Isolated microspore culture and its applications in plant breeding and genetics

Abstract

Isolated microspore culture (IMC) represents a unique system of single cell reprogramming in plants wherein a haploid male gametophyte, the microspore, switches its default gametophytic developmental pathway toward embryogenesis by specific stress treatment. The application of a stress treatment(s) is necessary for efficient embryogenesis induction. Depending on species, microspores are often induced by cold and heat shock, osmotic stress, starvation, anti-microtubular agents, stress hormones, antibiotics, or polyamines. This technique (IMC) is likely to remain as a well-known method in plant breeding since it allows for the rapid production of completely homozygous lines while, in the context of developmental biology, it allows for in vitro embryogenesis to be explored in greater detail. Isolated microspores also represent ideal recipients for several gene transfer techniques including electroporation, microprojectile bombardment, and Agrobacterium-mediated transformation. IMC is also extensively used for genetic studies, i.e., studying inheritance of quantitative traits, quantitative trait loci (QTL) mapping, and genomics and gene identification, for mutation and selection and also used for producing reversible male-sterile lines. Male sterility avoids the labor costs of manual emasculation and serves as a molecular strategy for transgene containment by preventing pollen release to the environment. Combination of this technique with doubled haploid (DH) production leads to an innovative environmentally friendly breeding technology. In addition, the usefulness of DHs for reverse breeding program, an applied plant breeding technique introduced to directly produce parental lines for any hybrid plant, is also generally discussed.