稻曲病菌侵染对水稻小穗发育的影响及H_2O_2的变化趋势

稻曲病是由稻绿核菌(Ustilaginoidea virens)侵染引起的水稻穗部病害,在全世界不同稻作区均有发生,并在近年呈加重趋势。本研究通过水稻穗期接种后的显微观察及H_2O_2检测,分析了稻曲病菌侵染引起的小穗结构变化及侵染过程中H_2O_2变化趋势。结果表明,稻曲病菌侵染会导致水稻花粉粒畸形、雌蕊发育受抑制、小穗无法正常扬花授粉,抑制谷粒的正常形成,造成稻曲球及白色秕粒的产生。受侵染小穗的H_2O_2含量显著高于对照,其中处于突破颖壳期的受侵染小穗H_2O_2含量是对照的7倍;形成白色秕粒的小穗H_2O_2含量是对照的11倍;二氨基联苯胺染色结果显示,形成稻曲球的小穗中,在受侵染小穗的花药基部、花药顶端、浆片等部位颜色变深,形成H_2O_2富集区;形成白色秕粒的小穗中,H_2O_2富集的特征更为明显,富集区域与病菌在小穗内的侵染途径密切相关。

Effect of Ustilaginoidea virens infection on rice spikelets growth and H2O2 variation

Rice false smut, caused by Ustilaginoidea virens (U. virens), is a ubiquitous disease in rice planting areas worldwide. In response to U. virens infection, the accumulation of reactive oxygen species (ROS) was significantly increased in rice. The infection of U. virens suppressed rice pollen germination and pistil development, and led to production of a large number of false smut balls and bleached grains. To detect the ROS in healthy, infected and bleached spikelets, H₂O₂ was stained and visualized by exposing to DAB. The absorbance of oxidized DAB at 465 nm was measured, and a significant increase in infected spikelets solution was detected compared to the healthy spikelets. After DAB treatment, brown oxidized DAB precipitates could be detected readily on the position of U. virens in infected spikelets but not on the mock-infected spikelets. DAB oxidation seemed to be associated with locations colonized by the fungus at spikelets.