Studies on phylogenetic divergence in genus Helicoverpa and resistance mechanism in chickpea genotypes against its major pests
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Date
2018-08
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G.B. Pant University of Agriculture and Technology, Pantnagar - 263145 (Uttarakhand)
Abstract
The present investigations were carried out on “Studies on phylogenetic divergence in genus Helicoverpa and resistance mechanism in chickpea genotypes against its major pests” during 2016-2018. The studies revealed that in genus Helicoverpa, Helicoverpa armigera species is present in all the thirteen districts of Uttarakhand at over altitude range of 227.7 m (Pantnagar) to 2049.7 m (Barsar). In Pantnagar H. armigera infestation was found throughout the year on forty plant species belonging to fifteen families, which includes thirteen field crops, eight vegetable crops, thirteen ornamental plants and six herbaceous weeds. Preferred host plants mostly from the Fabaceae family. The larval and adult populations of H. armigera showed negative correlation with the variables minimum temperature, morning relative humidity, evening relative humidity and rainfall whereas positive correlation with maximum temperature, and sun-shine hrs. Five peaks of adult male moth catches were recorded during 2016-17. Major peak of moth population catches was high during the 15th S.W. The studies of Inter-host phylogenetic analysis at Pantnagar, revealed a total of fifteen single nucleotide polymorphisms (SNPs), one semi- conserved amino acid among the eleven isolates of H.armigera population. Evolutionary adoptive change in wheat population of H. armigera was found to be newly establishing at Pantnagar where host fidelity factors playing an important role. Whereas, Inter-location phylogenetic analysis revealed that thirty three single nucleotide polymorphisms (SNPs), twelve semi conserved and seven un-conserved amino acid residues among the eleven different location isolates of H. armigera population. The high similarity may be attributed to the altitudinal similarity among the collected population i.e., Jakhdhar (1713.6m) and Ranichauri (1861 m). The H. armigera population of Dehradun, Ranipokhari and Chinayalisaur have formed same cluster depicting the trade route of agriculture products. In studies of resistance mechanism, out of thirty nine chickpea genotypes eleven genotypes showed resistance against H. armigera among them two genotypes NBeG1004 and GL25016 were having comparatively sparse trichome density and lengthier trichomes which were least infested by eggs of H. armigera. The biochemical experiments revealed the highest phenols, flavonoids, tannins and trypsin inhibitor observed in GL25016, ICCV97105, GL25016 and NBeG1004. The GCMS analysis showed that ICCV92944 was containing compounds such as Octanoic acid, 2-dimethylaminoethyl ester, Phytol, Phthalic acid and Tetradecanoic acid which might be showing some adverse effects on H. armigera growth and development and might be reason for resistance against H. armigera. Accessions having combination of suitable sparse and lengthier trichomes on leaves and pods and higher biochemical parameters viz., phenol, flavonoids, tannins and trypsin inhibitor content in their immature seeds offered resistance against pod borer attack in chickpea. The resistance towards the Callosobruchus chinensis was offered by HC1 and ICCV92944. The biochemical experiments revealed highest amounts of phenols, flavonoids, tannins and trypsin inhibitor observed in GL25016, HC1, ICC07104 and in NBeG1004. Bioactivity compound 9-Octadecenoic acid (Z) - was found in only HC 1 which may be reason for resistance against C. chinensis. The genotypes viz., ICCV 92944 and HC 1 which are least preferred by H. armigera and C. chinensis, respectively could be exploited as a source of resistance for the varietal development of chickpea germplasm against H. armigera.
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