鼠胃酸分泌的影响

尽管人们早巳注意到消化性溃疡病男性发病率明显高于女性,还发现雌激素对溃疡病的痊愈有明显疗效,但由于性激素治疗溃疡病的同时尚带来副作用,而一定程度上阻碍了人们对性激素与溃疡病关系的进一步研究。本实验利用大鼠急性实验,观察性激素对基础胃酸分泌的影响,以探索性激素影响消化性溃疡病发病之可能机理。     

外源水杨酸对低温胁迫下火龙果幼苗的形态及生理效应

为探究外源水杨酸(SA)对低温胁迫下火龙果幼苗形态及生理的影响，该研究以‘紫红龙’火龙果幼苗为材料，将4个不同浓度的SA(0.1、0.3、0.5、0.7 mmol·L^-1)喷施叶片，48 h后4℃低温培养，于第0、第3、第6、第9天观察火龙果幼苗形态及叶片组织结构的变化，并测定叶片相对电导率、丙二醛含量、渗透调节物(可溶性糖、可溶性蛋白、脯氨酸)含量及抗氧化酶(超氧化物歧化酶、过氧化物酶、过氧化氢酶、谷胱甘肽S-转移酶)活性等生理指标。结果表明：(1)低温胁迫下，火龙果幼苗呈现0级、Ⅰ级和Ⅱ级3个冷害等级，SA处理后的火龙果幼苗出现Ⅰ级冷害和Ⅱ级冷害的株数百分率均明显降低。(2)与低温对照相比，SA处理能降低火龙果幼苗叶片相对电导率和丙二醛含量并提高渗透调节物含量和抗氧化酶活性。(3)通过对不同SA处理结果进行比较分析，发现缓解冷害症状、降低相对电导率和丙二醛含量、提高可溶性糖和脯氨酸的含量、提高超氧化物歧化酶和谷胱甘肽S-转移酶的活性均以0.3 mmol·L^-1 SA效果最好，提高可溶性蛋白含量、过氧化物酶活性、过氧化氢酶活性分别以0.7、...     

火龙果果实的功效及保鲜贮存技术研究(综述)

火龙果果实含有丰富的糖、白蛋白、不饱和脂肪酸、膳食纤维、维生素及多种微量元素,在抗氧化、降血脂、美容养颜等方面具有较好的保健功效,开发利用前景广阔。本文综述火龙果果实的营养成分和保健价值以及在保鲜贮存方面的研究进展,以期为火龙果的生产和科研提供参考依据。     

火龙果愈伤组织诱导与植株再生

为了建立火龙果愈伤组织诱导与植株再生体系,以火龙果茎段、幼苗和子叶为外植体进行离体培养试验。结果表明：茎段诱导愈伤组织的最优培养基为1／2MS＋2,4-D2．0mg·L^-1＋6-BAO．5mg·L^-1,诱导子叶愈伤组织的最适培养基是1／2MS＋2,4-D2．0mg·L^-1＋6-BA1．0mg·L^-1,诱导愈伤组织分化的最优培养基为1／2MS＋6-BA4．0mg·L^-1＋NAA0．5mg·L^-1,最佳生根培养基为1／2MS＋6．BA1mg·L^-1＋NAA0-3mg·L^-1。     

铁皮石斛锈病病原鉴定及药剂筛选

为了明确铁皮石斛锈病的病原菌种类,筛选其有效防治药剂,通过对云南瑞丽铁皮石斛种植基地调查,运用形态学并结合分子生物学方法对病原菌进行鉴定,选用4种杀菌剂进行田间药效试验。结果表明,铁皮石斛锈病由真菌鞘锈菌(Coleosporium sp.)引起,发生期为每年2～11月,鞘锈菌的夏孢子直接侵染铁皮石斛叶片,以冬孢子越冬。10%苯甲·丙环唑悬浮剂450 mL·hm-2与75%肟菌·戊唑醇水分散粒剂300 g·hm-2的防效显著高于其他两种药剂,3次药后防效分别为82.16%和82.88%,这2种药剂可作为防治铁皮石斛锈病的有效药剂。     

火龙果茎基因组DNA提取方法改良

火龙果(Hylocereus undulatus)是近年发展起来的一种新兴热带水果, 其茎富含多糖、多酚及其它次生代谢物, 黏性极大, 很难从中提取高质量的DNA。特别是一年生以上的老茎, 目前尚未有较好的DNA提取方法。为了解决这一难题, 该研究对CTAB+Tris-HCl洗涤法进行了3种方式的改良。结果表明, “改进三”方法可不受取样时期和取样部位的限制, 从一年生以上火龙果茎中提取的DNA质量最好且不含黏性物质, 可用于酶切与分子标记等生化和分子生物学实验。该研究探索了一条较为理想的火龙果茎DNA提取方法, 值得推广应用。     

火龙果茎基因组DNA提取方法改良

火龙果(Hylocereus undulatus)是近年发展起来的一种新兴热带水果, 其茎富含多糖、多酚及其它次生代谢物, 黏性极大, 很难从中提取高质量的DNA。特别是一年生以上的老茎, 目前尚未有较好的DNA提取方法。为了解决这一难题, 该研究对CTAB+Tris-HCl洗涤法进行了3种方式的改良。结果表明, “改进三”方法可不受取样时期和取样部位的限制, 从一年生以上火龙果茎中提取的DNA质量最好且不含黏性物质, 可用于酶切与分子标记等生化和分子生物学实验。该研究探索了一条较为理想的火龙果茎DNA提取方法, 值得推广应用。     

Tebuconazole Sorption in Contrasting Soil Types

This study investigates the sorption of tebuconazole in contrasting soil types (Rendzic Leptosol, Haplic Arenosol, and Haplic Cambisol). Tebuconazole was used both as an analytical-grade chemical and as a commercial product. Sorption experiments were performed using the batch equilibrium approach. The sorption of analytical-grade tebuconazole in soils was lower compared to the commercial product, with the exception of the Cambisol. The highest sorption was observed for the Cambisol regardless of the tebuconazole form. In the experiment with the commercial formula containing tebuconazole, a higher sorption was observed for the Leptosol compared to the Arenosol; the experiment with analytical-grade tebuconazole showed an opposite trend. The differences in sorption of the commercially available and analytical-grade tebuconazole can be attributed to the additives present in the commercial product. Based on the obtained results, tebuconazole sorption is mainly influenced by soil organic matter and the mineralogical composition, but fungicide composition plays an important role as well. Additives present in the commercial products support fungicide sorption in soils. These findings confirm that tebuconazole is adsorbed in soils with high contents of organic matter and clay minerals and its application to such soils should not lead to risks associated with fungicide leaching.     

喜树内生真菌的分离、鉴定以及抗植物病原菌活性的初步研究

对喜树植株中的内生真菌进行分离纯化,共得到126株内生菌株。对126株内生菌株进行液体培养,并对其发酵产物进行抗菌活性测定。发现在供试质量浓度为5mg／mL时,126株菌株中有24株喜树内生真菌的发酵液对水稻纹枯病菌、稻瘟病菌以及辣椒疫霉具有不同程度的抑制菌丝生长的活性作用;其中,菌株XSY09的发酵液对此三种植物病原菌有明显的抑制作用,抑制率分别为74．97％、39．63％和58．49％。在0．1mg／mL的测试浓度下,菌株XSY09发酵液的乙酸乙酯相对三种植物病原菌均有较好的抑制作用。对该菌株的ITS序列进行测序分析,初步鉴定XSY09为炭疽菌属（Colletotrichum gloeosporioides）真菌。     

In vitro Evaluation of Wood Preservatives to Prevent Dispersal of Pitch Canker Pathogen,Fusarium circinatum

Fusarium circinatum, the causal agent of pitch canker disease on pines, can be disseminated by wood produced in infested areas. The purpose of the study was to evaluate the effect of wood preservatives, commonly used against sapstain and wood‐decay fungi, on growth and sporulation of Fusarium circinatum. Seven active ingredients of antisapstain and anti‐wood‐decay preservatives were evaluated by their inhibition of mycelial growth. Propiconazole, tebuconazole, and 3‐iodo‐2‐propinyl butyl carbamate (IPBC) were effective against F. circinatum, whereas hydroxycarbonate of cooper was not. An assay was also conducted to evaluate the efficacy of three commercial antisapstain and two anti‐wood‐decay preservatives on Pinus radiata sapwood blocks that were previously inoculated with Fusarium circinatum. The product with the best efficacy was an antidecay preservative composed of tebuconazole, propiconazole, and dichlofluanid. None of the antisapstain preservatives tested was effective even though they contained fungicidal ingredients. Effects of dosage, product application, and formulation on the efficacy of these preservatives are discussed.     

Biochemical and molecular identification of Enterococcus spp. from red pitaya

Red pitaya is a popular fruit worldwide due to its unique appearance and high nutrient contents. Many studies about the nutritional content and the physico-chemical characteristics of red pitaya have been performed but microorganisms that occurred naturally in the fruit remained unknown. Therefore, this study was conducted to characterize the enterococci present in red pitaya. Enterococci were isolated from red pitaya fruit and characterized with biochemical tests, randomly amplified polymorphic DNA (RAPD) and restriction fragment length polymorphism (RFLP) of the 16S rDNA region. A total of 30 bacteria were isolated from red pitaya, of which 20 isolates were confirmed as enterococci, genus Enterococcus. 13 isolates were further confirmed as Enterococcus casseliflavus and 7 were identified as Enterococcus gallinarum.     

Nutrient additions in pristine Patagonian Sphagnum bog vegetation: can phosphorus addition alleviate (the effects of) increased nitrogen loads

Sphagnum-bog ecosystems have a limited capability to retain carbon and nutrients when subjected to increased nitrogen (N) deposition. Although it has been proposed that phosphorus (P) can dilute negative effects of nitrogen by increasing biomass production of Sphagnum mosses, it is still unclear whether P-addition can alleviate physiological N-stress in Sphagnum plants. A 3-year fertilisation experiment was conducted in lawns of a pristine Sphagnum magellanicum bog in Patagonia, where competing vascular plants were practically absent. Background wet deposition of nitrogen was low (≈ 0.1-0.2 g · N · m(-2) · year(-1)). Nitrogen (4 g · N · m(-2) · year(-1)) and phosphorus (1 g · P · m(-2) · year(-1)) were applied, separately and in combination, six times during the growing season. P-addition substantially increased biomass production of Sphagnum. Nitrogen and phosphorus changed the morphology of Sphagnum mosses by enhancing height increment, but lowering moss stem density. In contrast to expectations, phosphorus failed to alleviate physiological stress imposed by excess nitrogen (e.g. amino acid accumulation, N-saturation and decline in photosynthetic rates). We conclude that despite improving growth conditions by P-addition, Sphagnum-bog ecosystems remain highly susceptible to nitrogen additions. Increased susceptibility to desiccation by nutrients may even worsen the negative effects of excess nitrogen especially in windy climates like in Patagonia.