Molecular evidence for Apple chlorotic leaf spot virus in wild and cultivated apricot in Himachal Pradesh, India.

Wild apricot (Prunus armeniaca) is known as “chuli” or “zardalu” in Himachal Pradesh (HP, India) where it grows in the hills at altitudes of 1000-1700 meters. The fruits have medicinal properties and seedlings are used as rootstocks for commercial apricot, peach and plum orchards (Parmar and Kaushal, 1982). Apple chlorotic leaf spot virus (ACLSV), genus Trichovirus, has been reported to cause “viruela” and “butteratura” diseases in apricot and is cause of apricot decline (Sutic et al., 1999). Infections are normally symptomless but can result in severe graft incompatibility with some Prunus combinations. During surveys for ACLSV infection in P. armeniaca, leaf samples (30 from cultivated and 23 from wild plants) were collected and subjected to ELISA in triplicate. Positive results were obtained from 14 samples. Inoculation of leaf extracts of the positive samples to Chenopodium amaranticolor resulted in small chlorotic spots on inoculated leaves. RT/PCR using degenerate primers (Accession Nos. AM490253 and AM490254) designed to yield amplicons corresponding to the complete coat protein gene gave a 758 bp product. Sequence analysis of amplicons from wild (AM498048) and cultivated (AM498045) apricot virus isolates showed 94% and 95% identity at the nucleotide and amino acid level among themselves, and were 92% to 96% identical at the amino acid level with two apple ACLSV isolates from HP. Indian ACLSV isolates were similar to others with the exception of a Turkish isolate [70% similarity (Ulubas and Ertunc, 2005)] (AJ586636). ACLSV from cultivated apricot was 91% similar to an Italian (AJ586635) and a Spanish (AJ586632) virus isolate. This is the first report of ACLSV infection of apricot in India, and of ACLSV infection of wild apricot