Photosynthetic tissues are dynamic structures whose homeostasis depends on the coordination of two antagonistic processes: self-maintenance and supporting sink tissues. The balance of these processes determines plant development, which might be mediated by cytokinin. However, little is known about the link between sucrose transport signaling and cytokinin. Rice (Oryza sativa) DNA BINDING WITH ONE FINGER11 (OsDOF11) is a transcription factor that mediates sucrose transport by inducing the expression of sucrose transporter genes. Here, we found that OsDOF11 loss-of-function mutants showed a semi-dwarf phenotype with a smaller cell length due to increased cytokinin content in source tissues. RNA sequencing and reverse transcription quantitative PCR (RT-qPCR) analyses revealed that genes involved in cytokinin signaling and metabolism were affected in osdof11 mutants. Yeast one-hybrid (Y-1-H), dual-luciferase reporter, and chromatin immunoprecipitation (ChIP) experiments showed that OsDOF11 directly binds to the promoter regions of Oryza sativa CYTOKININ OXIDASE/DEHYDROGENASE4 (OsCKX4). Moreover, mutation of osckx4 in the osdof11 osckx4 double mutant rescued the semi-dwarf phenotype of the osdof11 mutant. Interestingly, exogenous application of kinetin promoted OsDOF11 expression earlier than OsCKX4, and overexpression of Oryza sativa VIN3-LIKE 2 (OsVIL2) caused an increase in active cytokinin levels and induced OsDOF11 transcript levels. Taken together, our results suggest a model in which both a sucrose transport regulator (OsDOF11) and cytokinin via OsCKX4 establish a feedback loop to maintain dynamic tissue homeostasis.

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Background: Nanoparticle causes soil pollution, which affected plant development and then resulted in biomass decreased, especially in crops. However, little is known how sodium nanoparticles affect wheat root development at plant physiological level. Results: We used NaBiF 4 (size of 50-100 nm) to analyze the effect in wheat development at plant physiological level. Under exogenous application of 50 μM NaBiF 4 for treatment, wheat root elongation was inhibited, but fresh weight and dry weight were increased. We also found that NaBiF 4 induced that the plant had lower content of sodium than negative control. Used no-sodium nanoparticle of BiF 3 for another negative control, it was also supported that NaBiF 4 entered into cell to replace of sodium and exported sodium out of plant. These results implied NaBiF 4 might induce sodium export to maintain the balance between sodium and potassium elements. Additionally, metabolism analysis demonstrated that SOD activity was increased, but CAT and POD activity reduced under exogenous treatment of NaBiF4 nanoparticles. Conclusions: Sodium nanoparticles (NaBiF 4 ) inhibited plant development by nanoparticle accumulation and sodium homeostasis broken, and then involved reactive oxygen species (ROS) signaling system response. These results provided more sights of sodium nanoparticle effect in plant development.