磁处理改善豌豆根际土壤生物学性状

采用盆栽的方法,分析磁处理对豌豆根际土壤生物学性状的影响,旨在探究磁处理对豌豆根际土壤肥力及健康状况的影响。试验设置无处理（对照CK）,添加铁粉（A）、磁化铁粉（B）、场强为0.2特斯拉（T）磁铁+铁粉（C）以及0.2 T磁铁（D）的处理,基于高通量测序技术分析磁处理对豌豆根际土壤生物学性状的影响。结果表明：C处理显著增加豌豆根际土壤中可培养细菌和真菌数量,同时微生物生物量C、N、P与CK相比分别增加了34.0%、46.0%、44.2%;β-葡萄糖苷酶、氨肽酶、磷酸酶酶活性分别增加了24.6%、23.7%、31.8%;另一方面,C处理中土壤细菌丰富度和多样性指数Ace、Chao1、Shannon指数显著高于CK;属（Genus）分类水平韦恩图分析中上,CK处理特有的属细菌主要有3个：Sneathiella、Desulfurispora、nannocystaceae;A处理特有的属细菌有7个;B处理特有的属细菌亦有7个;C处理特有的属细菌有11个;D处理特有的属细菌有8个。综上所述,C处理能够显著提高豌豆根际土壤中可培养微生物数量、微生物生物量（C、N、P）、酶活性和细菌多样性等多项指示土壤肥力和健康状况的生物学指标,表明磁场强度为0.2 T的磁铁+5 g磁化铁粉处理具有提高土壤肥力抵御土传病害的能力。     

甘肃华山松溃疡病病原真菌类群的初步鉴定

近年来甘肃陇南地区华山松溃疡病发生严重，导致华山松大面积死亡，但有关病害发生的原因等尚不清楚。采用组织分离法从感病华山松的健康部位、病健交界处、子实体及病组织处分离获得97个真菌菌株，结合形态学及系统学对分离到的菌株进行初步分析。结果显示，所得菌株分为9个种，其中Neocosmospora silvicola占14.17%，Fusicolla violacea占1.67%，Microcera sp.占8.33%，Neonectria neomacrospora占11.67%，Dermea pinicola占8.33%，Nematogonum ferrugineum占9.17%，Pezicula sporulosa占4.17%，Phaeoacremonium fraxinopennsylvanicum占14.17%，Sarea resinae占9.17%。以丛赤壳科为优势菌群，占总菌株数量的44.33%；初步推断Neocosmospora silvicola为疑似病原菌。     

茉莉酸甲酯诱导辣椒抗青枯病与活性氧代谢的关系

为探究茉莉酸甲酯(Methyl Jasmonate,Me JA)诱导辣椒抗青枯病效应与活性氧代谢相关酶的关系,以辣椒易感青枯病品种‘粤红1号’和抗青枯病品种‘辛香8号’幼苗为试验材料,在0.1mmol·L-1 Me JA喷雾处理后12、24、48、72和96 h接种青枯劳尔氏菌(Ralstonia solanacearum),对其进行青枯病病情指数与活性氧代谢相关酶——超氧化酶歧化酶(Superoxide Dismutase,SOD)、过氧化氢酶(Catalase,CAT)、过氧化物酶(Peroxidase,POD)和抗坏血酸过氧化物酶(Ascorbate Peroxidase,APX)活性以及丙二醛(Malondialdehyde,MDA)含量测定及相互关系的分析。结果表明:‘粤红1号’和‘辛香8号’的病情指数随喷Me JA处理时间的推移表现为先降后升,但都低于对照;而诱导效果则相反,Me JA处理对两个辣椒品种幼苗抗性的最适诱导时间均为接种前48 h。接种后0~96 h,Me JA喷雾处理的辣椒幼苗叶片SOD、CAT、POD和APX酶活性均显示先升后降的趋势,且明显高于对照,接种后24~48 h达到最高,而MDA含量则明显低于对照。因此,Me JA可诱导辣椒幼苗抗青枯病,其实现途径可能与提高活性氧代谢相关酶活性和缓解膜脂过氧化有关。     

不同药剂对苹果树腐烂病伤口愈合效果研究

为探讨苹果腐烂病的有效防治方法,研究比较了春季休眠期和萌芽期用纯泥、多菌灵药泥、拂蓝克、人工树皮二代和愈合剂5种药剂处理对苹果树伤口愈合面积和形成愈伤组织鲜干重的影响。结果表明:休眠期形成的伤口愈合情况好于萌芽期形成的伤口;使用多菌灵药泥包裹处理伤口愈合面积、愈合比例最大,分别为7.05cm2和99.76%。愈伤组织鲜干重也最大,伤口愈合效果最好。建议春季在休眠期使用多菌灵药泥对苹果腐烂病进行伤口处理。     

Assessment of molecular detection of Fusarium circinatum in insects and passive spore traps in Pinus radiata plantations

Fusarium circinatum is the causal agent of pitch canker, a destructive disease that threatens natural and planted pine forests around the world. Although pitch canker has caused problems in Spain and Portugal, concerning Europe as a whole, the fungus is not established across the pine distribution area. Its dispersion by wind and/or insect vectors could nevertheless play a role in the colonization of currently uninfected stands. It is therefore crucial to develop monitoring tools for its detection. To this end, we assessed the molecular detection of the pathogen in environmental samples of bark beetles and passive spore traps, collected in two infected Pinus radiata plantations in Basque country, Spain. The spread pattern of F. circinatum was assessed by an experimental design that included insect and spore traps installed at the centre, at the edge and outside the plots. Our results showed that F. circinatum was detected in both types of samples, at almost all collection dates. In both type of samples, positive detections were mainly found at the centre of the plots, a lower proportion at the edge, and very few outside. This suggests that long‐distance dispersion of Fusarium circinatum does not rely on wind spore dispersal neither on insect flight. Our study also shows that molecular methods are a powerful tool to monitor the pathogen in environmental samples.     

Strong functional stability of soil microbial communities under semiarid Mediterranean conditions and subjected to long-term shifts in baseline precipitation

We investigated the effect of soil microclimate on the structure and functioning of soil microbial communities in a Mediterranean Holm-oak forest subjected to 10 years of partial rain exclusion manipulations, simulating average drought conditions expected in Mediterranean areas for the following decades. We applied a high throughput DNA pyrosequencing technique coupled to parallel measurements of microbial respiration (R_H) and temperature sensitivity of microbial respiration (Q₁₀). Some consistent changes in the structure of bacterial communities suggest a slow process of community shifts parallel to the trend towards oligotrophy in response to long-term droughts. However, the structure of bacterial communities was mainly determined by short-term environmental fluctuations associated with sampling date (winter, spring and summer) rather than long-term (10 years) shifts in baseline precipitation. Moreover, long-term drought did not exert any chronic effect on the functioning of soil microbial communities (R_H and Q₁₀), emphasizing the functional stability of these communities to this long-term but mild shifts in water availability. We hypothesize that the particular conditions of the Mediterranean climate with strong seasonal shifts in both temperature and soil water availability but also characterized by very extreme environmental conditions during summer, was acting as a strong force in community assembling, selecting phenotypes adapted to the semiarid conditions characterizing Mediterranean ecosystems. Relations of climate with the phylogenetic structure and overall diversity of the communities as well as the distribution of the individual responses of different lineages (genera) to climate confirmed our hypotheses, evidencing communities dominated by thermotolerant and drought-tolerant phenotypes.     

猪胆囊中沙门菌L型的分离培养与invA基因检测

为了解猪胆囊中沙门菌L型携带情况,在贵阳市屠宰场采集970例健康生猪的胆囊组织与胆汁标本,用常规细菌学方法和非高渗分离培养法分离沙门菌及其细菌L型,用PCR和核酸序列分析方法对稳定L型纯培养物进行沙门菌的invA基因检测。结果显示,970例生猪胆囊标本未检出沙门菌细菌型,细菌L型检出率为8.25%;80例细菌L型分离物中有50例invA检测阳性,占5.15%;占细菌L型阳性分离物62.50%。研究结果为生猪胆囊沙门菌L型感染的流行病学及其检查提供了依据。     

低温贮藏对猕猴桃果实成熟软化相关基因表达影响

为探究低温对果实采后成熟软化与淀粉降解的影响,以红阳猕猴桃果实为试验材料,研究在低温贮藏期间,猕猴桃果实硬度,可溶性固形物、乙烯、淀粉含量以及淀粉酶相关基因的变化。结果表明,低温贮藏能显著抑制猕猴桃果实采后成熟软化,延缓果实淀粉的降解和可溶性固形物含量的增加,维持贮藏期间果实较高的硬度。低温贮藏抑制乙烯合成关键基因AcACO1和AcACS1的表达,抑制乙烯合成。同时,低温贮藏显著抑制淀粉降解相关基因AcAMY1、AcBAM1/3、AcISA3、AcLDA1和AcDPE1的表达。在低温贮藏后期,淀粉酶相关基因AcAMY1、AcBAM1/3、AcLDA1和AcDPE1的表达与乙烯释放速率有关。综上,低温贮藏延缓猕猴桃采后成熟软化进程与淀粉降解密切相关,可能主要通过抑制乙烯合成,从而影响贮藏后期淀粉降解速率,最终延缓果实软化进程。本研究结果为猕猴桃采后低温贮藏提供了理论依据。     

Azospirillum brasilense mitigates water stress imposed by a vascular disease by increasing xylem vessel area and stem hydraulic conductivity in tomato

Water stress, with its negative consequences on plant growth and survival, can be mitigated by Azospirillum brasilense inoculation. In tomato, A. brasilense delays wilting caused by a vascular pathogen, Clavibacter michiganensis subsp. michiganensis, by yet unknown mechanisms. We studied morphological, anatomical and physiological changes induced by A. brasilense in tomato that relate to water stress tolerance, which could explain the deferral in symptom expression. For this purpose, tomato seeds were treated or not with A. brasilense BNM65, and 5 weeks later plants were challenged with C. michiganensis subsp. michiganensis or mock inoculated with water. There was a large growth promotion associated to Azospirillum: treated plants had higher total biomass and leaf area. In relation to water stress tolerance, Azospirillum treated plants had larger xylem vessel area, higher stem specific hydraulic conductivity, thicker stems, and lower shoot/root dry matter and specific leaf area. These changes were opposite to those induced by C. michiganensis subsp. michiganensis. We conclude that A. brasilense favoured a better adjustment of plant-water relations by several mechanisms, and thus, transitorily alleviated symptoms expression of a vascular disease.