Regeneration of Pinus halepensis (Mill.) through Organogenesis from Apical Shoot Buds

Cátia Pereira,Nina Bogdanchikova,Jorge Canhoto,Jéssica Tavares,Ana Pedrosa,Paloma Moncaleán,Alexey Pestryakov,Itziar A Montalbán

doi:10.3390/f12030363

Abstract

Organogenesis and somatic embryogenesis have been widely applied as the two main regeneration pathways in plant tissue cultures. However, recalcitrance is still the main restriction in the clonal propagation of many woody species, especially in conifers. They undergo a “phase change” that leads to significant loss of vegetative propagation capacity, reducing the aptitude of tissues and organs to be regenerated in vitro beyond this point. In line with this, the in vitro regeneration of mature conifer trees has been a long-cherished goal in many laboratories worldwide. Based on previous works in Pinus species regeneration from adult trees, we now present data about the culture of apical shoot buds in an attempt to induce organogenesis and somatic embryogenesis to clone mature trees of Aleppo pine (Pinus halepensis). Reinvigorated axillary shoots were submitted to conditions usually applied to induce somatic embryogenesis through the manipulation of culture media, including the use of auxins such as 2,4-Dichlorophenoxyacetic acid and 1-Naphthaleneacetic acid, cytokinins (6-benzyladenine and kinetin), and phytosulfokine (50, 100, and 200 nM). Although somatic embryos could not be obtained, an embryogenic-like tissue was produced, followed by the emergence of actively proliferating non-embryogenic calli. Variations in the consistence, texture, and color of non-embryogenic calli were observed; especially those arising in the media containing phytosulfokine. Reinvigorated shoots, induced by 22 or 44 µM 6-benzyladenine, were obtained through organogenesis and acclimatized, and phenotypically normal plants were obtained.

Highlights

Introduction iationsApproximately 52% of the land surface is occupied by forests [1]
Higher numbers of explants forming shoots (EFS) (%) and the number of shoots formed per explant (NS/E) were obtained from explants cultured in the induction medium supplemented with
Silver nanoparticles are quite effective at controlling physiochemical changes, preventing bacterial infections, and actively blocking ethylene through the release of silver ions, which could improve the induction of explants

Summary

Introduction

52% of the land surface is occupied by forests [1]. In vitro propagation techniques have been widely applied as a model system for plant regeneration analysis and as a large-scale propagation system for coniferous cloning [2,3]. Aleppo Pine (Pinus halepensis Mill.) is native to the Mediterranean region, thriving in the driest and warmest areas due to its tolerance to high temperatures and drought stress [4,5], which makes it a potential alternative for reforestation in the climate change scenarios predicted for large areas of the globe in the near future [6,7]. Multicellular organisms harbor multiple types of tissues, each consisting of cells with particular features and functions. In some cases, cell specificity can be totally

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