Influence of CO₂ and sucrose on photosynthesis and transpiration of Actinidia deliciosa explants cultured in vitro

Abstract

Explants of Actinidia deliciosa Chev. Liang and Ferguson var. Hayward were cultured in controlled CO2 atmospheres in the presence of different sucrose concentrations. Organogenesis was measured after 45 days in explants from the different assays, and quantification of photosynthesis, transpiration, chlorophylls, RUBISCO and total soluble protein content was performed in leaves from the different treatments. The best results were those of explants cultured at 600 &mgr;mol CO2 mol-1 on 20 g l-1 of sucrose for the first 20 days and then transferred to sucrose-free medium until the end of the culture period. Increasing CO2 to 2000 &mgr;mol CO2 mol-1 in the atmosphere of the culture vessel reduced all the parameters studied. Photosynthesis of autotrophically developed explants trebled that of the reference heterotrophic explants, as there was an apparent inverse relationship between photosynthesis and transpiration. Photosynthesis was saturated at 300 &mgr;mol m-2 s-1 PPFD and 600 &mgr;mol CO2 mol-1. Chlorophylls and RUBISCO presented differences between treatments, mainly between different CO2 concentrations, with the highest values in autotrophically cultured explants. Explants grown at 2000 &mgr;mol CO2 mol-1 showed the lowest RUBISCO/Prots ratio, probably due to negative adaptation of RUBISCO to long-term high CO2. In short, explants grown in a controlled microenvironment, with increased CO2 and under autotrophic conditions, developed wholly functional photosynthetic apparatus well prepared to be transferred to ex vitro conditions, which has many advantages in micropropagation.

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

“…One of the most important problems is the poor survival of plantlets following ex vitro transfer, during acclimatization to greenhouse or field conditions (Pospíšilová et al, 1999). This problem originates from the poor development of photosynthetic capacity in vitro, which has been attributed to the presence of sugar in the medium (Kozai, 1991a;Pospíšilová et al, 1992;Arigita et al, 2002), low light and inadequate CO 2 supply (Kozai and Iwanami, 1988;De et al, 1993), and poor control of water loss caused by high relative humidity (RH) within the vessel (Desjardins, 1995;Estrada-Luna et al, 2001). These conditions can ultimately influence plant development and photosynthetic performance ex vitro (Kozai, 1991b;Preece and Sutter, 1991).…”

Multiplicação fotoautotrófica de mirtilo através do uso de luz natural

“…A maioria dos fatores relacionados ao custo de produção das plantas micropropagadas está direta ou indiretamente ligada à natureza heterotrófica ou fotomixotrófica de crescimento das plantas na micropropagação convencional (Kozai & Kubota, 2001), onde os explantes são cultivados em frascos sem que ocorra troca gasosa, com alta umidade relativa do ar, alta concentração de etileno, baixa concentração de CO 2 , baixa densidade de fluxo de fótons fotossintéticos e com sacarose como maior fonte de energia metabólica (Arigita et al, 2002). Explantes desenvolvidos sob este regime heterotrófico originam plantas com elevado conteúdo de água, com grande risco de desidratação e morte durante a aclimatização (Kubota & Kozai, 1992) ou com desordens anatômicas e fisiológicas que não possibilitam que a maquinaria fotossintética opere normalmente (Arigita et al, 2002).…”

“…Explantes desenvolvidos sob este regime heterotrófico originam plantas com elevado conteúdo de água, com grande risco de desidratação e morte durante a aclimatização (Kubota & Kozai, 1992) ou com desordens anatômicas e fisiológicas que não possibilitam que a maquinaria fotossintética opere normalmente (Arigita et al, 2002). No entanto, muitos explantes ou plantas in vitro possuem a habilidade de se desenvolver de forma fotoautotrófica, sem sacarose no meio de cultura e sob condições ambientais que promovam a fotossíntese (Kozai, 1991).…”

<b>Growth and photosynthetic responses during <i>ex vitro</i> acclimatization of <i>Etlingera elatior</i> (Jack) rm smith (torch ginger)

“…Due to the competitive nature of the market and demands of producers and consumers, recent research has focused on the development of healthy plants with phytosanitary control using in vitro propagation techniques (COLOMBO et al, 2010;LIMA-BRITO et al, 2011;PÊGO et al, 2013 physiological phenotypic changes during propagation and require an acclimatization period (ARIGITA et al, 2002;KUBOTA;KOZAI, 1992;SANTANA et al, 2011a). However, the special environmental conditions inside the culture vessels and heterotrophic nutrition may generate anomalies at both anatomical and functional levels, such as hyperhydricity, poor water loss control, low photosynthesis, difficulty rooting and low functionality, in plants propagated using in vitro techniques (BADR;DESJARDINS, 2007;SANTANA et al, 2011b).…”