State Key Laboratory of Crop Stress Biology for Arid Areas and College of Plant Protection, Northwest A & F University, Yangling, Shaanxi, People's Republic of China.
PLoS One. 2012;7(11):e49262. doi: 10.1371/journal.pone.0049262. Epub 2012 Nov 6.
Calcineurin plays a key role in morphogenesis, pathogenesis and drug resistance in most fungi. However, the function of calcineurin genes in Puccinia striiformis f. sp. tritici (Pst) is unclear. We identified and characterized the calcineurin genes PsCNA1 and PsCNB1 in Pst. Phylogenetic analyses indicate that PsCNA1 and PsCNB1 form a calcium/calmodulin regulated protein phosphatase belonging to the calcineurin heterodimers composed of subunits A and B. Quantitative RT-PCR analyses revealed that both PsCNA1 and PsCNB1 expression reached their maximum in the stage of haustorium formation, which is one day after inoculation. Using barely stripe mosaic virus (BSMV) as a transient expression vector in wheat, the expression of PsCNA1 and PsCNB1 in Pst was suppressed, leading to slower extension of fungal hyphae and reduced production of urediospores. The immune-suppressive drugs cyclosporin A and FK506 markedly reduced the germination rates of urediospores, and when germination did occur, more than two germtubes were produced. These results suggest that the calcineurin signaling pathway participates in stripe rust morphogenetic differentiation, especially the formation of haustoria during the early stage of infection and during the production of urediospores. Therefore PsCNA1 and PsCNB1 can be considered important pathogenicity genes involved in the wheat-Pst interaction.
钙调神经磷酸酶在大多数真菌的形态发生、发病机制和耐药性中发挥关键作用。然而，钙调神经磷酸酶基因在小麦条锈菌（Puccinia striiformis f. sp. tritici，Pst）中的功能尚不清楚。我们鉴定并表征了 Pst 中的钙调神经磷酸酶基因 PsCNA1 和 PsCNB1。系统发育分析表明，PsCNA1 和 PsCNB1 形成钙/钙调蛋白调节的蛋白磷酸酶，属于由 A 亚基和 B 亚基组成的钙调神经磷酸酶异源二聚体。定量 RT-PCR 分析显示，PsCNA1 和 PsCNB1 的表达在吸器形成阶段达到最大值，即在接种后一天。使用大麦条纹花叶病毒（barley stripe mosaic virus，BSMV）作为瞬时表达载体，在 Pst 中抑制 PsCNA1 和 PsCNB1 的表达，导致真菌菌丝延伸速度减慢，产孢量减少。免疫抑制药物环孢素 A 和 FK506 显著降低了夏孢子的萌发率，当萌发确实发生时，产生了两个以上的芽管。这些结果表明，钙调神经磷酸酶信号通路参与条锈菌形态发生分化，特别是在侵染早期和产孢过程中吸器的形成。因此，PsCNA1 和 PsCNB1 可以被认为是参与小麦- Pst 互作的重要致病性基因。
