Acquired resistance functions in mlo barley, which is hypersusceptible to Magnaporthe grisea
Acquired resistance functions in mlo barley, which is hypersusceptible to Magnaporthe grisea
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DOI：
10.1094/mpmi.2003.16.2.107
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发表时间：
2003-02-01
影响因子：
3.5
通讯作者：
Schaffrath, U
中科院分区：
文献类型：
--
作者：
Jarosch, B;Jansen, M;Schaffrath, U
携带Mlo（大麦[Hordeum vulgare L.]栽培品种Ingrid）基因位点突变的大麦植株对稻瘟病菌Magnaporthe grisea非常敏感。据推测，基本病原体抗性的表达需要一个功能性的Mlo基因，而介导白粉病抗性的Mlo功能的丧失是这种特殊疾病的例外。在这里，我们报道了化学和生物处理后获得性抗性（AR）的发生足以克服回交系BCIngridmlo(5) （mlo）大麦植株对稻瘟病病菌的易感表型。此外，即使是携带功能性Mlo基因的大麦植物，在抗稻瘟病中表现出中等感染表型，在诱导AR后也表现出进一步增强的抗性。细胞学研究表明，Mlo基因型的获得性抗性表现为在试图渗透的部位恢复形成有效乳头的能力，与野生型Mlo植物相似。此外，Mlo植株的有效乳头形成率在AR发生后进一步提高。这些结果表明，导致大麦AR状态的处理独立于Mlo/ Mlo表型，并表明Mlo蛋白不是AR信号网络的组成部分。此外，似乎只有Mlo和AR的共同作用才能使大麦对稻瘟病具有高水平的抗性。在这种特殊的相互作用中观察到，较高的PR1和大麦化学诱导的mRNA稳态水平与较高的疾病严重程度相关，而不是与抗性程度相关。
Barley plants carrying a mutation in the Mlo (barley [Hordeum vulgare L.] cultivar Ingrid) locus conferring a durable resistance against powdery mildew are hypersusceptible to the rice blast fungus Magnaporthe grisea. It has been speculated that a functional Mlo gene is required for the expression of basic pathogen resistance and that the loss of Mlo function mediating powdery mildew resistance is an exception for this particular disease. Here, we report that the onset of acquired resistance (AR) after chemical as well as biological treatments is sufficient to overcome the hypersusceptible phenotype of backcross line BCIngridmlo(5) (mlo) barley plants against M. grisea. Moreover, even barley plants bearing a functional Mlo gene and thus showing a moderate infection phenotype against rice blast exhibit a further enhanced resistance after induction of AR. Cytological investigations reveal that acquired resistance in mlo genotypes is manifested by the restoration of the ability to form an effective papilla at sites of attempted penetration, similarly to wild-type Mlo plants. In addition, the rate of effective papillae formation in Mlo plants was further enhanced after the onset of AR. These results demonstrate that treatments leading to the AR state in barley function independently of the Mlo/mlo phenotype and suggest that the Mlo protein is not a component of the AR signaling network. Moreover, it seems that only concomitant action of Mlo together with AR permits high level resistance in barley against blast. Higher steady state levels of PR1 and barley chemically induced mRNA correlate with higher disease severity rather than with the degree of resistance observed in this particular interaction.