Department of Biology, Portland State University, PO Box 751, Portland, OR, 97201, USA.
BMC Ecol Evol. 2022 Feb 15;22(1):18. doi: 10.1186/s12862-022-01974-2.
While a considerable amount of research has explored plant community composition in primary successional systems, little is known about the microbial communities inhabiting these pioneer plant species. Fungal endophytes are ubiquitous within plants, and may play major roles in early successional ecosystems. Specifically, endophytes have been shown to affect successional processes, as well as alter host stress tolerance and litter decomposition dynamics-both of which are important components in harsh environments where soil organic matter is still scarce.
To determine possible contributions of fungal endophytes to plant colonization patterns, we surveyed six of the most common woody species on the Pumice Plain of Mount St. Helens (WA, USA; Lawetlat'la in the Cowlitz language; created during the 1980 eruption)-a model primary successional ecosystem-and found low colonization rates (< 15%), low species richness, and low diversity. Furthermore, while endophyte community composition did differ among woody species, we found only marginal evidence of temporal changes in community composition over a single field season (July-September).
Our results indicate that even after a post-eruption period of 40 years, foliar endophyte communities still seem to be in the early stages of community development, and that the dominant pioneer riparian species Sitka alder (Alnus viridis ssp. sinuata) and Sitka willow (Salix sitchensis) may be serving as important microbial reservoirs for incoming plant colonizers.
虽然已经有相当多的研究探索了初级演替系统中的植物群落组成，但对于栖息在这些先锋植物物种中的微生物群落知之甚少。真菌内生菌在植物中无处不在，它们可能在早期演替生态系统中发挥重要作用。具体来说，内生菌已被证明会影响演替过程，以及改变宿主的应激耐受性和凋落物分解动态——这两者都是在土壤有机质仍然稀缺的恶劣环境中非常重要的组成部分。
为了确定真菌内生菌对植物定殖模式的可能贡献，我们调查了圣海伦斯火山（美国华盛顿州；拉维特拉塔语中的 Lawetlat'la；1980 年喷发形成）火山灰平原上六种最常见的木本植物——这是一个典型的初级演替生态系统——发现了低定植率（<15%）、低物种丰富度和低多样性。此外，尽管内生菌群落组成在木本物种之间存在差异，但我们只发现了在一个单一的野外季节（7 月至 9 月）内群落组成的微小时间变化的证据。
我们的研究结果表明，即使在喷发后 40 年的时间里，叶片内生菌群落似乎仍处于群落发展的早期阶段，而优势先锋河岸物种——红花桤木（Alnus viridis ssp. sinuata）和西特卡柳（Salix sitchensis）——可能是重要的微生物储备库，为即将到来的植物定植者提供服务。
