Abstract：
Ganoderma boninense is a basidiomycete pathogen of African oil palm (Elaeis guineensis) and the causal agent of basal stem rot (BSR) disease, which is the most destructive fungal disease of oil palm in Southeast Asia. The disease is fatal for infected palms and can result in 50 to 80% losses in oil yields because of a reduction in productive life span and a yield decline of infected oil palms. In this study, G. boninense isolates collected from different locations and planting blocks with different palm ages were molecularly characterized using microsatellite genotyping. Results showed high pathogen genetic diversity (He = 0.67 to 0.74) among planting blocks and between oil palm estates. Two nearby planting blocks with similar planting ages (i.e., 1999 and 2001) had a similar percentage of BSR incidence (>20%) but showed distinct Ganoderma genetic structure as detected using STRUCTURE. Similar results were obtained from another trial site where planting blocks differing in planting age but located only less than 1 km apart showed a diverse genetic background. The pathogen genetic admixture of the oldest planting (>30% BSR incidence) differed significantly from the younger planting (1.8 to 2.8% BSR incidence, breeding trial block), suggesting that the host-pathogen genotype interaction may impact the Ganoderma genetic variation over time. The genetic structure of G. boninense, as revealed in this study, implies positive selection resulting from the pathogen genetic variation, host-pathogen interaction, and possible introductions of novel genetic variants (through spores) from adjacent plantings. These findings offer new insights into the genetic changes of G. boninense over time. The information is essential to design disease management strategies and breeding for BSR resistance in oil palm.
摘要：
灵芝是非洲油棕（Elaeisguinensis）的担子菌病原体，是基础茎腐烂（BSR）病的病原体，这是东南亚油棕最具破坏性的真菌病。该疾病对于受感染的棕榈是致命的，并且由于生产寿命的减少和受感染的油棕榈的产量下降，可能导致油产量损失50％至80％。在这项研究中,使用微卫星基因分型对从不同位置和不同棕榈年龄的种植区收集的G.boninense分离株进行了分子表征。结果表明，种植块之间和油棕庄园之间的病原体遗传多样性很高（He=0.67至0.74）。附近两个种植年龄相似的种植块(即，1999年和2001年）的BSR发病率百分比相似（>20％），但使用结构检测到的灵芝遗传结构不同。从另一个试验地点获得了类似的结果，该试验地点的种植年龄不同但相距不到1公里的种植块显示出不同的遗传背景。最古老的种植（>30％的BSR发生率）的病原体遗传混合物与较年轻的种植（1.8至2.8％的BSR发生率，育种试验块)，表明宿主-病原体基因型相互作用可能随着时间的推移影响灵芝遗传变异。G.boninense的遗传结构，正如这项研究所揭示的，意味着病原体遗传变异导致的正选择，宿主-病原体相互作用，以及可能从相邻植物中引入新的遗传变异（通过孢子）。这些发现为G.boninense随时间的遗传变化提供了新的见解。这些信息对于设计油棕的疾病管理策略和BSR抗性育种至关重要。
