First Report of Potato Virus H on Solanum muricatum in China

Abstract

Solanum muricatum, commonly known as pepino, pepino dulce, or tree melon, is a perennial shrub well known for its attractive, sweet, flavorful fruits and is frequently cultivated as an annual. It has gained increasing popularity in China and is grown as a cash crop in many provinces. S. muricatum belongs to the family Solanaceae and is closely related to tomato, eggplant, and potato. In 2012, during a study of serological relationships between PVH and PVM on potatoes, potato virus H (PVH) was detected serendipitously in symptomless pepino plantlets in Beijing, grown from tissue culture stocks. PVH is a recently discovered carlavirus reported from potato plants from Huhhot, Inner Mongolia Autonomous Region. Since then, it was found on potatoes in Yunnan, Hebei, Liaoning, Heilongjiang, and Xinjiang provinces. PVH induces mild symptoms with a slight leaf curl in systemic leaves, but most often it is almost symptomless or latent on potatoes (2). To confirm the presence of PVH on S. muricatum, surveys were conducted in 2012 and 2013 in Gansu, Yunnan, and Guangxi provinces and Beijing. Fruits and leaves were collected randomly from pepino plants displaying no obvious symptoms. For PVH detection, a combination of RT-PCR, genome sequencing and serological assays were used. RNAs extracted from fruits and leaves were amplified using RT-PCR with primer pairs PVHCPF and PVHCPR (2), and extracted samples were probed by Western blotting with the specific polyclonal antiserum against PVH (2). Among the 50 plants randomly collected, fruits and leaves of nine plants tested positive for PVH. Subsequently, an RT-PCR product of the expected size (2.6 kb) encompassing the triple-gene block, the capsid protein gene, and the cysteine-rich protein gene, was amplified with a specific primer pair (PVHB1F 5′-TGATGGAATTTACAAAAAC-3′ and PVHUR 5′-CTTATGCGCATCTATCAATC-3′), and then cloned into pMD19-T (TaKaRa, Dalian, China) and sequenced (PVH-Pepino with GenBank Accession No. KF546312). Further sequence comparison showed that PVH-Pepino shared 91 to 98% nucleotide sequence identity in the genes mentioned above with those of the reported potato isolates PVH-Ho and PVH-YN (HM584819 and JQ904630, respectively). PVH-Pepino shared deduced amino acid identity of 98 to 99% in CP gene with PVH-Ho and PVH-YN, respectively, but only shared 57 to 67% amino acid identities with other reported carlaviruses (1,2). Thus, latent infection of PVH on S. muricatum was confirmed. To our knowledge, this is the first report of S. muricatum as a natural host of PVH. Our results suggest that PVH, as a new member of the genus Carlavirus, has a wider host range than originally expected. Potatoes and pepinos are crops widely grown in China. The fact that no symptoms were expressed by PVH in pepino plants (symptomless carrier) and only mild symptoms expressed by PVH in diseased potatoes makes detection and remediation of this disease more difficult. Although this finding does not show that PVH is economically important to pepino, this cannot be excluded in the presence of other viruses (2). References: (1) A. King et al. Page 881 in: Virus Taxonomy, Ninth Report of the International Committee on Taxonomy of Viruses. Elsevier Academic Press, London, 2011. (2) Y. Y. Li et al. PLOS ONE 8(6):e69255, 2013.

Incidence of pests and viral disease on pepino (Solanum muricatum Ait.) in Kanagawa Prefecture, Japan

“…Pepino latent virus (PepLV; later reclassified as Potato virus S (PVS)) was detected from pepino cuttings in New Zealand, even though pepino plants with no symptoms had been imported from Chile (Thomas et al 1980). With the increase in pepino production in China, Potato virus H (PVH) infected pepino, with no obvious symptoms (Abouelnasr et al 2014) (Table 6). Pests and pathogens in many crops cause tremendous losses both in terms of quantity and quality.…”

“…In contrast, in regions where pepino was introduced other than Japan, such as New Zealand, China and Turkey, there are only a few records on the pests (two species: Galbreath and Clearwater 1983, Akyazi 2012) and viruses (two species: Thomas et al 1980, Abouelnasr et al 2014) in the academic literature. In Japan, little has been known in detail about the pests and viruses of pepino, except that inadequately identified pests such as spider mites and aphids damage to pepino.…”

The first de novo transcriptome of pepino (Solanum muricatum): assembly, comprehensive analysis and comparison with the closely related species S. caripense, potato and tomato

“…Nutritionally, the pepino has very high levels of potassium and vitamin C, and a low calorie content [ 3 ]. Apart from being cultivated in its region of origin, the pepino has been introduced in other countries like New Zealand, China and Turkey as a potential new horticultural crop [ 4 , 5 ].…”

Morphological and molecular characterization of local varieties, modern cultivars and wild relatives of an emerging vegetable crop, the pepino (Solanum muricatum), provides insight into its diversity, relationships and breeding history

“…The pepino is cultivated for its juicy and aromatic fruits. Although the pepino is locally important in the Andean region since long ago (Prohens et al 1996), in recent decades the increasing interest in exotic fruit markets has promoted increasing interest in pepino cultivation in several countries including New Zealand, Australia, Spain, Turkey, Israel and China (Levy et al 2006;Yalçin 2010;Rodríguez-Burruezo et al 2011;Abouelnasr et al 2014). Nutritionally, pepino fruits contain high levels of potassium and vitamin C, and it is low in calories.…”