Solomon Peter S, Rybak Kasia, Trengove Robert D, Oliver Richard P
Australian Centre for Necrotrophic Fungal Pathogens, SABC, School of Veterinary and Biomedical Sciences, Murdoch University, Perth, WA 6150, Australia.
Mol Microbiol. 2006 Oct;62(2):367-81. doi: 10.1111/j.1365-2958.2006.05380.x.
Three genes encoding different Ca2+/calmodulin-dependent protein kinases have been characterized in the wheat phytopathogenic fungus Stagonospora nodorum. The kinases were identified from the S. nodorum genome sequence on the basis of sequence homology to known Ca2+/calmodulin-dependent protein kinases. Expression analysis determined that each of the kinases was expressed during growth in vitro and also during infection. The onset of sporulation triggered increased transcript levels of each of the kinases, particularly CpkA where an 11-fold increase in expression was observed during sporulation in planta. The role of the kinases was further determined via a reverse genetics approach. The disruption of CpkA affected vegetative growth in vitro and also sporulation. The cpkA strains produced 20-fold less spores on complex media and were unable to sporulate on defined minimal media. Infection assays showed that CpkA was not required for lesion development but was essential for sporulation at the completion of the infection cycle. Microscopic analysis revealed that the disruption of CpkA resulted in Stagonospora nodorum being unable to differentiate the mycelial knot into immature pycnidia during sporulation. A metabolite analysis of infected leaves during sporulation excluded the possible involvement of mannitol, a compound previously shown to be involved in the sporulation of Stagonospora nodorum. The disruption of CpkB did not effect growth in vitro or pathogenicity. Stagonospora nodorum strains lacking CpkC appeared unaffected during growth in planta but showed delayed lesion development and sporulation during infection.
在小麦致病真菌小麦壳针孢中，已鉴定出三种编码不同钙调蛋白依赖性蛋白激酶的基因。这些激酶是根据与已知钙调蛋白依赖性蛋白激酶的序列同源性，从小麦壳针孢基因组序列中鉴定出来的。表达分析表明，每种激酶在体外生长期间以及感染期间均有表达。孢子形成的开始引发了每种激酶转录水平的增加，尤其是CpkA，在植物体内孢子形成期间观察到其表达增加了11倍。通过反向遗传学方法进一步确定了这些激酶的作用。CpkA的破坏影响了体外营养生长以及孢子形成。cpkA菌株在复杂培养基上产生的孢子减少了20倍，并且在限定的基本培养基上无法形成孢子。感染试验表明，病变发展不需要CpkA，但对于感染周期结束时的孢子形成至关重要。显微镜分析显示，CpkA的破坏导致小麦壳针孢在孢子形成过程中无法将菌丝结分化为未成熟的分生孢子器。对孢子形成期间感染叶片的代谢物分析排除了甘露醇的可能参与，甘露醇是一种先前已证明参与小麦壳针孢孢子形成的化合物。CpkB的破坏不影响体外生长或致病性。缺乏CpkC的小麦壳针孢菌株在植物体内生长期间似乎未受影响，但在感染期间显示出病变发展和孢子形成延迟。
