GIGANTEA and EARLY FLOWERING 4 in Arabidopsis Exhibit Differential Phase-Specific Genetic Influences over a Diurnal Cycle

The endogenous circadian clock regulates many physiological processes related to plant survival and adapt- ability. GIGANTEA （GI）, a clock-associated protein, contributes to the maintenance of circadian period length and ampli- tude, and also regulates flowering time and hypocotyl growth in response to day length. Similarly, EARLY FLOWERING 4 （ELF4）, another clock regulator, also contributes to these processes. However, little is known about either the genetic or molecular interactions between GI and ELF4 in Arabidopsis. In this study, we investigated the genetic interactions between GI and ELF4 in the regulation of circadian clock-controlled outputs. Our mutant analysis shows that GI is epistatic to ELF4 in flowering time determination, while ELF4 is epistatic to GI in hypocotyl growth regulation. Moreover, GI and ELF4 have a synergistic or additive effect on endogenous clock regulation. Gene expression profiling of gi, elf4, and gi elf4 mutants further established that GI and ELF4 have differentially dominant influences on circadian physiological outputs at dusk and dawn, respectively. This phasing of GI and ELF4 influences provides a potential means to achieve diversity in the regulation of circadian physiological outputs, including flowering time and hypocotyl growth.

iNID： An Analytical Framework for Identifying Network Models for Interplays among Developmental Signaling in Arabidopsis

Integration of internal and external cues into developmental programs is indispensable for growth and development of plants, which involve complex interplays among signaling pathways activated by the internal and external factors （IEFs）. However, decoding these complex interplays is still challenging. Here, we present a web-based platform that identifies key regulators and Network models delineating Interplays among Developmental signaling （iNID） in Arabidopsis. iNID provides a comprehensive resource of （1） transcriptomes previously collected under the conditions treated with a broad spectrum of IEFs and （2） protein and genetic interactome data in Arabidopsis. In addition, iNID provides an array of tools for identifying key regulators and network models related to interplays among IEFs using transcriptome and interactome data. To demonstrate the utility of iNID, we investigated the interplays of （1） phytohormones and light and （2） phytohormones and biotic stresses. The results revealed 34 potential regulators of the interplays, some of which have not been reported in association with the interplays, and also network models that delineate the involvement of the 34 regulators in the interplays, providing novel insights into the interplays collectively defined by phytohormones, light, and biotic stresses. We then experimentally verified that BME3 and TEM1, among the selected regulators, are involved in the auxin-brassinosteroid （BR）-blue light interplay. Therefore, iNID serves as a useful tool to provide a basis for understanding interplays among IEFs.