半夏丛枝菌根真菌侵染模式及侵染率动态变化

通过染色镜检法观察栽培及野生半夏丛枝茵根,研究其类型、结构,阐述栽培及野生半夏丛枝茵根真茵的侵染模式及全年中侵染率的动态变化.结果表明:半夏根内存在茵丝、丛枝、泡囊等典型丛枝茵根结构,茵根结构类型包括Arum型、Paris型及其交叉型等.丛枝茵根真茵对半夏的侵染率随季节变化而变化,从早春开始上升.夏秋季达到顶峰.而后开始下降;且同一季节中丛枝茵根真茵侵染率野生半夏高于栽培半夏.表明,野生半夏生长环境更适宜丛枝茵根真菌生长,栽培半夏退化可能与半夏共生真菌有关.     

Arbuscular mycorrhizal fungi improve the growth and phosphorus uptake of mung bean plants fertilized with composted rock phosphate fed dung in alkaline soil environment

Abstract

Inoculation effect of arbuscular mycorrhizal fungi (AMF) on phosphorus (P) transfer from composted dung of cattle with a diet supplemented with powdered rock phosphate (RP) and their successive uptake by mung bean plants was assessed in alkaline soil. The efficacy of composted RP fed dung alone or/and in combination with AMF inoculums containing six different species were compared with SSP in six replicates per treatment in pots. The results showed that the association of AMF with composted RP fed dung had a positive effect on mung bean shoot (3.04?g) and root (2.62?g) biomass, chlorophyll (a, b), carotenoid contents and N (58.38?mg plant^?1) and P (4.61?mg plant^?1) uptake. Similarly, the percent roots colonization (56%) and nodulation of mung bean plant roots and their post-harvest soil properties were also improved by the inoculation of AMF together with composted RP fed dung. It is concluded that the combined application of AMF with composted RP fed dung has almost the same effect as SSP for improving mung bean plants growth and their nutrients uptake. Moreover, AMF inoculants can be used as a suitable biofertilizer in combination with locally available organic sources of fertilizers for improving P status and growth of plants in alkaline soils.     

Mycorrhizal (Rhizophagus Intraradices) Symbiosis and Fe and Zn Availability in Calcareous Soil

Greenhouse experiment was conducted to assess the iron (Fe) and zinc (Zn) fractionation patterns in soils of arbuscular mycorrhizal (AM) fungus-inoculated and uninoculated maize plants fertilized with varying levels of Fe and Zn. Soil samples were collected for Fe and Zn fractions and available Fe, Zn and phosphorus (P) contents besides organic and biomass carbon (BMC), soil enzymes and glomalin. Major portion of Fe and Zn fractionations was found to occur in the residual form. Mycorrhizal symbiosis increased the organically bound forms of Fe and Zn while reducing the crystalline oxide, residual Fe and Zn fractions, indicating the transformation of unavailable forms into available forms. Soil enzymes, viz. dehydrogenase and acid phosphatase activities in M+ soils, were significantly higher than M? soil consistently. Overall, the data suggest that mycorrhizal symbiosis enhanced the availability of Fe and Zn as a result of preferential fractionation and biochemical changes that may alleviate micronutrient deficiencies in calcareous soil.

Abbreviations: AM: arbuscular mycorrhiza; Fe: Iron; Zn: Zinc; P: Phosphorous; Amox-Zn: amorphous oxide bound zinc; Cryox-Zn: crystalline oxide bound zinc; DAS: days after sowing; DTPA: diethylene Triamine Penta Acetic Acid; MnO₂-Zn: manganese oxide bound zinc; OC-Zn: organically bound zinc; WSEX: water soluble plus exchangeable zinc; MnO₂ Fe: manganese oxide bound iron; OC-Fe: Organically bound iron; WSEX Fe: water soluble plus exchangeable iron.     

丛枝菌根对干旱胁迫下油用牡丹幼苗光化学活性的影响

采用盆栽法,对重度干旱(土壤相对含水量为30%)和轻度干旱(土壤相对含水量为55%)胁迫3 d和6 d的接种丛枝菌根真菌(Gigaspora rosea)的油用牡丹‘凤丹’幼苗叶片叶绿素荧光参数进行测定。结果显示：与未接菌相比,干旱胁迫下接菌‘凤丹’的PSII潜在活性Fv/Fo和性能指数PIabs均升高;重度干旱胁迫3、6 d,接菌‘凤丹’的Mo和Vj较未接菌处理分别显著降低14.5%、29.8%和12.9%和16.2%,φEo和φo分别显著提高9.7%、52.2%和8%、23.6%;与未接菌相比,轻度干旱胁迫3、6 d,接菌‘凤丹’的单位面积吸收的光能ABS/CSo、单位面积捕获的光能Tro/CSo、单位面积电子传递的量子产额ETo/CSo、单位面积传递到PSⅠ末端的量子产额REo/CSo均提高,但不显著;重度干旱胁迫3、6 d,接菌‘凤丹’的Tro/CSo、ETo/CSo和单位面积反应中心数RC/CSm分别显著提高37.8%、41.1%、47.7%、73.8%、50.1%、141.8%;干旱胁迫下,接菌‘凤丹’的调节性能量耗散量子产量Y(NPQ)均显著高于未接菌处理,非调节性能量耗散量子产量Y(NO)显著低于未接菌处理。表明,丛枝菌根可以提高干旱胁迫下(尤其是重度干旱下)PSII反应中心活性,增加对光能的吸收和捕获,提高电子传递能力和光化学效率,同时将剩余的光能以热耗散的形式散发,从而避免光损伤,进而提高干旱胁迫下油用牡丹幼苗的光化学活性和抗旱性。     

Mycorrhiza induced resistance in potato plantlets challenged by Phytophthora infestans

Biological control of soil-borne pathogens by arbuscular mycorrhizal (AM) fungi has been repeatedly demonstrated. However, their role in the control of above-ground hemibiotrophic pathogens is less conclusive. Here, we investigated in vitro the impact of an AM fungus on Phytophthora infestans in potato plants. The leaf infection index was decreased in mycorrhizal potato plants. Real-Time Quantitative PCR revealed the induction of two pathogenesis related genes (PR1 and PR2) in the leaves of mycorrhizal plants shortly after infection with P. infestans. These results suggested a systemic resistance in mycorrhizal plants, related to the priming of the two PR genes in potato.     

农牧交错带柠条根围丛枝菌根真菌的空间分布

2009年10月在冀蒙农牧交错带选取3个样地,从柠条(Caragana korshinskii Kom.)根围0～10 cm、10～20 cm、20～30 cm、30～40 cm和40～50 cm 5个土层分别采集土壤样品,研究了丛枝菌根真菌的空间分布及其与土壤酶活性和土壤养分的关系.结果表明,不同样地和土层深度对丛枝菌根各结构真菌定殖率和孢子密度有显著影响.菌丝、泡囊、丛枝定殖率和孢子密度最大值均出现在0～20 cm土层.菌丝定殖率和脲酶活性呈极显著正相关,泡囊定殖率和孢子密度与脲酶、碱性磷酸酶、酸性磷酸酶活性呈极显著正相关.孢子密度与各土壤养分因子均呈极显著正相关.说明在冀蒙农牧交错带柠条能与丛枝菌根真菌形成良好的共生关系,丛枝菌根不同结构和孢子密度有助于土壤状况的监测和评价.