RESUMEN
Wheat blast, a devastating disease having spread recently from South America to Asia and Africa, is caused by Pyricularia oryzae (synonym of Magnaporthe oryzae) pathotype Triticum, which first emerged in Brazil in 1985. Rmg8 and Rmg7, genes for resistance to wheat blast found in common wheat and tetraploid wheat, respectively, recognize the same avirulence gene, AVR-Rmg8. Here we show that an ancestral resistance gene, which had obtained an ability to recognize AVR-Rmg8 before the differentiation of Triticum and Aegilops, has expanded its target pathogens. Molecular cloning revealed that Rmg7 was an allele of Pm4, a gene for resistance to wheat powdery mildew on 2AL, whereas Rmg8 was its homoeologue on 2BL ineffective against wheat powdery mildew. Rmg8 variants with the ability to recognize AVR-Rmg8 were distributed not only in Triticum spp. but also in Aegilops speltoides, Aegilops umbellulata and Aegilops comosa. This result suggests that the origin of resistance gene(s) recognizing AVR-Rmg8 dates back to the time before differentiation of A, B, S, U and M genomes, that is, ~5 Myr before the emergence of its current target, the wheat blast fungus. Phylogenetic analyses suggested that, in the evolutionary process thereafter, some of their variants gained the ability to recognize the wheat powdery mildew fungus and evolved into genes controlling dual resistance to wheat powdery mildew and wheat blast.
Asunto(s)
Ascomicetos , Resistencia a la Enfermedad , Enfermedades de las Plantas , Triticum , Triticum/microbiología , Triticum/genética , Triticum/inmunología , Enfermedades de las Plantas/microbiología , Enfermedades de las Plantas/inmunología , Enfermedades de las Plantas/genética , Resistencia a la Enfermedad/genética , Ascomicetos/fisiología , Genes de Plantas , Evolución Molecular , Aegilops/genética , Aegilops/microbiología , Proteínas de Plantas/genética , Proteínas de Plantas/metabolismo , FilogeniaRESUMEN
Wheat blast caused by Pyricularia oryzae pathotype Triticum (MoT) has been transmitted from South America to Bangladesh and Zambia and is now spreading in these countries. To prepare against its further spread to Asian countries, we introduced Rmg8, a gene for resistance to wheat blast, into a Japanese elite cultivar, Chikugoizumi (ChI), through recurrent backcrosses and established ChI near-isogenic lines, #2-1-10 with the Rmg8/Rmg8 genotype and #4-2-10 with the rmg8/rmg8 genotype. A molecular analysis suggested that at least 96.6% of the #2-1-10 genome was derived from the recurrent parent ChI. The #2-1-10 line was resistant to MoT not only in primary leaves at the seedling stage but also in spikes and flag leaves at the heading stage. The strength of the resistance in spikes of this Rmg8 carrier was comparable to that of a carrier of the 2NS segment, which has been the only genetic resource released to farmers' fields for wheat blast resistance. On the other hand, the 2NS resistance was not expressed on leaves at the seedling stage nor flag leaves at the heading stage. Considering that leaf blast has been increasingly reported and regarded as an important inoculum source for spike blast, Rmg8 expressed at both the seedling and heading stages, or more strictly in both leaves and spikes, is suggested to be useful to prevent the spread of MoT in Asia and Africa.
Asunto(s)
Resistencia a la Enfermedad , Enfermedades de las Plantas , Plantones , Triticum , Triticum/genética , Triticum/microbiología , Plantones/microbiología , Plantones/genética , Plantones/crecimiento & desarrollo , Enfermedades de las Plantas/microbiología , Enfermedades de las Plantas/inmunología , Resistencia a la Enfermedad/genética , Hojas de la Planta/microbiología , Hojas de la Planta/genética , Ascomicetos/fisiología , Fitomejoramiento , Genotipo , Genes de PlantasRESUMEN
The number of wheat grains is one of the major determinants of yield. Many quantitative trait loci (QTLs) and some causal genes such as GNI-A1 and WAPO-A1 that are associated with grain number per spike (GNS) have been identified, but the underlying mechanisms remain largely unknown. We analyzed QTLs for grain number and other related traits using 188 doubled haploid lines derived from the Japanese high-yield variety, Kitahonami, as a parent to elucidate the genetic mechanism determining grain number. The major QTLs for grain number at the apical, central, and basal parts of the spike were identified in different chromosomal regions. We considered GNI-A1 and WAPO-A1 as candidate genes controlling grain number at the central and basal parts of the spike, respectively. Kitahonami had the favorable 105Y allele of GNI-A1 and WAPO-A1b allele and unfavorable alleles of QTLs for grain number at the apical part of spikes. Pyramiding the favorable alleles of these QTLs significantly increased GNS without significantly reducing thousand-grain weight (TGW). In contrast, the accumulation of favorable alleles of QTLs for TGW significantly decreased GNS, whereas days to heading positively correlated with GNS. Late heading increased the spikelet number per spike, resulting in a higher GNS. Pyramiding of the QTLs for TGW and days to heading also altered the GNS. In conclusion, GNS is a complex trait controlled by many QTLs, and it is essential for breeding to design. Supplementary Information: The online version contains supplementary material available at 10.1007/s11032-021-01255-8.
RESUMEN
Climate change is considered a major threat to world agriculture and food security. To improve the agricultural productivity and sustainability, the development of high-yielding stress-tolerant, and climate-resilient crops is essential. Of the abiotic stresses, flooding stress is a very serious hazard because it markedly reduces plant growth and grain yield. Proteomic analyses indicate that the effects of flooding stress are not limited to oxygen deprivation but include many other factors. Although many flooding response mechanisms have been reported, flooding tolerance mechanisms have not been fully clarified for soybean. There were limitations in soybean materials, such as mutants and varieties, while they were abundant in rice and Arabidopsis. In this review, plant proteomic technologies are introduced and flooding tolerance mechanisms of soybeans are summarized to assist in the improvement of flooding tolerance in soybeans. This work will expedite transgenic or marker-assisted genetic enhancement studies in crops for developing high-yielding stress-tolerant lines or varieties under abiotic stress.
Asunto(s)
Adaptación Fisiológica , Inundaciones , Glycine max/fisiología , Cambio Climático , Proteínas de Plantas/metabolismo , Plantas Modificadas Genéticamente , Proteoma , Glycine max/metabolismoRESUMEN
Cytosolic ascorbate peroxidases (cAPXs) of soybean have been found by proteome analysis to be downregulated in submerged seedlings. To elucidate the physiological meaning of this downregulation, soybean cAPXs were characterized in this study. Vigorous synthesis was detected in germinating seeds and seedlings. Expression of the corresponding genes was detected clearly in tissues that actively underwent cell division. The gene expression was suppressed by flooding stress, but not by salinity, cold or drought stress. The expression recovered 1 d after release from flooding stress, accompanied by growth resurgence.
Asunto(s)
Ascorbato Peroxidasas/genética , Regulación de la Expresión Génica de las Plantas , Glycine max/genética , Proteínas de Plantas/genética , Plantones/genética , Semillas/genética , Ascorbato Peroxidasas/biosíntesis , División Celular , Citosol/enzimología , Inundaciones , Isoenzimas/biosíntesis , Isoenzimas/genética , Células Vegetales/enzimología , Proteínas de Plantas/biosíntesis , Plantones/enzimología , Semillas/enzimología , Glycine max/enzimología , Estrés FisiológicoRESUMEN
Alcohol dehydrogenase (Adh) is the key enzyme in alcohol fermentation. We analyzed Adh expression in order to clarify the role of Adh of soybeans (Glycine max) to flooding stress. Proteome analysis confirmed that expression of Adh is significantly upregulated in 4-day-old soybean seedlings subjected to 2 days of flooding. Southern hybridization analysis and soybean genome database search revealed that soybean has at least 6 Adh genes. The GmAdh2 gene that responded to flooding was isolated from soybean cultivar Enrei. Adh2 expression was markedly increased 6 h after flooding and decreased 24 h after floodwater drainage. In situ hybridization and Western blot indicated that flooding strongly induces Adh2 expression in RNA and protein levels in the root apical meristem. Osmotic, cold, or drought stress did not induce expression of Adh2. These results indicate that Adh2 is a flooding-response specific soybean gene expressed in root tissue.
Asunto(s)
Alcohol Deshidrogenasa/genética , Inundaciones , Glycine max/genética , Raíces de Plantas/genética , Proteínas de Soja/genética , Alcohol Deshidrogenasa/metabolismo , Secuencia de Aminoácidos , Frío , Electroforesis en Gel Bidimensional , Perfilación de la Expresión Génica , Regulación de la Expresión Génica de las Plantas/efectos de los fármacos , Hipocótilo/genética , Hipocótilo/metabolismo , Hipoxia , Immunoblotting , Hibridación in Situ , Datos de Secuencia Molecular , Raíces de Plantas/metabolismo , Reacción en Cadena de la Polimerasa de Transcriptasa Inversa , Plantones/genética , Plantones/metabolismo , Homología de Secuencia de Aminoácido , Cloruro de Sodio/farmacología , Proteínas de Soja/metabolismo , Glycine max/metabolismo , Estrés Fisiológico , Factores de Tiempo , Agua/farmacologíaRESUMEN
In yellow soybean, seed coat pigmentation is inhibited via endogenous RNA interference (RNAi) of the chalcone synthase (CHS) genes. Genetic studies have shown that a single dominant gene, named the I gene, inhibits pigmentation over the entire seed coat in soybean. We previously isolated a candidate for the I gene from the yellow soybean genome with the I/I genotype, and designated it GmIRCHS. A structural feature of GmIRCHS is a perfect inverted repeat of the pseudoCHS gene lacking 5'-coding region. This suggests that the double-stranded RNA (dsRNA) structure of the pseudoCHS gene may be formed in the GmIRCHS transcript. RNAi is triggered by the dsRNA for a target gene, so the GmIRCHS transcript is likely to be a trigger for RNAi of CHS genes. In this study, we identified a 1087-bp dsRNA, including pseudoCHS region ranging from most of exon 2 to 3'-UTR, in the GmIRCHS transcript. Interestingly, this dsRNA was detected not only in the seed coat but also in the cotyledon and leaf tissues. Previously, CHS RNAi has been shown to be restricted to the seed coat, and we reported that endogenous short interfering RNAs of CHS genes (CHS siRNAs) are detected only in the seed coat and not in the cotyledon and leaf tissues. Taken together with these previous reports, our result suggests that seed-coat specificity of CHS RNAi may be determined in the amplification step of CHS siRNAs rather than dsRNA formation in the GmIRCHS transcript. Our studies further revealed that CHS siRNAs are modified at the 3' ends and bear 5' monophosphorylated ends, suggesting that CHS siRNA duplexes are generated by Dicer-like enzyme from CHS dsRNA and subsequently modified at the 3' ends for stabilizing CHS siRNAs.
Asunto(s)
Aciltransferasas/genética , Glycine max/genética , Interferencia de ARN , ARN Interferente Pequeño/metabolismo , Aciltransferasas/metabolismo , Genes Dominantes , Genes de Plantas , Conformación de Ácido Nucleico , Fosforilación , Seudogenes , ARN Bicatenario/genética , ARN Bicatenario/metabolismo , Semillas/enzimología , Semillas/genética , Glycine max/enzimología , Transcripción Genética , Regiones no TraducidasRESUMEN
We investigated selective culturing conditions for the production of transgenic soybeans. In this culturing system, we used the acetolactate synthase (ALS)-inhibiting herbicide-resistance gene derived from rice (Os-mALS gene) as a selectable marker gene instead of that derived from bacteria, which interfered with the cultivation and practical usage of transgenic crops. T(1) soybeans grown from one regenerated plant after selection of the ALS-targeting pyrimidinyl carboxy (PC) herbicide bispyribac-sodium (BS) exhibited herbicide resistance, and the introduction and expression of the Os-mALS gene were confirmed by genetic analysis. The selective culturing system promoted by BS herbicide, in which the Os-mALS gene was used as a selectable marker, was proved to be applicable to the production of transgenic soybeans, despite the appearance of escaped soybean plants that did not contain the Os-mALS transgene.
Asunto(s)
Acetolactato Sintasa/genética , Glycine max/genética , Oryza/enzimología , Proteínas de Plantas/genética , Resistencia a los Herbicidas/genética , Herbicidas/farmacología , Oryza/genética , Plantas Modificadas Genéticamente/efectos de los fármacos , Plantas Modificadas Genéticamente/genética , Plásmidos , ARN de Planta/genética , Glycine max/efectos de los fármacos , Transformación Genética , TransgenesRESUMEN
We transformed a construct containing the sense coat protein (CP) gene of Soybean dwarf virus (SbDV) into soybean somatic embryos via microprojectile bombardment to acquire SbDV-resistant soybean plants. Six independent T(0) plants were obtained. One of these transgenic lines was subjected to further extensive analysis. Three different insertion patterns of Southern blot hybridization analysis in T(1) plants suggested that these insertions introduced in T(0) plants were segregated from each other or co-inherited in T(1) progenies. These insertions were classified into two types, which overexpressed SbDV-CP mRNA and accumulated SbDV-CP-specific short interfering RNA (siRNA), or repressed accumulation of SbDV-CP mRNA and siRNA by RNA analysis prior to SbDV inoculation. After inoculation of SbDV by the aphids, most T(2) plants of this transgenic line remained symptomless, contained little SbDV-specific RNA by RNA dot-blot hybridization analysis and exhibited SbDV-CP-specific siRNA. We discuss here the possible mechanisms of the achieved resistance, including the RNA silencing.
Asunto(s)
Proteínas de la Cápside/metabolismo , Glycine max/fisiología , Proteínas de la Cápside/genética , Luteovirus/metabolismo , Plantas Modificadas Genéticamente , ARN Viral/genética , ARN Viral/metabolismo , Glycine max/genética , Glycine max/virologíaRESUMEN
In an attempt to generate soybean plants resistant to soybean dwarf virus (SbDV), we transformed a construct containing inverted repeat-SbDV coat protein (CP) genes spaced by beta-glucuronidase (GUS) sequences into soybean somatic embryos via microprojectile bombardment. Three T(0) plants with an introduced CP gene were obtained, and one generated T(1) seeds. The presence of the transgene in T(1) plants was confirmed by PCR and Southern blot hybridization analysis, but expression of CP was not detected by northern blot hybridization analysis. Two months after inoculation of SbDV by aphid, T(2) plants contained little SbDV-specific RNA and remained symptomless. These plants contained SbDV-CP-specific siRNA. These results suggest that the T(2) plants achieved resistance to SbDV by an RNA-silencing-mediated process.
Asunto(s)
Proteínas de la Cápside/genética , Glycine max/genética , Luteovirus/genética , Plantas Modificadas Genéticamente/genética , Plantas Modificadas Genéticamente/virología , Interferencia de ARN , ARN Viral/metabolismo , Secuencias Repetitivas de Ácidos Nucleicos , Semillas/genética , Semillas/virología , Glycine max/virología , Transformación GenéticaRESUMEN
Germination of lettuce (Lactuca sativa L. cv. 'Grand Rapids') seeds was inhibited at high temperatures (thermoinhibition). Thermoinhibition at 28 degrees C was prevented by the application of fluridone, an inhibitor of abscisic acid (ABA) biosynthesis. At 33 degrees C, the sensitivity of the seeds to ABA increased, and fluridone on its own was no longer effective. However, a combined application of fluridone and gibberellic acid (GA3) was able to restore the germination. Exogenous GA3 lowered endogenous ABA content in the seeds, enhancing catabolism of ABA and export of the catabolites from the intact seeds. The fluridone application also decreased the ABA content. Consequently, the combined application of fluridone and GA3 decreased the ABA content to a sufficiently low level to allow germination at 33 degrees C. There was no significant temperature-dependent change in endogenous GA1 contents. It is concluded that ABA is an important factor in the regulation of thermoinhibition of lettuce seed germination, and that GA affects the temperature responsiveness of the seeds through ABA metabolism.