Colour break in reverse bicolour daffodils is associated with the presence of Narcissus mosaic virus

Table 2 Viral particle count in Narcissus flowers, leaves and bulbs after electron microscopic examination

Daffodil cultivar	Viral length (nm)	Colour break	Location	No. virus particles tepals	No. virus particles leaves	No. virus particles bulbs
Twilight Zone	580 ± 13	Yes	Ashhurst	29 ± 4	-	-
Twilight Zone	658	No	Ashhurst	0¹	-	-
Twelve Gauge	543 ± 8	Yes	Foxton	12 ± 3	-	-
Twelve Gauge	637	No	Foxton	0²	-	-
21/92A seedling	569 ± 12	Yes	Nelson	51 ± 14	4 ± 1	1 ± 0²
21/92A seedling		No	Nelson	0³	0³	0³
Lighthouse Reef	502 ± 14	Yes	Ashhurst	28 ± 5	-	-
Daydream	519 ± 33	Yes	Nelson	20 ± 2	-	-
20/87H seedling	544 ± 3	Yes	Nelson	17 ± 1	-	-
Culfind (offset Bulb)⁴	644 ± 10	Yes	Nelson	15 ± 1	-	-
Culfind (parent bulb)		No	Nelson	2 ± 0	-	-

Viral counts were determined from TEM photos. The photos were taken from at least three randomly chosen observations of a grid under magnification of 21200 X. When randomly chosen grid views did not reveal presence of particles the whole extract was screened to determine presence of viral particles. ¹Only one virus particle found in whole extract; ²Very hard to find virus particles, with extensive screening of petal extract required (i.e., many randomly chosen observations contained no viral particles); ³No virus particles found anywhere in extract; ⁴Non reverse bicolour '-' = not measured.

ISSN: 1743-422X