A mosaic disease of Centrosema pubescens Benth. caused by passionfruit woodiness virus

A mosaic disease of centro (Centrosema pubescens) in Queensland was shown by physical, morphological and serological comparisons of the causal virus to be due to infection by a strain of passionfruit woodiness virus (PWV). This strain produced an almost latent infection of passionfruit (Passifiora edulis) and although it had a similar leguminous host range to PWV, symptoms were sometimes distinguishable. Naturally infected centro and Passifiora suberosa, growing in close association, each carried a characteristic and easily distinguishable strain of PWV

Some characteristics of Tobacco streak virus isolated from Queensland

Tobacco streak virus (TSV) has not previously been reported from Australia. It was isolated from Dahlia pinnata, Ageratum houstonianum, Solanum auriculatum, Nicandra physalodes, Solanum nigrum and Asclepias physocarpa, growing in scattered locations in south-eastern Queensland. Serological relationship to English and American strains of TSV was demonstrated. Typical TSV virus particles were demonstrated by electron microscopy and a three-component system was visible in sucrose density gradient separations. The host range and symptoms were generally similar to those of the type strain of TSV, but red node in bean (Phaseolus vu/garis) resulted from inoculation of this species with some highly infective preparations. Antisera were produced using two different virus purification methods

Virus diseases of Queensland strawberries and the epidemiological effects of the strawberry runner approval scheme

Four viruses infecting strawberry cvs. in Qd, were identified. Tobacco streak virus was isolated mechanically and reinoculated to strawberry plants. It was identified serologically, morphologically and by host range. Strawberry mild yellow edge, strawberry mottle and strawberry latent A viruses were identified by indicator reactions. SMV was readily transmitted by both Chaetosiphon fragaefolii and Aphis gossypii but no experimental aphid transmission of SMYEV was obtained. No virus particles were seen by electron microscope examination of thin sections of material infected by SMV, SMYEV or SLAV. The reactions of Duchesnea indica to inoculation with SMV, SMYEV and TSV were investigated. This naturalised sp. is a poor host of these viruses and would have little epidemiological importance. Examination of symptoms on 7 indicators showed that the Fragaria vesca clones were better indicators than F. virginiana clones for these viruses. Severe symptoms were produced on plants of the main commercial cv. (Redlands Crimson) by artificial virus complexes of SMYEV + SMV and TSV + SMV, but the latter was not severe in the chronic phase. The virtual eradication of strawberry viruses from commercial plantings in Qd, is attributed to distribution of uninfected material and a reduction in vector populations.ADDITIONAL ABSTRACT:Four viruses infecting strawberries were identified, namely tobacco streak virus (TSV), strawberry mild yellow edge (MYEV), strawberry mottle virus (SMV) and strawberry latent A virus (SLAV). SMV was readily transmitted by Chaetosiphon fragaefolii and Aphis gossypii but MYEV could not be transmitted experimentally. Fragaria vesca clones were better indicators than F. virginiana clones for these 4 viruses. It was concluded that the virtual eradication of strawberry viruses from commercial plantings could be attributed to distribution of healthy planting material and a reduction in vector populations.ADDITIONAL ABSTRACT:Of 4 viruses identified in strawberry in Queensland, strawberry mottle virus (SMV) was readily transmitted by Chaetosiphon fragaefolii (Ckll.) and Aphis gossypii Glov.; both aphids were present on strawberry in the field. The ornamental Duchesnea indica, which is widely grown and occurs as a naturalised weed, was a poor acquisition source for SMV by the aphids. C. fragaefolii has almost disappeared from commercial strawberry crops in Queensland in the past 15 years, and it is suggested that transmission of SMV within field plantings of the first release of the Redlands Crimson cultivar was probably by A. gossypii. The virtual eradication of strawberry viruses from commercial plantings in Queensland is attributed to the distribution of uninfected material and a reduction in aphid vector populations

Inheritance of resistance to zucchini yellow mosaic virus in Cucurbita maxima cv. Queensland Blue X C. ecuadorenesis

Inheritance of resistance to a Queensland isolate of ZYMV in Cucurbita ecuadorensis was investigated in a glasshouse using C. maxima as susceptible parent (P1), C. ecuadorensis as resistant parent (P2), F1 , F2 , backcross and self-pollinated backcross populations. Major gene models did not fit all the data well but estimates of heritability were high (h2B = 97%; h2N = 90%), implying that selection of C. maxima genotypes with resistance to ZYMV should be efficient

A novel species of mastrevirus (family Geminiviridae) isolated from Digitaria didactyla grass from Australia.

Mastreviruses (family Geminiviridae) that infect monocotyledonous plants occur throughout the temperate and tropical regions of Asia, Africa, Europe and Australia. Despite the identification of a very diverse array of mastrevirus species whose members infect African monocots, few such species have been discovered in other parts of the world. For example, the sequence of only a single monocot-infecting mastrevirus, Chloris striate mosaic virus (CSMV), has been reported so far from Australia, even though earlier biological and serological studies suggested that other distinct mastreviruses were present. Here, we have obtained the complete nucleotide sequence of a virus from the grass Digitaria didactyla originating from Australia. Analysis of the sequence shows the virus to be a typical mastrevirus, with four open reading frames, two in each orientation, separated by two non-coding intergenic regions. Although it showed the highest levels of sequence identity to CSMV (68.7%), their sequences are sufficiently diverse for the virus to be considered a member of a new species in the genus Mastrevirus, based on the present species demarcation criteria. We propose that the name first used during the 1980s be used for this species, Digitaria didactyla striate mosaic virus (DDSMV)

Bromus catharticus striate mosaic virus: a new mastrevirus infecting Bromus catharticus from Australia.

Although monocotyledonous-plant-infecting mastreviruses (in the family Geminiviridae) are known to cause economically significant crop losses in certain areas of the world, in Australia, they pose no obvious threat to agriculture. Consequently, only a few Australian monocot-infecting mastreviruses have been described, and only two have had their genomes fully sequenced. Here, we present the third full-genome sequence of an Australian monocot-infecting mastrevirus from Bromus catharticus belonging to a distinct species, which we have tentatively named Bromus catharticus striate mosaic virus (BCSMV). Although the genome of this new virus shares only 57.7% sequence similarity with that of its nearest known relative, Digitaria didactyla striate mosaic virus (DDSMV; also from Australia), it has features typical of all other known mastrevirus genomes. Phylogenetic analysis showed that both the full genome and each of its probable expressed proteins group with the two other characterised Australian monocot-infecting mastreviruses. Besides the BCSMV genome sequence revealing that Australian monocot-infecting mastrevirus diversity rivals that seen in Africa, it has enabled us, for the first, to time detect evidence of recombination amongst the Australian viruses. Specifically, it appears that DDSMV possesses a short intergenic region sequence that has been recombinationally derived from either BCSMV or a close relative that has not yet been identified