Prevalence of Yellow Leaf Disease (YLD) and its Associated Areca Palm Velarivirus 1 (APV1) in Betel Palm (Areca catechu) Plantations in Hainan, China

Abstract

Yellow leaf disease (YLD) is an economically important disease affecting betel palm in several countries, the cause of which remains unclear despite associations with putative agents, including phytoplasmas. In this study, we screened the potential casual agents associated with YLD in Hainan, China using next-generation sequencing and revealed the association of areca palm velarivirus 1 (APV1) with the YLD-affected palm. The complete genome of the APV1-WNY isolate was determined to be 17,546 nucleotides in length, approximately 1.5 kb longer than the previously reported APV1_HN genome. Transmission electron microscopy showed that APV1 particles are flexuous and filamentous, a typical morphology of species in the Closteroviridae family. Comparison of symptomatic and symptomless tree populations showed a strong association between APV1 and YLD. APV1 was detected in Pseudococcus sp. mealybugs sampled from YLD-affected trees in many locations, suggesting that mealybugs are a potential transmission vector for APV1. Although further studies are needed to confirm a causal relationship, these results provide timely information for the prevention and management of YLD associated with APV1.

Effect of temperature on yellow leaf disease symptoms and its associated areca palm velarivirus 1 titer in areca palm (Areca catechu L.)

“…The most grievous threat to areca palm plantations worldwide is yellow leaf disease (YLD), the disease that affects the economy of areca palm up to a high extent in different countries by destroying a large number of areca palm plantations in China (40,000 ha) (Yu et al, 1986;Wang et al, 2020), Sri Lanka (11,968 ha) (Kanatiwela de Silva et al, 2015), and India (about 10,000 ha) (Rawther, 1976;Purushothama et al, 2007). The YLD first emerged in India (Raghavan and Baruah, 1958;Rawther, 1976;Nair et al, 2016); after that, the disease was also examined in Hainan, China (Yu et al, 1986;Wang et al, 2020) and Sri Lanka (Kanatiwela de Silva et al, 2015). Areca palm widely grows in the Pacific, tropical areas of Asia, and East Africa despite the belief that its origin is in the Philippines and Malaysia (Kurian and Peter, 2007).…”

“…Religious and masticatory purposes make their significance more unique (Kurian and Peter, 2007). The areca palm plantation is under attack by different pathogens, including bacteria (Kumar, 1983;Nair et al, 2016), fungi (To-anun et al, 2009;Wang et al, 2019), insects such as Tirathaba rufivena (Zhong et al, 2017) and Brontispa longissima (Li et al, 2007), phytoplasmas (Ramaswamy et al, 2013;Kanatiwela de Silva et al, 2015), and viruses (Yu et al, 2015;Yang et al, 2018a;Yang et al, 2018b;Wang et al, 2020;Cao et al, 2021;Zhang et al, 2022). The approved causal agent of YLD specifically in Hainan, China is the novel virus named areca palm velarivirus 1 (APV1) based on de novo assembly, RNA-seq, and next-generation sequencing (Yu et al, 2015;Wang et al, 2020;Cao et al, 2021), while the responsible transmission vectors of APV1 in Hainan are mealybugs Pseudococcus cryptus and Ferrisia virgata on the basis of immunocapture RT-PCR and immunofluorescence assays (Zhang et al, 2022).…”

“…The areca palm plantation is under attack by different pathogens, including bacteria (Kumar, 1983;Nair et al, 2016), fungi (To-anun et al, 2009;Wang et al, 2019), insects such as Tirathaba rufivena (Zhong et al, 2017) and Brontispa longissima (Li et al, 2007), phytoplasmas (Ramaswamy et al, 2013;Kanatiwela de Silva et al, 2015), and viruses (Yu et al, 2015;Yang et al, 2018a;Yang et al, 2018b;Wang et al, 2020;Cao et al, 2021;Zhang et al, 2022). The approved causal agent of YLD specifically in Hainan, China is the novel virus named areca palm velarivirus 1 (APV1) based on de novo assembly, RNA-seq, and next-generation sequencing (Yu et al, 2015;Wang et al, 2020;Cao et al, 2021), while the responsible transmission vectors of APV1 in Hainan are mealybugs Pseudococcus cryptus and Ferrisia virgata on the basis of immunocapture RT-PCR and immunofluorescence assays (Zhang et al, 2022). The most conspicuous symptom of YLD is the yellowing of the leaves; the symptoms emergence that was observed and recorded in the present research work was the same as those described by Wang et al (2020) and Zhang et al (2022), although the severity of the symptoms towards different temperatures and seasonal effects was not known exactly before, and was needed to be explored.…”

“…The approved causal agent of YLD specifically in Hainan, China is the novel virus named areca palm velarivirus 1 (APV1) based on de novo assembly, RNA-seq, and next-generation sequencing (Yu et al, 2015;Wang et al, 2020;Cao et al, 2021), while the responsible transmission vectors of APV1 in Hainan are mealybugs Pseudococcus cryptus and Ferrisia virgata on the basis of immunocapture RT-PCR and immunofluorescence assays (Zhang et al, 2022). The most conspicuous symptom of YLD is the yellowing of the leaves; the symptoms emergence that was observed and recorded in the present research work was the same as those described by Wang et al (2020) and Zhang et al (2022), although the severity of the symptoms towards different temperatures and seasonal effects was not known exactly before, and was needed to be explored. The YLD symptoms start with the yellowing of leaflet tips of the lowermost leaves or the midcrown, or the lowest leaves.…”

Metagenomic analysis reveals the predominance of Candidatus Patescibacteria in the rhizosphere of arecanut palms in yellow leaf disesase (YLD) endemic areas of India

“…Arecanut (Areca catechu L.) is an important plantation and industrial crop cultivated predominantly in South and South-East Asia, especially in India, China and Malaysia. Arecanut production has been hampered by environmental and disease pressures, especially the increased incidence of yellow leaf disease (YLD) in countries like India and China (Nampoothiri et al, 2000;Wang et al, 2020). The rhizosphere microbiome has been linked with beneficial aspects such as plant health by enhancing plant growth, meeting the nutrient requirements of plants, and imparting abiotic and biotic stress tolerance (Olanrewaju et al, 2019).…”