Dataset Information

The lipoxygenase gene family: a genomic fossil of shared polyploidy between Glycine max and Medicago truncatula.

ABSTRACT: BACKGROUND: Soybean lipoxygenases (Lxs) play important roles in plant resistance and in conferring the distinct bean flavor. Lxs comprise a multi-gene family that includes GmLx1, GmLx2 and GmLx3, and many of these genes have been characterized. We were interested in investigating the relationship between the soybean lipoxygenase isozymes from an evolutionary perspective, since soybean has undergone two rounds of polyploidy. Here we report the tetrad genome structure of soybean Lx regions produced by ancient and recent polyploidy. Also, comparative genomics with Medicago truncatula was performed to estimate Lxs in the common ancestor of soybean and Medicago. RESULTS: Two Lx regions in Medicago truncatula showing synteny with soybean were analyzed. Differential evolutionary rates between soybean and Medicago were observed and the median Ks values of Mt-Mt, Gm-Mt, and Gm-Gm paralogs were determined to be 0.75, 0.62, and 0.46, respectively. Thus the comparison of Gm-Mt paralogs (Ks = 0.62) and Gm-Mt orthologs (Ks = 0.45) supports the ancient duplication of Lx regions in the common ancestor prior to the Medicago-Glycine split. After speciation, no Lx regions generated by another polyploidy were identified in Medicago. Instead tandem duplication of Lx genes was observed. On the other hand, a lineage-specific duplication occurred in soybean resulting in two pairs of Lx regions. Each pair of soybean regions was co-orthologous to one Lx region in Medicago. A total of 34 Lx genes (15 MtLxs and 19 GmLxs) were divided into two groups by phylogenetic analysis. Our study shows that the Lx gene family evolved from two distinct Lx genes in the most recent common ancestor. CONCLUSION: This study analyzed two pairs of Lx regions generated by two rounds of polyploidy in soybean. Each pair of soybean homeologous regions is co-orthologous to one region of Medicago, demonstrating the quartet structure of the soybean genome. Differential evolutionary rates between soybean and Medicago were observed; thus optimized rates of Ks per year should be applied for accurate estimation of coalescence times to each case of comparison: soybean-soybean, soybean-Medicago, or Medicago-Medicago. In conclusion, the soybean Lx gene family expanded by ancient polyploidy prior to taxon divergence, followed by a soybean- specific duplication and tandem duplications, respectively.

SUBMITTER: Shin JH

PROVIDER: S-EPMC2644698 | biostudies-literature | 2008

REPOSITORIES: biostudies-literature

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The lipoxygenase gene family: a genomic fossil of shared polyploidy between Glycine max and Medicago truncatula.

Shin Jin Hee JH Van Kyujung K Kim Dong Hyun DH Kim Kyung Do KD Jang Young Eun YE Choi Beom-Soon BS Kim Moon Young MY Lee Suk-Ha SH

BMC plant biology 20081223

<h4>Background</h4>Soybean lipoxygenases (Lxs) play important roles in plant resistance and in conferring the distinct bean flavor. Lxs comprise a multi-gene family that includes GmLx1, GmLx2 and GmLx3, and many of these genes have been characterized. We were interested in investigating the relationship between the soybean lipoxygenase isozymes from an evolutionary perspective, since soybean has undergone two rounds of polyploidy. Here we report the tetrad genome structure of soybean Lx regions ...[more]

PMID: 19105811

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Project description:BACKGROUND:As our world becomes warmer, agriculture is increasingly impacted by rising soil salinity and understanding plant adaptation to salt stress can help enable effective crop breeding. Salt tolerance is a complex plant phenotype and we know little about the pathways utilized by naturally tolerant plants. Legumes are important species in agricultural and natural ecosystems, since they engage in symbiotic nitrogen-fixation, but are especially vulnerable to salinity stress. RESULTS:Our studies of the model legume Medicago truncatula in field and greenhouse settings demonstrate that Tunisian populations are locally adapted to saline soils at the metapopulation level and that saline origin genotypes are less impacted by salt than non-saline origin genotypes; these populations thus likely contain adaptively diverged alleles. Whole genome resequencing of 39 wild accessions reveals ongoing migration and candidate genomic regions that assort non-randomly with soil salinity. Consistent with natural selection acting at these sites, saline alleles are typically rare in the range-wide species' gene pool and are also typically derived relative to the sister species M. littoralis. Candidate regions for adaptation contain genes that regulate physiological acclimation to salt stress, such as abscisic acid and jasmonic acid signaling, including a novel salt-tolerance candidate orthologous to the uncharacterized gene AtCIPK21. Unexpectedly, these regions also contain biotic stress genes and flowering time pathway genes. We show that flowering time is differentiated between saline and non-saline populations and may allow salt stress escape. CONCLUSIONS:This work nominates multiple potential pathways of adaptation to naturally stressful environments in a model legume. These candidates point to the importance of both tolerance and avoidance in natural legume populations. We have uncovered several promising targets that could be used to breed for enhanced salt tolerance in crop legumes to enhance food security in an era of increasing soil salinization.

Dataset Information

The lipoxygenase gene family: a genomic fossil of shared polyploidy between Glycine max and Medicago truncatula.

Publications

The lipoxygenase gene family: a genomic fossil of shared polyploidy between Glycine max and Medicago truncatula.

Similar Datasets

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