Molecular, Biological and Phylogenetic Analysis of Chinese Isolates ofHop stunt viroidAssociated with Citrus Cachexia Disease

Abstract

Citrus cachexia is an economically important disease of citrus hosts caused by specific variants of Hop stunt viroid (HSVd) that are usually referred to as Citrus cachexia viroid (CCaVd). Eight cachexia-associated HSVd isolates were collected from six citrus growing areas of China, where citrus cachexia had not been reported previously. Forty-seven independent cDNA clones were used for genetic diversity and phylogenetic analysis. There were no sequence variant-cultivar correlation and no distinct regional specificity among or within the cachexia-associated HSVd populations analysed. Three clusters consisting of three major HSVd variants were identified by phylogenetic analysis, suggesting that most Chinese isolates contain a mixture of cachexia and non-cachexia variants. Biological properties of eight CCaVd isolates were determined by inoculating ParsonÕs Special mandarin (Citrus reticulata). Our results suggest that the interactions between CCaVd and non-CCaVd variants might play an important role in suppressing cachexia symptom expression.

Insights on genetic diversity and phylogenetic analysis of Hop stunt viroid (HSVd) population from symptomatic citrus tree in Tunisia

“…Interestingly, one clone (HSVd1.7) had 100% identity compared with cachexia variant from Japan (AB211242). In addition, the same variant was recently reported in China (FJ716175) (Wang et al, 2010), Iran (GQ246200) and Spain.…”

“…A second cluster, formed by CVd-IIa group, contained 2 cDNA clones from Washington navel isolate, two clementine variant previously reported by Elleuch et al (2006) and two other variants recently reported by Wang et al (2010). Four cDNA clones (17F-HSV, 16F-HSV, HSVd1.5 and HSVd2.6) clustered in CVd-IIc group.…”

Transcriptome sequencing reveals novel Citrus bark cracking viroid (CBCVd) variants from citrus and their molecular characterization

“…So far, the molecular characteristics and evolutionary analysis of several citrus viroids have been reported [ 14 , 28 , 31 – 33 ]. In this study, CBCVd-LSS was detected in six citrus cultivars from Pakistan.…”

Xyloporosis: A history of the emergence and eradication of a citrus viroid disease

“…Further evidence for the Near East origin of CVds has been found in the People's Republic of China, where tests conducted in the late 1970s showed that only imported citrus varieties were infected with viroids (e.g., CEVd and HSVd; Wang et al 2010). This was easy to determine as all varieties were propagated on widely planted trifoliate orange and Satsuma, both of which showed no symptoms of exocortis (Broadbent et al 1979;P Barkley, personal communication).…”