Molecular markers associated with aluminium tolerance in Sorghum bicolor

Background: Sorghum (Sorghum bicolor, L. Moench) production in many agro-ecologies is constrained by a variety of stresses, including high levels of aluminium (Al) commonly found in acid soils. Therefore, for such soils, growing Al tolerant cultivars is imperative for high productivity. Methods: In this study, molecular markers associated with Al tolerance were identified using a mapping population developed by crossing two contrasting genotypes for this trait. Results: Four SSR (Xtxp34, Sb5_236, Sb6_34, and Sb6_342), one STS (CTG29_3b) and three ISSR (811_1400, 835_200 and 884_200) markers produced alleles that showed significant association with Al tolerance. CTG29_3b, 811_1400, Xtxp34 and Sb5_236 are located on chromosome 3 with the first two markers located close to AltSB, a locus that underlie the Al tolerance gene (SbMATE) implying that their association with Al tolerance is due to their linkage to this gene. Although CTG29_3b and 811_1400 are located closer to AltSB, Xtxp34 and Sb5_236 explained higher phenotypic variance of Al tolerance indices. Markers 835_200, 884_200, Sb6_34 and Sb6_342 are located on different chromosomes, which implies the presence of several genes involved in Al tolerance in addition to SbMATE in sorghum. Conclusion: These molecular markers have a high potential for use in breeding for Al tolerance in sorghum. Keywords: Aluminium tolerance, Mapping population, Molecular markers, Net root length in aluminium, Sorghum bicolo

Cell membrane integrity, callose accumulation, and root growth in aluminum-stressed sorghum seedlings

Aluminum stress usually reduces plant root growth due to the accumulation of Al in specific zones of the root apex. The objectives of this study were to determine the localization of Al in the root apex of Sorghum bicolor (L.) Moech. and its effects on membrane integrity, callose accumulation, and root growth in selected cultivars. Seedlings were grown in a nutrient solution containing 0, 27, or 39 μM Al3+ for 24, 48, and 120 h. The Al stress significantly reduced root growth, especially after 48 and 120 h of exposure. A higher Al accumulation, determined by fluorescence microscopy after staining with a Morin dye, occurred in the root extension zone of the sensitive cultivar than in the tolerant cultivar. The membrane damage and callose accumulation were also higher in the sensitive than resistant cultivar. It was concluded that the Al stress significantly reduced root growth through the accumulation of Al in the root extension zone, callose accumulation, and impairment of plasma membrane integrity

Biologia planturum-sept 2014

Aluminum stress usually reduces plant root growth due to the accumulation of Al in specific zones of the root apex. The objectives of this study were to determine the localization of Al in the root apex of Sorghum bicolor (L.) Moech. and its effects on membrane integrity, callose accumulation, and root growth in selected cultivars. Seedlings were grown in a nutrient solution containing 0, 27, or 39 μM Al3+ for 24, 48, and 120 h. The Al stress significantly reduced root growth, especially after 48 and 120 h of exposure. A higher Al accumulation, determined by fluorescence microscopy after staining with a Morin dye, occurred in the root extension zone of the sensitive cultivar than in the tolerant cultivar. The membrane damage and callose accumulation were also higher in the sensitive than resistant cultivar. It was concluded that the Al stress significantly reduced root growth through the accumulation of Al in the root extension zone, callose accumulation, and impairment of plasma membrane integrity

Phylogenetic Relationship among Kenyan Sorghum_Cheprot et al 2013.pdf

Eighty nine (89) sorghum lines sourced from various parts of Kenya were used to determine phylogenetic relationships based on 10 DNA fragments at AltSB loci with SbMATE, ORF9 and MITE primers. Nine lines of varying aluminium tolerance levels were selected to compare their SbMATE gene expression via the real-time PCR quantification of SbMATE gene expression. The sorghum line MSCR O2 expressed a thousandfold more SbMATEgene activity than the sensitive lines (MSCRM49, MSCRN84 and MSCRN61) under Al treatment. Analysis was done by agarose gel electrophoresis stained with ethidium bromide. The objective of this study was to assess the level of phylogenetic relationships among the Kenyan sorghum germplasms at a known Al tolerance locus. Hierarchical cluster analysis joined at 70% simple matching coefficient using average linkage similarity level produced nine groups in which 67 lines fell in three major clusters of 39, 15 and 13 lines each. The three Al tolerant lines MSCRO2, MSCRC1 and MSCRN60 were clustered together. Lines MSCRO2, MSCRC1 and MSCRN60, screened to be Al tolerant were genetically related at 70% average linkage similarity level and therefore recommend their further development as a food security measure in Kenya

article1400775075_Too et al_African Journal of Agricultural Research

Sorghum (Sorghum bicolor L. (Moench) is an important food security crop in sub-Saharan Africa. Its production on acid soils is constrained by aluminium (Al) stress, which primarily interferes with root growth. Sorghum cultivation is widespread in Kenya, but there is limited knowledge on response of the Kenyan sorghum cultivars to aluminium stress. The aim of the study was to identify and morphologically characterise aluminium tolerant sorghum accessions. The root growth of three hundred and eighty nine sorghum accessions from local or international sources was assessed under 148 μM Al in soaked paper towels, and 99 of these were selected and further tested in solution. Ten selected accessions were grown out in the field, on un-limed (0 t/ha) or limed (4 t/ha) acid (pH 4.3) soils with high (27%) Al saturation, and their growth and grain yield was assessed. Although the Al stress significantly (P ≤ 0.05) reduced root growth in most of the accessions, there were ten accessions; MCSRP5, MCSR 124, MCSR106, ICSR110, Real60, IS41764, MCSR15, IESV93042-SW, MCSRM45 and MCSRM79f, that retained relatively high root growth and were classified as tolerant. The stress significantly (P ≤ 0.05) reduced seedling root and shoot dry matter in the Al-sensitive accessions. Plant growth and yield on un-limed soil was very poor, and liming increased grain yield by an average 35%. Most of Kenya sorghums were sensitive to Al stress, but a few tolerant accessions were identified that could be used for further breeding for improved grain yield in high aluminium soils