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United States Department of Agriculture

Agricultural Research Service

Title: Inheritance of Imidazolinone-Herbicide Resistance in Sunflower

Authors
item Bruniard, J - ACA, PERGAMINO, ARGENTINA
item Bruniard, J - ACA, PERGAMINO, ARGENTINA
item Miller, Jerry
item Miller, Jerry

Submitted to: Helia
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: December 1, 2001
Publication Date: N/A

Interpretive Summary: Broadleaf weeds cause considerable yield losses to sunflower producers in all regions of the world. Resistance to the imidazolinone herbicides, imazethapyr and imazamox, found in a population of wild sunflower, could have great value for controlling many broadleaf weeds. The herbicide resistance was successfully transferred from resistant wild sunflower plants to a cultivated sunflower inbred line, HA 425. The objective of this investigation was to determine the inheritance of resistance to the herbicide imazamox in HA 425. Segregation ratios of plants in F2 and testcross populations indicated that resistance was controlled by two genes, a major gene having a semi-dominant type of gene action (Imr1), and a second gene (Imr2) with a modifier effect when the major gene is present. Resistance in sunflower can only be achieved with homozygocity (Imr1,Imr1,Imr2,Imr2) of both resistance genes in an inbred line or in a hybrid. Completely resistant hybrids require having resistance factors in both parents.

Technical Abstract: Broadleaf weeds cause considerable yield losses to sunflower (Helianthus annuus L.) producers in all regions of the world. Resistance to the imidazolinone herbicides, imazethapyr and imazamox, found in a population of wild sunflower, could have great value for controlling many broadleaf weeds. The herbicide resistance was successfully transferred from resistant wild sunflower plants to a cultivated sunflower inbred line, HA 425. The objective of this investigation was to determine the inheritance of resistance to the herbicide imazamox in HA 425. Segregation ratios of plants in F2 and testcross populations indicated that resistance was controlled by two genes, a major gene having a semi-dominant type of gene action (Imr1), and a second gene (Imr2) with a modifier effect when the major gene is present. Resistance in sunflower can only be achieved with homozygocity (Imr1,Imr1,Imr2,Imr2) of both resistance genes in an inbred line or in a hybrid. Completely resistant hybrids require having resistance factors in both parents.

Submitted to: Helia
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: December 1, 2001
Publication Date: N/A

Interpretive Summary: Broadleaf weeds cause considerable yield losses to sunflower producers in all regions of the world. Resistance to the imidazolinone herbicides, imazethapyr and imazamox, found in a population of wild sunflower, could have great value for controlling many broadleaf weeds. The herbicide resistance was successfully transferred from resistant wild sunflower plants to a cultivated sunflower inbred line, HA 425. The objective of this investigation was to determine the inheritance of resistance to the herbicide imazamox in HA 425. Segregation ratios of plants in F2 and testcross populations indicated that resistance was controlled by two genes, a major gene having a semi-dominant type of gene action (Imr1), and a second gene (Imr2) with a modifier effect when the major gene is present. Resistance in sunflower can only be achieved with homozygocity (Imr1,Imr1,Imr2,Imr2) of both resistance genes in an inbred line or in a hybrid. Completely resistant hybrids require having resistance factors in both parents.

Technical Abstract: Broadleaf weeds cause considerable yield losses to sunflower (Helianthus annuus L.) producers in all regions of the world. Resistance to the imidazolinone herbicides, imazethapyr and imazamox, found in a population of wild sunflower, could have great value for controlling many broadleaf weeds. The herbicide resistance was successfully transferred from resistant wild sunflower plants to a cultivated sunflower inbred line, HA 425. The objective of this investigation was to determine the inheritance of resistance to the herbicide imazamox in HA 425. Segregation ratios of plants in F2 and testcross populations indicated that resistance was controlled by two genes, a major gene having a semi-dominant type of gene action (Imr1), and a second gene (Imr2) with a modifier effect when the major gene is present. Resistance in sunflower can only be achieved with homozygocity (Imr1,Imr1,Imr2,Imr2) of both resistance genes in an inbred line or in a hybrid. Completely resistant hybrids require having resistance factors in both parents.

Last Modified: 9/10/2014
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