Elimination of the Potato Viruses from the Local Landraces through in Vitro Culture
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Date
2022
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Abstract
The present investigation on local landraces of potatoes from Assam was
conducted to eliminate the viral infections. For this the local landraces were collected
from different districts of Assam viz., Jorhat, Biswanath, Sonitpur, Barpeta, Dibrugarh
and Kokrajhar. Different symptoms like puckering of leaves, cupping of leaves, leaf
rolling, purple colouration on leaves, calico pattern, mosaic symptoms, crinkling of
leaves, etc. were observed. It was observed that the landrace from Barpeta had the
highest disease incidence of 62.22 per cent and the lowest incidence of 10.00 per cent
was observed in Badami aloo collected from Kokrajhar. PCR analysis of the
symptomatic samples showed the presence of different viruses like PVY, PLRV, PVM,
PVX, PVS and AMV. The potato tubers were also subjected to PCR analysis and only
PLRV was detected with the highest incidence in Barpeta landrace (75.00 %). The
growth and yield attributing characters of the landraces collected were also recorded.
Plant height was observed to be highest in the landrace of Dibrugarh with 43.36 cm.
The highest number of branches was observed in Dibrugarh landrace. The weight of
tubers per plant was observed to be highest in case of Dibrugarh landrace (383.48 g). In
the in vitro studies, three types of explants (nodal segment, tuber eyes and apical
meristem) with two types of media (MS and PM media) were used to conduct the
experiment. Among the various hormonal combinations used for shooting, the best
hormonal combination observed was 2 mg/ l GA3 + 4mg/ l NAA + 2 mg/ l BAP
irrespective of the explant and media used in case of the parameters viz., time required
for shooting, number of shoots developed and length of shoots. Similarly in case of
rooting the best hormonal combination observed was 1.5 mg/ l IAA + 1.5 mg/ l GA3 +
1.5 mg/ l KIN irrespective of the explant and media used in case of the parameters viz.,
time required for rooting, number of roots developed and length of roots. The potato
plantlets survived highest (86.67 %) when grown from tuber eyes whereas the disease
incidence of PLRV was lowest (20.00 %) in case of plantlets grown from apical
meristem. Further SAR chemicals were applied exogenously in the potato plants grown
in field condition and it was observed that BTH applied at 1.5 mM had the highest
reduction of incidence over control (87.03 %). The results of application of SAR
chemicals were also supported by the biochemical analysis of DAB assay and PPO
assay. On application of thermotherapy, no disease incidence was observed at 40 ⁰C for
2 hours 30 minutes where germination was 50 per cent.