Browsing by Author "Silva Ferreira, Demetryus"
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Item Open Access BIFURCATE FLOWER TRUSS: a novel locus controlling inflorescence branching in tomato contains a defective MAP kinase gene(Oxford University Press, 2018-03-02) Silva Ferreira, Demetryus; Kevei, Zoltan; Kurowski, Tomasz J.; de Noronha Fonseca, Maria Esther; Mohareb, Fady R.; Boiteux, Leonardo S.; Thompson, Andrew J.A mutant line, bifurcate flower truss (bif), was recovered from a tomato breeding program. Plants from the control line LAM183 produced a mean of 0.16 branches per truss, whereas the value for bif plants was 4.1. This increase in branching was accompanied by a 3.3-fold increase in flower number and showed a significant interaction with exposure to low temperature during truss development. The LAM183 and bif genomes were resequenced and the bif gene was mapped to a 2.01 Mbp interval on chromosome 12; all coding region polymorphisms in the interval were surveyed and five candidate genes displaying altered protein sequences were detected. One of these genes, SlMAPK1, encoding a MAP kinase, contained a leucine-to-stop codon mutation predicted to disrupt kinase function. SlMAPK1 is an excellent candidate for bif because knock-out mutations of an Arabidopsis orthologue MPK6 were reported to have increased flower number. An introgression browser was used to demonstrate that the origin of the bif genomic DNA at the BIF locus was Solanum galapagense and that the SlMAPK1 null mutant is a naturally occurring allele widespread only on the Galápagos Islands. This work strongly implicates SlMAPK1 as part of the network of genes controlling inflorescence branching in tomato.Item Open Access Missense mutation of a class B heat shock factor is responsible for the tomato bushy root-2 phenotype(Biomed Central, 2022-02-08) Kevei, Zoltan; Silva Ferreira, Demetryus; Perez Casenave, Cristina Maria; Kurowski, Tomasz J.; Mohareb, Fady; Rickett, Daniel; Stain, Chris; Thompson, Andrew J.The bushy root-2 (brt-2) tomato mutant has twisting roots, and slower plant development. Here we used whole genome resequencing and genetic mapping to show that brt-2 is caused by a serine to cysteine (S75C) substitution in the DNA binding domain (DBD) of a heat shock factor class B (HsfB) encoded by SolycHsfB4a. This gene is orthologous to the Arabidopsis SCHIZORIZA gene, also known as AtHsfB4. The brt-2 phenotype is very similar to Arabidopsis lines in which the function of AtHsfB4 is altered: a proliferation of lateral root cap and root meristematic tissues, and a tendency for lateral root cap cells to easily separate. The brt-2 S75C mutation is unusual because all other reported amino acid substitutions in the highly conserved DBD of eukaryotic heat shock factors are dominant negative mutations, but brt-2 is recessive. We further show through reciprocal grafting that brt-2 exerts its effects predominantly through the root genotype even through BRT-2 is expressed at similar levels in both root and shoot meristems. Since AtHsfB4 is induced by root knot nematodes (RKN), and loss-of-function mutants of this gene are resistant to RKNs, BRT-2 could be a target gene for RKN resistance, an important trait in tomato rootstock breeding.Item Open Access Understanding the genetic and morphological basis of bushy root and bifuricate, two mutations affecting plant architecture in Solanum lycopersicum L.(Cranfield University, 2017-03) Silva Ferreira, Demetryus; Thompson, Andrew J.; Mohareb, Fady R.The classical ethyl methanesulfonate (EMS) tomato mutant bushy root (brt) was studied using a homozygous near isogenic line (brtNIL) in the Micro-Tom (MT) genetic background. The mutation has a pleiotropic phenotype comprising slow seedling development, which may be a consequence of a maternally-inherited small seed phenotype, and a more compact, smaller but not bushier, root phenotype. The number of lateral roots, total root length and taproot size are all smaller in brtNIL than the WT. The BRT locus was mapped to a 137 kbp region containing 9 candidate genes on chr 12; an InDel in the promoter region of Solyc12g014590 – containing two highly conserved pirin domains (Pirin_C and Pirin), was detected. Different expression patterns were confirmed by transcriptomic results, supporting Solyc12g014590 as the gene responsible for the brt phenotype. A naturally occurring recessive mutant named bifuricate (bif) shows an increase in inflorescence (truss) branching in comparison to the wild type (WT) control line, LAM183. In addition, the number of flowers per truss was 235% higher in bif plants than WT. Low temperature is known to increase truss branching, and so a four day low temperature treatment was applied and it was demonstrated that flowering increased significantly more in bif than in LAM183. The BIF locus was mapped to a 2.01 Mbp interval of chromosome 12 containing 53 genes. All coding region polymorphisms in the interval were surveyed, and two genes Solyc12g019420 (a BTB/TAZ transcription factor) and Solyc12g019460 (a MAP kinase) contained one stop codon predicted to disrupt gene function; both genes are excellent candidates for inflorescence branching control based on literature evidence. A newly developed introgression browser was used to demonstrate that the origin of the bif mutant haplotype is Solanum galapagense.