小麦条锈病罹病植株对水分胁迫的响应

水分胁迫时,小麦条锈病病叶的叶片扩散阻力(LDR)明显增大,蒸腾速率(Tp)、相对含水量(RWC)、水势(ψw)、渗透势(ψπ)和压力势(ψp)明显降低。亲和与不亲和性反应寄主病叶对水分胁迫的反应明显不同。亲和性反应寄主叶片在水分胁迫时表现出较低的反应型,产孢期推迟;Tp、LDR、RWC、ψw、ψp和ψπ在产孢前轻微下降或升高;在开始产孢后病叶Tp急剧升高,LDR、Tp、RWC、ψw、ψπ和ψp大幅降低,在健叶尚可有效控制水分蒸腾散失时病叶已丧失了这种能力。不亲和性反应寄主病叶的蒸腾作用在显症期亦有轻微变化,但之后病叶Tp、LDR、RWC和ψw渐趋健叶水平,并保持了较健叶更低的ψπ和更高的ψw,具备了更强的水分调控能力。病株健叶与病叶具有相似的气孔行为。

Responses of Wheat Plants Infected with Stripe Rust to Water Stress

After 1-st leaves of wheat, under different levels of water stress, were inoculated with virulent race (CY-29) and its avirulent mutant (CY29-mut3) of Puccinia striformis West at various stages, water relations were compared in same time. The diseased leaves of wheat under water stress showed great increasesin LDR (leaf diffusive resistance) ( Fig.2)and apparent decreases in Tp (transpirationrate) (Fig.1), RWC (relative water content) (Fig.4), ψw(water potential), ψπ( osmatic potential) and ψp(turgor potential) (Fig.5), compared with diseased leaves of wheat with normal level of water contents. However, responses of diseased leaves of compatible and incompatible combination to water stress were significantly different. In the leaves of compatible combination, lower degree of reaction and later sporulation were observed. Slight variations in Tp, LDR, RWC, ψw, ψπ, and ψp occurred before sporulation. Great increases in Tp (Fig.1) and significant decreases in LDR (Fig.2) were observed during sporulation of the fungus, accompanied by obvious decreasesof RWC ( Fig. 4 ), ψw, ψp and ψπ ( Fig. 5 ).The leaves of wheat in compatible combinationhad lost the ability to control water loss andmaintain normal water balance. For diseasedleaves of incompatible combination, transpira-tion varied slightly in symptom-appearing peri-od and then recovered ( Fig. 1 ) , with lower ψπand higher ψp ( Fig. 5 ) than the healthy leav-es. The leaves of wheat in incompatible combi-nation had maintained an effective mechanismto regulate their water balance. The healthy leaves of diseased wheat had similar stomatal behavior with diseased leaves of the same plant (Fig.3).