Hydrogen peroxide mediates high-intensity blue light-induced hypocotyl phototropism of cotton seedlings

Phototropism is a classic adaptive growth response that helps plants to enhance light capture for photosynthesis.It was shown that hydrogen peroxide(H_(2)O_(2))participates in the regulation of blue light-induced hypocotyl phototropism;however,the underlying mechanism is unclear.In this study,we demonstrate that the unilateral high-intensity blue light(HBL)could induce asymmetric distribution of H_(2)O_(2) in cotton hypocotyls.Disruption of the HBL-induced asymmetric distribution of H_(2)O_(2) by applying either H_(2)O_(2) itself evenly on the hypocotyls or H_(2)O_(2) scavengers on the lit side of hypocotyls could efficiently inhibit hypocotyl phototropic growth.Consistently,application of H_(2)O_(2) on the shaded and lit sides of the hypocotyls led to reduced and enhanced hypocotyl phototropism,respectively.Further,we show that H_(2)O_(2) inhibits hypocotyl elongation of cotton seedlings,thus supporting the repressive role of H_(2)O_(2) in HBL-induced hypocotyl phototropism.Moreover,our results show that H_(2)O_(2) interferes with HBL-induced asymmetric distribution of auxin in the cotton hypocotyls.Taken together,our study uncovers that H_(2)O_(2) changes the asymmetric accumulation of auxin and inhibits hypocotyl cell elongation,thus mediating HBL-induced hypocotyl phototropism.

Quantitative contrast of urban agglomeration colors based on image clustering algorithm:Case study of the Xia-Zhang-Quan metropolitan area

Color is an important element to consider when shaping urban characteristics.However,previous studies seldom included quantitative analyses of color relationships between urban agglomerations within proximal regions and with similar cultures to distinguish and shape individual urban personalities.This study focused on Xiamen,Zhangzhou,and Quanzhou metropolitan areas,which are influenced by Minnan culture,and collected natural and cultural landscape network images that collectively represent the urban landscape in China.Color extraction,computer vision processing technologies,and clustering algorithms,such as k-means partitioning,hierarchical methods,and co-occurrence frequency,were applied using image recognition.We then established an urban color database and quantified color attributes.Finally,we conducted a comparative analysis of dominant colors and color combination associations in Xiamen,Zhangzhou,and Quanzhou metropolitan areas to explore their similarities and differences and define their characteristics.We also considered other cities of the same type for comparison.