Characterization of Nitrogen use efficiency in sweet sorghum

Abstract

Sweet sorghum (Sorghum bicolor L. Moench) has the potential to augment the increasing demand for alternative fuels and for the production of input efficient, environmentally friendly bioenergy crops. Nitrogen (N) and water availability are considered two of the major limiting factors in crop growth. Nitrogen fertilization accounts for about 40% of the total production cost in sorghum. In cereals, including sorghum, the nitrogen use efficiency (NUE) from fertilizer is approximately 33% of the amount applied. There is therefore extensive concern in relation to the N that is not used by the plant, which is lost by leaching of nitrate, denitrification from the soil, and loss of ammonia to the atmosphere, all of which can have deleterious environmental effects. To improve the potential of sweet sorghum as a leading and cost effective bioenergy crop, the enhancement of NUE must be addressed. To this end, we have identified a sorghum line (SanChi San) that displays about 25% increase in NUE over other sorghum lines. As such, the overarching goal of this project is to employ three complementary strategies to enhance the ability of sweet sorghum to become an efficient nitrogen user. To achieve the project goal, we will pursue the following specificmore » objectives: Objective 1: Phenotypic characterization of SanChi San/Ck60 RILs under low and moderate N-availability including biochemical profiles, vegetative growth and seed yield Objective 2: Conduct quantitative trait loci (QTL) analysis and marker identification for nitrogen use efficiency (NUE) in a grain sorghum RIL population. Objective 3: Identify novel candidate genes for NUE using proteomic and gene expression profiling comparisons of high- and low-NUE RILs. Candidate genes will be brought into the pipeline for transgenic manipulation of NUE This project will apply the latest genomics resources to discover genes controlling NUE, one of the most complex and economically important traits in cereal crops. As a result of the completion of the proposed work, we will have: 1) identified novel alleles in wild sorghum germplasm that is useful to improve both cultivated grain and sweet sorghum; 2) been able to select individuals plants that exhibit high NUE within a breeding population on the basis of these markers; 3) acquired essential information necessary to examine the roles of GS and GOGAT, AlaT, along with impact of transcription factor Dof1, on N assimilation in sweet sorghum; and 4) The information learned will provide new opportunities for improving NUE in sorghum and other cereals.« less