White root rot (WRR) disease caused by Rigidoporus microporus is a major disease affecting tropical rubber tree (Hevea brasiliensis) and some agricultural crops throughout the world. In Malaysia, rubber industry is an important revenue as natural rubber for export and domestic consumption. The objectives of this study were to determine WRR disease prevalence and characterise R. microporus isolates collected from different regions in Malaysia using cultural and molecular characteristics. During July 2017 to May 2018, diseased samples showing WRR symptoms such as presence of basidiocarps and rhizomorphs in five states of Malaysia including Kedah (Baling), Kelantan (FELCRA Machang and Smallholder in Machang), Perak (Ipoh) and Selangor (Sungai Buloh and UPM Serdang), Sarawak (Bintulu) were obtained. In the field observation, all sampling areas were infected by the root rot disease. Findings revealed that field disease incidence was in the range of 5–40% based on random sampling. The collected R. microporus isolates were pure white and displayed fluffy mycelial growth when cultured on malt extract agar (MEA) medium. For molecular identification, BLASTn analysis showed 98–100% identical to existing reference sequences in the GenBank database. All 27 isolates of R. microporus were characterised based on internal transcribed spacer (ITS) and Beta-tubulin (β-tubulin) gene sequences data. Phylogenetic tree analyses of R. microporus isolates formed two major clades, i.e. Asian and African clades. There was also no clear geographical origin structuring observed within the Asian clade. However, phylogenetic analysis of Beta-tubulin (β-tubulin) gene region revealed distinct geographical origin amongst 27 local isolates. The outcomes of this study provide useful information to improve the existing disease control strategy, hence improving the rubber production in Malaysia.

由微孔刚毛孢菌引起的白根腐烂病是影响热带橡胶树（巴西橡胶树）和世界各地一些农作物的主要疾病。在马来西亚，橡胶工业作为天然橡胶，是出口和国内消费的重要收入。这项研究的目的是确定WRR疾病的患病率并表征微孔菌利用文化和分子特征从马来西亚不同地区收集的分离株。在2017年7月至2018年5月期间，患病样品显示出WRR症状，例如在马来西亚的五个州，包括吉打（Baling），吉兰丹（FELCRA Machang和Machang的Smallholder），霹雳（Ipoh）和雪兰莪（Sungai Buloh和获得了UPM Serdang，砂拉越（民都鲁）。在野外观察中，所有采样区均被根腐病感染。调查结果表明，根据随机抽样，现场疾病发病率在5-40％的范围内。收集的微孔菌分离物是纯白色的，当在麦芽提取物琼脂（MEA）培养基上培养时显示出蓬松的菌丝生长。对于分子鉴定，BLASTn分析显示与GenBank数据库中现有参考序列的98-100％相同。根据内部转录间隔区（ITS）和β-微管蛋白（β-微管蛋白）基因序列数据对微孔菌的所有27个分离株进行了表征。微孔菌的系统发育树分析分离株形成两个主要进化枝，即亚洲和非洲进化枝。在亚洲进化枝中也没有观察到明确的地理起源结构。但是，对β-微管蛋白（β-微管蛋白）基因区域的系统发育分析显示，在27个本地分离株中有明显的地理起源。这项研究的结果为改善现有的疾病控制策略提供了有用的信息，从而提高了马来西亚的橡胶产量。