Turina Massimo, Prodi Antonio, Alfen Neal K Van
Department of Plant Pathology, College of Agricultural and Environmental Sciences, University of California, Davis, 95616-5270, Davis, CA, USA.
Fungal Genet Biol. 2003 Dec;40(3):242-51. doi: 10.1016/s1087-1845(03)00084-7.
Site-directed recombination was used to obtain a Cryphonectria parasitica strain carrying deletions at the Mf1-1 gene locus. Macroscopic features such as growth rate and conidia production were unaffected by Mf1-1 deletions, but, when a strain containing a complete deletion of Mf1-1 was used as spermatia it was male sterile. The same strain was fully competent as a female parent. Deletion of three of the seven putative pheromone peptide repeats within the gene had no effect on mating. Male fertility of the complete deletion strain was restored when an ectopic copy of the Mf1-1 gene was returned by transformation. Expression of the mating type specific pheromone precursor gene Mf1-1 was stimulated by growth in nutritionally poor liquid media. It was found that age and source of inoculum of liquid cultures influences pheromone precusor gene expression, i.e., conidia did not express Mf1-1 and cultures derived from conidia were significantly delayed in expression of this gene, as were cultures derived from young mycelium. Cultures inoculated with older hyphae, however, expressed Mf1-1 within 1 day after inoculation.
利用定点重组技术获得了在Mf1-1基因位点携带缺失的寄生隐孢壳菌株。诸如生长速率和分生孢子产生等宏观特征不受Mf1-1缺失的影响，但是，当将一个完全缺失Mf1-1的菌株用作精子时，它是雄性不育的。同一菌株作为母本时完全有育性。该基因内七个假定的信息素肽重复序列中的三个缺失对交配没有影响。当通过转化导入Mf1-1基因的异位拷贝时，完全缺失菌株的雄性育性得以恢复。交配型特异性信息素前体基因Mf1-1的表达在营养贫乏的液体培养基中生长时受到刺激。发现液体培养物的接种物年龄和来源会影响信息素前体基因的表达，即分生孢子不表达Mf1-1，来自分生孢子的培养物在该基因的表达上显著延迟，来自幼龄菌丝体的培养物也是如此。然而，用老龄菌丝接种的培养物在接种后1天内表达Mf1-1。
