The PsEND1 promoter: a novel tool to produce genetically engineered male-sterile plants by early anther ablation

Abstract

PsEND1 is a pea anther-specific gene that displays very early expression in the anther primordium cells. Later on, PsEND1 expression becomes restricted to the epidermis, connective, endothecium and middle layer, but it is never observed in tapetal cells or microsporocytes. We fused the PsEND1 promoter region to the cytotoxic barnase gene to induce specific ablation of the cell layers where the PsEND1 is expressed and consequently to produce male-sterile plants. Expression of the chimaeric PsEND1::barnase gene in two Solanaceae (Nicotiana tabacum and Solanum lycopersicon) and two Brassicaceae (Arabidopsis thaliana and Brassica napus) species, impairs anther development from very early stages and produces complete male-sterile plants. The PsEND1::barnase gene is quite different to other chimaeric genes previously used in similar approaches to obtain male-sterile plants. The novelty resides in the use of the PsEND1 promoter, instead of a tapetum-specific promoter, to produce the ablation of specific cell lines during the first steps of the anther development. This chimaeric construct arrests the microsporogenesis before differentiation of the microspore mother cells and no viable pollen grains are produced. This strategy represents an excellent alternative to generate genetically engineered male-sterile plants, which have proved useful in breeding programmes for the production of hybrid seeds. The PsEND1 promoter also has high potential to prevent undesirable horizontal gene flow in many plant species.

Two similar but distinct second intron fragments from tobacco AGAMOUS homologs confer identical floral organ-specific expression sufficient for generating complete sterility in plants

“…This strategy was Wrst used for engineering male sterility in plants with a tapetum-speciWc promoter driving a Barnase gene encoding an extracellular ribonuclease over a decade ago (Mariani et al 1990(Mariani et al , 1992. Since then, similar engineered reproductive sterility has been reported in Arabidopsis (Konagaya et al 2008), Brassica (Block and Debrouwer 1993;Roque et al 2007), cabbage (Lee et al 2003), tobacco (Twell 1995;HoWg et al 2006), tomato (Gomez et al 2004;Roque et al 2007), and wheat (Block et al 1997), but in all cases they are restricted primarily to male sterility, which has a limited application for the containment of both male and female gamete-mediated gene Xow from transgenic plants. As diverse promoters speciWc for Xoral tissues have recently become available in a variety of plant species, this strategy has been successfully used for the engineering of bisexual sterility.…”

Silencing of meiosis-critical genes for engineering male sterility in plants

“…This was first achieved almost two decades ago using the tapetum-specific TA29 promoter fused to the Barnase gene, which encodes an extracellular ribonuclease, to eliminate pollen production and thus elicit male sterility in tobacco and Brassica napus (Mariani et al 1990). Since then, a similar approach has been applied for generating male sterility in numerous other species (e.g., Block et al 1997;Höfig et al 2006;Konagaya et al 2008;Luo et al 2006;Roque et al 2007).…”

Bioengineering of Male Sterility in Rice (Oryza sativa L.)

“…In transgenic Nicotiana tabacum plants, the argE gene products that were controlled by tapetal specific promoter Ta29 lead to empty anthers, resulting in male sterile plants (Kriete et al 1996). Similarly, Roque et al (2007) fused the PsEND1 promoter to the barnase gene which permits identification of male sterile line before flowering. The PsEND1 is an anther-specific promoter that drives gene expression in a tightly specific pattern restricted to developing anther.…”