FIRST REPORT OF TOMATO YELLOW LEAF CURL CHINAVIRUS INFECTING MALVA ROTUNDIFOLIA IN CHINA

Abstract

Malva rotundifolia L. is a common medicinal herb in China. In 2010, samples of 10 symptomatic Malva parviflora L. plants showing yellow vein and leaf crinkling, and of two symptomless plants were collected in Sichuan (China). A 500 bp DNA fragment was successfully amplified from the 10 symptomatic samples with the degenerate primers PA/PB specific to begomoviruses (family Geminiviridae) (Deng et al., 1994). The fragment of isolate SC226 was randomly selected for cloning and sequencing (GenBank accession No. KP293739). Based on the sequence obtained, the specific primers Y6F1 (5’-ACCGGATGTACAGAAGCCCTGA-3’) and Y6R (5’-CTTCCGATACATGGGCCTGTTTG-3’) were designed to amplify the remaining DNA-A sequence. Sequence analysis showed that the full-length sequence of SC226 was 2738 nt long (JX679252) with the highest nucleotide sequence identity with isolate Y25 of Tomato yellow leaf curl China virus (TYLCCNV-[China:Yunnan 25:2002] (AJ457985)). Then, a 1200 nt long fragment specific to TYLCCNV was amplified from all symptomatic samples using primers Y10F1 and Y35+10R (Qing and Zhou, 2009). With the universal abutting primers (Briddon et al., 2002) for betasatellite DNA, an amplicon of 1300 bp was obtained from 10 symptomatic samples. Sequence comparison showed that the betasatellite is 1335 bp long (JX679253) and has a 85.8% identity with Tomato yellow leaf curl China betasatellite (TYLCCNB-[China:Yunnan 149:2009] (GU058280)). An approximate 900 bp amplicon specific to TYLCCNB was detectable in all symptomatic samples using the primers Y10β/β02 (Qing and Zhou, 2009). Neither TYLCCNV nor TYLCCNB was detectable in symptomless samples. This is the first report of TYLCCNV associated with its betasatellite infecting Malva rotundifolia.