Kinane J, Dalvin S, Bindslev L, Hall A, Gurr S, Oliver R
Department of Physiology, Carlsberg Laboratory, Copenhagen Valby, Denmark.
Mol Plant Microbe Interact. 2000 May;13(5):494-502. doi: 10.1094/MPMI.2000.13.5.494.
Development of conidia of barley powdery mildew involves the formation of a primary germ tube (PGT), an appressorial germ tube (AGT), and an appressorium. Previously, it was found that cyclic AMP (cAMP) was involved in these developmental processes. Comparison of development on the host surface with two types of cellulose membrane revealed that frequency of PGT emergence was surface independent. On one type of cellulose, where the frequencies of both AGT and appressorial differentiation were similar to that on the host surface, cAMP levels and protein kinase A (PKA) activities had a biphasic pattern with peaks at 15 min and 4 h after inoculation (prior to PGT and AGT emergence, respectively). The effect of manipulating cAMP levels was tested on another type of cellulose membrane, which stimulated a lower degree of AGT and appressorial formation than the host surface. Cholera toxin and forskolin, activators of adenylyl cyclase, significantly increased PGT emergence, but cAMP did not. Cholera toxin, forskolin, and cAMP increased the frequency of AGT and appressorial formation, but in a time-dependent manner.
大麦白粉病菌分生孢子的发育涉及初生芽管（PGT）、附着胞芽管（AGT）和附着胞的形成。此前发现，环磷酸腺苷（cAMP）参与了这些发育过程。通过在宿主表面与两种类型的纤维素膜上进行发育比较发现，PGT出现的频率与表面无关。在一种纤维素膜上，AGT和附着胞分化的频率与宿主表面相似，cAMP水平和蛋白激酶A（PKA）活性呈现双相模式，分别在接种后15分钟和4小时达到峰值（分别先于PGT和AGT出现）。在另一种纤维素膜上测试了调节cAMP水平的效果，该膜刺激形成的AGT和附着胞程度低于宿主表面。霍乱毒素和福斯可林，即腺苷酸环化酶的激活剂，显著增加了PGT的出现，但cAMP没有。霍乱毒素、福斯可林和cAMP增加了AGT和附着胞形成的频率，但呈时间依赖性。
