Preliminary studies on plants regenerated from endosperm-derived callus of kiwifruit (Actinidia deliciosa var. deliciosa)

To show differences between plants of Actinidia deliciosa var. deliciosa regenerated from endosperm-derived callus (with 3C amounts of DNA) and those obtained from seeds, observation of their stomata and leaf hairs density was carried out. Stomata and leaf hairs are the features which are often related to ploidy status of plants. Our observation revealed that for plants, which represents 3C DNA level, stomata density was higher than for plantlets showing 2C DNA content. Additionally, density of leaf hairs seems to be also higher in regenerants. This is the first morpho-histological studies of plants regenerated from kiwifruits endosperm tissue

Extracellular matrix and wall composition are diverse in the organogenic and non‑organogenic calli of Actinidia arguta

Key message Differences in the composition and the structural organisation of the extracellular matrix correlate with the morphogenic competence of the callus tissue that originated from the isolated endosperm of kiwifruit. Abstract The chemical composition and structural organisation of the extracellular matrix, including the cell wall and the layer on its surface, may correspond with the morphogenic competence of a tissue. In the presented study, this relationship was found in the callus tissue that had been differentiated from the isolated endosperm of the kiwiberry, Actinidia arguta. The experimental system was based on callus samples of exactly the same age that had originated from an isolated endosperm but were cultured under controlled conditions promoting either an organogenic or a non-organogenic pathway. The analyses which were performed using bright field, fluorescence and scanning electron microscopy techniques showed significant differences between the two types of calli. The organogenic tissue was compact and the outer walls of the peripheral cells were covered with granular structures. The non-organogenic tissue was composed of loosely attached cells, which were connected via a net-like structure. The extracellular matrices from both the non- and organogenic tissues were abundant in pectic homogalacturonan and extensins (LM19, LM20, JIM11, JIM12 and JIM20 epitopes), but the epitopes that are characteristic for rhamnogalacturonan I (LM5 and LM6), hemicellulose (LM25) and the arabinogalactan protein (LM2) were detected only in the non-organogenic callus. Moreover, we report the epitopes, which presence is characteristic for the Actinidia endosperm (LM21 and LM25, heteromannan and xyloglucan) and for the endosperm-derived cells that undergo dedifferentiation (loss of LM21 and LM25; appearance or increase in the content of LM5, LM6, LM19, JIM11, JIM12, JIM20, JIM8 and JIM16 epitopes)

Application of photochemical parameters and several indices based on phenotypical traits to assess intraspecific variation of oat (Avena sativa L.) tolerance to drought

Functionality of the photosynthetic system under water stress is of major importance in drought tolerance. Oat (Avena sativa L.) doubled haploid (DH) lines obtained by pollination of F_{1} oat crosses with maize were used to assess the differences in plant genotypic response to soil drought. The investigations were based on the measurements of gas exchange and chlorophyll a fluorescence kinetics. Drought was applied to 17-day-old seedlings by withholding water for 14 days and subsequent plant recovery. Non-stressed optimally watered plants served as controls. Yield components were determined when plants reached full maturity. It was shown differences among the oat lines with respect to drought stress susceptibility (SI) and stress tolerance index mean productivity and drought susceptibility index. Sensitivity to drought of individual DH lines was significantly different, as demonstrated by the correlation between drought susceptibility index and yield components, such as dry weight (GW) or grain number (GN) of the harvested plants. GW and GN were lower in drought-sensitive genotypes exposed to drought stress compared to those resistant to drought. The principal component analysis allow to separate three groups of lines differing in their sensitivity to drought stress and indicated that tolerance to drought in oat has a common genetic background

Rooting affects the photosystem II activity : in vitro and ex vitro studies on energy hybrid sorrel

Rumex tianschanicus x Rumex patientia is a high-biomass-yielding plant suitable for fuel and biogas production. The protocol of the hybrid sorrel micropropagation was used to study the changes in the photosystem II (PSII) activity as well as to analyse the ultrastructure of the chloroplasts. The lowest effective PSII quantum yield [Y(II)] and an apparent electron transport rate of PSII [ETR(II)] were observed for adventitious shoots that had been regenerated in vitro, before rooting. These fluorescence parameters were higher and similar for both the leaves of the same adventitious shoots that had been rooted under in vitro conditions and for the shoots that had been acclimated and grown in ex vitro conditions. The analysis indicated that the PSII activity strongly depends on the formation of properly functioning roots and that in vitro or ex vitro culture conditions are, at least to some degree, less important. TEM analysis revealed that chloroplasts from plants rooted in vitro were sufficiently mature and acclimatization processes have less impact on their devel- opment. This is the first report concerning the analysis of PSII activity and the ultrastructure of the chloroplasts at all of the stages of micropropagation, i.e. adventitious shoot formation in vitro, rooting in vitro and acclimation to ex vitro conditions. It strongly indicated that rooting under in vitro conditions, rather than the acclimation to ex vitro conditions, plays a key role in the development of a completely functional photosynthetic apparatus in hybrid sorrel

The dynamics of cytokinin changes after grafting of vegetative apices on flowering rapeseed plants

Despite numerous studies, the role of hormones in the induction of shoot apical meristem leading to reproductive development, especially regarding thermoperiodic plants, is still not fully understood. The key problem is separating the effects of the low temperature required for vernalization from those responsible for low temperature stress. An earlier experiment demonstrated the correlation between an increase of cytokinin level in the apical parts of winter rapeseed and the transition time into their reproductive phase during vernalization, i.e., low temperature treatment. From data obtained from the presented experiments, this study aims to contribute to the understanding the role of cytokinins in the induction of flowering based on the grafting of vegetative apical parts of winter rapeseed (scion) on the reproductive (stock) winter and spring genotypes. On the basis of analyses carried out using ultra-high-performance liquid chromatography coupled with tandem mass spectrometry in combination with microscopic observation of changes at the apical meristem, it was indicated that the increase in the amount of trans-zeatin and trans- and cis-zeatin-O-glucoside derivatives appeared in the early stages of apex floral differentiation. During further development, the content of all investigated cytokinins passed through the maximum level followed by their decrease. The final level in reproductive apices was found to be higher than that in vegetative ones