Biology subjects

Hirsz, D.

Publications and source records attributed to Hirsz, D..

3 recordsLinked to original sources

bioRxiv2025

VERNALIZATION2 (VRN2) alters early tiller development in a facultative spring hexaploid bread wheat (Triticum aestivum)

Plants coordinate growth and development with environmental signals. Specifically, temperature and photoperiod are important regulators to time the transition from vegetative to floral growth. Through utilising these environmental signals potential reproductive success is optimised, which is critical for the production of high crop yields. For cereals, some require a winter before undergoing reproductive development. This extended period of cold exposure enables the process of vernalization and is also important for the synchronised timing of the floral transition. The cereal-specific floral repressor VERNALIZATION2 (VRN2) has an integral role in this pathway, yet this locus remains poorly characterised in hexaploid wheat. Our research in a facultative wheat suggests that the tandemly duplicated genes comprising the VRN2 locus, ZCCT1 and ZCCT2, respond to multiple environmental factors and have differences in gene expression patterns at a gene and sub-genome level. These genes also show co-regulation, forming a regulatory loop between ZCCT-D1 and ZCCT-D2. The function of these genes beyond the classic vernalization response is explored in a facultative wheat with VRN-D2 identified to regulate early tiller development, with an accelerated rate of secondary tiller emergence and presence of coleoptile tillers. This phenotype increases ground coverage more rapidly, which provides agronomic benefits including improved competition with biological stressors. The findings identify that the VRN2 loci in bread wheat is formed of multiple genes which have overlapping but also unique regulation and function. Selecting these genes individually may offer a route to alter wheat plant architecture without directly impacting vernalization requirement. Highlight

plant biology↗

bioRxiv2021

A new protocol for speed vernalisation of winter cereals

There are many challenges facing the development of high-yielding, nutritious crops for future environments. One limiting factor is generation time, which prolongs research and plant breeding timelines. Recent advances in speed breeding protocols have dramatically reduced generation time for many short-day and long-day species by optimising light and temperature conditions during plant growth. However, winter crops with a vernalisation requirement still require up to 6-10 weeks in low-temperature conditions before transition to reproductive development. Here, we tested a suite of environmental conditions and protocols to investigate if vernalisation can be satisfied more efficiently. We identified a vernalisation method consisting of exposing seeds at the soil surface to an extended photoperiod of 22 h day:2 h night at 10{degrees}C with transfer to speed breeding conditions that dramatically reduces generation time in both winter wheat (Triticum aestivum) and winter barley (Hordeum vulgare). Implementation of this protocol achieved up to five generations per year for winter wheat or barley, instead of the two typically obtained under standard vernalisation and plant growth conditions. The protocol has great potential to enhance training and to accelerate research, pre-breeding, and breeding outcomes focussed on winter crop improvement.

plant biology↗

bioRxiv2021

CRISPR targeting of MEIOTIC-TOPOISOMERASE VIB-dCas9 to a recombination hotspot is insufficient to increase crossover frequency in Arabidopsis

During meiosis, homologous chromosomes pair and recombine, which can result in reciprocal crossovers that increase genetic diversity. Crossovers are unevenly distributed along eukaryote chromosomes and show repression in heterochromatin and the centromeres. Within the chromosome arms crossovers are often concentrated in hotspots, which are typically in the kilobase range. The uneven distribution of crossovers along chromosomes, together with their low number per meiosis, creates a limitation during crop breeding, where recombination can be beneficial. Therefore, targeting crossovers to specific genome locations has the potential to accelerate crop improvement. In plants, meiotic crossovers are initiated by DNA double strand breaks (DSBs) that are catalysed by SPO11 complexes, which consist of two catalytic (SPO11-1 and SPO11-2) and two non-catalytic subunits (MTOPVIB). We used the model plant Arabidopsis thaliana to target a dCas9-MTOPVIB fusion protein to the 3a crossover hotspot via CRISPR. We observed that this was insufficient to significantly change meiotic crossover frequency or pattern within 3a. We discuss the implications of our findings for targeting meiotic recombination within plant genomes.

plant biology↗