Regeneration of Plant Organs in Vitro and Its Mechanistic Basis

Excised plant organs grown in vitro can produce adventitious buds or roots under some conditions. Factors that affect organ regeneration include external stimuli, such as the application of plant growth regulators, light or darkness, water logging, temperature, etc., and internal parameters and signals, such as plant genotype, wounding, the age of plant donors, or the position on the plant donor where the explants are derived, etc. The process of plant regeneration in vitro is complex and varies for different species and explant sources. In some cases, adventitious buds or roots can be directly grown out of the tissue explants incubated in vitro, but more often than not full organs have to be regenerated from the callus. What is the mechanistic basis for this variability? To answer this question, we need to better understand the interplay between internal and external factors that impact regeneration efficiency, such as plant genetics, epigenetics, and the environment. For example, an exogenous factor, such as a plant growth regulator added to the growth media, may differentially affect specific signalling pathways in different explants, in turn dictating which genes are expressed, altering the explants’ metabolic and epigenetic profiles, triggering changes in the production or stability of certain microRNAs, etc.

Many foundational questions in the field of plant regeneration remain unanswered, such as why some plant organs grown in vitro can produce both adventitious buds and roots, while others can regenerate neither or only one of the two. Resolving these issues requires that scientists approach plant regeneration from different perspectives and explore the contribution of multiple parameters in parallel, such as the donor plant age, physiology and biochemistry, organ position, growth environment, plant anatomy, genetics, regulatory gene expression, epigenetics, and small RNA. To enable such a multi-faceted inquiry, a combination of approaches--including genetics, genomics, epigenetics, metabolomics, molecular and cell biology--needs to be deployed.

In this Research Topic, we invite all article types published by Frontiers in Plant Science that explore plant regeneration in vitro, e.g., the formation of adventitious buds or roots in plant organs in vitro, and shed new light on the underlying physiological and genetic basis of plant regeneration. Studies that improve our understanding of the mechanistic aspects of organ regeneration are especially welcome. Representative examples of the topics of interest are provided below (but are not limited to):

• Techniques and methods to promote the regeneration of adventitious buds and/or roots in vitro culture.
• Internal and external factors that affect adventitious bud or root regeneration in vitro.
• Mechanisms underlying the effects of cyclophysis and topophysis in adventitious bud or root formation in woody plants.
• The role of DNA methylation, histone modification, and chromatin remodelling in plant regeneration.
• Regulatory mechanisms controlling adventitious bud or root formation in vitro.

Please note: Descriptive studies that report promoting the regeneration of plant organs will not be considered if they do not progress physiological understanding of these responses.