Marker assisted mobilization of cry1Ac gene from transgenic chickpea into cultivated chickpea (Cicer arietinum L.) for pod borer [Helicoverpa armigera (Hübner)] resistance
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Date
2019
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Punjab Agricultural University, Ludhiana
Abstract
Helicoverpa armigera (Hübner) poses a serious threat to chickpea production world-wide.
cry1Ac gene is known to be most effective in controlling infestation of pod borer. The present
investigation was undertaken to incorporate cry1Ac gene from T5 transgenic chickpea lines
BS 100B-T5 and BS 100E-T5 into cultivated chickpea (Cicer arietinum L.) varieties PBG 7
and L 552, respectively through crossing and recurrent backcrossing. The BC1F1 progenies [F1
(PBG 7 x BS 100B-T5) x PBG 7] and [F1 (L 552 x BS 100E-T5) x L 552] were tested for
cry1Ac gene presence using gene specific primers. ELISA on the positive plants revealed
Cry1Ac protein content between 10.57 to 11.72 µg/g leaf tissue. Therefore, on the basis of
foreground selection and ELISA, positive BC1F1 plants were propagated to obtain BC1F2
populations, which were also subjected to foreground selection. A BC2F2 population of 83
plants was also grown by selfing [F1 (PBG 7 x BS 100E-T5) x PBG 7] x PBG 7. Foreground
selection using cry1Ac specific primers on BC2F2 population resulted in ten (12.04 %) cry1Ac
positive plants (1, 2, 8, 9, 12, 20, 26, 33, 39 and 44); their background selection using 12
polymorphic SSR markers revealed average recurrent parent genome restoration of 88.9 %.
As a result, BC2F3 population comprising 128 plants was obtained from ten cry1Ac positive
BC2F2 plants. Each BC2F3 row of positive plants was then tested using cry1Ac specific primers
to identify BC2F2 plants homozygous for cry1Ac gene. The analysis revealed that three (30 %)
BC2F2 plants 26, 39 and 44 were homozygous for cry1Ac gene, whereas remaining seven
plants 1, 2, 8, 9, 12, 20 and 33 segregated in ratios of 6:1, 2.3:1, 1.25:1, 3:1, 1.6:1, 4:1 and
3:1, respectively.
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