cAMP介导的梨果表皮物化信号对链格孢侵染的调控

采用药理学方法,用cAMP抑制剂阿托品（atropine）处理链格孢Alternaria alternata孢子悬浮液,通过体外试验分析cAMP信号级联通路在链格孢响应梨果皮蜡质疏水性、化学组分和外源乙烯利等刺激后启动孢子萌发、附着胞形成的调控作用,并通过体内试验研究其对链格孢致病性的调控。结果表明,高疏水性表面和梨果蜡涂膜表面及1μmol/L的乙烯利均可显著促进链格孢的孢子萌发和附着胞形成。cAMP信号级联通路抑制剂atropine处理后显著抑制了表皮疏水性、蜡质和外源乙烯介导的链格孢的孢子萌发和附着胞形成,其中抑制剂处理后4h,链格孢在疏水性、果蜡涂膜表面和乙烯等处理中附着胞形成率分别较对照降低了75.3%、63.7%和74.3%,同时抑制剂处理还可抑制损伤接种链格孢早酥梨黑斑病的扩展。外源cAMP可以部分恢复抑制剂的作用,外源cAMP+atropine处理后4h,在高疏水性（108°）和果蜡涂膜表面,链格孢附着胞形成率为抑制剂atropine单独处理的2.4倍和1.6倍,表明cAMP信号级联通路可通过调控侵染结构的形成而影响链格孢对梨果表皮物理化学信号的识别和应答。

Regulation of cAMP-mediated physicochemical signal of pear fruit epidermis to Alternaria alternata infection

Through pharmacological method, a series of in vitro tests were conducted to investigate regulatory role of cAMP signal cascade pathway in spore germination and appressorium formation of Alternaria alternata after responding to stimulation of hydrophobicity and chemical composition of pear wax, and exogenous ethephon. The regulatory role of the cAMP inhibitor in pathogenicity of A. alternata was also observed through in vivo test. The results showed that highly hydrophobic surface, fruit wax-coated gelbond film surface and the 1μmol/L ethephon treatment could significantly promote spore germination rate and appressorium formation rate of A. alternata. Atropine treatment significantly inhibited higher hydrophobicity, and pear wax and exogenous ethylene stimulated spore germination rate and appressorium formation rate of A. alternata. In 4h of inhibitor treatment, the rate of appressorium formation on the hydrophobic surface, fruit wax-coated surface and ethephon treated gelbond film surface decreased by 75.3%, 63.7% and 74.3%, respectively. The inhibitor treatment also inhibited the development of pear black spot. Exogenous cAMP could partially restore the inhibitory effect of cAMP inhibitor on spore germination and appressorium formation. After 4h of incubation, appressorium formation rate of A. alternata on the high hydrophobic surface and fruit wax-coated gelbond film surface treated with exogenous cAMP+atropine was respectively 2.4 times and 1.6 times higher than that on the surface treated with atropine alone. The findings suggested that the cAMP signal cascade pathway might affect the recognition and response of A. alternata to the physicochemical signal of pear fruit peel through regulating the formation of infection structures.