【作者】 陈名君；

【导师】 李增智； 黄勃；

【作者基本信息】 安徽农业大学 ， 微生物学， 2008， 博士

【摘要】 本论文以虫生真菌的群落多样性和生态位测度以及球孢白僵菌的遗传多样性为研究对象,首次对三种不同森林生态系统中虫生真菌分布特点、生态位各项指标及资源竞争进行了系统分析研究。并利用ISSR分子标记技术研究了3种森林生态系统中球孢白僵菌的遗传多样性,综合比较分析了各森林生态系统中球孢白僵菌的遗传特点。调查发现:皖东琅琊山虫生真菌资源丰富,共确认分离得到672个菌株,分属于4科9属20种,其中以球孢白僵菌最多,占菌株总数的比例高达92.7%。发现虫草属一新变种根足虫草琅琊山变种,其无性型为被毛孢一新种。该群落的多样性指数(H)和均匀度(E)均在温湿度较低的季节较大,而在高温高湿季节较小;6～8月的均匀度显著地低于其他月份,但多样性指数普遍较小,最高仅为1.9505。同时研究了3种优势虫生真菌各项生态位指标,研究表明:球孢白僵菌的营养、时间生态位宽度最大,而粉棒束孢空间生态位宽度最大;环链棒束孢与粉棒束孢的营养生态位重叠度最大;球孢白僵菌和环链棒束孢之间时间生态位重叠度较大,最高达0.8957;球孢白僵菌与环链棒束孢空间生态位重叠度较小。本文研究了大别山鹞落坪的虫生真菌群落多样性,研究发现:该区虫生真菌资源非常丰富,共采集标本687个,约27种,隶属于4目4科11属,其中下垂虫草为最多。该区夏季虫生真菌丰度和多度均达到最高峰。研究发现该区虫生真菌群落多样性指数以1100～1150m海拔最高,第一优势属—虫草属分布主要集中在1050～1200m范围内,以下垂虫草分布最为明显,而棒束孢属则分布广泛。生态位研究表明:鹞落坪球孢白僵菌的营养、时间、空间资源生态位宽度均为最大。其中下垂虫草与其他3种优势虫生真菌的营养重叠度最小,下垂虫草与粉棒束孢时间生态位重叠度最大,粉棒束孢与细脚棒束孢的空间资源生态位重叠度最大。4种虫生真菌的空间-时间二维生态位重叠度均不大,但依据不同公式获得的结果有所不同。总体来看,仅下垂虫草与粉棒束孢的二维生态位重叠度较大。此外,还研究了皖南麻姑山林场马尾松人工纯林的虫生真菌群落多样性,确认得到355个菌株,约14种,隶属于3科5属,均为常见种,其中以环链棒束孢的多度最大。6月菌种数最多,早春、晚秋、冬季虫生真菌丰度和多度都很低,总体来说,该林区多样性指数较低。同时还研究了3种优势虫生真菌的生态位宽度,麻姑山林场内球孢白僵菌时间生态位宽度和营养生态位宽度最大。研究生态位重叠度发现:环链棒束孢和粉棒束孢营养生态位重叠度最大,而环链棒束孢和球孢白僵菌的时间资源生态位重叠度最大,结果与营养生态位重叠正好相反。3种虫生真菌二维生态位宽度依据不同的计算公式结果相同,球孢白僵菌的营养-时间生态位宽度最大,是3种虫生真菌中生存能力最强的;其次是粉棒束孢,而环链棒束孢的二维生态位最小,表明其对生存环境的要求比较苛刻。利用ISSR分子标记技术研究了琅琊山阔叶次生林497株球孢白僵菌遗传多样性和种群遗传结构。8个引物共得到90个位点,其中多态位点比率为95.56%。球孢白僵菌具有丰富的遗传变异(不同采集地水平,H=0.2687,I=0.4181,以山谷多样性指数最高;不同采集时间水平,H=0.2696,I=0.4193,以6月份多样性指数最高;不同寄主水平,H=0.2652,I=0.4128,以鳞翅目多样性指数最高)。Nei’s遗传多样性分析了各种群间的遗传分化系数(不同采集地居群,Gst=0.0198,Nm=24.7810;不同采集时间居群,Gst=0.2634,Nm=1.3980;不同寄主居群,Gst=0.0800,Nm=5.7473)。不同采集地种群遗传距离很小,溪旁与山坡的遗传距离最小,为0.0052;鞘翅目和鳞翅目之间遗传距离也很小,仅为0.0059;不同采集时间种群的遗传距离相对较大,其中9月与11月的遗传距离最小,为0.0253。可见该实验地球孢白僵菌具有很高的多态位点比率,较强适应环境能力。对鹞落坪天然阔叶林的35株球孢白僵菌的遗传多样性研究结果发现:8个引物共得到69个位点,其中多态位点比率为92.75%。Nei’s基因多样性(H)为0.2896,Shannon信息指数(I)为0.4416,种群间的基因分化系数(Gst)为0.3181,基因流Nm=1.0718,其中7月和10月间的遗传距离最小为0.0438;Nei’s基因多样性(H)为0.2871,Shannon信息指数(I)为0.4850,种群间的基因分化系数(Gst)为0.2180,基因流Nm=1.7935,其中海拔900m和1000～1050m间的遗传距离最小为0.0086。结果表明:鹞落坪自然保护区球孢白僵菌有很高的遗传多样性,种群间遗传变异稍大,种群内表现出较高水平的遗传分化。对麻姑山马尾松人工纯林的111株球孢白僵菌进行遗传多样性分析,7个引物共得到58个位点,其中多态位点比率为93.10%。不同采集时间种群的Nei’s基因多样性(H)为0.2552,Shannon信息指数(I)为0.3825,种群间的基因分化系数(Gst)为0.2269,基因流Nm=1.7037,其中5月和7月间的遗传距离最小为0.0408;不同寄主居群的Nei’s基因多样性(H)为0.2623,Shannon信息指数(I)为0.3884,种群间的基因分化系数(Gst)为0.1965,基因流Nm=2.0441,其中鞘翅目和鳞翅目间的遗传距离最小为0.0163。根据基因流可知麻姑山球孢白僵菌居群内的遗传变异相对较大,群体间的遗传变异较小。以上结果表明:森林生态状况对其中虫生真菌群落多样性和球孢白僵菌的各项遗传多样性指数影响很大。地形复杂、雨水充足、郁闭度大的原始落叶阔叶林,其虫生真菌物种资源丰富,球孢白僵菌的遗传多样性也丰富;而人为干扰频繁、生态环境单一的马尾松人工纯林区不仅虫生真菌资源单调,而且球孢白僵菌的遗传多样性也单调;人为干扰较少的天然次生林居中。不同的森林生态系中球孢白僵菌的生态位宽度较大,与其他虫生真菌生态位重叠度相对较小,可见球孢白僵菌适应森林环境能力最强,可以长期、广泛地存在于各种林区。更多还原

【Abstract】 In the present dissertation,community diversity and distribution of entomogenous fungi,niche measurement and niche indices were investigated and systematically analyzed,and genetic diversity of Beauveria bassiana were studied by ISSR marker,in 3 different forest ecosystems:National Langyashan Forest Park in Chuzhou City,eastern Anhui,National Yaoluoping Nature Reserve in Dabie Mountains in Yuexi County, Western Anhui,and Magushan Forest Farm in Xuanzhou,Southeastern Anhui.The investigation revealed 672 specimens of entomogenous fungi belonging to 20 species of 9 genera in 4 families from Langyashan.Among them,B.bassiana was the most dominant with relative abundance of 92.7%.Cordyceps heteropoda var. langyashaneasis was a new variety,and its anamorph was a new species,Hirsutella heteropoda.The diversity index(H) and evenness(E) of entomogenous fungi were both high in cool and less humid season,and low in the hot and humid season.Evenness in June to August was significantly lower than in others months.Diversity Index was generally low with the maximum only at 1.9505.In the study on niche of 3 dominating entomogenous fungi,the results showed that B.bassiana had the widest nutritional and time niches breadth,and Isaria farinosus had widest space niche breadth.The nutritional niche overlap was largest between Isaria cateniannulata and I.farinosa,and time niche overlap was largest among B.bassiana and I.cateniannulata up to 0.8957,while there was small space niche overlap among B.bassiana and I.cateniannulata.In Yaoluoping,abundant community diversity was recorded with 687 isolates belonging to 27 species of 11 genera in 4 families.Among them,Cordyceps nutans was the most dominant.Abundance and richness of entomogenous fungi reached peak level in summer.Community index of the community was the highest at altitude of 1100～1150m.Cordyceps,the dominant genus in this area,distributed intently within 1050～1200m,particularly C.nutans.Comparably,Isaria distributed widely at various altitudes.In the study on niche here:B.bassiana had the biggest nutritional,space and time niche widths.The nutritional niche overlap was smallest between C.nutans and the other 3 entomogenous fungi.C.nutans had the largest time niche overlap to I.farinosa, while I.farinosa and I.tenuipes had the biggest space niche overlap.Two-dimensional niche overlap of time and space among these 4 fungi were all small,and only that between C.nutans and I.farinosa was comparably big.In Magushan,the artificial forest ecosystem of pure Masson’s pines,simple community diversity was revealed by a collection of 355 specimens belonging to 14 species of 5 genera in 3 families with I.cateniannulata as the most abundant.Biggest species number appeared in June.In general,the diversity index was low here.Study on niche width of 3 dominant species showed that B.bassiana had largest time and nutritional niche width.Nutritional niche overlap was largest between I.cateniannulata and I.farinosa,while time niche overlap was biggest between I.cateniannulata and B. bassiana.As for two-dimensional niche width of The 3 fungi,B.bassiana had the biggest,the followed by I.farinosa,and I.cateniannulata had the smallest.All suggested that B.bassiana had strongest viability while I.cateniannulata had the poorest.The genetic diversity of 497 isolates of B.bassiana from Langyashan was investigated using ISSR markers.The result showed that 90 bands were amplified by 8 informative and reliable primers,of which 86(95.56%) were polymorphic.A relatively high level of genetic diversity was revealed with H=0.2687,I=04181 at origins level and with indices at valley as the highest;H=0.2696,I=04193 at time level with that of June as the highest;Nei’s genetic diversity H=0.2652,Shannon’s information index I=04128 at the host level and with that of Lepidoptera as the highest.A higher level of genetic differentiation was detected in the population with Nei’s analysis.The result of the analysis on molecular variance showed genetic differentiation factor Gst=0.0198,gene flow Nm=24.7810 at origins level;Gst=0.2634,Nm=1.3980 at time level;and Gst=0.0800,Nm=5.7473 at host level.The genetic distance of different origin groups was small with that between stream and hillside as the smallest.The genetic distance between groups from Coleoptera and Lepidoptera was also small.The genetic distance of different time groups was relatively large between those of September and November were smallest.It suggested that B.bassiana in Langyashan had high rate of polymorphic loci, i.e.,it had strong adaptability to the environment.The genetic diversity of 35 isolates of B.bassiana from Yaoluoping was estimated using inter-simple sequence repeat(ISSR) marker.With 8 rimers scored,total 69 fragments were amplified,in which 64(92.75%) were polymorphic with H=0.2896 and I=0.4416.Gst of among populations was 0.3181 with gene flow at 1.0718.Genetic distance between groups of July and October was smallest.The polymorphic loci percentage of different altitudes was also 92.75%with H=0.2781 and I=0.4850.Gst among populations was 0.2180 with Nm=1.7935;The genetic distance between isolates in latitudes of 900m and 1000～1050m was smallest.It suggested that B.bassiana from Yaoluoping had high genetic diversity,with slightly large interpopulation genetic variation and high level intrapopulation genetic differentiation.The analysis by ISSR on genetic diversity of 111 isolates of B.bassiana from Magushanrevealed that 7 ISSR primers chosen amplified a total of 58 fragments,54 of which(93.10%) were polymorphic.For groups of isolates based on time,H=0.2552, I=0.3825,Gst=0.2269,and Nm=1.7037.Genetic distance between May and July was shortest.For groups of isolates based on host,H=0.2623,I=0.3884.Gst=0.1965,and Nm=2.0441.The genetic distance between isolates from Coleoptera and Hymenotera was shortest.According to gene flow,it was known that intrapopulation genetic variation of B. bassiana was relatively small,while interpopulation genetic variation was pretty big.All above results showed that:the genetic diversity indices of B.bassiana were substantially influenced by forest ecological condition.Community of entomogenous fungi and genetic diversity of B.bassiana are abundant in virgin forest ecosystem where exist complex terrain,flourish broad-leaf and deciduous forest,and adequate rainfall.On the contrary,those are simple in pure pine plantation ecosystem where ecological environment was monotone and exists frequent artificial disturbance.While those in less interfered natural forest are intermediate.B.bassiana has large niche width in all different forest ecosystems,and its niche overlap to other entomogenous fungi is small. All evidences suggest that B.bassiana has strong adaptability to the environment.It can widely exist for long term in different forest ecosystems.更多还原