Potato leafroll virus (PLRV) causes yield and quality losses in
potato. PLRV is identified by plant symptoms and serological tests
such as an enzyme-linked immunosorbent assay (ELISA). A similar
serological test, direct tissue blotting assay (DTBA), was used to
detect and monitor PLRV movement in field-inoculated Russet Burbank
plants and plant tissues from Russet Burbank and Russet Norkotah seed
tubers submitted by growers for winter certification tests.
DTBA was as accurate as ELISA and easier to use for detecting
tuber-perpetuated PLRV in stems and petioles of plants grown from
grower-submitted seed tubers. ELISA detected twice as many PLRV
positives as DTBA in leaflet tests. DTBA detected PLRV in tuber tissue
but results matched ELISA in only 74% or less of the samples. Results
of DTBA tuber tests were sometimes difficult to interpret while stem
and petiole results were distinct and unambiguous.
As inoculations were delayed later in the season and as plants
matured, PLRV infection levels decreased sharply, most often within a
two week period in early July. In same-age plants inoculated 43 days
after planting but 18 days apart, early inoculation produced higher
PLRV levels. Conversely, when same-age plants were inoculated 62 days
after planting but 19 days apart, late inoculation produced higher PLRV
levels. This discrepancy is not fully understood, but larger tuber
size at the later inoculation probably produced a stronger sink for
source-to-sink translocation of nutrients and phloem-limited viruses.
Results of DTBA winter grow-out tests of summer-infected tubers
approximated those of ELISA and visual inspections. Indirect DTBA
testing of tubers utilizing stem and petiole tissues from winter growout
plants detected more PLRV than directly testing tuber tissue 21
days post inoculation in summer. DTBA detected current season
(primary) PLRV less reliably than secondary (tuber-borne) PLRV, similar
to reported ELISA results.
PLRV infection increased tuber numbers but decreased size. Size
reduction was most evident in plants infected early in the season.
Average tuber size in healthy plots was always larger than the average
tuber size in infected plots. Within an infected plant, small tubers
tended to be infected less often than large tubers. / Graduation date: 1993
| Identifer | oai:union.ndltd.org:ORGSU/oai:ir.library.oregonstate.edu:1957/36239 |
| Date | 26 April 1993 |
| Creators | Whitworth, Jonathan L. |
| Contributors | Mosley, Alvin R., Reed, Gary L. |
| Source Sets | Oregon State University |
| Language | en_US |
| Detected Language | English |
| Type | Thesis/Dissertation |
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