Biology subjects

Riboni, M.

Publications and source records attributed to Riboni, M..

3 recordsLinked to original sources

bioRxiv2026

VigExp: A functionally verified platform for aiding cowpea (Vigna unguiculata) and related legume crop improvement

Legumes include some of the worlds most significant crop species, such as cowpea (Vigna unguiculata), a subsistence crop widely grown in sub-Saharan Africa. Despite their importance, legume crop improvement is hindered by a lack of high-resolution expression data, particularly for reproductive tissues and cell types. Here, we report on VigExp, a tool for visualising cowpea gene expression datasets. We demonstrate its utility across a range of vegetative and reproductive cell types of varieties IT97K-499-35 and IT86D-1010, which exhibit 93.75% protein sequence conservation and are amenable to stable transformation. This includes previously published transcriptomes of vegetative, floral and seed tissues, combined with developmentally staged male and female reproductive tissues. Also integrated are novel transcriptomes of laser-captured cell types covering reproductive development from meiosis to early embryo formation post-fertilisation. Spatial expression patterns and transcript levels can be visualised through an electronic fluorescent pictograph (eFP) browser. Validated by RT-qPCR, in situ hybridisation, transgenic, and CRISPR gene editing analyses, the predictive accuracy of VigExp matches prior cowpea functional study observations. Critical genes for nodule development and regulation were also identified and their expression patterns established in cowpea. Novel reference genes, constitutively expressed gene promoters for visualisation markers/gene-editing, and tissue- and cell-specific gene promoters for targeting these regions, were identified. The A-type cyclin, VuTAM2, was also identified, with a critical role in male meiosis established. Collectively, VigExp represents an adaptable and updatable resource to support crop improvement in cowpea and other legumes, which are often highly syntenic with respect to genome composition.

plant biology↗

bioRxiv2026

BABYBOOM-like expression in the cowpea egg and central cellenables parthenogenesis, endosperm development, and viable haploid seed formation

Introductory Paragraph (Nature Plants format)Parthenogenesis or fertilization-independent embryogenesis occurs at low frequency in sexual plants. Expression of BABYBOOM-like (BBML) and PARTHENOGENESIS (PAR) genes in the egg cell of several diploid dicot crops induce parthenogenesis at varying frequency; however, recovery of viable haploid seeds has rarely been reported, perhaps due to a lack of viable endosperm formation. In the legume cowpea (Vigna unguiculata L. Walp), ectopic egg cell expression of the endogenous BBML homolog (VuBBML1) and PAR from Taraxacum officinale induces parthenogenesis; however, seeds abort as endosperm formation is blocked following self-pollination. Expression of VuBBML1 in both the egg cell and central cell, together with central cell fertilization following self-pollination, results in viable seeds that germinate and give rise to haploid plants. VuBBML1 has a functional role in the formation of cowpea embryo and endosperm seed compartments. This finding opens possibilities for establishing double haploid production during homozygous parental breeding, and asexual seed induction for fixing hybrid vigor in cowpea.

plant biology↗

bioRxiv2020

Gene expression in reproductive cell-types isolated in temporal sequence from meiosis to early seed initiation in cowpea (Vigna unguiculata L. Walp)

Molecular knowledge of pathways regulating seed formation in legumes, remains scarce. Thirteen isolated cell-type transcriptomes were developed, spanning temporal events of male and female gametogenesis and seed initiation, to examine pathways involved in cowpea seed formation. In situ hybridization confirmed localization of in silico identified cell-specific genes, verifying transcriptome utility. Cowpea and Arabidopsis reproductive cells showed some conservation in regulators enabling cell-type expression as some cowpea cell-specific genes promoters and their Arabidopsis homologs directed expression to identical reproductive cell-types in transgenic plants. In silico analyses revealed gene expression similarities and differences with genes in pathways regulating reproductive events in other plants. Meiosis-related genes were expressed at mitotic stages of gametogenesis and during sporophytic development in cowpea. Plant hormone pathways showing preferential expression at particular reproductive stages were identified. Expression of epigenetic pathways, resembling those found in Arabidopsis, including microRNA mediated gene silencing, RNA directed DNA methylation and histone modification were associated with particular stages of male and female gametophyte development, suggesting roles in gametogenic cell specification and elaboration. Analyses of cell-cycle related gene expression in mature cowpea female gametophytes, indicated that the egg and central cell were arrested at the G1/S and G2/M cell cycle phases, respectively, prior to fertilization. Pre-fertilization female gametophyte arrest was characterized by barely detectable auxin biosynthesis gene expression levels, and elevated expression of genes involved in RNA-mediated gene silencing and histone modification. These transcriptomes provide a useful resource for additional interrogation to support functional analyses for development of higher yielding cowpea and syntenic legume crops. One sentence summaryAnalyses of laser capture derived cell-type transcriptomes spanning meiosis to seed initiation revealed gene expression profiles during cell specification and reproductive development in cowpea.

plant biology↗