BARE1andBAGY2Retrotransposon Movements and Expression Analyses in Developing Barley Seedlings

Neonicotinoid insecticides exert diverse cytotoxic and genotoxic effects on cultivated sunflower

Contamination with neonicotinoids is a global problem affecting environment and target and non-target organisms including plants. The present study explored the potential genotoxic and cytotoxic effects of the insecticides Actara 25 WD and Nuprid 200 SL containing the active substances thiamethoxam (TMX) and imidacloprid (IMI), respectively, on cultivated sunflower (Helianthus annuus L.). The half maximal effective concentration (½EC₅₀) of the tested substances was calculated using a dose-response inhibition analysis of the growth of plant roots relative to the corresponding controls. Application of approximately ½EC₅₀ or higher TMX doses significantly increased the antioxidant activity in sunflower leaves, whereas IMI led to a significant decrease in root antioxidant capacity, indicating organ-specific insecticide effects on sunflower plants. Even low doses (½EC₅₀) of the studied neonicotinoids led to irregularities in mitotic phases and abnormalities in the cytokinesis and chromosome segregation, such as bridges, laggards, stickiness, and C-mitosis. Genotoxic effects manifested by a dose-independent induction of primary DNA damages and retrotransposon dynamics were also observed. The used set of physiological, biochemical, and genetic traits provides new information about the organ-specific effects of neonicotinoids in sunflower plants and elaborates on the complexity of mechanisms underpinning these effects that include DNA damages, cytokinesis defects, and genome instability.

Physiological and molecular changes in barley and wheat under salinity

In this study, it was aimed to compare salinity-induced changes in barley (Hordeum vulgare L. cv. Bornova-92) and bread wheat (Triticum aestivum L. cv. Gerek-79). Seeds were germinated under saline conditions (0, 50, 100, 250, and 500 mM NaCl) for 2 days and recovered under non-saline conditions for 2 days. At the end of the salt treatment, germination, water content (WC), total soluble protein content, and catalase (CAT, EC 1.11.1.6) activity were affected in both species, while superoxide dismutase (SOD, EC 1.15.1.1) activity was affected in barley. Salinity affected WC, protein content, and CAT activity in both species, while it affected germination in barley and affected fresh weight and SOD activity in wheat after recovery. Physiological responses of both species were correlated. Expression of α-tubulin, Atls1, and Lls1 genes was down-regulated in barley after 250 mM NaCl treatment. HVA1 gene was highly (more than 50-fold) stimulated by salinity in barley. However, α-tubulin and Atls1 genes were down-regulated, and Lls1 gene was up-regulated in wheat after recovery from 250-mM NaCl treatment. Increase in HVA1 expression was not significant in wheat. The expression profiles of barley and wheat under salinity are different, and barley tended to regulate gene expression faster than wheat.

BAGY2 retrotransposon analyses in barley calli cultures and regenerated plantlets

The stability of aging barley calli and regenerated plantlets from those calli was investigated by the BAGY2 retrotransposon-specific IRAP technique. Mature embryos of barley (Hordeum vulgare cv. Golden Promise) were cultured in Murashige and Skoog medium supplemented with 4 mg/L dicamba and maintained on the same medium for 45 and 90 days. Two IRAP-based primers were used, and the levels of variation of DNA isolated from 45- and 90-day-old calli and regenerated plantlets were found to be increased 0-21%, depending on the mature embryo material and the age of the callus. It has been observed that culture conditions cause genetic variations and evident BAGY2 retrotransposon alterations. Internal domains of BAGY2 were also analyzed by qPCR, and copy numbers were found to be increased. These findings are expected to contribute to understanding of how retrotransposons affect features like tissue culture (especially callus tissue) formation and genetic engineering studies.