Stress-Induced Microspore Embryogenesis in Crop Plants: Cell Totipotency Acquisition and Embryo Development

Abstract

Stress-induced microspore embryogenesis is an in vitro system in which the haploid microspore is reprogramed by the application of stress treatments and, as a totipotent cell, enters into an embryogenesis pathway, producing double-haploid (DH) embryos and plants. DHs are important biotechnological tools in plant breeding programs, widely used by companies, as a source of new genetic variability, fixed in complete homozygous plants in only one generation step. However, their applications are limited in many crop and forest species due to low or nulle efficiency. Microspore embryogenesis is also a convenient system to analyze the cellular processes underlying cell reprogramming, totipotency acquisition and embryogenesis. In the last years, investigation on stress-induced microspore embryogenesis has unveiled the involvement of several cellular processes like autophagy, cell death, epigenetic modifications, auxin and cell wall remodeling, whose role is not yet completely elucidated. In the present chapter, we review recent findings on the determinant factors that underlie stress-induced microspore embryogenesis induction and progression. These findings have provided new insights into the regulating mechanisms of microspore embryogenesis initiation and progression, opening up new intervention pathways through pharmacological treatments with small bioactive compounds (autophagy, epigenetic and auxin modulators), very promising to enhance in vitro embryo production yield for breeding programs of crop and forest species, especially for those recalcitrant.