Development of Dual Resistance to Tomato Leaf Curl Virus and its Vector Whitefly (Bemisia tabaci) using Lycopersicon hirsutum (LA1777) Introgressed Lines in Tomato (Lycopersicon esculentum)
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Date
2007-09-17
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University of Agricultural Sciences GKVK, Bangalore
Abstract
Tomato Leaf Curl Virus (ToLCV) is one of the most important and major
constraints in tomato cultivation which is solely transmitted by whitefly. Hence it
is appropriate to develop varieties that show resistance to both virus and whitefly
infestation. In the present study, Lycopersicon hirsutum introgressed Nearisogenic
Lines and Back Cross Recombinant Inbred Lines were screened for
whitefly resistance, ToLCV resistance, yield and fruit quality parameters. A total
of eight lines (LA3913, LA3914, LA3916, LA3921, LA3942, LA3946, LA3948
and LA3978) were selected based on high whitefly resistance. These lines were
crossed to ToLCV resistant varieties -Nandi, Sankranti and Vybhav for combining
vector and virus resistances. Three hybrids viz., Sankranti x LA3916, Nandi x
LA3948 and Sankranti x LA3948 were found to have similar yield potential as
that of standard check Vybhav and were also resistant to both ToLCV and
whitefly. With regard to fruit quality parameters, Sankranti x LA3916 possessed
high acidity values whereas Nandi x LA3948 and Sankranti x LA3948 have
exhibited lower acidity values with high ratio of total soluble solids to acidity
which is good for processing industry. The combining ability analysis revealed
that the additive gene action is predominantly governing most of the traits
suggesting choice of combination breeding with pedigree selection to identifying
transgressive segregants. The best hybrid Nandi x LA3948 was forwarded to F2
generation and six F2 plants were selected based on their yield potential. Their
yield levels were on par with the standard check Vybhav but significantly higher
than Nandi and Sankranti. The SCAR markers were developed based on sequence
information of RFLP markers mapped in the Lycopersicon hirsutum introgressed
regions specific to the selected whitefly resistant lines. Majority of these markers
showed monomorphism in the respective lines except SCTG554 in the line
LA3921. The RFLP marker, TG105 linked to ToLCV resistance was also
converted to SCAR and it differentiated ToLCV resistant and susceptible varieties.
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