Transcriptomic,proteomic,and phosphoproteomic analyses reveal dynamic signaling networks influencing long-grain rice development

The LGS1(Large grain size 1)gene,also known as GS2/GL2/Os GRF4,is involved in regulating grain size and quality in rice,but the mechanism governing grain size has not been elucidated.We performed transcriptomic,proteomic,and phosphoproteomic analyses of young rice panicles in Samba(a wild-type cultivar with extra-small grain)and NIL-LGS1(a nearly isogenic line of LGS1 with large grain in the Samba genetic background)at three developmental stages(4–6)to identify internal dynamic functional networks determining grain size that are mediated by LGS1.Differentially expressed proteins formed seven highly functionally correlated clusters.The concordant regulation of multiple functional clusters may be key features of the development of grain length in rice.In stage 5,16 and 24 phosphorylated proteins were significantly up-regulated and down-regulated,and dynamic phosphorylation events may play accessory roles in determining rice grain size by participating in protein–protein interaction networks.Transcriptomic analysis in stage 5 showed that differentially expressed alternative splicing events and dynamic gene regulatory networks based on 39 transcription factors and their highly correlated target genes might contribute to rice grain development.Integrative multilevel omics analysis suggested that the regulatory network at the transcriptional and posttranscriptional levels could be directly manifested at the translational level,and this analysis also suggested a regulatory mechanism,regulation of protein translation levels,in the biological process that extends from transcript to protein to the development of grain.Functional analysis suggested that biological processes including MAPK signaling,calcium signaling,cell proliferation,cell wall,energy metabolism,hormone pathway,and ubiquitin-proteasome pathway might be involved in LGS1-mediated regulation of grain length.Thus,LGS1-mediated regulation of grain size is affected by dynamic transcriptional,posttranscriptional,translational and posttranslational changes.

Negative Phototropism of Chlorophytum comosum Roots and Their Mechanisms

The aerial roots of Chlorophytum comosum were grown hydroponically,allowing us to study the performance and mechanism of negative phototropism. The results of this study were as follows. All the adventitious roots and their branch roots bent away from light with a maximum curvature of approximately 88.5°. Blue-violet light prominently induced negative phototropism while red light had no effect. The root cap was the site of photo perception. Roots with shaded or divested root caps exposed to unilateral light showed no negative phototropism,but resumed their original characteristics when the shade was removed or when new root caps grew. The curvature increased when the light intensity ranged 0–110 μmol·m^(-2)·s^(-1). The negative phototropism curvature could be promoted by exogenous CaCl_2 but was inhibited by exogenous LaCl_3; exogenous CaCl_2 could reduce the inhibitory effect of LaCl_3. Unilateral light induced the horizontal transport of IAA from the irradiated side to the shaded side,resulting in an unequal distribution of IAA in both the sides,leading to negative phototropism. The horizontal transport of IAA was promoted by exogenous Ca^(2+) but inhibited by exogenous La^(3+).