Biology subjects

Koltunow, A.

Publications and source records attributed to Koltunow, A..

3 recordsLinked to original sources

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↗

bioRxiv2025

Induction of synthetic apomixis in two sorghum hybrids enables seed yield and genotype preservation over multiple generations

Apomixis, a process of clonal reproduction through seed, has the potential to significantly change agriculture by enabling a clonal seed propagation system for hybrid crops. Here, we demonstrate that hybrid seed from synthetically induced apomictic sorghum hybrids can be generated and maintained across multiple seed generations. This was achieved through the combination of avoidance of meiosis and induced parthenogenesis. Avoidance of meiosis was generated by the CRISPR/Cas9 knockout of the sorghum meiosis genes Spo11, Rec8, and OsdL1 and OsdL3. Parthenogenesis was induced in the resultant diploid egg cell using a maize egg cell promoter to express the Cenchrus ASGR-BBML2 gene coding sequence. Two strategies incorporating these components were used to induce synthetic apomixis in two different sorghum hybrids. Each hybrid used Tx623 as a female parent and either Tx430 or the African landrace Macia as a male parent. Seed yields in the induced apomictic hybrids were consistent and stable for multiple generations following self-pollination but reduced relative to the sexual hybrids. Sorghum contains two copies of the Osd1 gene that function in meiotic non-reduction. CRISPR/Cas9 knockout of both OsdL1 and OsdL3 loci was sufficient to produce clonal hybrid progeny in conjunction with the other apomixis induction components, but this led to a significant reduction in seed set. By contrast, a single in-frame edit of either OsdL1 or OsdL3 significantly improved seed set of clonal hybrid progeny. Fine-tuning OsdL activity appears to be essential to optimizing fertility. As the efficiency of seed set in the induced synthetic sorghum apomicts was lower than that of the sexual hybrid control, additional improvements are required to unlock the agronomic potential of synthetically induced apomictic sorghum in the field.

plant biology↗

bioRxiv2020

Unequal contribution of two paralogous centromeric histones to function the cowpea centromere

The legume cowpea (Vigna unguiculata, 2n=2x=22) has significant tolerance to drought and heat stress. Here we analysed and manipulated cowpea centromere-specific histone H3 (CENH3) genes, aiming to establish a centromere-based doubled-haploid method for use in genetic improvement of this dryland crop in future. Cowpea encodes two functional CENH3 variants (CENH3.1 and CENH3.2) and two CENH3 pseudogenes. Phylogenetic analysis suggests that gene duplication of CENH3 occurred independently during the speciation of V. unguiculata and the related V. mungo without a genome duplication event. Both functional cowpea CENH3 variants are transcribed, and the corresponding proteins are intermingled in subdomains of different types of centromere sequences in a tissue-specific manner together with the outer kinetochore protein CENPC. CENH3.2 is removed from the generative cell of mature pollen, while CENH3.1 persists. Differences between both CENH3 paralogs are restricted to the N-terminus. The complete CRISPR/Cas9-based inactivation of CENH3.1 resulted in delayed vegetative growth and sterility, indicating that this variant is needed for plant development and reproduction. By contrast, CENH3.2 knockout individuals did not show obvious defects during vegetative and reproductive development, suggesting that the gene is an early stage of subfunctionalization or pseudogenization. One-sentence summaryThe two paralogous centromeric histones (CENH3) of cowpea contribute unequal to the function of the centromere.

genetics↗