Transient Induction of plant Regeneration
In vitro propagation techniques are routinely applied in plant breeding programs to clonally propagate material (somatic embryogenesis) or as a fast route to generate homozygous lines (doubled-haploid production). Species and genotype recalcitrance for in vitro propagation is the major bottleneck limiting the widespread use of these biotechnology tools for crop breeding and production. Classically, recalcitrance is overcome by a trial and error approach in which the different combinations of explant, growth regulators and culture conditions are evaluated. Empirical identification of the in vitro culture parameters that contribute to efficient regeneration for every plant genotype is time consuming and inefficient, as only a few parameters can be tested at one time.
Plant regeneration can also be enhanced by ectopic expression of a number of embryo-expressed transcription factors, including the AP2 domain protein BABY BOOM and the CAAT-box binding factor LEAFY COTYLEDON1 (LEC1). BBM and LEC1 proteins have been used to enhance or overcome recalcitrance for plant regeneration in a wide range of model and crop plants. These approaches rely on generation of transgenic lines. We aim to overcome this problem by developing tools for transient activation of endogenous BBM/LEC1 gene expression that can be used to enhance plant regeneration.
The project is targeted to professional plant breeding companies. The project partners are Enza Zaden, Syngenta, Ramiro Arnedo, Semillas Fitó, Vegenov and KWS SAAT SE & Co. KGaA.
This project contributes to the MMIP and Key Technology 2 (ST2) ‘Biotechnology and Breeding’, specifically Mission 44 ‘Generic Key Technologies’. This proposal addresses multiple sub-themes within this priority, among which ‘innovative breeding methods’ and ‘gene editing for genetic variation’. The project will deliver new technologies for haploid and clonal breeding. The technologies developed in this project will accelerate plant breeding by avoiding the need for lengthy breeding pipelines.
MMIP Mission 44 aims to develop innovative breeding methods. The main goal of this project is to gain new knowledge about the regulation and function one of the key plant regeneration-regulators (BBM) and to use this knowledge to develop novel technologies for clonal (asexual) and doubled-haploid plant propagation. Development of gene editing technology is also an objective in MMIP Mission 44, and new BBM genetic variants with enhanced regeneration potential will also be generated in the project.
This project will generate and use knowledge on the BBM and LEC1 transcription factors and their regulation to provide novel tools for transient plant regeneration in crops.
The foreseen results of the project are:
1. Identification of DNA binding proteins and cis-regulatory elements that can be used to ectopically express LEC1 and BBM;
2. Identification of epidrugs and their target proteins that can be used to induce ectopic LEC1/BBM expression;
3. Development of a dCas9 system to transiently increase endogenous BBM/LEC1 gene expression; and
4. Training to companies in transient dCas9-based expression and chemical screening.