Drought is the most significant abiotic stress in agriculture; thus, this area of studies seems to be one of the most important challenges in plant biology. Data about gene expression under drought are crucial to study drought response mechanisms and to select the genes for a transgenic approach. Quantitative RT-PCR is a powerful method for gene expression analysis; however, obtaining proper data normalization requires internal reference genes with stable level of expression. In the present paper ten potential reference genes were examined in two developmental stages of barley for their expression stability during leaf growth and increasing drought level. The results indicated that leaf growth per se affects the expression of studied genes to the similar extent as the drought and showed that different genes were most stably expressed in the seedling and the heading stage. As a result, different sets of reference genes were selected for different applications. For instance, ADP-ribozylation factor 1 and ubiquitin encoding genes were most suitable to study drought-induced changes in gene expression at the seedling stage, whereas actin and GAPDH genes were useful during heading, and ADP-ribozylation factor 1 and HSP90 allowed for the comparison between these two stages. Our data proved the necessity for validation of commonly used reference genes. The results indicate that expression of ADP seems to be the least affected by all the factors studied in the present experiment. However, when the effect of only one factor among those investigated in this work will be studied, different genes should be considered to be used as the references due to the higher stability of their expression.

In the food industry around the world, pulse electric field (PEF) is becoming one of the most popular methods of preserving food products at low temperature. PEF is an excellent alternative to standard food preservation processes (such as high temperature, changing water activity or pH, or adding preservatives), because it does not heat the product and does not lose valuable ingredients, while maintaining the health-promoting nature of food [1]. In turn, health-promoting ingredients in food show a greater ability to ultimately emit photons. Therefore, the level of photon emission in selected soft fruits was examined before and after the impact of the pulse electric field (PEF) on them. The mean values of photons emitted by the product samples were compared and the standard deviation was analyzed. The analysis of the results showed slight differences in the number of photons emitted, both between different types of fruit and between samples of the same fruit (before and after exposure to PEF).