Genotypic variation for cellular thermotolerance in Aegilops tauschii Coss., the D genome progenitor of wheat |
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Authors: | Shaina Gupta Sukhjit Kaur Sunish Sehgal Achla Sharma Parveen Chhuneja Navtej S. Bains |
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Affiliation: | (1) Department of Crop Science, North Carolina State University, Raleigh, NC 27695-7620, USA;(2) Division of Grassland & Forages, National Institute of Animal Science, #9 Eoryong-ri, Seonghwan eup, Cheonan-si, Chungnam, 330-801, South Korea;(3) Department of Tropical Plant and Soil Sciences, University of Hawaii at Manoa, 3190 Maile Way, St. John 102, Honolulu, HI 96822, USA; |
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Abstract: | Corn leaf aphids (Rhopalosiphum maidis Fitch) are found throughout the year on maize in Hawaii and occasionally cause yield loss. Sweet corn inbred Hi38-71 was observed to have high field resistance to aphids and was chosen for this genetic study. An artificial infestation technique was developed using hair-pin clip cages (2.2 cm diameter) which we devised and built. The cages were applied to field-grown plants into which three wingless viviparous adults were placed. Aphid populations were classified on a 1–10 rating scale after about 2 weeks based on digital images of the cages. Mean aphid coverage ratings were 2.97 for the resistant parent and 7.28 for the susceptible parent (representing >200 insects per cage). The F1 hybrids showed similar susceptibility (6.72), showing resistance to be recessive in nature. Six generations of the cross between Hi38-71 and susceptible inbred Hi27 were artificially infested to provide a generation mean analysis of 360 treated plants over two growing seasons. A joint scaling test showed that the fit to a 3-parameter additive-dominance model satisfactorily explained the observed variability with no assumed linkage or epistasis. We conclude that resistance to corn leaf aphid in Hi38-71 is conferred by a single recessive gene labeled aph. These results concur with a previous study under uncontrolled natural infestation in a single environment. The hair-pin clip cage method was most effective in distinguishing resistant and susceptible genotypes under diverse natural growing conditions in Hawaii. |
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