Screening for Resistance to Potato Virus Y and Potato Virus X in Potato (Solanum Tuberosum L.)
Abstract
Studies were conducted at KARI-Tigoni and KARI-Marindas (Molo) with the aim of
assessing the value of using varieties with Potato Virus Y (PVX) and Potato Virus X
(PVX) resistance in preventing crop losses under the local (Kenyan) potato growing
conditions and also to assess suitability of these PVY and PYX resistant clones as
resistant parents for developing new potato varieties in Kenya.
In the first study, seven PVY and PYX resistant clones from the International Potato
Centre (CIP) Lima, Peru together with six local susceptible check varieties were
subjected to natural virus infection over three cropping seasons during Short Rains (SR)
2005 at KARI-Tigoni and in both sites (KARI- Tigoni and Molo) during the Long
Rains(LR) 2006 and SR 2006. ELISA tests conducted on the tuber samples at the end of
every season indicated significant (P = 0.05) higher percentage of 40 - 100% PVY and
PYX infection in the susceptible check varieties and significant (P = 0.05) lower
percentage of 0 - 5% infection in the best resistant clones. The CIP clones experienced
significant (P= 0.05) lower yield reduction ranging from 1.2 to 2.3 T/ha compared to the
susceptible check varieties which had a higher yield reduction of 12.2 to 15.4 T/ha.
Among the CIP clones evaluated, CIP 394905.8 was found to be the best in with standing
virus related yield losses since instead of experiencing a yield reduction like other
genotypes; it experienced yield increase ranging from 0.83 to 1.2 T/ha in both sites of the
study.
In the second experiment, five CIP resistant clones were crossed with two susceptible
cultivars and the progeny seedlings obtained were subjected to PVY and PYX sap
inoculation to screen for virus resistance in the seedlings. Successful development of
berries from the crosses was higher (ranging from 18.6 % to 61.5 %) in the crosses
conducted in the field under lower temperature ranges of 12 - 31°C, 14 - 20 °C and 1118°C
compared to the crosses conducted in the glasshouses (0 - 3.7 %) under relatively
higher temperature ranges of 21 - 36°C and 18 - 31 °C. Number of true potato seeds
obtained from the crosses and planted in each of the crossing combinations ranged from
1253 to 1791 and percentage emergence of seedlings ranged from 65 % to 90 %. Among
the CIP clones used as resistant parents, CIP clone 395438.1 was identified as the best
with 2 single dominant genes for PVY and PYX resistance out of four (Ry Ry ry ry) and
it produced 84 % of resistant progenies when crossed with susceptible cultivar Tigoni.
The studies recommended the utilization of PYY and PYX resistant clones/varieties in
reducing virus related crop losses and as parents for developing new virus resistant
genotypes.
Citation
Master of Science Degree in Plant BreedingSponsorhip
University of NairobiPublisher
University of Nairobi School of Biological Sciences
Subject
Screening for ResistancePotato Virus Y
Potato Virus X
Potato (Solanum Tuberosum L.)
Screening
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Screening for Resistance to Potato Virus Y and Potato Virus X in Potato (Solanum Tuberosum L.)
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