两种不同白粉病抗性野生蔷薇内生真菌群落结构

Fungal endophytic communities of two wild Rosa species with different powdery mildew susceptibility

摘要:

【背景】白粉病是蔷薇、月季等观赏植物的主要病害，提高其白粉病抗性是花卉产业亟待解决的难题。内生菌在增强植物抗病性能方面的益处已经得到证实。大理紫花是一种白粉病高抗野生蔷薇，而七姐妹是一种高感野生蔷薇，目前对两者在内生菌群落结构及功能方面的异同尚不清楚。【目的】对比研究白粉病高抗和高感两种野生蔷薇内生菌群落组成的异同，探索内生菌在宿主植物白粉病抗性中可能发挥的生态学功能，为蔷薇白粉病防治提供新思路。【方法】通过传统的内生真菌分离培养方法，结合形态学特征和分子生物学分析确定所获菌株的分类地位，对白粉病高抗和高感两种野生蔷薇内生真菌群落组成进行对比分析。【结果】从两种不同白粉病抗性野生蔷薇的2 880个组织块中，共分离得到2 003株内生真菌，其中从大理紫花得到1 333株，从七姐妹得到670株。它们分属于链格孢属(Alternaria)、炭角菌属(Xylaria)和拟盘多毛孢属(Pestalotiopsis)等30个分类单元。其中链格孢(A. alternata)、平头刺盘孢(C. truncatum)和拟茎点霉(Phomopsis amygdali)为两种蔷薇在白粉病暴发各时期的共有优势菌，而盘毛孢(Seimatosporium sp.)、鬼伞(Coprinellus sp.)和球毛壳菌(Chaetomium globosum)等则只存在于大理紫花或七姐妹一种植物中。【结论】在白粉病暴发进程中，白粉病高抗野生蔷薇大理紫花与高感蔷薇七姐妹的内生真菌多样性及群落结构明显不同。且随着时间的推移，七姐妹的内生真菌多样性逐渐增加，而大理紫花的却逐渐减少。但在各采样时间点，高抗蔷薇内生真菌的数量和平均定殖率均明显高于高感蔷薇(P<0.05，卡方检验)。大理紫花中存在一些特有和优势内生真菌，它们在大理紫花白粉病抗性中的功能有待进一步深入研究。

Abstract:

[Background] Powdery mildew (PM) is one of the most devasting diseases in rose and other ornamental plants, however, there is no better way to control it untill now. Previous studies have demonstrated that endophytes are beneficial to host plant’s disease resistance. Rosa multiflora and R. multiflora var. carnea is a PM resistant and susceptible rose species, respectively. It’s not clear about the difference of their fungal endophytic communities and their function. [Objective] To study the difference of the fungal endophytic communities between two rose species and to understand the possible role of endophytes on PM resistance. [Methods] The culturable endophytic fungi (EF) were isolated from two rose species at different developing stage of PM by traditional EF isolation methods. [Results] A total of 2?003 endophytic fungi were isolated from 2 880 tissue segments of 24 samples of two rose species, of which 1 333 from R. multiflora and 670 from R. multiflora var. carnea. The isolates were identified to 30?taxa according to the morphological charateristics and the rDNA internal transcribed spacer (ITS) analysis, of which Alternaria alternata, C. truncatum and Phomopsis amygdali were the dominant genera of two rose species at different developing stage of PM. Contrary to this, Seimatosporium sp., Coprinellus sp. and Chaetomium globosum etc. were only found in R. multiflora or R. multiflora var. carnea. [Conclusion] The fungal endophytic community of R. multiflora showed significantly difference from that of R. multiflora var. carnea. The average colonization rate (CR) of EF from R. multiflora was significantly higher than that of R. multiflora var. carnea at each developing stage of PW (P<0.05, Chi-square test). The role of the specific and dominant EF of R. multiflora in PM resistance were further studied in the future.