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Abstract Detail

Integrative Plant Physiology

Distelfeld, Assaf [1], Uauy, Cristobal [2], Fahima, Tzion [3], Blechl, Ann [4], Dubcovsky, Jorge [2].

The wheat Gpc-B1 QTL for grain protein, Zn, and Fe content is a transcription factor associated with senescence and mineral remobilization.

Enhancing the nutritional value of food crops is a means of improving human nutrition and health. Despite its importance, efforts to increase wheat grain protein content (GPC) and micronutrient levels have been hindered by their large environmental dependency and their complex inheritance. A potential source for nutritional improvement was detected in wild emmer wheat (Triticum turgidum ssp. dicoccoides), where a QTL for GPC (Gpc-B1) was shown to confer consistent GPC increases when introgressed into tetraploid and hexaploid wheat varieties (on average ~10-15%). Recently, we showed that the high GPC allele also accelerates senescence (by 3-4 days) and increases Zn and Fe content in the grains (on average ~10-20%).We report here the positional cloning of Gpc-B1, a wheat quantitative trait locus associated with increased grain protein, zinc, and iron content. The ancestral wild wheat allele encodes a NAC transcription factor (NAM-B1), whereas modern wheat varieties carry a nonfunctional NAM-B1 allele due to a frame shift mutation. Reduction in RNA levels of the multiple NAM homologs by RNA interference delayed senescence by more than 3 weeks and reduced wheat grain protein, zinc, and iron content by more than 30% compared to the non-transgenic control lines. These results show that lines with higher amounts of NAM transcripts (non-transgenic controls) were able to remobilize more minerals, in a shorter time frame, therefore suggesting a more efficient remobilization to the grain. The absence of the functional NAM-B1 allele in modern germplasm suggests a broad potential impact of the functional allele in cultivated durum and bread wheat varieties.

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1 - University of California, Plant Sciences, Mail stop 1, Hunt Hall, room 267, Davis, CALIFORNIA, 95616-8780, USA
2 - University of California, Plant Sciences
3 - University of Haifa, Institute of Evolution
4 - USDA-ARS, Western Regional Research Center

grain protein content
wild emmer wheat
transcription factor.

Presentation Type: Plant Biology Abstract
Session: P
Location: Exhibit Hall (Northeast, Southwest & Southeast)/Hilton
Date: Sunday, July 8th, 2007
Time: 8:00 AM
Number: P04001
Abstract ID:74

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