陕西榆林沙区樟子松根内真菌群落结构和功能群特征

樟子松Pinus sylvestris var. mongolica是我国北方沙区生态环境建设的重要树种之一,但衰退问题严重。根内真菌与樟子松生长密切相关,可能是影响樟子松衰退的重要因素。为揭示根内真菌群落结构和功能群特征,以陕西榆林沙区中龄（27a）、近熟（33a）、成熟（44a）3个龄组樟子松人工林为研究对象,采用野外调查与分子生物学相结合的研究方法,鉴定分析樟子松根内真菌群落结构和功能群。结果表明：（1）樟子松根尖样品共获得855个OTUs,不同林龄樟子松根内真菌多样性不存在显著差异（P>0.05）。（2）根内真菌隶属于6门18纲48目87科197属,子囊菌门Ascomycota和担子菌门Basidiomycota比例高达97.31%,优势属为青霉属Penicillium和Archaeorhizomyces。（3）随林龄增加,樟子松根系中病理营养型和腐生营养型真菌比例先增加后下降,而共生营养型真菌比例先下降后上升。榆林沙区樟子松根内真菌物种组成丰富,功能群类型多样,外生菌根真菌为主要功能群,近熟林腐生营养型真菌相对丰度高于共生营养型真菌,可能是樟子松退化的潜在原因。

Root-associated fungal community structure and functional group of Pinus sylvestri var. mongolica in the desertified lands of Yulin in Shaanxi Province,western China

Plantations of Pinus sylvestris var. mongolia, one of the most important conifer species for environmental restoration in the desertified northern China, have become increasingly declined. Root-associated fungi (RAF) are closely related to the growth of P. sylvestris var. mongolia, and they are probably potentially connected with the decline. Field investigation on P. sylvestris var. mongolia plantations of three stand age, middle-age (27a), nearly mature (33a), mature (44a), was conducted to reveal the community structure and functional group of RAF in the desertified lands of Yulin in Shaanxi Province. Root tip samples were identified by high-throughput sequencing and FUNGuild platform. 855 OTUs were obtained, and there was no significant difference in the RAF’s diversity indices in different stand ages (P>0.05). The RAF were assigned to six phyla, 18 classes, 48 orders, 87 families, and 197 genera. Ascomycota and Basidiomycota accounted for 97.31% in relative abundance. The dominant genera were Penicillium and Archaeorhyzomyces. With the stand aging, the proportion of pathotrophic and saprophytic fungi increased first and then decreased, meanwhile symbiotic fungi were in a converse trend. The community structure and functional group of the RAF associated with P. sylvestris var. mongolia are diversiform, and ectomycorrhizal fungi are dominant functional group. The relative abundance of saprophytic fungi is higher than that of symbiotic fungi in the near-mature plantation, implying the potential decline of P. sylvestris var. mongolia.