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SO2/H2SO3 can damage plants. However, its toxic mechanism has still been controversial. Two models have been proposed, cytosolic acidification model and cellular oxidation model. Here, we assessed the toxic mechanism of H2SO3 in three cell types of Arabidopsis thaliana , mesophyll cells, guard cells (GCs), and petal cells. The sensitivity of GCs of Chloride channel a (CLC a)-knockout mutants to H2SO3 was significantly lower than those of wildtype plants. Expression of other CLC genes in mesophyll cells and petal cells were different from GCs. Treatment with antioxidant, disodium 4,5-dihydroxy-1,3-benzenedisulfonate (tiron), increased the median lethal concentration (LC50) of H2SO3 in GCs indicating the involvement of cellular oxidation, while the effect was negligible in mesophyll cells and petal cells. These results indicate that there are two toxic mechanisms of SO2 to Arabidopsis cells: cytosolic acidification and cellular oxidation, and the toxic mechanism may vary among cell types. [ABSTRACT FROM AUTHOR]

Dihydroxyacetone (DHA) occurs in wide-ranging organisms, including plants, and can undergo spontaneous conversion to methylglyoxal (MG). While the toxicity of MG to plants is well-known, the toxicity of DHA to plants remains to be elucidated. We investigated the effects of DHA and MG on Arabidopsis. Exogenous DHA at up to 10 mm did not affect the radicle emergence, the expansion of green cotyledons, the seedling growth, or the activity of glyoxalase II, while DHA at 10 mm inhibited the root elongation and increased the activity of glyoxalase I. Exogenous MG at 1.0 mm inhibited these physiological responses and increased both activities. Dihydroxyacetone at 10 mm increased the MG content in the roots. These results indicate that DHA is not so toxic as MG in Arabidopsis seeds and seedlings and suggest that the toxic effect of DHA at high concentrations is attributed to MG accumulation by the conversion to MG. Is dihydroxyacetone toxic in Arabidopsis? [ABSTRACT FROM AUTHOR]

SUMMARY: The depletion of cellular zinc (Zn) adversely affects plant growth. Plants have adaptation mechanisms for Zn‐deficient conditions, inhibiting growth through the action of transcription factors and metal transporters. We previously identified three defensin‐like (DEFL) proteins (DEFL203, DEFL206 and DEFL208) that were induced in Arabidopsis thaliana roots under Zn‐depleted conditions. DEFLs are small cysteine‐rich peptides involved in defense responses, development and excess metal stress in plants. However, the functions of DEFLs in the Zn‐deficiency response are largely unknown. Here, phylogenetic tree analysis revealed that seven DEFLs (DEFL202–DEFL208) were categorized into one subgroup. Among the seven DEFLs, the transcripts of five (not DEFL204 and DEFL205) were upregulated by Zn deficiency, consistent with the presence of cis‐elements for basic‐region leucine‐zipper 19 (bZIP19) or bZIP23 in their promoter regions. Microscopic observation of GFP‐tagged DEFL203 showed that DEFL203‐sGFP was localized to the apoplast and plasma membrane. Whereas a single mutation of the DEFL202 or DEFL203 genes only slightly affected root growth, defl202 defl203 double mutants showed enhanced root growth under all growth conditions. We also showed that the size of the root meristem was increased in the double mutants compared with the wild type. Our results suggest that DEFL202 and DEFL203 are redundantly involved in the inhibition of root growth under Zn‐deficient conditions through a reduction in root meristem length and cell number. Significance Statement: Defensins are small cysteine‐rich peptides, and a plant genome contains a large number of defensin‐like (DEFL) genes; however, their function remains unclear. Here, we showed that five DEFL genes were upregulated in roots under Zn‐depleted conditions, and that DEFL202 and DEFL203 might function as inhibitors of root growth by modulating root meristem length and cell number. [ABSTRACT FROM AUTHOR]

Central to student learning and academic success, the school engagement of immigrant children also reflects their adaptation to a primary institution in their new country. Analysis of questionnaire responses of 276,165 fifteen-year-olds (50% female) and their 10,789 school principals in 41 countries showed that school engagement has distinct, weakly-linked cognitive and emotional components. Native students had weaker attitudes toward school (cognitive engagement) but greater sense of belonging at school (emotional engagement) than immigrant students or students who spoke a foreign language at home. Students with better teacher-student relationships, teacher support or a classroom disciplinary climate often had a greater sense of belonging at school and had better attitudes toward school than other students. While immigrant students often have solid attitudes toward school, teachers can help them feel a greater sense of belonging at school. (Contains 4 tables and 2 figures.)

Prodigious growth in out-of-school, private educational activities meant to supplement formal schooling is observed worldwide. Why has shadow education expanded, and what does it mean for the future of education in postmodern society? Illustrated by the historical development and recent changes in the Japanese shadow education industry, it is suggested that shadow education follows the institutional logic of formal education. And as this logic has become more homogenized and expansive globally, so have the forms and goals of shadow education. Because of its focus on learning and achievement, which are central to formal education, it is predicted that shadow education will be increasingly incorporated into the broader culture of education. (Contains 1 table, 1 figure, and 11 footnotes.)