Apomixis: A Foresight from Genetic Mechanisms to Molecular Perspectives

Abstract

Apomixis is considered to be a natural mode of clonal propogation from seed to seed, in which progeny serves as a replica of maternal genotype. The process evades creation of variation by circumventing sexual fusion and recombination, offering great advantage to fix heterosis or hybrid vigour in plants. As this would permit the conservation of complex favourable genotypes that are of agricultural value, it has immense potential in crop seed production. In order to accomplish this, a comprehensive knowledge on the genetic basis and the molecular mechanisms regulating different components of apomixis stands as a key prerequisite. So far, despite of the persistent interest and extensive research on apomixis, the underlying gene regulatory networks and their evolutionary origins are not well deciphered and still remain unclear. From the developmental perspective, apomixis is widely accepted to be controlled or deviated form of sexual reproduction and studies based on comparative analysis of genes or mutants regulating sexual and apomictic pathways revealed their resemblance across various plant species. Since apomixis is a complex, yet well regulated phenomenon that constantly requires action of specific genes during all developmental stages, the present review summarises recent advances in apomixis and compiles information on vital genes and mutants involved in regulating apomixis during various stages of development.

Graphical abstract

Graphical abstract: Brief illustration on mechanisms of apomictic and sexual life cycle in angiosperms. Apomixis avoids the process of meiosis and recombination offering advantage over sexuals by conservation of heterosis or vigor for several generations, easy maintenance of superior genotypes and rapid production of homozygous lines. In sexuals owing to nuclear division and fertilization, fixation of heterosis cannot be achieved and maintenance/development of homozygous lines becomes intricate.*Based on the fertilization the ploidy of endosperm may vary.