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Different techniques have been suggested to protect plants from environmental stress. Therefore, new techniques should be developed to produce salt-resistant genotypes. Selection and improvement of desirable genotypes for this objective require suitable screening methods. Tissue culture can help in the efforts to produce new cultivars against environmental stress factors. In addition, in vitro culture studies permit relatively faster responses, shorter generation time, and regular environmental conditions as compared to classical breeding methods (Zhao et al., 2009;Elmaghrabi et al., 2013). A high level of salt in soil or in tissue culture may lead to numerous genetic and biochemical changes, causing problems such as limitation in mineral nutrient uptake, nutritional imbalance, mineral deficiency, osmotic stress, ion toxicity, and oxidative stress (Rozema and Flower, 2008;Rahnama et al., 2010;James et al., 2011). It has been reported that oxidative and osmotic stresses affect the cellular membrane integrity, enzyme activity, DNA, and chlorophyll content (Lokhande et al., 2010), which inhibits the functioning of most plant species.Proline is the most common metabolite that accumulates in response to salinity stress, shown to serve as a main osmotic regulator, and was reported in various plant species (Koca et al., 2007). The role of proline accumulation in plants' osmotic regulation is still unclear (Koskeroglu and Tuna, 2010). Soluble sugar is known to commonly accumulate in higher plants against salinity stress, which could play a role in osmotic protection (Khedr, 2003). Salt stress usually inhibits the plant growth. When plants are exposed to different abiotic stresses, some reactive oxygen species (ROS) removing enzymes such as superoxide dismutase (SOD), peroxidase (POD), ascorbate peroxidase (APX), and catalase (CAT) are produced (Li and Staden, 1998). The antioxidant enzyme activity is positively associated with salt tolerance in plants (Lokhande et al., 2011). Many researchers have indicated that the salt resistance mechanism is activated during the entire plant stage and this has been tested in both in vitro and ex vitro situations (Watanabe et al., 2000; Troncoso et al., 2002). A close relationship between physiological changes and callus cultures by salt stress has been previously reported in different genotypes (Piwowarczyk et al., 2016).

Key message Ca 2+ NPs enhanced tolerance of Triticale callus under salt stress by improving biochemical activity and confocal laser scanning analysis, conferring salt tolerance on callus cells. Abstract CaO NPs (Ca 2+ ) are significant components that act as transducers in many adaptive and developmental processes in plants. In this study, effect of Ca 2+ NPs on the response and regulation of the protective system in Triticale callus under short and long-salt treatments was investigated. The activation of Ca 2+ NPs was induced by salt stress in callus of Triticale cultivars. MDA, H 2 O 2 , POD, and protein activities were determined in callus tissues. Concerning MDA, H 2 O 2 , protein activities, it was found that the Ca 2+ NPs treatment was significant, and it demonstrated a high correlation with the tolerance levels of cultivars. Tatlıcak cultivar was detected for better MDA activities in the short time with 1.5 ppm Ca 2+ NPs concentration of 50 g and 100 g NaCl. Similarly, the same cultivar responded with better H 2 O 2 activity at 1.5 ppm Ca 2+ NPs 100 g NaCl in the short time. POD activities exhibited a decreasing trend in response to the increasing concentrations of Ca 2+ NPs. The best result was observed at 1.5 ppm Ca 2+ NPs 100 g NaCl in the short term. Based on the protein content, treatment of short-term cultured callus cells with 1.5 ppm Ca 2+ NPs inhibited stress response and it significantly promoted Ca 2+ NPs signals as compared to control callus. Confocal laser scanning analysis proved that the application of Ca 2+ NPs could alleviate the adverse effects of salt stress by the inhibition of stress severity in callus cells. This study demonstrated, under in vitro conditions, that the application of Ca 2+ NPs can significantly suppress the adverse effects of salt stress on Triticale callus; it was also verified that the concentration of Ca 2+ NPs could be important parameter to be considered in adjusting the micronutrient content in the media for this plant.

Aulacaspis yasumatsui Takagi continues to threaten the extinction of the endemic and endangered Cycas taitungensis (Shen et al.) in Taiwan. Failure to understand its population demographic parameters in detail will continue to hinder the success of pest management practices. An in-depth knowledge of the development, survival, and fecundity of A. yasumatsui under different environmental conditions is necessary to understand its' population growth. The demography of A. yasumatsui was studied in the laboratory based on the age-stage, two-sex life table at 20, 23, 25, 28, and 31 degrees C, 70% relative humidity, and a photoperiod of 16:8 (L:D) h. The intrinsic rate of increase (r) under these temperatures was 0.06, 0.07, 0.09, 0.10, and 0.08 d(-1), respectively. The net reproductive rate (R0) was 46.27, 47.78, 69.50, 96.08, and 56.65 offsprings per individual and the mean generation time (T) was 65.60, 55.81, 47.82, 44.15, and 51.42 d, respectively. A. yasumatsui does well at warmer temperatures (25-28 degrees C); however, its performance is disrupted at lower temperatures. This study provides insight on how to minimize growth and destruction of A. yasumatsui and conservation of Cy. taitungensis; new cycad reserves should be set up in cooler areas in Taiwan.

Oriental melon (Cucumis melo L. var. makuwa) is an important fruit for human consumption. However, this plant species is one of the most recalcitrant to genetic transformation. The lack of an efficient in vitro system limits the development of a reproducible genetic transformation protocol for Oriental melon. In this study, an efficient transgenic production method for Agrobacterium-mediated transformation using cotyledon explants of Oriental melon was developed. Cotyledon explants were pre-cultivated for two days in the dark, and the optimal conditions for transformation of melon were determined to be a bacteria concentration of OD600 0.6, inoculation for 30 min, and two days of co-cultivation. Transgenic melon plants were produced from kanamycin-resistant shoots. A total of 11 independent transgenic plants were regenerated with a transformation efficiency of 0.8% of the inoculated explants. The transgenic plants were phenotypically normal and fully fertile, which might be a consequence of the co-cultivation time.