FAC1基因对禾谷镰刀菌的菌丝膨大处细胞核分裂的影响

The division of the nucleus of swelling hypha involved in DON synthesis in Fusarium graminearum

与大多数丝状真菌一样,禾谷镰刀菌中也存在依赖cAMP信号调节的蛋白激酶A(protein kinase A,PKA)信号通路—cAM P-PKA信号通路。前期研究发现,该信号通路在脱氧雪腐镰刀菌烯醇(Deoxynivalenol,DON)的合成中扮演着重要角色。FAC1作为cAMP-PKA信号通路上游基因,它的缺失可导致DON无法合成。本研究发现,FAC1的缺失可严重影响DON合成相关基因TRI1在转录水平和翻译水平上的表达。显微观察发现,Tri1定位在细胞核周围,并且与野生型菌株PH-1相比,fac1突变体在产毒培养基内菌丝膨大结构的形成增多。此外,与未膨大菌丝相比,野生型菌株PH-1菌丝膨大结构处细胞核分裂明显增多,该位点多于4个细胞核的比例达到65.4%,而fac1突变体中菌丝膨大结构处核分裂数仅为0～3个,其中0～2个的占90.7%。研究结果表明,在产毒培养基中特有形成的菌丝膨大结构与DON合成之间并没有必然联系,DON毒素的合成应与菌丝膨大结构处细胞核分裂密切相关。

Like many other filamentous fungi,cyclic AMP(cAMP)-dependent signaling pathway is one of the major signal transduction pathways in Fusarium graminearum.It has been reported that c AMP-PKA pathway plays an important role in DON biosynthesis.FAC1 acts upstream the c AMP-dependent signaling pathway.Lack of FAC1 can block the DON biosynthesis.In this study,FAC1 mutant exhibited defects in the expression of TRI1 on the levels of transcription and translation.Microscopic observations revealed that Tri1 was located around the nucleus and the hyphal swelling structure of fac1 mutant had a significant increase compared with that of PH-1.In addition,the number of nuclear division in the swelling structures was more than that in normal hypha of PH-1.In the swelling structure of PH-1,the nuclear division number was more than 4,whose ratio had reached to 65.4%.Whereas the nuclear division number of fac1 mutant was only 0 to 3,in which the nuclear number with 0 to 2 was up to 90.7%.This study suggests that there is no direct connection between hyphal swelling structure and DON production,and that the DON biosynthesis is closely related to nuclear division in the hyphal swelling structure.