May 20, 2004
From: British Society of Plant Pathology, New Disease Reports [edited]

Natural infection of maize by Pennisetum mosaic virus in China

ZF Fan <fanzf@cau.edu.cn>, X Jiang, XM Liang, HF Li, Department of Plant Pathology and State Key Laboratory for Agrobiotechnology, China Agricultural University, Beijing 100094; WJ Wang (as for Fan, and Shanxi Academy of Agricultural Sciences, Xinzhou, Shanxi 034000, PR China; FR Wang, Maize Research Institute, Shanxi Academy of Agricultural Sciences, Xinzhou, Shanxi 034000, PR China. Accepted for publication 20 Apr 2004.

In mid-2002, a potyvirus was isolated from maize (_Zea mays_) showing mild mosaic symptoms in northern Xinzhou District of northern Shanxi Province, China. This isolate was mechanically transmitted to maize (cultivar Ye-Dan No.2) and _Sorghum bicolour_ (4 cultivars: Atlas, Xin-Liang Nos. 7 and 52, and Xiong-Yue 191). All inoculated plants developed systemic mosaic symptoms.

In serological tests, the virus was distantly related to sugarcane mosaic virus (SCMV), the prevalent potyvirus infecting maize across China (1), but it is closely related to the newly identified Pennisetum mosaic virus
(PenMV) isolated from a perennial grass (_Pennisetum centrasiaticum_) (2).

The nucleotide sequence of the putative coat protein (CP) gene of the isolated virus has been determined (accession number AY543166) and is comprised of 909 nucleotides, encoding 302 amino acid residues. Sequence comparisons among all potyviruses reported to date showed that this isolate was most closely related to PenMV (accession number AY172336) (2). The sequence identity between the putative CP genes of the maize isolate and PenMV was 92 per cent, while between the CPs it was 99 per cent at the amino acid level, thus identifying the virus isolated from maize as PenMV.

This is the first report of PenMV in maize in China. Previously SCMV had been the only potyvirus infecting maize in the country. It occurs in most maize-growing areas of China, and its symptoms, on most cultivars of sorghum, are mosaic followed by reddening and necrosis of the lamina. In contrast, the distribution of PenMV appears limited, as maize from only 1 region of China has been found to be infected and the symptoms it caused, especially on sorghum, were significantly milder when compared to those of SCMV.

References:
1. Fan Z, Chen H, Liang X, Li H. Complete sequence of the genomic RNA of the prevalent strain of a potyvirus infecting maize in China. Arch Virol 2003; 148: 773-82.
2. Fan Z, Chen H, Cai S, Deng C, Wang W, Liang X, et al. Molecular characterization of a distinct potyvirus from whitegrass in China. Arch Virol 2003; 148: 1219-24.

[Zaifeng Fan stated to me in correspondence that the provisionally designated PenMV is restricted to Shanxi Province in northern China. Because it is a potyvirus, PenMV can be expected to spread via several aphid species, and seed transmission should be examined in maize and perhaps other species such as _Panicum_, _Eleusine_, and _Setaria_. Sequence comparisons and phylogenetic analysis showed 3 distinct groups of Chinese SCMV sequences (sugarcane isolates from Zhejiang province, a maize isolate from Guangdong and maize isolates from other provinces). It will be interesting to know more about the genomic relationships between PenMV and other maize-infecting potyviruses such as Maize dwarf mosaic, Johnsongrass mosaic, Sugarcane mosaic, and Sorghum mosaic. - Mod.DH]