Massimo Nicholas C, Nandi Devan M M, Arendt Kayla R, Wilch Margaret H, Riddle Jakob M, Furr Susan H, Steen Cole, U'Ren Jana M, Sandberg Dustin C, Arnold A Elizabeth
School of Plant Sciences, The University of Arizona, 1140 E. South Campus Drive, Forbes 303, Tucson, AZ, 85721, USA.
Microb Ecol. 2015 Jul;70(1):61-76. doi: 10.1007/s00248-014-0563-6. Epub 2015 Feb 3.
In hot deserts, plants cope with aridity, high temperatures, and nutrient-poor soils with morphological and biochemical adaptations that encompass intimate microbial symbioses. Whereas the root microbiomes of arid-land plants have received increasing attention, factors influencing assemblages of symbionts in aboveground tissues have not been evaluated for many woody plants that flourish in desert environments. We evaluated the diversity, host affiliations, and distributions of endophytic fungi associated with photosynthetic tissues of desert trees and shrubs, focusing on nonsucculent woody plants in the species-rich Sonoran Desert. To inform our strength of inference, we evaluated the effects of two different nutrient media, incubation temperatures, and collection seasons on the apparent structure of endophyte assemblages. Analysis of >22,000 tissue segments revealed that endophytes were isolated four times more frequently from photosynthetic stems than leaves. Isolation frequency was lower than expected given the latitude of the study region and varied among species a function of sampling site and abiotic factors. However, endophytes were very species-rich and phylogenetically diverse, consistent with less arid sites of a similar latitudinal position. Community composition differed among host species, but not as a function of tissue type, sampling site, sampling month, or exposure. Estimates of abundance, diversity, and composition were not influenced by isolation medium or incubation temperature. Phylogenetic analyses of the most commonly isolated genus (Preussia) revealed multiple evolutionary origins of desert-plant endophytism and little phylogenetic structure with regard to seasonality, tissue preference, or optimal temperatures and nutrients for growth in vitro. Together, these results provide insight into endophytic symbioses in desert-plant communities and can be used to optimize strategies for capturing endophyte biodiversity at regional scales.
在炎热的沙漠中，植物通过包括紧密微生物共生关系在内的形态和生化适应机制来应对干旱、高温和贫瘠土壤。虽然旱地植物的根际微生物群落受到了越来越多的关注，但对于许多在沙漠环境中繁茂生长的木本植物，影响其地上组织中共生体组合的因素尚未得到评估。我们评估了与沙漠树木和灌木光合组织相关的内生真菌的多样性、宿主关联和分布，重点关注物种丰富的索诺兰沙漠中的非肉质木本植物。为了了解我们推断的力度，我们评估了两种不同的营养培养基、培养温度和采集季节对内生菌组合表观结构的影响。对超过22000个组织片段的分析表明，从光合茎中分离内生菌的频率是从叶片中分离的四倍。考虑到研究区域的纬度，分离频率低于预期，并且因物种而异，是采样地点和非生物因素的函数。然而，内生菌种类非常丰富且系统发育多样，这与类似纬度位置的干旱程度较低的地点一致。宿主物种之间的群落组成不同，但不是组织类型、采样地点、采样月份或暴露程度的函数。丰度、多样性和组成的估计不受分离培养基或培养温度的影响。对最常分离的属（普雷乌西亚菌属）的系统发育分析表明，沙漠植物内生现象有多个进化起源，并且在季节性、组织偏好或体外生长的最佳温度和营养方面几乎没有系统发育结构。这些结果共同为沙漠植物群落中的内生共生关系提供了见解，并可用于优化在区域尺度上获取内生菌生物多样性的策略。
