Citrus Greening disease (CG) in South Africa (SA) is associated with the fastidious bacterium ‘Candidatus Liberibacter africanus’ (Laf). It has been observed that Laf isolates obtained from different geographic localities in SA differed in the rate of transmission during grafting experiments leading to the hypothesis that genetic variation of Laf may exist in this country. To determine this, 167 Laf isolates obtained from Limpopo, North West, Mpumalanga and the Western Cape were subjected to microsatellite analyses, using four polymorphic markers. From UPGMA and STRUCTURE analysis, it was shown that most sources belong to one of two major genetic groups of Laf and these comprise 25 distinct haplotypes. Four samples included within this study did not group with these two major groups, suggesting a potential third and fourth genetic group of Laf being present, which can be validated by further sampling. Results further indicate that Laf populations in SA are formed by geographic locality. The high genetic diversity observed for Laf within this study is consistent with the hypothesis that Laf originated on the African continent, warranting further genetic analysis of Laf populations from Africa. This is the first study to unveil the genetic diversity of Laf.

南非（SA）的柑橘绿化病（CG）与挑食性细菌'念珠菌（Candidatus）相关非洲自由杆菌（Laf）。已经观察到，从南非不同地理位置获得的拉夫分离株在嫁接实验中的传播速率不同，这导致了该国可能存在拉夫遗传变异的假说。为了确定这一点，使用四个多态性标记对从林波波河，西北，姆普马兰加省和西开普省获得的167个Laf分离株进行了微卫星分析。从UPGMA和STRUCTURE分析中可以看出，大多数来源都属于Laf的两个主要遗传组之一，并且它们包含25个不同的单倍型。这项研究中包括的四个样本未与这两个主要类别归类，这表明存在潜在的Laf第三和第四遗传群，可以通过进一步采样进行验证。结果进一步表明，南非的Laf人口是由地理位置组成的。在这项研究中观察到的Laf的高遗传多样性与Laf起源于非洲大陆的假说是一致的，因此有必要对来自非洲的Laf种群进行进一步的遗传分析。这是揭示Laf基因多样性的第一项研究。