Project description:In this study, proteomics was used to sequence the salt stress treatment group and the control group of Medicago sativa and Medicago truncatula. The aim was to discover the kegg pathway of the two alfalfa varieties under salt stress, which was of great significance to the exploration of the salt tolerance mechanism of alfalfa.
Project description:Advances in alfalfa [Medicago sativa (L.) subsp. sativa] breeding, molecular genetics and genomics have been slow because this crop is an allogamous autotetraploid (2n = 4x = 32) with complex polysomic inheritance. Increasing cellulose and decreasing lignin in alfalfa stem cell walls would improve this crop as a cellulosic ethanol feedstock. We selected two alfalfa genotypes (252, 1283) that differ in cellulose and Klason lignin concentration in stem cell walls. Analysis of GeneChip expression data files of alfalfa stem internodes of genotypes 252 and 1283 at two growth stages (elongating, post-elongation) revealed 10,887 SFPs in 8,230 probe sets. Validation analysis by PCR-sequencing of a random sample of SFPs indicated a 12% false discovery rate. Functional classification and over-representation analysis showed that both genotypes were highly enriched in SFP-harboring cell wall genes. We mapped 5,833 of the 8,230 SFP-harboring genes onto putative orthologous loci on Medicago truncatula chromosomes. Clustering and over-representation of SFP-harboring genes within the same functional class (e.g. cell wall genes) was observed on some chromosomes. Prior to analysis of expression data for the two alfalfa genotypes, SFP probes were masked to reduce false positives and false negatives. The combination of SFP and gene expression analysis provide a list of candidate cell wall genes that can be used as molecular markers in a breeding program to improve alfalfa as a cellulosic feedstock. The results of this study will also be useful in advancing understanding of genome organization in alfalfa and for comparative genomics research with other legume species. Keywords: Stem development and genotype comparison
Project description:Alfalfa (Medicago sativa L.) is a forage legume with significant agricultural value worldwide. MicroRNAs (miRNAs) are key components of post-transcriptional gene regulation and essentially control almost all aspect of plant growth and development. Although miRNAs have been reported from alfalfa but their expression profiles in different tissues and novel miRNAs as well as their targets have not been confirmed in this plant species. Therefore, we sequenced small RNAs in whole plantlets, shoots and roots of three different alfalfa genotypes (Altet-4, NECS-141 and NF08ALF06) to identify tissue-specific profiles. After comprehensive analysis using bioinformatics methods, we have identified 100 miRNA families, of which 21 belongs to the highly conserved families whereas the remaining 79 families are conserved between M. truncatula and M. sativa. The profiles of the six highly expressed conserved miRNA families (miR156, 159, 166, 319, 396, 398,) were relatively similar between the plantlets, roots and shoots of three genotypes. Contrastingly, the differenecs were robust between shoots and roots for miR160 and miR408 levels, which were low in roots compared to shoots. The study also has identified 17 novel miRNAs that also differed in their abundanecs between tissues of the alfalfa genotypes. Additionally, we have generated and analyzed the degradome libraries from three alfalfa genotypes that has confirmed 69 genes as targets for 31 miRNA families in alfalfa. The identification of conserved and novel miRNAs as well as their targets in different tissues of three genotypes not only enhanced our understanding of miRNA-mediated gene regulation in alfalfa but could also be useful for practical applications in alfalfa as well as related legume species.
Project description:We have previously showed a strong genetic determinant governing resistance of the M. truncatula A17 line to C. trifolii is located in a chromosomal region at the top of chromosome 4 (Ameline-torregrosa et al., 2008). This region also contains the RCT1 gene which has been shown to confer resistance to C. trifolii when transferred to a susceptible alfalfa plants (Zhu et al.), In order to evaluate the role of this region in the response to non-adapted Colletorichum species and to compare this response to those induce by C. trifolii, two M. truncatula near-isogenic lines differing only in this chromosomal region were used for transcript profiling experiments. These two lines were issued from a recombinant-inbred collection obtained from a A17-F83005.5 cross (Cazaux et al., in preparation). Plant inoculations were done on two-week-old entire plants by spraying a conidial suspension of C. trifolii or C. lindemuthianum to avoid possible artifacts which can be observed on detached leaves (Liu et al., 2007). RNA was extracted from leaves collected at 1dpi and 3dpi and transcript profiling was performed using Mt16kOLI1Plus chips (Thompson et al., 2005).
Project description:We studied the application of transcriptome technology in alfalfa selenium treatment. After spraying sodium selenite on the leaves, the process of selenium absorption and assimilation of alfalfa is unknown. The time point of transcriptome determination was determined by measuring the change of selenium content. Our results showed that 12 h was the key point of the change of selenium content in alfalfa, that is, the selenium content increased continuously before 12 h, decreased gradually after 12 h, and remained stable after 48 h. Transcriptome sequencing showed that phosphorus transporter and endocytosis related genes may be involved in selenium absorption at 12 h compared with 0 H. 12-48 h, some thiometabolic pathways may be involved in selenium metabolism and ubiquitination pathway, which may be the detoxification pathway of selenoprotein.
Project description:Advances in alfalfa [Medicago sativa (L.) subsp. sativa] breeding, molecular genetics and genomics have been slow because this crop is an allogamous autotetraploid (2n = 4x = 32) with complex polysomic inheritance. Increasing cellulose and decreasing lignin in alfalfa stem cell walls would improve this crop as a cellulosic ethanol feedstock. We selected two alfalfa genotypes (252, 1283) that differ in cellulose and Klason lignin concentration in stem cell walls. Analysis of GeneChip expression data files of alfalfa stem internodes of genotypes 252 and 1283 at two growth stages (elongating, post-elongation) revealed 10,887 SFPs in 8,230 probe sets. Validation analysis by PCR-sequencing of a random sample of SFPs indicated a 12% false discovery rate. Functional classification and over-representation analysis showed that both genotypes were highly enriched in SFP-harboring cell wall genes. We mapped 5,833 of the 8,230 SFP-harboring genes onto putative orthologous loci on Medicago truncatula chromosomes. Clustering and over-representation of SFP-harboring genes within the same functional class (e.g. cell wall genes) was observed on some chromosomes. Prior to analysis of expression data for the two alfalfa genotypes, SFP probes were masked to reduce false positives and false negatives. The combination of SFP and gene expression analysis provide a list of candidate cell wall genes that can be used as molecular markers in a breeding program to improve alfalfa as a cellulosic feedstock. The results of this study will also be useful in advancing understanding of genome organization in alfalfa and for comparative genomics research with other legume species. SUBMITTER_CITATION: Mesfin Tesfaye, S.S. Yang, J.F. Lamb, H.J. Jung, D.A. Samac, J. Gronwald, C.P. Vance and K.A. VandenBosch (2009). Medicago truncatula as a model for dicot cell wall development. BioEnergy Research 2: 59-76 Experiment Overall Design: The alfalfa clonal lines 252 and 1283 were propagated from cuttings and grown in the greenhouse. The greenhouse experiments consisted of three replicates arranged in a randomized complete block design. There were eight plants of each clone, in individual pots, in each replicate. Plant material for analysis was composited within each replicate at harvest. Stem internode tissues were harvested at full bloom. Based on tissue pliability and coloration, the internode in transition from elongation to post-elongation cambial growth was identified. The internodes immediately above (elongating internodes) and below this transition internode (post-elongation internodes) were collected for RNA extraction.