High-resolution genetic mapping of QTL governing resistance to corn leaf aphid, Rhopalosiphum maidis (Fitch) in barley

Singh, Beant and Bhatia, Dharminder and Narang, Deepika and Kaur, Rajwinder and Chhuneja, Parveen (2023) High-resolution genetic mapping of QTL governing resistance to corn leaf aphid, Rhopalosiphum maidis (Fitch) in barley. CEREAL RESEARCH COMMUNICATIONS, 51 (2). pp. 379-389. ISSN 0133-3720 (print), 1788-9170 (online)

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Abstract

A mapping population, recombinant inbred lines (RILs), was developed from the cross of aphid susceptible cv. PL426 and resistant genotype BK 9816 to identify genetic loci conferring corn leaf aphid (CLA) Rhopalosiphum maidis (Fitch) resistance in barley. RILs showed wide range of aphid infestation (2.2–65.0 aphids/tiller) indicating quantitative inheritance of aphid resistance. All the traits related to aphid resistance, viz. aphid fecundity, chlorophyll content and tiller dry weight of plants, also showed quantitative variation. RILs were further genotyped by sequencing to identify SNPs covering whole barley genome. A total of 605 high-quality bin-mapped SNPs were positioned in seven linkage groups with a total map length of 1208.9 cM and average marker distance of 2.02 cM. Composite interval mapping identified five different quantitative trait loci (QTLs) on chromosomes 1H, 3H, 5H and 6H associated with aphid resistance and related traits. Two QTLs on chromosome 6H, QCLA.pau-6H.1 and QCLA.pau-6H.2, were mapped at genetic intervals of 1.7 cM and 4.9 cM, respectively. QCLA.pau-6H.1 explained 9.76 percent of phenotypic variation for aphid count and 12.78 percent for aphid score. Similarly, QCLA.pau-6H.2 explained 10.96 percent of phenotypic variation for aphid score. The QTL for chlorophyll content and tiller dry weight spanned the same region of QCLA.pau-6H.2, explained 13.08 and 13.20 percent phenotypic variation, respectively. Another QTL associated with chlorophyll content was mapped on chromosome 3H at 3.6-cM interval explained 12.90 percent phenotypic variation. In addition, QTL regions were also identified for aphid resistance and related traits on chromosome 1H and 5H.

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