We have identified a viable-yellow and a lethal-yellow chlorophyll-deficient mutant in soybean. Segregation patterns suggested single-gene recessive inheritance for each mutant. The viable- and lethal-yellow plants showed significant reduction of chlorophyll a and b. Photochemical energy conversion efficiency and photochemical reflectance index were reduced in the viable-yellow plants relative to the wildtype, whereas the lethal-yellow plants showed no electron transport activity. The viable-yellow plants displayed reduced thylakoid stacking, while the lethal-yellow plants exhibited failure of proplastid differentiation into normal chloroplasts with grana. Genetic analysis revealed recessive epistatic interaction between the viable- and the lethal-yellow genes. The viable-yellow gene was mapped to a 58kb region on chromosome 2 that contained seven predicted genes. A frame shift mutation, due to a single base deletion in Glyma.02g233700, resulted in an early stop codon. Glyma.02g233700 encodes a translocon in the inner membrane of chloroplast (GmTic110) that plays a critical role in plastid biogenesis. The lethal-yellow gene was mapped to an 83kb region on chromosome 3 that contained 13 predicted genes. Based on the annotated functions, we sequenced three potential candidate genes. A single base insertion in the second exon of Glyma.03G230300 resulted in a truncated protein. Glyma.03G230300 encodes for GmPsbP, an extrinsic protein of Photosystem II that is critical for oxygen evolution during photosynthesis. GmTic110 and GmPsbP displayed highly reduced expression in the viable- and lethal-yellow mutants, respectively. The yellow phenotypes in the viable- and lethal-yellow mutants were due to the loss of function of GmTic110 or GmPsbP resulting in photooxidative stress.
BackgroundComplex mosaic structures of HIV-1 were found in the Democratic Republic of Congo (DRC). Currently, there is limited information on the circulating HIV-1 strains, the distribution of these strains and antiretroviral (ART) resistant viruses in different regions of the country, and the HIV-1 strains harbored by the high-risk groups like female sex workers (FSW) reported to be the source of recombinant and ART resistant viruses. MethodsDried Blood Spots (DBS), collected from 325 infected FSWs in ten cities from 2012 DRC HIV/STI Integrated Biological and Behavioral Surveillance Survey, were tested for HIV-1 genotypes and antiretroviral resistance mutations. Regional segregation of HIV-1 clades was detected using phylogenetics. The significance for differences in HIV-1 subtype and drug resistance mutations were evaluated using Chi-square tests. ResultsThere were 145 (env) and 93 (pol) sequences analyzed. Based on env sequences, the predominant subtype was A1 (44%), and recombinants as defined pol sequences comprised 35% of the total sample. Paired sequences of pol and env from DRC FSW revealed mosaic recombinant in 54% of the sequences. Distinct geographic distributions of different HIV-1 subtypes and recombinants were observed. Subtype A1 was prevalent (40%) in Goma located in the East and significantly higher than in Mbuji-Mayi (p<0.05) in the South-central PLOS ONE | https://doi.
. 2015. Evaluation of spontaneous generation of allelic variation in soybean in response to sexual hybridization and stress. Can. J. Plant Sci. 95: 405Á415. Intracultivar variation reported in pure lines of soybean has been hypothesized to result from genetic mechanisms contributing to de novo genetic variation. In this study we have detected allele switching by following segregation patterns of Aconitase-4 isozyme in sexual crosses and pure lines. In sexual crosses, one F 2 plant showed a switch at the Aconitase-4 (Aco4) locus from the expected heterozygous genotype Aco4-ac to Aco4-ab. In the pure lines grown in a honeycomb planting design and treated with an accelerated aging test, multiple cases of allele switching were detected at the Aco4 locus. Both single and double switches were detected that were stable and heritable. These findings indicate that the generation of endogenous variation continues in pure lines as a result of intrinsic genetic mechanisms. With a long-term goal of understanding the genetic nature of the changes, we genetically mapped the Aco4 gene to a 3.3 cM region on Chromosome 11. The corresponding physical region is Â293 kb with 39 predicted genes. Of these, Glyma.11g080600 is of particular interest, as it shows 93% and 88% identity to Medicago truncatula and Arabidopsis aconitase genes, respectively. Further characterization of the soybean Aco4 gene may shed light on genetic mechanisms responsible for allele switching.Key words: Allele switching, soybean, aconitase, linkage mapping, isozyme Espinosa, K., Boelter, J., Lolle, S., Hopkins, M., Goggi, S., Palmer, R. G. et Sandhu, D. 2015. É valuation des variations alle´liques spontane´es chez le soja conse´cutivement a`l'hybridation et au stress. Can. J. Plant Sci. 95: 405Á415. On a formuleĺ 'hypothe`se que les variations intra-cultivar signale´es chez les ligne´es pures de soja pourraient de´couler de me´canismes ge´ne´tiques autorisant une variation ge´ne´tique de novo. Les auteurs ont identifie´la permutation d'alle`les en suivant la se´gre´gation de l'isozyme aconitase-4 dans les croisements sexuels et les ligne´es pures. Dans les croisements sexuels, un plant de la F 2 pre´sentait une permutation au locus Aconitase-4 (Aco4) du ge´notype he´te´rozygote pre´vu Aco4-ac au ge´notype Aco4-ab. Dans les ligne´es pures cultive´es en quinconce et soumises a`un essai de vieillissement acce´le´re´, les auteurs ont de´tecte´de nombreux cas de permutation d'alle`les au locus Aco4. Des permutations simples et doubles stables et transmissibles ont ainsi e´te´discerne´es. Ces re´sultats indiquent que les variations endoge`nes se poursuivent dans les ligne´es pures en raison de me´canismes ge´ne´tiques intrinse`ques. Dans le but ultime d'e´lucider la nature ge´ne´tique de tels changements, les auteurs ont situe´le ge`ne Aco4 sur une re´gion de 3,3 cM du chromosome 11. La zone physique correspondante mesure environ 293 kb et comprend 39 ge`nes explicatifs. Parmi eux, Glyma.11g080600 reveˆt un inte´reˆt particulier, car il ressemble a`93 % et a`88 % au...
Aconitase catalyzes the reversible isomerization of two tricarboxylic acids, citrate and isocitrate, during the Krebs cycle. Five aconitase genes, namely, Aco1, Aco2, Aco3, Aco4, and Aco5, have been identified in soybean. Previously, Aco4 was mapped on chromosome 11. The purpose of this investigation was to isolate and sequence the candidate gene for Aco4. We mapped the Aco4 gene to a 148 kb region on chromosome 11 that contained 19 predicted genes. One of these, Glyma.11G080600, codes for aconitate hydratase. Sequencing of two isozyme variants (A-line and B-line) for Glyma.11G080600 revealed three synonymous and two non-synonymous substitutions. Perhaps, the two non-synonymous substitutions resulted in a variable isozyme pattern between the variants. Glyma.11G080600 contains a catalytic domain and a swivel domain that are known to catalyze isomerization of citrate to isocitrate and swiveling conformational change in the enzyme mechanism, respectively. Conservation of both the domains implies the role of Glyma.11G080600 in the interconversion of citrate and isocitrate. Glyma.11G080600 is expressed in most tissues, with maximum expression in leaves. Phylogenetic analysis of 25 genes from different species displayed three major clusters. Glyma.11G080600 (Aco4) and Glyma.01G162800, which are conserved in Glycine max (L.) Merr. and Glycine soja Siebold. & Zucc., may have common ancestry before G. max and G. soja split.
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