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Zhang L.,Henan Normal University | Zhang L.,Engineering Laboratory of Green Medicinal Material Biotechnology | Wang T.,Henan Normal University | Zheng F.,Henan Normal University | And 3 more authors.
Ecotoxicology and Environmental Safety | Year: 2016

The toxic effects of ionic liquids (ILs) have attracted increasing attention in recent years. However, the knowledge about the toxic effects of ILs on tropism in organisms remains quite limited. In this study, the effects of 1-hexyl-3-methylimidazolium bromide [C6mim]Br on root gravitropism were evaluated using Arabidopsis seedlings. Our results showed that the root growth and gravity response were significantly inhibited with increasing IL concentration. [C6mim]Br treatment affected the amount and distribution pattern of amyloplasts in root cap compared with controls. The auxin distribution marked with DR5rev::VENUS was altered in IL-treated seedlings. The signal intensity and gene expression of auxin efflux carriers PIN2 and PIN3 were obviously decreased by IL stress. Moreover, as consequences in response to gravity stimulus, the asymmetric DR5 signals in control root apex were impaired by IL treatment. The predominant PIN2 signals along the lower flank of root and PIN3 polarization in columella cells were also significantly reduced in seedlings exposed to IL. Our results suggest that the ionic liquid [C6mim]Br affects the amount and distribution of amyloplasts and disturbs the deployment of PIN2 and PIN3, thus impairing auxin flows in response to gravity stimulus and causing deficient root gravitropism in Arabidopsis seedlings. © 2015 Elsevier Inc. Source


Zhang L.,Henan Normal University | Zhang L.,Engineering Laboratory of Green Medicinal Material Biotechnology | Zheng F.,Henan Normal University | Qi W.,Henan Normal University | And 5 more authors.
Ecotoxicology and Environmental Safety | Year: 2016

Gamma irradiation at low doses can stimulate the tolerance to environmental stress in plants. However, the knowledge regarding the mechanisms underlying the enhanced tolerance induced by low-dose gamma irradiation is far from fully understood. In this study, to investigate the physiological and molecular mechanisms of heat stress alleviated by low-dose gamma irradiation, the Arabidopsis seeds were exposed to a range of doses before subjected to heat treatment. Our results showed that 50-Gy gamma irradiation maximally promoted seedling growth in response to heat stress. The production rate of superoxide radical and contents of hydrogen peroxide and malondialdehyde in the seedlings irradiated with 50-Gy dose under heat stress were significantly lower than those of controls. The activities of antioxidant enzymes, glutathione (GSH) content and proline level in the gamma-irradiated seedlings were significantly increased compared with the controls. Furthermore, transcriptional expression analysis of selected genes revealed that some components related to heat tolerance were stimulated by low-dose gamma irradiation under heat shock. Our results suggest that low-dose gamma irradiation can modulate the physiological responses as well as gene expression related to heat tolerance, thus alleviating the stress damage in Arabidopsis seedlings. © 2016 Elsevier Inc.. Source


Zhang L.,Henan Normal University | Zhang L.,Engineering Laboratory of Green Medicinal Material Biotechnology | Li W.,Henan Normal University | Li W.,Engineering Laboratory of Green Medicinal Material Biotechnology | And 4 more authors.
Plant Growth Regulation | Year: 2015

Membrane fusion between transport vesicles and target membranes is mediated by SNARE complex, a key regulator of vesicular traffic. A functional SNARE complex consists of four coiled-coil helical bundles supplied by Q-SNARE and R-SNARE. Here, we analyze the Arabidopsis R-SNAREs VAMP721 and VAMP722. Reciprocal crosses indicated that the transmission of vamp721vamp722 allele was slightly reduced through gametophytes of VAMP721−/−VAMP722+/− plants and obviously blocked through pollen of VAMP721+/−VAMP722−/− plants. The observation of embryogenesis showed that vamp721vamp722 mutations resulted in abnormal embryo morphology, such as embryos with asymmetric developing cotyledons, three developing cotyledons, unfolded cotyledons and roots, and partial arrested embryo development at globular stage. Moreover, double mutant seedlings grew rudimentary roots displaying reduced meristem zone, disorganized QC cells, and disordered cell layer pattern and cell file alignment. Confocal images revealed that VAMP721 and VAMP722 were expressed throughout whole root. Taken together, our results suggest that VAMP721 and VAMP722 are involved in gametophyte transmission, embryo development and seedling root growth in Arabidopsis. © 2015, Springer Science+Business Media Dordrecht. Source


Li M.,Henan Normal University | Li M.,Henan University | Li M.,Engineering Laboratory of Green Medicinal Material Biotechnology | Li J.,Henan Normal University | And 13 more authors.
Pakistan Journal of Botany | Year: 2015

Dioscorea opposita Thunb. (Chinese yam) is an important tuber crop in East Asia because of its dual benefits edible and medicinal properties. Microtubers may provide a feasible alternative to in-vitro-grown plantlets as a means of micropropagation and a way to exchange healthy planting material. In this study, we have developed a simplified culture method for In vitro production of microtubers from D. opposita cv. ‘Tiegun’. In this method, microtubers formed in 98% of the internodes of single nodal segments after four weeks of dark-incubation when cultured in MS medium supplemented with 60 g sucrose l-1 with shaking. Anatomical observations strongly supported the process of tuberization. We also found that 66% of the microtubers produced In vitro sprouted two months after transfer to vermiculite. The protocol presented here provides a simple model for studying the physiological, biochemical, and molecular mechanisms of tuberization in D. opposita, and shows good potential for large-scale production of microtubers as well. © 2015, Pakistan Botanical Society. All rights reserved. Source

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