Photosynthetic and carbohydrate status of easy-and difficult-to-acclimatize sea oats (Uniola paniculata L.) genotypes during In vitro culture and Ex vitro acclimatization

Abstract

SummaryThe photosynthetic and carbohydrate status of an easy-to-acclimatize (EK 16-3) and a difficult-to-acclimatize (EK 11-1) genotype of Uniola paniculata L. (sea oats), a native dune species of the southeastern US, were evaluated during in vitro culture and ex vitro acclimatization. Net photosynthetic rate was eight times greater for EK 16-3 than EK 11-1 plantlets after ex vitro transfer. In vitro-produced leaves were morphologically similar to ex vitro-produced leaves and exhibited similar photosynthetic competence. EK 11-1 plantlets exhibited greater transpiration rates at the time of ex vitro transfer than EK 16-3 plantlets. However, the small magnitude of this difference, although significant, indicated that control of water loss was probably not the main cause for poor acclimatization of EK 11-1 plantlets. Carbohydrate analysis in vitro revealed that EK 16-3 plantlets utilized leaf starch reserves more rapidly than EK 11-1 plantlets. Starch utilization correlated with the development of leaves with expanded leaf blades during in vitro rooting in EK 16-3 plantlets. After ex vitro transfer, both genotypes exhibited significant decreases of starch and soluble sugar content in shoots and roots. However, the higher photosynthetic ability of shoots in EK 16-3 resulted in greater accumulation of shoot soluble sugars than EK 11-1 after 2-wk ex vitro culture. After 6-wk in vitro rooting, there were significantly higher chlorophyll and soluble protein contents, ribulose 1,5-bisphosphate carboxylase (rubisco) and phosphoenolpyruvate carboxylase activities in EK 16-3 than EK 11-1 shoots. These differences also correlated with the development of anatomical and morphological leaf features in EK 16-3 similar to those of greenhouse-produced leaves.

Influence of in vitro growth conditions on in vitro and ex vitro photosynthetic rates of easy- and difficult-to-acclimatize sea oats (Uniola paniculata L.) genotypes

“…With sea oats genotypes such as EK 16-3, we observed that the development of elongated leaves with fully expanded blades produced in vitro was critical to shoot establishment ex vitro. We have observed this response in previous studies (Valero-Aracama et al, 2006). EK 16-3 plantlets cultured in vitro under control conditions had greater photosynthetic capacity at the time of ex vitro transfer than EK 11-1 control plantlets as indicated by their initial P nl ex vitro.…”

The possibilities and challenges of in vitro methods for plant conservation

“…The identification of genotypes differing in responses is particularly useful. For example, easy-and difficultto-acclimatise genotypes of Uniola paniculata L. have been used to study physiological factors correlated with acclimatisation (Valero- Aracama et al 2006;Aracama et al 2008). Continued physiological, developmental and morphological research directed at the responses needed for in vitro propagation and preservation can only improve the usefulness of these methods.…”

Photochemical Efficiency during the Establishment and Consolidation Phases of in Vitro Pinus radiata Micrograft Made from Scions of Different Ontogenetic Age

“…Only during the first day of in vitro introduction, a decrease in Fv/Fm was observed in basal scions (P = 0.01; Figure 3). Such small Fv/Fm reduction could be attributable to the physiological stress imposed by the excision from ortet, and then the in vitro introduction [39] [40]. Despite this, we find a fast scions Fv/Fm recovery, due to the in vitro culture conditions, which also exert the surpass of Fv/Fm values measured in the ortet Figure 2.…”