THE EFFECT OF HEAT STRESS ON HYPERHYDRICITY AND GUAIACOL PEROXIDASE ACTIVITY (GPOX) AT THE FOLIAR LAMINA OF SEDUM TELEPHIUM L. SSP. MAXIMUM (L.) KROCK. VITROPLANTLETS
Journal Title: Analele Stiintifice ale Universitatii Alexandru Ioan Cuza din Iasi, Serie noua, Sectiunea II a. Biologie vegetala - Year 2014, Vol 60, Issue 2
Abstract
Heat stress causes an array of physiological, biochemical and morphological changes in plants, affecting plant growth and development. In order to confirm the connection between oxidative stress in plants and hyperhydricity (vitrification), we used a Sedum telephium ssp. maximum plant as a test material. The changes of the antioxidant enzyme guaiacol peroxidase (GPOX) activity in in vitro Sedum plantlets were studied under increased temperatures and compared with in vitro plantlets kept at 21ºC as the control. The results showed that the highest activity of GPOX was in response to heat stress of 41°C on day 10 after treatment (102,32 UI/mL), compared with the control where the GPOX activity remained unchanged (38,1 UI/mL) until the end of the experiment (40 days). In case of plants subjected to heat stress starting from the first days of vitroculture, the vitrification process has begun and with increasing of GPOX activity, vitrification was becoming more intense. However, the vitroplantlets grown for 40 days under constant temperature showed no signs of vitrification. Cytological studies of the hyperhydric foliar lamina were also performed at the end of 40 days of the experiment. Microscopic studies have shown that the hyperhydric mesophyll cells of S. telephium ssp. maximum are in a process of necrosis, disorganization, extremely low on cytoplasm, have an imploded cellular content and big gaps between them. The results from this study suggest that the heat stress plays a role in triggering the vitrification process in the in vitro micropropagated plants.
Authors and Affiliations
MIRELA ARDELEAN, DORINA CACHIŢĂ-COSMA, AUREL ARDELEAN, CALIN LADAŞIU, VALENTIN MIHALI
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