OsRELA Regulates Leaf Inclination by Repressing the Transcriptional Activity of OsLIC in Rice

Leaf angle is one of the most important agronomic traits in rice, and changes in leaf angle can alter plant architecture to affect photosynthetic efficiency and thus determine grain yield. Therefore, it is important to identify key genes controlling leaf angle and elucidate the molecular mechanisms to improve rice yield. We obtained a mutant rela (regulator of leaf angle) with reduced leaf angle in rice by EMS mutagenesis, and map-based cloning revealed that OsRELA encodes a protein of unknown function. Coincidentally, DENSE AND ERECT PANICLE 2 (DEP2) was reported in a previous study with the same gene locus. RNA-seq analysis revealed that OsRELA is involved in regulating the expression of ILI and Expansin family genes. Biochemical and genetic analyses revealed that OsRELA is able to interact with OsLIC, a negative regulator of BR signaling, through its conserved C-terminal domain, which is essential for OsRELA function in rice. The binding of OsRELA can activate the expression of downstream genes repressed by OsLIC, such as OsILI1, a positive regulator of leaf inclination in rice. Therefore, our results suggest that OsRELA can act as a transcriptional regulator and is involved in the regulation of leaf inclination by regulating the transcriptional activity of OsLIC.

Wheat Posture Acquisition System Based on Infrared Tracer Robot Design and Experiment

Background:To investigate the effect of drought stress on wheat posture.Methods:An image acquisition system based on an infrared tracing robot was developed and a graphical user interface (GUI) software was designed to simplify the operation control of the robot. In this experiment, three genotypes of wheat, Ruihuamai 523, Jimai 22 and Xumai 33, were grown in indoor pots, and the images of wheatposture from flowering stage to maturity were collected to extract morphological parameters such as plant height, stem width and leaf inclination angle. Results:The experimental results showed that the deviation of linear trajectory was less than 3 mm when the robot traveled in a straight line at 0.4 m/s in the greenhouse; the image acquisition efficiency was about 18 images/min;the collected pictures of drought-stressed and control potted wheat groups can be used for posture assessment; the accuracy of wheat plant height and stem width with manual acquisition was 84.6% and 79.2%, respectively. After statistical analysis, it was concluded that drought stress and genotype and other influencing factors had no significant effect on plant height and stem width, but had a greater effect on leaf inclination angle.Conclusions:Therefore, this system can be used for posture collection of wheat.

Modulation of Rice Leaf Angle and Grain Size by Expressing OsBCL1 and OsBCL2 under the Control of OsBUL1 Promoter

Leaf angle and grain size are important agronomic traits affecting rice productivity directly and/or indirectly through modulating crop architecture. OsBC1, as a typical bHLH transcription factor, is one of the components comprising a complex formed with LO9-177 and OsBUL1 contributing to modulation of rice leaf inclination and grain size. In the current study, two homologues of OsBC1, OsBCL1 and OsBCL2 were functionally characterized by expressing them under the control of OsBUL1 promoter, which is preferentially expressed in the lamina joint and the spikelet of rice. Increased leaf angle and grain length with elongated cells in the lamina joint and the grain hull were observed in transgenic rice containing much greater gibberellin A3 (GA3) levels than WT, demonstrating that both OsBCL1 and OsBCL2 are positive regulators of cell elongation at least partially through increased GA biosynthesis. Moreover, the cell elongation was likely due to cell expansion rather than cell division based on the related gene expression and, the cell elongation-promoting activities of OsBCL1 and OsBCL2 were functional in a dicot species, Arabidopsis.