Search

Thinopyrum elongatum is an important relative of wheat, it is favored by many researchers for the disease resistant genes that exist in its E genome. Some studies have showed that the 7E chromosome of Th. elongatum contains resistance genes related to Fusarium head blight and wheat rust. Therefore, developing 7E chromosome-specific molecular markers linked to resistance genes will provide an important tool for exploring and using the resistant genes of Th. elongatum. In addition, it would greatly contribute in the effort to cultivate disease-resistant wheat varieties. Featured in high throughput, high-accuracy and low-cost, SLAF-seq technology has been widely used in molecular breeding, system evolution, and germplasm resource detection. Based on SLAF-seq, 518 specific fragments on the 7E chromosome of Th. elongatum were successfully amplified. A total of 135 primers were designed according to 135 randomly selected fragments, and 89 specific molecular markers of Th. elongatum were developed, with efficiencies up to 65.9%. These markers were all detected in a variety of materials, and they are all proved to be specific and stable. These markers can be used not only for detecting the 7E chromosome of Th. elongatum but also for providing an important theoretical and practical basis for wheat breeding by marker-assisted selection (MAS). This paper reports the first application of SLAF-seq technology with a high success rate in developing specific molecular markers for Th. elongatum, providing a strong case for the application of this new technology. [ABSTRACT FROM AUTHOR]

To extend our understanding of flowering time control in eudicots, we screened for mutants in the model legume Medicago truncatula (Medicago). We identified an early flowering mutant, spring1, in a T-DNA mutant screen, but spring1 was not tagged and was deemed a somaclonal mutant. We backcrossed the mutant to wild type R108. The F1 plants and the majority of F2 plants were early flowering like spring1, strongly indicating that spring1 conferred monogenic, dominant early flowering. We hypothesized that the spring1 phenotype resulted from over expression of an activator of flowering. Previously, a major QTL for flowering time in different Medicago accessions was located to an interval on chromosome 7 with six candidate flowering-time activators, including a CONSTANS gene, MtCO, and three FLOWERING LOCUS T (FT) genes. Hence we embarked upon linkage mapping using 29 markers from the MtCO/FT region on chromosome 7 on two populations developed by crossing spring1 with Jester. Spring1 mapped to an interval of ∼0.5 Mb on chromosome 7 that excluded MtCO, but contained 78 genes, including the three FT genes. Of these FT genes, only FTa1 was up-regulated in spring1 plants. We then investigated global gene expression in spring1 and R108 by microarray analysis. Overall, they had highly similar gene expression and apart from FTa1, no genes in the mapping interval were differentially expressed. Two MADS transcription factor genes, FRUITFULLb (FULb) and SUPPRESSOR OF OVER EXPRESSION OF CONSTANS1a (SOC1a), that were up-regulated in spring1, were also up-regulated in transgenic Medicago over-expressing FTa1. This suggested that their differential expression in spring1 resulted from the increased abundance of FTa1. A 6255 bp genomic FTa1 fragment, including the complete 59 region, was sequenced, but no changes were observed indicating that the spring1 mutation is not a DNA sequence difference in the FTa1 promoter or introns. [ABSTRACT FROM AUTHOR]