Brachypodium distachyon: a model species for aluminium tolerance in Poaceae

2014 ◽  
Vol 41 (12) ◽  
pp. 1270 ◽  
Author(s):  
Roberto Contreras ◽  
Ana M. Figueiras ◽  
Francisco J. Gallego ◽  
Cesar Benito

Aluminium (Al) toxicity is the main abiotic stress limiting plant productivity in acidic soils. Studies on Al tolerance have been conducted in Poaceae but their genomes are very complex. Fifty-nine diploid lines (2n = 10) of Brachypodium distachyon (L.) P. Beauv. and 37 allotetraploid samples (2n = 30) of Brachypodium hybridum Catalán, Joch. Müll., Hasterok & Jenkins sp. nov. were used to evaluate their tolerance to different Al concentrations. B. distachyon is Al-sensitive compared with oat, rice and rye. The diploid lines (except ABR8) were sensitive like barley and Arabidopsis; however, 10 allotetraploid samples were Al-tolerant. Four different root-staining methods were used to detect Al accumulation, cell death, lipid peroxidation and H2O2 production in diploid and allotetraploid plants. The roots treated with Al showed more intense staining in sensitive than tolerant lines. Also, without any staining, the Al treated roots of sensitive plants appear darker than roots from tolerant ones. The study concerning to the organic acids exudation shows that the exudation of citrate and malate was induced only in the roots from tolerant diploid line (ABR8) and tolerant allotetraploid samples. In contrast, the mRNA expression changes of several candidate genes for Al-activated transporters belonging to the ALMT and MATE families were analysed by quantitative PCR (qRT–PCR). The data obtained indicate that the transcripts from BdALMT1, BdMATE1 and BdMATE2 were present mainly in roots and, moreover, that the BdALMT1 transcript is present in higher amounts in the tolerant ABR8 than in the sensitive ABR1 plants indicating that this gene may be involved in Al tolerance. Finally, an insertion was detected in the promoter region of the BdALMT1 of tolerant diploid and allotetraploid plants.

2020 ◽  
Author(s):  
Dharmendra Singh ◽  
Chandan Kumar Singh ◽  
Jyoti Taunk ◽  
Ram Sewak Singh Tomar ◽  
Madan Pal ◽  
...  

Abstract Background: Aluminium (Al) stress hinders crop productivity in acidic soils. Lentil contains rich source of protein and micronutrients and cultivated in different parts of world. To enhance knowledge about Al toxicity tolerance, present study emphasizes on mechanistic analysis of genes associated with Al stress through de novo transcriptomic analysis of tolerant (L-4602), wild (ILWL-15) and sensitive (BM-4) genotypes. Result: Illumina HiSeq 2500 platform evaluated contigs ranging from 15,305 to 18,861 for all the samples with N 50 values of 1795 bp. Four annotation softwares revealed differential regulation of several genes where 30,158 genes were specifically up-regulated for combinations under Al stress conditions alone. Top up-regulated Differentially Expressed Genes (DEGs) in tolerant cultivar when compared to the sensitive one were found to be involved in protein transport as well as degradation, defences, cell growth and development. Wild v/s cultivar comparison revealed upregulation of wild DEGs that are involved in regulation of transcription in differentiating cells, pre-mRNA splicing, catalysis and protein ubiquitination. Based on assembled Unigenes, 89,722 high-quality SNPs and 39,874 SSRs were detected. Twelve selected genes were validated using qRT-PCR. KEGG pathway analysis extracted 8,757 GO annotation terms within molecular, cellular and biological processes. Pathway analysis indicated that organic acid synthesis and their transportation along with detoxification of ROS, an alternate pathway involving metacaspase-1,4,9 for programmed cell death were also significantly induced due to Al stress. Conclusion: Present study unveils the characterization of differential transcripts generated under Al stress indicating Al tolerance as a multiplex phenomenon which will directly widen crop improvement programmes for Al toxicity utilizing molecular approaches.


Author(s):  
Claudia Teixeira Guimaraes ◽  
Jurandir Vieira de Magalhaes

Abstract Citrate transporters belonging to the multidrug and toxic compound extrusion (MATE) family of membrane transporters in sorghum and maize, SbMATE and ZmMATE1, respectively, play a major role in aluminium (Al) tolerance. However, these MATE members show regulatory differences, as well as peculiarities in their genetic effect and mode of action. These aspects, which are discussed in this chapter, have to be considered to design successful breeding programmes in order to achieve maximum Al tolerance and, consequently, to improve grain and biomass production in regions of the world with Al toxicity. As shown in this chapter, target genes with major effects and molecular tools are available for marker-assisted breeding for improving Al tolerance both in sorghum and maize. However, wide adaptation to acid soils should be sought by pyramiding genes controlling different traits such as drought tolerance, P acquisition, resistance to diseases and other stresses commonly found in each agroecological environment.


2020 ◽  
Author(s):  
Dharmendra Singh ◽  
Chandan Kumar Singh ◽  
Jyoti Taunk ◽  
Shristi Sharma ◽  
RamSewak Singh Tomar ◽  
...  

Abstract Background: Aluminium (Al) stress hinders crop productivity in acidic soils. Lentil contains rich source of protein and micronutrients and cultivated in different parts of world. To enhance knowledge about Al toxicity tolerance, present study emphasizes on mechanistic analysis of genes associated with Al stress through de novo transcriptomic analysis of tolerant (L-4602), wild (ILWL-15) and sensitive (BM-4) genotypes. Result: Illumina HiSeq 2500 platform evaluated contigs ranging from 15,305 to 18,861 for all the samples with N50 values of 1795 bp. Four annotation softwares revealed differential regulation of several genes where 30,158 genes were specifically up-regulated for combinations under Al stress conditions alone. Top up-regulated Differentially Expressed Genes (DEGs) in tolerant cultivar when compared to the sensitive one were found to be involved in protein transport as well as degradation, defences, cell growth and development. Wild v/s cultivar comparison revealed upregulation of wild DEGs that are involved in regulation of transcription in differentiating cells, pre-mRNA splicing, catalysis and protein ubiquitination. Based on assembled Unigenes, 89,722 high-quality SNPs and 39,874 SSRs were detected. Twelve selected genes were validated using qRT-PCR. KEGG pathway analysis extracted 8,757 GO annotation terms within molecular, cellular and biological processes. Pathway analysis indicated that organic acid synthesis and their transportation along with detoxification of ROS, an alternate pathway involving metacaspase-1,4,9 for programmed cell death were also significantly induced due to Al stress.Conclusion: Present study unveils the characterization of differential transcripts generated under Al stress indicating Al tolerance as a multiplex phenomenon which will directly widen crop improvement programmes for Al toxicity utilizing molecular approaches.


Genome ◽  
2005 ◽  
Vol 48 (5) ◽  
pp. 781-791 ◽  
Author(s):  
Harsh Raman ◽  
Kerong Zhang ◽  
Mehmet Cakir ◽  
Rudi Appels ◽  
David F Garvin ◽  
...  

The major aluminum (Al) tolerance gene in wheat ALMT1 confers. An Al-activated efflux of malate from root apices. We determined the genomic structure of the ALMT1 gene and found it consists of 6 exons interrupted by 5 introns. Sequencing a range of wheat genotypes identified 3 alleles for ALMT1, 1 of which was identical to the ALMT1 gene from an Aegilops tauschii accession. The ALMT1 gene was mapped to chromosome 4DL using 'Chinese Spring' deletion lines, and loss of ALMT1 coincided with the loss of both Al tolerance and Al-activated malate efflux. Aluminium tolerance in each of 5 different doubled-haploid populations was found to be conditioned by a single major gene. When ALMT1 was polymorphic between the parental lines, QTL and linkage analyses indicated that ALMT1 mapped to chromosome 4DL and cosegregated with Al tolerance. In 2 populations examined, Al tolerance also segregated with a greater capacity for Al-activated malate efflux. Aluminium tolerance was not associated with a particular coding allele for ALMT1, but was significantly correlated with the relative level of ALMT1 expression. These findings suggest that the Al tolerance in a diverse range of wheat genotypes is primarily conditioned by ALMT1.Key words: aluminum, tolerance, genetic marker, Triticum aestivum, QTL, deletion mapping.


1993 ◽  
Vol 41 (5) ◽  
pp. 541 ◽  
Author(s):  
LM Egerton-Warbuton ◽  
BJ Griffin ◽  
BB Lamont

Selection for aluminium (Al) tolerance was assessed by studying pollen-pistil interactions in Eucalyptus calophylla trees colonising a 30-year-old abandoned coal mine-site (soil pH 4.3) compared with E. calophylla trees on an adjacent forest-site (soil pH 5.3). Energy-dispersive X-ray micro-analysis of reproductive tissues demonstrated that low levels of Al occurred in the stigma, lower style and unfertilised ovules of forest-site flowers. In contrast, significantly higher levels of Al were detected in all reproductive tissues of mine-site flowers. Al concentrations were higher at the base of the style than in the stigma. Al was also detected in stigmatic exudates of mine-site flowers. Selection for Al tolerance occurred in the anther of mine-site flowers as pollen from mine-site flowers germinated six-fold (15.6%) compared with forest-site pollen (2.6%) at the highest concentration of Al (22 ppm) used. However, the rate of pollen tube growth was not significantly different between mine- and forest-sites at any Al concentration. Tolerance of Al by the mine-site pollen was not shared by the progeny as there was no increase in the survival or growth of mine-site seedlings in mine soils over forest-site seedlings. Controlled pollinations between mine-/forest-site pollen and mine-site pistils demonstrated that there was no significant difference in the number of mine- or forest-site pollen tubes at any level in the style in mine-site pistils. Pollen tube abnormalities principally occurred in mine-site pistils. We concluded that there is no evidence yet for a genetically-based tolerance of Al in E. calophylla on coal mining soils.


Agronomy ◽  
2019 ◽  
Vol 9 (7) ◽  
pp. 388 ◽  
Author(s):  
Isis Vega ◽  
Miroslav Nikolic ◽  
Sofía Pontigo ◽  
Karina Godoy ◽  
María de La Luz Mora ◽  
...  

Aluminum (Al) toxicity is one of the main growth and yield limiting factors for barley grown on acid soils. Silicon (Si) ameliorates Al toxicity as well as it promotes the phenolic compounds production that have antioxidant or structural role. We evaluated the time-dependent kinetics of Al and Si uptake and the impact of Si on the production of antioxidant- or structural- phenols in barley cultivars at the short-term. Two barley cultivars with contrasting Al tolerance (Hordeum vulgare ‘Sebastian’, Al tolerant; and H. vulgare ‘Scarlett’, Al sensitive), exposed to either −Al (0 mM) or +Al (0.2 mM) nutrient solutions without Si (−Si) or with 2 mM (+Si) were cultured for 48 h. Aluminum and Si concentration decreased in plants at all harvest times when Al and Si were simultaneously supplied; this effect was more noticeable in ‘Scarlett’. Nevertheless, Si influenced the antioxidant system of barley irrespective of the Al tolerance of the cultivar, decreasing oxidative damage and enhancing radical scavenging activity, the production of phenolic compounds, and lignin accumulation in barley with short-term exposure to Al.


1999 ◽  
Vol 133 (4) ◽  
pp. 371-377 ◽  
Author(s):  
X. G. ZHANG ◽  
R. S. JESSOP ◽  
F. ELLISON

Root re-growth, following aluminium (Al) stress, has been used as an indicator of Al stress tolerance. Genetic variation in root re-growth characteristics among eight triticale genotypes was investigated by a diallel analysis. Highly significant variation due to both general combining ability (GCA) effects and specific combining ability (SCA) effects indicated that both additive effects and non-additive effects were important in explaining the genetic variation for Al tolerance. The high estimates of heritability and the predictability ratio for root re-growth revealed the preponderance of additive genetic variance in the inheritance of Al tolerance. Differences in patterns of GCA effects and SCA effects among the parents provided strong evidence that the genetic control of variation for Al tolerance as assessed by root re-growth was a complex polygenic system. Three Al-tolerant genotypes, Tahara, Abacus, and 19th ITSN 70–4, were found to be the best general combiners for larger root re-growth, and they could be used in hybridization programmes to improve Al stress tolerance by following a simple pedigree method of selective breeding.


2013 ◽  
Vol 2013 ◽  
pp. 1-16 ◽  
Author(s):  
Lin-Tong Yang ◽  
Yi-Ping Qi ◽  
Huan-Xin Jiang ◽  
Li-Song Chen

Approximately 30% of the world’s total land area and over 50% of the world’s potential arable lands are acidic. Furthermore, the acidity of the soils is gradually increasing as a result of the environmental problems including some farming practices and acid rain. At mildly acidic or neutral soils, aluminium(Al) occurs primarily as insoluble deposits and is essentially biologically inactive. However, in many acidic soils throughout the tropics and subtropics, Al toxicity is a major factor limiting crop productivity. The Al-induced secretion of organic acid (OA) anions, mainly citrate, oxalate, and malate, from roots is the best documented mechanism of Al tolerance in higher plants. Increasing evidence shows that the Al-induced secretion of OA anions may be related to the following several factors, including (a) anion channels or transporters, (b) internal concentrations of OA anions in plant tissues, (d) temperature, (e) root plasma membrane (PM) H+-ATPase, (f) magnesium (Mg), and (e) phosphorus (P). Genetically modified plants and cells with higher Al tolerance by overexpressing genes for the secretion and the biosynthesis of OA anions have been obtained. In addition, some aspects needed to be further studied are also discussed.


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