Genome size and base composition in Medicago sativa and M. truncatula species

Blondon, F.; Marie, Dominique; Brown, Spencer C.; Kondorosi, Ádám

doi:10.1139/g94-037

Cited by 133 publications

(78 citation statements)

References 21 publications

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“…As a legume, alfalfa forms a symbiotic association with the soil bacterium Sinorhizobium meliloti, which fixes atmospheric nitrogen (N), providing N for the plant and increasing soil N fertility for subsequent crops in a rotation. Alfalfa has a genome size of about 800-1000 Mbp [3], has a base chromosome number of x = 8, and exists at two ploidy levels (diploid, 2n = 2x = 16, and tetrasomic tetraploid, 2n = 4x = 32).…”

Section: Introductionmentioning

confidence: 99%

Applied Genetics and Genomics in Alfalfa Breeding

2012

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Alfalfa (Medicago sativa L.), a perennial and outcrossing species, is a widely planted forage legume for hay, pasture and silage throughout the world. Currently, alfalfa breeding relies on recurrent phenotypic selection, but alternatives incorporating molecular marker assisted breeding could enhance genetic gain per unit time and per unit cost, and accelerate alfalfa improvement. Many major quantitative trait loci (QTL) related to agronomic traits have been identified by family-based QTL mapping, but in relatively large genomic regions. Candidate genes elucidated from model species have helped to identify some potential causal loci in alfalfa mapping and breeding population for specific traits. Recently, high throughput sequencing technologies, coupled with advanced bioinformatics tools, have been used to identify large numbers of single nucleotide polymorphisms (SNP) in alfalfa, which are being developed into markers. These markers will facilitate fine mapping of quantitative traits and genome wide association mapping of agronomic traits and further advanced breeding strategies for alfalfa, such as marker-assisted selection and genomic selection. Based on ideas from the literature, we suggest several ways to improve selection in alfalfa including (1) diversity selection and paternity testing, (2) introgression of QTL and (3) genomic selection.

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Section: Introductionmentioning

confidence: 99%

Applied Genetics and Genomics in Alfalfa Breeding

2012

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“…M. truncatula is autogamous and has a relatively small diploid genome and a number of genetically distinguishable ecotypes. These properties contribute to its suitability for molecular genetic analyses (Barker et al, 1990;Blondon et al, 1994;Cook et al, 1997). Genetic screens for plants with altered symbiotic phenotypes and various molecular approaches have identified several interesting mutations and genes (Benaben et al, 1995;Cook et al, 1995;Sagan et al, 1995;Gamas et al, 1996;Harrison, 1996;Peng et al, 1996;Burleigh and Harrison, 1997;Penmetsa and Cook, 1997).…”

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confidence: 99%

Expressed Sequence Tags from a Root-Hair-Enriched Medicago truncatula cDNA Library1

Covitz¹,

Smith

Long

1998

Plant Physiology

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The root hair is a specialized cell type involved in water and nutrient uptake in plants. In legumes the root hair is also the primary site of recognition and infection by symbiotic nitrogenfixing Rhizobium bacteria. We have studied the root hairs of Medicago truncatula, which is emerging as an increasingly important model legume for studies of symbiotic nodulation. However, only 27 genes from M. truncatula were represented in GenBank/EMBL as of October, 1997. We report here the construction of a root-hairenriched cDNA library and single-pass sequencing of randomly selected clones. Expressed sequence tags (899 total, 603 of which have homology to known genes) were generated and made available on the Internet. We believe that the database and the associated DNA materials will provide a useful resource to the community of scientists studying the biology of roots, root tips, root hairs, and nodulation.

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“…R108-1 corresponding to 22,122,13,061,6,530,3,265, and 1,632 copies of Mtchit 5, Mtchit 4 and ubiquitin. Copy numbers were calculated based on a haploid genome weight of 0.49 pg (Blondon et al 1994) under the assumption of Mtchit 5 and Mtchit 4 being singlecopy genes (Salzer et al 2000). DNA was isolated from axenically grown seedlings with DNeasy (Qiagen) and subsequently treated with RNase following the manufacturer's instructions.…”

Section: Semi Quantitative and Quantitative Rt-pcrmentioning

confidence: 99%

Sinorhizobium meliloti-induced chitinase gene expression in Medicago truncatula ecotype R108-1: a comparison between symbiosis-specific class�V and defence-related class�IV chitinases

Salzer

Feddermann

Wiemken

et al. 2004

Planta

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The Medicago truncatula (Gaertn.) ecotypes Jemalong A17 and R108-1 differ in Sinorhizobium meliloti-induced chitinase gene expression. The pathogen-inducible class IV chitinase gene, Mtchit 4, was strongly induced during nodule formation of the ecotype Jemalong A17 with the S. meliloti wild-type strain 1021. In the ecotype R108-1, the S. meliloti wild types Sm1021 and Sm41 did not induce Mtchit 4 expression. On the other hand, expression of the putative class V chitinase gene, Mtchit 5, was found in roots of M. truncatula cv. R108-1 nodulated with either of the rhizobial strains. Mtchit 5 expression was specific for interactions with rhizobia. It was not induced in response to fungal pathogen attack, and not induced in roots colonized with arbuscular mycorrhizal (AM) fungi. Elevated Mtchit 5 gene expression was first detectable in roots forming nodule primordia. In contrast to Mtchit 4, expression of Mtchit 5 was stimulated by purified Nod factors. Conversely, Mtchit 4 expression was strongly elevated in nodules formed with the K-antigen-deficient mutant PP699. Expression levels of Mtchit 5 were similarly increased in nodules formed with PP699 and its parental wild-type strain Sm41. Phylogenetic analysis of the deduced amino acid sequences of Mtchit 5 (calculated molecular weight = 41,810 Da, isoelectric point pH 7.7) and Mtchit 4 (calculated molecular weight 30,527 Da, isoelectric point pH 4.9) revealed that the putative Mtchit 5 chitinase forms a separate clade within class V chitinases of plants, whereas the Mtchit 4 chitinase clusters with pathogen-induced class IV chitinases from other plants. These findings demonstrate that: (i) Rhizobium-induced chitinase gene expression in M. truncatula occurs in a plant ecotype-specific manner, (ii) Mtchit 5 is a putative chitinase gene that is specifically induced by rhizobia, and (iii) rhizobia-specific and defence-related chitinase genes are differentially influenced by rhizobial Nod factors and K antigens.Keywords Class IV and V chitinase AE K antigen AE Medicago truncatula ecotypes R108-1 and Jemalong A17 AE Nod factors AE Sinorhizobium AE Suppression of plant defence

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Genome size and base composition in Medicago sativa and M. truncatula species

Cited by 133 publications

References 21 publications

Applied Genetics and Genomics in Alfalfa Breeding

Applied Genetics and Genomics in Alfalfa Breeding

Expressed Sequence Tags from a Root-Hair-Enriched Medicago truncatula cDNA Library1

Sinorhizobium meliloti-induced chitinase gene expression in Medicago truncatula ecotype R108-1: a comparison between symbiosis-specific class�V and defence-related class�IV chitinases

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