ABSTRACT

Take-all, caused by the fungal pathogen Gaeumannomyces graminis var. tritici (Ggt) is an important root disease of cereals and grasses. An increasing occurrence of very light seeds in some New Zealand perennial ryegrass (Lolium perenne L.) seed crops may have been associated with Ggt, but any Ggt effects on grass seed yield were unknown. A glasshouse experiment, using prairie grass (Bromus wildenowii Kunth) as a model system was used to investigate the effect of Ggt on seed yield in the presence and absence of moisture stress (drought), and to determine whether strains of the fungal symbiont Trichoderma atroviride would allow the plant to better cope with both the biotic and abiotic stresses. Ggt significantly reduced seed yield by reducing the number of seeds per plant, while moisture stress significantly reduced all seed yield components. There was a significant interaction between Ggt and moisture stress because the moisture stress induced seed yield loss was greater in the presence of Ggt than in the absence of Ggt. In the absence of both abiotic and biotic stress, Trichoderma treatment had no effect on seed yield. However, Trichoderma significantly reduced Ggt root infection and this led to an increased seed yield. In the presence of Ggt and moisture stress, Trichoderma further increased seed yield by around double the increase for individual stress. Whether similar responses can be obtained in the field is currently being investigated.

摘要

通吃，由真菌病原体Gaeumannomyces graminis var.引起。小麦(Ggt) 是谷物和禾本科植物的重要根病。在一些新西兰多年生黑麦草 ( Lolium perenne L.) 种子作物中，越来越多的极轻种子可能与 Ggt 相关，但 Ggt 对禾本科种子产量的影响尚不清楚。使用草原草 ( Bromus wildenowii Kunth) 作为模型系统的温室试验用于研究Ggt在存在和不存在水分胁迫（干旱）的情况下对种子产量的影响，并确定真菌共生菌Trichoderma atroviride 的菌株是否存在将使植物更好地应对生物和非生物胁迫。Ggt 通过减少每株植物的种子数量显着降低了种子产量，而水分胁迫显着降低了所有种子产量成分。Ggt 和水分胁迫之间存在显着的相互作用，因为存在 Ggt 时水分胁迫引起的种子产量损失比不存在 Ggt 时更大。在没有非生物和生物胁迫的情况下，木霉处理对种子产量没有影响。然而，木霉显着减少 Ggt 根感染，这导致种子产量增加。在 Ggt 和水分胁迫下，木霉进一步增加种子产量，大约是个体压力增加的两倍。目前正在调查是否可以在该领域获得类似的反应。