Biotic and abiotic regulation of resting spore formation in vivo of obligate aphid pathogen Pandora nouryi: modeling analysis and biological implication.
Biotic and abiotic regulation of resting spore formation in vivo of obligate aphid pathogen Pandora nouryi: modeling analysis and biological implication.
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DOI：
10.1016/j.jip.2009.11.003
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发表时间：
2010-02
影响因子：
3.4
通讯作者：
Xiaoping Zhou;M. Feng
中科院分区：
文献类型：
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作者：
Xiaoping Zhou;M. Feng
诺氏虫霉（Pandora nouryi）是一种专性蚜虫病原菌，其能够产生休眠孢子（azygospores）以在宿主缺席的情况下存活。为了探讨体内休眠孢子形成的可能调控机制，将40-60头绿色桃蚜（Myzuspersicae）在培养皿中的甘蓝叶盘上24小时内产生的寄主群体暴露于诺氏潜蝇孢子雨中，孢子雨的浓度（C）从很少到接近2000个分生孢子/mm 2，然后在10-25 ℃（T）和8- 16小时日光（HL）或环境（17.5±3.1°C，13：11 L：D）。在每种处理下，35-83个队列（分别淋浴）的蚜虫死亡率呈典型的S形趋势，符合一般逻辑斯蒂方程（0.79 × r2 × 0.88），得出相似的LC 50估计值为1.7- 6.1分生孢子/mm 2。在除10°C（宿主-病原体相互作用的低温）外的所有试验条件下，队列中形成休眠孢子的尸体比例（P）也符合相同的方程（0.73 × r2 × 0.85）。这表明休眠孢子的形成依赖于孢子浓度。T和HL对P相对于C的影响通过拟合的修改的逻辑斯谛方程P=0.578/{1+exp[1.710-（0.136 - 0.0053T）C]}和P=0.534/{1+exp[1.639+（0.034 - 0.0053HL）C]}（均为r2=0.79）很好地阐明。我们的研究结果强调，休眠孢子的形成在体内的诺氏疫霉主要是由浓度的主机感染分生孢子排出的尸体和促进较低的温度和较长的日照。
Entomophthoralean fungus Pandora nouryi is an obligate aphid pathogen that enables to produce resting spores (azygospores) for surviving host absence. To explore possible mechanisms involved in the regulation of resting spore formation in vivo, host cohorts consisting of 40–60 nymphs of green peach aphid Myzus persicae produced within 24h on cabbage leaf discs in petri dishes were exposed to spore showers of P. nouryi at the concentrations (C) from a very few to nearly 2000conidia/mm2and then reared for 7–11days at the regimes of 10–25°C (T) and 8–16h daylight (HL) or ambient (17.5±3.1°C, 13:11 L:D). Aphid mortalities observed from 35–83 cohorts (showered separately) at each regime showed typical sigmoid trend and fit well a general logistic equation (0.79⩽r2⩽0.88), yielding similar LC50estimates of 1.7–6.1conidia/mm2. The proportions (P) of cadavers forming resting spores in the cohorts also fit the same equation (0.73⩽r2⩽0.85) at all tested regimes except at 10°C, a low temperature for the host-pathogen interaction. This indicates the dependence of resting spore formation on the spore concentration. The effects of T and HLon P over C were well elucidated by the fitted modified logistic equations P=0.578/{1+exp[1.710−(0.136−0.0053T)C]} and P=0.534/{1+exp[1.639+(0.034−0.0053HL)C]} (both r2=0.79). Our results highlight that the resting spore formation in vivo of P. nouryi is regulated primarily by the concentration of host-infecting conidia discharged from cadavers and facilitated by lower temperature and longer daylight.