RESUMEN
Many plant species have succeeded in colonizing a wide range of diverse climates through local adaptation, but the underlying molecular genetics remain obscure. We previously found that winter survival was a direct target of selection during colonization of Japan by the perennial legume Lotus japonicus and identified associated candidate genes. Here, we show that two of these, FERONIA-receptor like kinase (LjFER) and a S-receptor-like kinase gene (LjLecRK), are required for non-acclimated freezing tolerance and show haplotype-dependent cold-responsive expression. Our work suggests that recruiting a conserved growth regulator gene, FER, and a receptor-like kinase gene, LecRK, into the set of cold-responsive genes has contributed to freezing tolerance and local climate adaptation in L. japonicus, offering functional genetic insight into perennial herb evolution.
Asunto(s)
Lotus , Lotus/metabolismo , Haplotipos/genética , Congelación , Aclimatación/genética , Adaptación Fisiológica/genética , Regulación de la Expresión Génica de las PlantasRESUMEN
To investigate the genetic diversity and understand the process of horizontal gene transfer (HGT) in nodule bacteria associated with Lotus japonicus, we analyzed sequences of three housekeeping and five symbiotic genes using samples from a geographically wide range in Japan. A phylogenetic analysis of the housekeeping genes indicated that L. japonicus in natural environments was associated with diverse lineages of Mesorhizobium spp., whereas the sequences of symbiotic genes were highly similar between strains, resulting in remarkably low nucleotide diversity at both synonymous and nonsynonymous sites. Guanine-cytosine content values were lower in symbiotic genes, and relative frequencies of recombination between symbiotic genes were also lower than those between housekeeping genes. An analysis of molecular variance showed significant genetic differentiation among populations in both symbiotic and housekeeping genes. These results confirm that the Mesorhizobium genes required for symbiosis with L. japonicus behave as a genomic island (i.e., a symbiosis island) and suggest that this island has spread into diverse genomic backgrounds of Mesorhizobium via HGT events in natural environments. Furthermore, our data compilation revealed that the genetic diversity of symbiotic genes in L. japonicus-associated symbionts was among the lowest compared with reports of other species, which may be related to the recent population expansion proposed in Japanese populations of L. japonicus.
Asunto(s)
Transferencia de Gen Horizontal , Variación Genética , Lotus , Mesorhizobium , Nódulos de las Raíces de las Plantas , Lotus/microbiología , Mesorhizobium/clasificación , Mesorhizobium/genética , Filogenia , Nódulos de las Raíces de las Plantas/microbiología , Simbiosis/genéticaRESUMEN
Ever since Darwin, one of the major challenges in evolutionary biology is to unravel the process and mechanisms of adaptation and speciation. Population genomics-the analysis of whole-genome polymorphism data from large population samples-is a critical approach to study adaptation and speciation, as population genomics datasets enable us to: (1) perform genome-wide association studies (GWAS) to find genes underlying adaptive phenotypic variations; (2) scan the footprints of selection across the genome to pinpoint loci under selection; and (3) infer the structure and demographic history of populations. Here, we review recent studies of plants using population genomics, covering those focusing on interactions with other organisms, adaptations to local climatic conditions, and the genomic causes and consequences of reproductive isolation. Integrative studies involving GWAS, selection scans, functional studies, and fitness measurements in the field have successfully identified loci for adaptation, revealed the molecular basis of genetic trade-offs, and shown that fitness can be predicted by polygenic effects of a number of loci associated with local climate. We highlight the importance of the measurement of fitness and phenotypes in the field, which can be powerful tools when combined with population genomic analyses.
Asunto(s)
Adaptación Biológica/genética , Especiación Genética , Genoma de Planta/genética , Genómica , Plantas/clasificación , Plantas/genética , FenotipoRESUMEN
To understand the geographic distributions of rhizobia that associated with widely distributed wild legumes, 66 nodules obtained from 41 individuals including three sea-dispersed legumes (Vigna marina, Vigna luteola, and Canavalia rosea) distributed across the tropical and subtropical coastal regions of the world were studied. Partial sequences of 16S rRNA and nodC genes extracted from the nodules showed that only Bradyrhizobium and Sinorhizobium were associated with the pantropical legumes, and some of the symbiont strains were widely distributed over the Pacific. Horizontal gene transfer of nodulation genes were observed within the Bradyrhizobium and Sinorhizobium lineages. BLAST searches in GenBank also identified records of these strains from various legumes across the world, including crop species. However, one of the rhizobial strains was not found in GenBank, which implies the strain may have adapted to the littoral environment. Our results suggested that some rhizobia, which associate with the widespread sea-dispersed legume, distribute across a broad geographic range. By establishing symbiotic relationships with widely distributed rhizobia, the pantropical legumes may also be able to extend their range much further than other legume species.
Asunto(s)
Fabaceae/microbiología , Rhizobiaceae/aislamiento & purificación , Proteínas Bacterianas/genética , Bradyrhizobium/clasificación , Bradyrhizobium/aislamiento & purificación , Genes Bacterianos , Tipificación Molecular , N-Acetilglucosaminiltransferasas/genética , Océano Pacífico , Filogenia , ARN Bacteriano , ARN Ribosómico 16S/genética , Rhizobiaceae/clasificación , Rhizobiaceae/genética , Rhizobium/clasificación , Rhizobium/aislamiento & purificación , Sinorhizobium/clasificación , Sinorhizobium/aislamiento & purificación , SimbiosisRESUMEN
The biological interactions between plants and their root microbiomes are essential for plant growth, and even though plant genotype (G), soil microbiome (M), and growth conditions (environment; E) are the core factors shaping root microbiome, their relationships remain unclear. In this study, we investigated the effects of G, M, and E and their interactions on the Lotus root microbiome and plant growth using an in vitro cross-inoculation approach, which reconstructed the interactions between nine Lotus accessions and four soil microbiomes under two different environmental conditions. Results suggested that a large proportion of the root microbiome composition is determined by M and E, while G-related (G, G × M, and G × E) effects were significant but small. In contrast, the interaction between G and M had a more pronounced effect on plant shoot growth than M alone. Our findings also indicated that most microbiome variations controlled by M have little effect on plant phenotypes, whereas G × M interactions have more significant effects. Plant genotype-dependent interactions with soil microbes warrant more attention to optimize crop yield and resilience.
Asunto(s)
Genotipo , Lotus , Microbiota , Raíces de Plantas , Microbiología del Suelo , Lotus/microbiología , Lotus/crecimiento & desarrollo , Lotus/genética , Raíces de Plantas/microbiología , Raíces de Plantas/crecimiento & desarrollo , Microbiota/genética , Suelo/químicaRESUMEN
Grafting is widely used as a method to increase stress tolerance in good fruiting lines of Solanaceae plants. However, little is known about how grafting, affects epigenetic modifications and leads to stress tolerance, especially within the same line. Here, we studied the effects of self-grafting in tomato plants on histone and DNA modifications and changes in gene expression related to drought stress. We found that at the three-leaf stage, 1 week after self-grafting, histone H3 K4 trimethylation and K27 trimethylation changes were observed in more than 500 genes each, and DNA methylation changes in more than 5,000 gene regions at the shoot apex compared to the non-grafted control. In addition, two weeks after the epigenomic changes, global expression changes continued to be observed at the shoot apex in several genes related to the metabolic process of nitrogen compounds, responses to stimulus, chromosome organization, cell cycle-related genes, and regulation of hormone levels. Finally, these grafted seedlings acquired remarkable drought tolerance, suggesting that epigenomic modifications during the wound-healing process mitigate stress tolerance in tomato plants.
Asunto(s)
Sequías , Solanum lycopersicum , Solanum lycopersicum/genética , Epigenómica , Hojas de la Planta/genética , Epigénesis Genética , Estrés FisiológicoRESUMEN
Grafting is a method used in agriculture to improve crop production and tolerance to biotic and abiotic stress. This technique is widely used in tomato, Solanum lycopersicum L.; however, the effects of grafting on changes in gene expression associated with stress tolerance in shoot apical meristem cells are still under-discovered. To clarify the effect of grafting, we performed a transcriptomic analysis between non-grafted and grafted tomatoes using the tomato variety Momotaro-scion and rootstock varieties, TD1, GS, and GF. Drought tolerance was significantly improved not only by a combination of compatible resistant rootstock TD1 but also by self-grafted compared to non-grafted lines. Next, we found the differences in gene expression between grafted and non-grafted plants before and during drought stress treatment. These altered genes are involved in the regulation of plant hormones, stress response, and cell proliferation. Furthermore, when comparing compatible (Momo/TD1 and Momo/Momo) and incompatible (Momo/GF) grafted lines, the incompatible line reduced gene expression associated with phytohormones but increased in wounding and starvation stress-response genes. These results conclude that grafting generates drought stress tolerance through several gene expression changes in the apical meristem.
RESUMEN
As soybean cultivars are adapted to a relatively narrow range of latitude, the effects of climate changes are estimated to be severe. To address this issue, it is important to improve our understanding of the effects of climate change by applying the simulation model including both genetic and environmental factors with their interactions (G×E). To achieve this goal, we conducted the field experiments for soybean core collections using multiple sowing times in multi-latitudinal fields. Sowing time shifts altered the flowering time (FT) and growth phenotypes, and resulted in increasing the combinations of genotypes and environments. Genome-wide association studies for the obtained phenotypes revealed the effects of field and sowing time to the significance of detected alleles, indicating the presence of G×E. By using accumulated phenotypic and environmental data in 2018 and 2019, we constructed multiple regression models for FT and growth pattern. Applicability of the constructed models was evaluated by the field experiments in 2020 including a novel field, and high correlation between the predicted and measured values was observed, suggesting the robustness of the models. The models presented here would allow us to predict the phenotype of the core collections in a given environment.
Asunto(s)
Estudio de Asociación del Genoma Completo , Glycine max , Alelos , Genotipo , Fenotipo , Glycine max/genéticaRESUMEN
Variation in partner quality is commonly observed in diverse cooperative relationships, despite the theoretical prediction that selection favoring high-quality partners should eliminate such variation. Here, we investigated how genetic variation in partner quality could be maintained in the nitrogen-fixing mutualism between Lotus japonicus and Mesorhizobium bacteria. We reconstructed de novo assembled full-genome sequences from nine rhizobial symbionts, finding massive variation in the core genome and the similar symbiotic islands, indicating recent horizontal gene transfer (HGT) of the symbiosis islands into diverse Mesorhizobium lineages. A cross-inoculation experiment using 9 sequenced rhizobial symbionts and 15 L. japonicus accessions revealed extensive quality variation represented by plant growth phenotypes, including genotype-by-genotype interactions. Variation in quality was not associated with the presence/absence variation in known symbiosis-related genes in the symbiosis island; rather, it showed significant correlation with the core genome variation. Given the recurrent HGT of the symbiosis islands into diverse Mesorhizobium strains, local Mesorhizobium communities could serve as a major source of variation for core genomes, which might prevent variation in partner quality from fixing, even in the presence of selection favoring high-quality partners. These findings highlight the novel role of HGT of symbiosis islands in maintaining partner quality variation in the legume-rhizobia symbiosis.
Asunto(s)
Lotus , Mesorhizobium , Rhizobium , Genómica , Mesorhizobium/genética , Rhizobium/genética , SimbiosisRESUMEN
When the biosynthesis of homocysteine (Hcy), an amino acid containing thiol, exceeds its elimination, plasma Hcy concentration increases and results in hyperhomocysteinemia (HHC). Most of the Hcy in plasma covalently binds to the cysteine residues of albumin by disulfide bonds. Meanwhile tiopronin (TP), a thiol-containing compound, is used for treatment of cysteinuria to decrease the amount of insoluble cystine in urine, by replacing a cysteine molecule in cystine with TP to form soluble TP-cysteine complexes. The present study investigated the effect of TP on the total (protein-unbound and protein-bound) Hcy concentration and the ratio of protein-unbound Hcy to total Hcy in plasma, and the urinary excretion of Hcy. Methionine was administered orally to rats to induce temporary hyperhomocysteinemia, and then TP was administered and the plasma and urine were collected. The amount of Hcy excreted in urine was higher but the plasma concentration of Hcy was lower in the TP group than in the control group until 3 h after TP administration. In addition the ratio of protein-unbound Hcy in plasma tended to be increased by TP administration. These results demonstrated that TP enhanced the urinary excretion of Hcy, which might cause the decrease of its plasma concentration in rats.
Asunto(s)
Homocisteína/metabolismo , Tiopronina/farmacología , Animales , Homocisteína/sangre , Homocisteína/orina , Masculino , Ratas Sprague-DawleyRESUMEN
Hyperhomocysteinemia (HHC) has been reported to be one of risk factors for cardiovascular disease. We investigated the effects of HHC on blood pressure regulation and its association with damage to the thoracic aorta and imbalance of redox in plasma in rats. Rats were fed a methionine enriched diet (Met diet) or a methionine and cholesterol (Met+Chol diet) enriched diet for 16 weeks to create a subchronic HHC model, in which the plasma concentration of homocysteine was about 7 times higher than that of control rats. The increase in systolic blood pressure (Δ-SBP) from sympathetic stimulation by L-epinephrine was 2- to 3-fold larger in HHC model in rats than that in control rats after several weeks of the treatment. These findings suggest that HHC deteriorates vaso-regulatory function, which could bring on an increased risk of cardiovascular events in humans. In addition, some of the elastic lamellae in the aorta were disrupted in the HHC group. However, the content of cross-linkages which give elasticity and mechanical strength in the lamellae, was not significantly different between HHC and control rats. Also plasma concentrations of thiobarbituric acid reactive substance and glutathione as indicators for redox balance in plasma were not different. In conclusion, the deterioration of vaso-regulation in HHC model in rats might be caused by the damage to elastic lamellae in the aorta, and not by oxidative stresses.
Asunto(s)
Aorta Torácica/patología , Presión Sanguínea/fisiología , Tejido Elástico/patología , Hiperhomocisteinemia/patología , Hiperhomocisteinemia/fisiopatología , Animales , Enfermedades Cardiovasculares/etiología , Modelos Animales de Enfermedad , Epinefrina/farmacología , Homocisteína/sangre , Humanos , Hiperhomocisteinemia/complicaciones , Hiperhomocisteinemia/metabolismo , Masculino , Metionina/administración & dosificación , Metionina/efectos adversos , Oxidación-Reducción , Ratas Sprague-Dawley , Factores de Riesgo , Tiobarbitúricos/sangreRESUMEN
We assessed the effects of D-penicillamine (D-PA) on cross-linkages in elastin and vaso-regulatory function in rats. After administration of D-PA at a dose of 100 mg/kg/day for 7 weeks to adult and young rats, the thoracic aortas were isolated. The elastic lamellae in the aorta were disrupted histopathologically in all the treated groups. The content of cross-linkages in elastin, i.e. desmosine and isodesmosine, which gives elasticity to the aortic wall, was significantly reduced in the D-PA treated groups versus the control groups. On the other hand, the content of pyridinoline as a marker of insoluble collagen was significantly reduced in the D-PA treated groups, even though the total collagen content was not changed. In addition, after 7 weeks of treatment with D-PA, the change between systolic blood pressure before and after sympathetic stimulation (Δ-SBP) by L-epinephrine was about 2.5-fold larger than that in the control group. Similar results were obtained using angiotensin II or ouabain instead of L-epinephrine. These findings demonstrated that D-PA disrupted elastic lamellae of the rat aorta by reduction of the cross-linkages in elastin and collagen, which caused dysfunction of vaso-regulation. Also, they suggested the possibility that long-term treatment with D-PA in patients could cause a decrease in vaso-regulatory function and could increase the risk of cardiovascular events.