Mean symptom severity index (Standard Deviation above 0 in parenthesis) of virus infection on plants expressed 35 dpi.

<p>The presence (Y) or absence (N) of an insertion/deletion (indel) mutation in the <i>RDR1</i> is indicated. GenBank accession codes of partial <i>RDR1</i> coding sequences are given.</p><p>^aYTMMV, yellow tailflower mild mottle virus; BYMV, bean yellow mosaic virus: CMV, cucumber mosaic virus; TSWV, tomato spotted wilt virus.</p><p>^bMean symptom indices (Standard deviation)</p><p>0. Systemic infection not detected</p><p>1. No visible symptoms of infection.</p><p>2. Mild symptoms of chlorosis, mosaic and/or leaf deformation evident. Slight stunting may be evident. Ring patterns or small necrotic spots sometimes visible. Little to no obvious impact on the numbers of flowers or viable seed produced.</p><p>3. Moderate symptoms of chlorosis, mosaic and/or leaf deformation. Moderate to significant stunting of growth and small necrotic patches may be present. Some flowers and seed may be produced.</p><p>4. Large patches of leaf/stem necrosis, severe stunting. Plant remained alive.</p><p>5. The plant was dead.</p><p>NL = necrotic lesion; rings = ring patterns</p><p>Mean symptom severity index (Standard Deviation above 0 in parenthesis) of virus infection on plants expressed 35 dpi.</p

<i>Nicotiana</i> plants in their natural habitats in Australia.

<p>Top left, a <i>N</i>. <i>benthamiana</i> plant growing amongst rocks beside the Indian Ocean in the Pilbara region. Top right, a <i>N</i>. <i>occidentalis</i> ssp <i>occidentalis</i> plant growing on coastal spinifex grasslands near Roeburn. Lower left, a <i>N</i>. <i>rotundifolia</i> plant on a dry riverbed in the Murchison Region. Lower right, a group of <i>N</i>. <i>occidentalis</i> ssp <i>obliqua</i> plants growing at the base of a rock face in the Pilbara region.</p

Symptoms of infection.

<p>A. Leaf of <i>N</i>. <i>occidentalis ssp hesperis</i> Nt-5 infected with BYMV exhibiting small necrotic lesions within 7 days of infection. B. <i>N</i>. <i>simulans</i> SL19 exhibited small chlorotic rings (arrow) 15 dpi with BYMV. C. Symptoms of infection of YTMMV on <i>N</i>. <i>benthamiana</i> RA-4 20 dpi. D. <i>N</i>. <i>benthamiana</i> VL552B2.1 exhibiting symptoms of leaf mottling and deformation 20 dpi with YTMMV. E. <i>N</i>. <i>benthamiana</i> Kx-1 (left) exhibiting chlorotic spots 20 dpi with BYMV. Plant on the right is uninfected.</p

Accessions used, showing species and their origins.

<p>^a NT, Northern Territory; QLD, Queensland; SA, South Australia; VIC, Victoria; WA, Western Australia</p><p>Accessions used, showing species and their origins.</p

Symptom indices.

<p>A: Index 2, mild symptoms including faint mosaic, little stunting or leaf distortion. Example given is from <i>N</i>. <i>benthamiana</i> accession KL-1 infected with BYMV. B: Index 3, moderate symptoms of infection including strong mosaic and some leaf distortion and plant stunting. Example given is from <i>N</i>. <i>benthamiana</i> accession KL-1 infected with YTMMV. C: Index 4, severe necrosis affecting most of the plant. No flowers. Example given is from <i>N</i>. <i>umbratica</i> accession Wea-1 infected with YTMMV (left). Plant on the right is uninfected. D: Index 5, whole plant is dead.</p