Jia Tong, Oberhofer Martina, Shymanovich Tatsiana, Faeth Stanley H
Institute of Loess Plateau, Shanxi University, Taiyuan, 030006, China.
Department of Biology, University of North Carolina Greensboro, 321 McIver Street, Greensboro, NC, 27412, USA.
Microb Ecol. 2016 Jul;72(1):185-196. doi: 10.1007/s00248-016-0743-7. Epub 2016 Feb 24.
Asexual Epichloë endophytes are prevalent in cool season grasses, and many are of hybrid origin. Hybridization of asexual endophytes is thought to provide a rapid influx of genetic variation that may be adaptive to endophyte-host grass symbiota in stressful environments. For Arizona fescue (Festuca arizonica), hybrid symbiota are commonly found in resource-poor environments, whereas non-hybrid symbiota are more common in resource-rich environments. There have been very few experimental tests where infection, hybrid and non-hybrid status, and plant genotype have been controlled to tease apart their effects on host phenotype and fitness in different environments. We conducted a greenhouse experiment where hybrid (H) and non-hybrid (NH) endophytes were inoculated into plant genotypes that were originally uninfected (E-) or once infected with either the H or NH endophytes. Nine endophyte and plant genotypic group combinations were grown under low and high water and nutrient treatments. Inoculation with the resident H endophyte enhanced growth and altered allocation to roots and shoots, but these effects were greatest in resource-rich environments, contrary to expectations. We found no evidence of co-adaptation between endophyte species and their associated host genotypes. However, naturally E- plants performed better when inoculated with the hybrid endophyte, suggesting these plants were derived from H infected lineages. Our results show complex interactions between endophyte species of hybrid and non-hybrid origin with their host plant genotypes and environmental factors.
无性Epichloë内生真菌在冷季型禾本科植物中普遍存在，且许多是杂交起源的。无性内生真菌的杂交被认为会迅速引入遗传变异，这可能有利于在压力环境下的内生真菌-宿主禾本科植物共生体。对于亚利桑那羊茅（Festuca arizonica）来说，杂交共生体常见于资源匮乏的环境中，而非杂交共生体在资源丰富的环境中更为常见。很少有实验能同时控制感染情况、杂交与非杂交状态以及植物基因型，以区分它们在不同环境下对宿主表型和适合度的影响。我们进行了一项温室实验，将杂交（H）和非杂交（NH）内生真菌接种到原本未感染（E-）或曾感染过H或NH内生真菌的植物基因型中。九种内生真菌和植物基因型组合在低水和高水以及低养分和高养分处理下生长。接种本地的H内生真菌能促进生长并改变根和地上部分的分配，但与预期相反，这些影响在资源丰富的环境中最为显著。我们没有发现内生真菌物种与其相关宿主基因型之间存在共适应的证据。然而，天然的E-植物接种杂交内生真菌后表现更好，这表明这些植物源自感染了H的谱系。我们的结果显示了杂交和非杂交起源的内生真菌物种与其宿主植物基因型和环境因素之间的复杂相互作用。
