Fusarium agapanthi sp nov., a novel bikaverin and fusarubin-producing leaf and stem spot pathogen of Agapanthus praecox (African lily) from Australia and Italy
Fusarium agapanthi sp nov., a novel bikaverin and fusarubin-producing leaf and stem spot pathogen of Agapanthus praecox (African lily) from Australia and Italy
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DOI：
10.3852/15-333
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发表时间：
2016-09-01
期刊：
影响因子：
2.8
通讯作者：
O'Donnell, Kerry
中科院分区：
文献类型：
--
作者：
Edwards, Jacqueline;Auer, Desmond;O'Donnell, Kerry
本研究对一种新的镰刀菌进行了鉴定，该镰刀菌在意大利北部的非洲百合Agapanthus praecox （Agapanthus，非洲百合）上引起叶片和茎斑，在澳大利亚墨尔本的同一寄主上引起叶片腐烂和斑。正式名称为镰刀菌（Fusarium agapanthi），利用表型、植物致病性、次级代谢物、分子系统发育和基因组数据对该病原体进行了分析。共鉴定出5株菌株，其中1株于1999年从意大利Saluzzo的有症状的雷梅中分离得到，4株于2010年从澳大利亚维多利亚皇家植物园墨尔本花园同一寄主的有腐叶和斑点症状的病叶组织中分离得到。对6个个体基因部分的最大简约性和最大似然性分子系统发育分析以及综合数据集都有力地支持了F. agapanthi要么是F. fujikuroi物种复合体美洲分支中最早的分离谱系，要么是美洲分支的一个新的单型谱系姐妹。科赫的假设在矮小的蓝花和大白花的早熟花品种上得到了证实，其中两种分离的agapanthi在接种到叶子和花茎上时产生了缓慢扩散的坏死损伤。镰刀菌与其他镰刀菌的区别在于，它在合成的营养贫乏的琼脂上产生密集分枝的气生分生孢子，其气生菌丝体中含有多酚。对agapanthi F. NRRL 31653和NRRL 54464 （= VPRI 41787）基因组序列进行BLASTn搜索，预测有性生殖方式和霉菌毒素潜能。结果表明，它们分别具有MATT-2和MATT-1自形，表明该物种可能是异thallic。此外，基于在agapanthi基因组中存在的bikaverin和fusarubin生物合成基因簇的同源物，进行了液相色谱-质谱分析，并证实了真菌在水稻和玉米籽粒培养物中产生了这些次生代谢物。
This study was conducted to characterize a novel Fusarium species that caused leaf and stem spot on Agapanthus praecox (Agapanthus, African lily) in northern Italy and leaf rot and spot on the same host in Melbourne, Australia. Formally described as Fusarium agapanthi, this pathogen was analyzed using phenotypic, phytopathogenic, secondary metabolite, molecular phylogenetic and genomic data. Five strains were characterized, including one isolated in 1999 from symptomatic A. praecox in Saluzzo, Italy, and four in 2010 from diseased leaf tissue from the same host exhibiting leaf rot and spot symptoms in the Melbourne Gardens, Royal Botanic Gardens Victoria, Australia. Maximum parsimony and maximum likelihood molecular phylogenetic analyses of portions of six individual genes and the combined dataset all strongly supported F. agapanthi either as the earliest diverging genealogically exclusive lineage in the American Clade of the F. fujikuroi species complex, or alternatively a novel monotypic lineage sister to the American Clade. Koch's postulates were completed on dwarf blue- and large white-flowering varieties of A. praecox, where two isolates of F. agapanthi produced slowly spreading necrotic lesions when inoculated onto leaves and flower stems. Fusarium agapanthi is distinguished from other fusaria by the production of densely branched aerial conidiophores with polyphialides throughout the aerial mycelium on synthetic nutrient-poor agar. BLASTn searches of the F. agapanthi NRRL 31653 and NRRL 54464 (= VPRI 41787) genome sequences were conducted to predict sexual reproductive mode and mycotoxin potential. Results indicated that they possessed MATT-2 and MATT-1 idiomorphs, respectively, indicating that this species might be heterothallic. Furthermore, based on the presence of homologs of the bikaverin and fusarubin biosynthetic gene clusters in the F agapanthi genomes, liquid chromatography-mass spectrometry analysis was conducted and confirmed production of these secondary metabolites in rice and corn kernel cultures of the fungus.