Physiological and molecular bases of the boron deficiency response in tomatoes

Boron is an essential microelement for plant growth.Tomato is one of the most cultivated fruits and vegetables in the world,and boron deficiency severely inhibits its yield and quality.However,the mechanism of tomato in response to boron deficiency remains largely unclear.Here,we investigated the physiological and molecular bases of the boron deficiency response in hydroponically grown tomato seedlings.Boron deficiency repressed the expression of genes associated with nitrogen metabolism,while it induced the expression of genes related to the pentose phosphate pathway,thereby altering carbon flow to provide energy for plants to cope with stress.Boron deficiency increased the accumulation of copper,manganese and iron,thereby maintaining chlorophyll content and photosynthetic efficiency at the early stage of stress.In addition,boron deficiency downregulated the expression of genes involved in cell wall organization and reduced the contents of pectin and cellulose in roots,ultimately retarding root growth.Furthermore,boron deficiency markedly altered phytohormone levels and signaling pathways in roots.The contents of jasmonic acid,jasmonoy1-L-isoleucine,trans-zeatin riboside,abscisic acid,salicylic acid,and SA glucoside were decreased;in contrast,the contents of isopentenyladenine riboside and ethylene precursor 1-aminocyclopropane-1-carboxylic acid were increased in the roots of boron-deficient tomato plants.These results collectively indicate that tomato roots reprogram carbon/nitrogen metabolism,alter cell wall components and modulate phytohormone pathways to survive boron deficiency.This study provides a theoretical basis for further elucidating the adaptive mechanism of tomato in response to boron deficiency.

Elasticity-based-exfoliability measure for high-throughput computational exfoliation of two-dimensional materials

Two-dimensional(2D)materials are promising candidates for uses in next-generation electronic and optoelectronic devices.However,only a few high-quality 2D materials have been mechanically exfoliated to date.One of the critical issues is that the exfoliability of 2D materials from their bulk precursors is unknown.To assess the exfoliability of potential 2D materials from their bulk counterparts,we derived an elasticity-based-exfoliability measure based on an exfoliation mechanics model.The proposed measure has a clear physical meaning and is universally applicable to all material systems.We used this measure to calculate the exfoliability of 10,812 crystals having a first-principles calculated elastic tensor.By setting the threshold values for easy and potential exfoliation based on already-exfoliated materials,we predicted 58 easily exfoliable bulk crystals and 90 potentially exfoliable bulk crystals for 2D materials.As evidence,a topology-based algorithm indicates that there is no interlayer bondingtopology for 93%predicted exfoliable bulk crystals,and the analysis on packing ratios shows that 99%predicted exfoliable bulk crystals exhibit a relatively low packing ratio value.Moreover,literature survey shows that 34 predicted exfoliable bulk crystals have been experimentally exfoliated into 2D materials.In addition,the characteristics of these predicted 2D materials were discussed for practical use of such materials.