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Manhattan, KS, United States

Li P.,Northwest University, China | Chen J.,University of Idaho | Wu P.,National Engineering Research Center for Water Saving Irrigation at Yangling | Zhang J.,University of Idaho | And 7 more authors.
Crop Science | Year: 2011

It has been documented that the dwarfing genes, Rht-B1b and Rht-D1b, can reduce wheat (Triticum aestivum L.) coleoptile length (CL), but their effects on number of roots (RN) and root length (RL) have not been determined. Our objectives were to identify quantitative trait loci (QTL) controlling CL, RN, and RL and to determine if any of the QTL correspond to wheat dwarfing genes. A population consisting of 159 recombinant inbred lines (RILs) was derived from the cross of Rio Blanco (Rht-B1b, Rht-D1a), a semidwarf cultivar with short CL, and IDO444 (Rht-B1a, Rht-D1a), a tall germplasm with long CL. The CL, RN, longest root length (LRL), and total root length (TRL) were evaluated at two temperature regimes (18 and 22°C). A major QTL mapped to the Rht-B1 locus on chromosome 4B explained 64% of the phenotypic variation for CL, 9% for LRL, 26% for TRL, and 14% for plant height. The CL of the semidwarf RILs was significantly less than that of the tall lines while the reverse results were observed for LRL and TRL. Our results indicated that the Rht-B1 gene had the pleiotropic effect of decreasing CL while increasing LRL and TRL. None of the six QTL for RN were mapped to the regions containing the Rht-B1 locus although semidwarf RILs had more roots than the tall lines. This study suggested that selection of the Rht-B1b allele tended to increase root biomass, perhaps ameliorating its negative effect of reduced CL. © Crop Science Society of America.

Anderson N.A.,Purdue University | Anderson N.A.,Heartland Plant Innovations | Bonawitz N.D.,Purdue University | Bonawitz N.D.,Dow AgroSciences | And 3 more authors.
Plant Physiology | Year: 2015

Phenylpropanoids are phenylalanine-derived specialized metabolites and include important structural components of plant cell walls, such as lignin and hydroxycinnamic acids, as well as ultraviolet and visible light-absorbing pigments, such as hydroxycinnamate esters (HCEs) and anthocyanins. Previous work has revealed a remarkable degree of plasticity in HCE biosynthesis, such that most Arabidopsis (Arabidopsis thaliana) mutants with blockages in the pathway simply redirect carbon flux to atypical HCEs. In contrast, the ferulic acid hydroxylase1 (fah1) mutant accumulates greatly reduced levels of HCEs, suggesting that phenylpropanoid biosynthesis may be repressed in response to the loss of FERULATE 5-HYDROXYLASE (F5H) activity. Here, we show that in fah1 mutant plants, the activity of HCE biosynthetic enzymes is not limiting for HCE accumulation, nor is phenylpropanoid flux diverted to the synthesis of cell wall components or flavonol glycosides. We further show that anthocyanin accumulation is also repressed in fah1 mutants and that this repression is specific to tissues in which F5H is normally expressed. Finally, we show that repression of both HCE and anthocyanin biosynthesis in fah1 mutants is dependent on the MED5a/5b subunits of the transcriptional coregulatory complex Mediator, which are similarly required for the repression of lignin biosynthesis and the stunted growth of the phenylpropanoid pathway mutant reduced epidermal fluorescence8. Taken together, these observations show that the synthesis of HCEs and anthocyanins is actively repressed in a MEDIATOR-dependent manner in Arabidopsis fah1 mutants and support an emerging model in which MED5a/5b act as central players in the homeostatic repression of phenylpropanoid metabolism. © 2015 American Society of Plant Biologists. All rights Reserved.

Friesen T.L.,U.S. Department of Agriculture | Friesen T.L.,North Dakota State University | Chu C.,North Dakota State University | Chu C.,Heartland Plant Innovations | And 2 more authors.
Molecular Plant Pathology | Year: 2012

The Stagonospora nodorum-wheat interaction involves multiple pathogen-produced necrotrophic effectors that interact directly or indirectly with specific host gene products to induce the disease Stagonospora nodorum blotch (SNB). Here, we used a tetraploid wheat mapping population to identify and characterize a sixth effector-host gene interaction in the wheat-S.nodorum system. Initial characterization of the effector SnTox5 indicated that it is a proteinaceous necrotrophic effector that induces necrosis on host lines harbouring the Snn5 sensitivity gene, which was mapped to the long arm of wheat chromosome 4B. On the basis of ultrafiltration, SnTox5 is probably in the size range 10-30kDa. Analysis of SNB development in the mapping population indicated that the SnTox5-Snn5 interaction explains 37%-63% of the variation, demonstrating that this interaction plays a significant role in disease development. When the SnTox5-Snn5 and SnToxA-Tsn1 interactions occurred together, the level of SNB was increased significantly. Similar to several other interactions in this system, the SnTox5-Snn5 interaction is light dependent, suggesting that multiple interactions may exploit the same pathways to cause disease. © 2012.

Chu C.,North Dakota State University | Chu C.,Heartland Plant Innovations | Niu Z.,U.S. Department of Agriculture | Zhong S.,North Dakota State University | And 7 more authors.
Theoretical and Applied Genetics | Year: 2011

Fusarium head blight (FHB) is a devastating disease of wheat worldwide. Novel sources of resistance are critical for improving FHB resistance levels in wheat. From a large-scale evaluation of germplasm for reactions to FHB, we identified one wheat accession (PI 277012) that consistently showed a high level of resistance in both greenhouse and field experiments. To characterize the FHB resistance in this accession, we developed a doubled haploid (DH) mapping population consisting of 130 lines from the cross between PI 277012 and the hard red spring wheat cultivar 'Grandin'. The DH population was then evaluated for reactions to FHB in three greenhouse seasons and five field environments. Based on a linkage map that consisted of 340 SSR markers spanning 2,703 cM of genetic distance, two major quantitative trait loci (QTLs) for FHB resistance were identified on chromosome arms 5AS and 5AL, with each explaining up to 20 and 32% of the variation in FHB severity, respectively. The two QTLs also showed major effects on reducing the percentage of Fusarium damaged kernels (FDK) and deoxynivalenol (DON) accumulation in seeds. FHB resistance has not previously been reported to be associated with this particular genomic region of chromosome arm 5AL, thus indicating the novelty of FHB resistance in PI 277012. Plant maturity was not associated with FHB resistance and the effects of plant height on FHB resistance were minor. Therefore, these results suggest that PI 277012 is an excellent source for improving FHB resistance in wheat. The markers identified in this research are being used for marker-assisted introgression of the QTLs into adapted durum and hard red spring wheat cultivars. © 2011 Springer-Verlag (outside the USA).

Barkley A.,Kansas State University | Chumley F.G.,Heartland Plant Innovations
International Food and Agribusiness Management Review | Year: 2012

This research evaluates the use of doubled haploid lines (DHs) to accelerate breeding and gene discovery in wheat breeding. The DH biotechnology greatly accelerates time to market for new wheat varieties and speeds genetic gains in wheat yields. An economic model was built based on previous literature, knowledge of the wheat industry, and information gleaned from wheat breed-er interviews. Results show that DH methods would provide large economic gains to Kansas wheat producers and global wheat consumers. The results are robust to a wide variety of scenari-os. © 2012 International Food and Agribusiness Management Association (IFAMA).

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