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New Mexico State University (2010)

In vitro clonal propagation of arid rangeland species

Reyes-Vera, Isaac

Titre : In vitro clonal propagation of arid rangeland species

Auteur : Reyes-Vera, Isaac

Université de soutenance : New Mexico State University

Grade Doctor of Philosophy (PhD) 2010

Atriplex canescens, A. griffithsii and Sporobulus cryptandrus are representative species of the major vegetation types in plant communities in the Chihuahuan desert, and are significantly ecological and economically. Plant tissue culture technology allows for clonal mass propagation of elite genotypes of desirable species for revegetation, restoration, and reclamation. These valuable species of native shrubs and grasses currently require efficient plant regeneration protocols. The aim of this research was to apply in vitro plant clonal propagation procedures to A. canescens, A. griffithsii and S. cryptandrus to test their regeneration potential. In vitro propagation of A. canescens exhibited severe symptoms of hyperhydricity. The restoration of hyperhydric A. canescens shoots to normal shoots was achieved using a modified culture medium formulation with vented closures. Resulting normal shoots also showed significant improvements in rooting in vitro, transplantation to soil, and survival. Anatomical differences among tissues of germinated seedlings, restored and hyperhydric in vitro cultured A. canescens shoots were compared. While control plants and restored shoots tissue showed anatomically normal differentiation of palisade and spongy parenchyma, and abundance of starch-filled chloroplasts, hyperhydric shoots lacked differentiation between palisade and spongy parenchyma. An in vitro propagation protocol using an axillary branching propagation strategy was developed for A. griffithsii. Shoot propagation was most successful using woody plant medium (WPM) amended with indole 3-acetic acid and 6-(γ-γ-dimethylallylamino) purine, resulting in a two-fold number level of shoots. Roots were induced by using hormone-free WMP medium, resulting in rooting of 55%, which when transplanted resulted in 80% establishment. Sporobulus cryptandrus was regenerated from long-term cultured calluses maintained on Schenk and Hildebrandt solid medium amended with BAP and PIC for one year. Adventitious shoot proliferation was greatest on 0.05 or 0.1 mg/L of either BAP or 2iP. Generated shoots rooted readily after transfer to an auxin-free medium, grew into intact plants and were established in soil with a survival of 85%. Mass micropropagation of Atriplex canescens, Atriplex griffithsii and Sporobulus cryptandrus resulting in the production of intact plantlets was accomplished. These regeneration systems can improve Atriplex species, and contribute to a better understanding of the basic biology of these species.

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