Detection of NAM-A1 Natural Variants in Bread Wheat Reveals Differences in Haplotype Distribution between a Worldwide Core Collection and European Elite Germplasm

Abstract

Abstract:In wheat, remobilization of nitrogen absorbed before anthesis and regulation of monocarpic senescence is a major issue in breeding for nutrient use efficiency. We identified natural variants of NAM-A1, a gene having the same role as its well-characterized homoeolog NAM-B1, a NAC transcription factor associated with senescence kinetics and nutrient remobilization to the grain. Differences in haplotype frequencies between a worldwide core collection and a panel of European elite varieties were assessed and discussed. Moreover, hypotheses for the loss of function of the most common haplotype in elite European germplasm are discussed. OPEN ACCESSAgronomy 2015, 5 144

NAM gene allelic composition and its relation to grain-filling duration and nitrogen utilisation efficiency of Australian wheat

“…The NAM-B1 transcription factor increases nutrient remobilisation and accelerates monocarpic senescence coupled with a slight yield penalty [ 16 , 37 ], and is being considered as a genetic factor influencing NUE. NAM-A1 is a gene with a similar function to NAM-B1 involved in remobilising nutrients and accelerating senescence, with beneficial effects on protein content and yield [ 17 ]. However, NAM-D1 has never been reported with any influence on NUE.…”

“…Medium vegetative phase was linked to absent or mixed NAM-B1 allele and short grain-filling period related to NAM-A1a allele. Accelerated senescence might improve N remobilisation and grain protein content but it resulted in reduced TGW and lower grain number, thus resulting in decreased grain yield in cultivars carrying the NAM-A1a allele [ 17 ].…”

“…The non-functional NAM-B1 allele delayed leaf senescence [ 13 , 39 ]. Increased duration of grain-filling due to the presence of NAM-A1c and d might provide more carbon and nitrogen, resulting a higher grain yield [ 17 , 23 ]. At the same NAM-A1 background, a negative correlation between the non-functional NAM-B1 allele and grain protein content was observed.…”

“…The functional NAM-B1 allele, which encodes a transcription factor of the NAC family, accelerates senescence and increases nutrient remobilisation from leaf tissues into the developing grain [ 16 ]. NAM-A1 is a gene with similar function to NAM-B1 , with beneficial effects on grain nutritional quality and several bread-making properties [ 17 ]. However, the modern wheat cultivars that carry a non-functional NAM-B1 allele result in delayed senescence and reduced wheat GPC by over 30% [ 18 ].…”

New genetic resources in wheat breeding for an increased grain protein content

“…У Gpc-A1 идентифицировано пять аллелей, при-чем активный аллель Gpc-A1a выявлен преимущественно у яровой мягкой пшеницы из Непала, Китая и Японии, а неактивные Gpc-A1b и Gpc-A1d -у одного местного сорта из Грузии и в современных сортах Европы соответ-ственно (Cormier et al, 2015). Более того, на хромосомах второй гомеологичной группы обнаружены паралогичные гены Gpc-2 (NAM-2) (Uauy et al, 2006b).…”