Abstract：
Lasiodiplodia is a widely distributed genus that is associated with a variety of diseases in many plant species, especially fruit trees. In this study, a disease survey of fruit trees growing in 12 orchards located in the Henan and Shandong provinces of China was conducted between 2020 and 2022. The symptoms observed included stem canker, branch dieback, and gummosis. Phylogenetic analyses of internal transcribed spacer, tub2, tef1, and rpb2 sequence data combined with morphological characteristics revealed that the 19 isolates collected during the survey belonged to five documented Lasiodiplodia species, namely, Lasiodiplodia citricola, L. chiangraiensis, L. huangyanensis, L. pseudotheobromae, and L. theobromae, and two previously undescribed species, L. xinyangensis and L. ziziphi. In addition, the survey identified three novel host-pathogen interactions: L. chiangraiensis on loquat, L. citricola on apple, and L. huangyanensis on grapevine. Furthermore, the detailed phylogenic analysis indicated that four previously described Lasiodiplodia species were genetically very closely related that they would be better classified as synonyms rather than distinct species, so L. paraphysoides and L. nanpingensis should be considered synonyms of L. citricola, L. fujianensis should be a synonym of L. iraniensis, and L. henanica should be a synonym of L. huangyanensis. Pathogenicity tests confirmed that representative isolates of the two novel species and three new host-pathogen interactions identified in the current study were pathogenic to their original hosts, thereby fulfilling Koch\'s postulates. Similarly, all of the isolates were found to be pathogenic on four alternative hosts, although a high degree of variation in virulence was observed.
摘要：
Lasiodium是一种广泛分布的属，与许多植物物种的多种疾病有关，尤其是果树。本研究在2020年至2022年间对中国河南和山东两省的12个果园中生长的果树进行了病害调查。观察到的症状包括茎溃疡，分支死回，还有牙龈病.内部转录间隔区（ITS）的系统发育分析，tub2、tef1和rpb2序列数据结合形态特征，透露在调查中收集的19个分离株属于五个有记录的Lasiodiplodia物种，包括CitricolaLasiodium,L.Chiangraiensis,L.黄岩，L.假可可，还有L.Theobromae,以及两个以前未描述的物种，新阳落叶松和酸乳杆菌。此外,该调查确定了三种新的宿主/病原体相互作用，包括枇杷上的Chiangraiensis，L.苹果上的柑橘，和黄岩L.此外，详细的系统发育分析表明，四个先前描述的Lasiodiplodia物种在遗传上是如此密切相关，以至于它们被更好地归类为同义词而不是不同的物种，因此，顺齿乳杆菌和南平乳杆菌应被视为柠檬酸乳杆菌的同义词，福建乳杆菌应该是伊朗乳杆菌的同义词，和L.henanica黄羊的同义词。致病性测试证实，本研究中确定的两个新物种和三个新的宿主/病原体相互作用的代表性分离株对其原始宿主具有致病性。实现了科赫的假设。同样，所有的分离株都被发现对四个替代宿主有致病性，尽管观察到毒力的高度变化。
