Abstract Groundnut (Arachis hypogaea) is an important legume in western Kenya, but yields are low and declining. Pests and diseases are ranked high among the yield reducing factors. Groundnut rosette disease (GRD) is the main disease and can cause up to 100% yield loss. Groundnut rosette disease is transmitted by the groundnut aphid, Aphis craccivora Koch and caused by two synergistic viruses; groundnut rosette assistor virus (GRAV) and groundnut rosette virus (GRV) associated with a satellite-ribonucleic acid (sat-RNA). Inadequate information was available on the occurrence and molecular diversity of GRAV in western Kenya, which is a limiting factor on proper diagnosis and management. This study determined the occurrence and molecular diversity of GRAV on groundnuts in western Kenya. A survey of GRD was conducted in 144 farms in Bungoma and Kakamega counties during the short and long rains of 2016–2017. A total of 301 symptomatic leaf samples were collected and preserved until use. Incidence and severity data was collected and subjected to pairwise comparison of means using the standardized disease diagnostic score sheet at P ≤ 0.05. Screening for resistance/tolerance to GRD was done on five popular legume varieties (Arachis hypogaea, Phaseolus vulgaris, Vigna unquiculata, Glycine max and Vigna radiata) and one solanaceous Physalis peruviana. The plants were monitored for GRD symptoms development in the screenhouse for 8 weeks. Total RNA was extracted from the leaf samples using RNeasy Mini Kit (Qiagen) according to the manufacturers’ protocol. DNA libraries were prepared and sequenced on the MiSeq platform (Illumina). Phylogenetic analyses and comparisons were performed using the MEGA X software. From the sequences obtained, primers were designed for use in RT-PCR. Groundnut rosette disease was prevalent in all the surveyed areas with chlorotic rosette symptoms being dominant followed by green rosette and mosaic rosette. Groundnut rosette disease incidence ranged between 31 and 67%, but was higher in Bungoma (67%) than Kakamega (61%) county, while the short rains had higher incidence than the long rains season. All screened indicator plants developed typical GRD viral symptoms and tested positive for GRAV. Nucleotide sequences of GRAV coat protein (CP) gene revealed 97–99% identity among the western Kenya isolates and those from Ghana, Malawi and Nigeria respectively. The fact that GRD occurs wherever groundnuts are grown in western Kenya, is of great concern and may be the reason for the observed low yields. Incorporation of GRD resistance genes in the local cultivars/varieties may be the only practical solution.

中文翻译：

---

肯尼亚西部花生莲座丛辅助病毒的发生和遗传多样性

摘要 落花生（Arachis hypogaea）是肯尼亚西部重要的豆科植物，但产量低且不断下降。病虫害在减产因素中排名靠前。花生花环病 (GRD) 是主要病害，可导致高达 100% 的产量损失。花生花环病由花生蚜虫Aphis craccivora Koch 传播，由两种协同作用的病毒引起；花生花环辅助病毒 (GRAV) 和与卫星核糖核酸 (sat-RNA) 相关的花生花环病毒 (GRV)。关于肯尼亚西部 GRAV 的发生和分子多样性的信息不足，这是正确诊断和管理的一个限制因素。本研究确定了肯尼亚西部花生上 GRAV 的发生和分子多样性。在 2016-2017 年的短雨和长雨期间，对班戈马和卡卡梅加县的 144 个农场进行了 GRD 调查。共收集了 301 个有症状的叶子样品并保存直至使用。收集发病率和严重程度数据，并在 P ≤ 0.05 时使用标准化疾病诊断评分表对均值进行成对比较。对五种流行的豆科植物品种（Arachis hypogaea、Phaseolus vulgaris、Vigna unquiculata、Glycine max 和 Vigna radiata）和一种茄科 Physalis peruviana 进行了 GRD 抗性/耐受性筛选。在屏蔽室中监测植物的 GRD 症状发展 8 周。根据制造商的方案，使用 RNeasy Mini Kit (Qiagen) 从叶样品中提取总 RNA。DNA 文库在 MiSeq 平台 (Illumina) 上制备和测序。使用 MEGA X 软件进行系统发育分析和比较。从获得的序列中，设计了用于 RT-PCR 的引物。调查区花生莲座丛病流行，以萎蔫莲座丛症状为主，其次是绿色莲座丛和花叶莲座丛。花生莲座丛病发病率介于 31% 至 67% 之间，但班戈马（67%）高于卡卡梅加（61%）县，而短雨季的发病率高于长雨季。所有筛选的指示植物都出现了典型的 GRD 病毒症状，并且检测出 GRAV 呈阳性。GRAV 外壳蛋白 (CP) 基因的核苷酸序列显示，肯尼亚西部分离物与加纳、马拉维和尼日利亚分离物分别具有 97-99% 的同一性。GRD 发生在肯尼亚西部任何种植花生的地方，非常令人担忧，可能是观察到的低产量的原因。在当地栽培品种/品种中引入 GRD 抗性基因可能是唯一可行的解​​决方案。