Modulation of sugar metabolism by an INDETERMINATE DOMAIN transcription factor contributes to photoperiodic flowering in Arabidopsis

Abstract

SUMMARYThere has been a long-standing interest in the role played by sugars in flowering. Of particular interest is how sugar-related signals are integrated into flowering genetic pathways. Here, we demonstrate that the INDETERMINATE DOMAIN transcription factor AtIDD8 regulates photoperiodic flowering by modulating sugar transport and metabolism. We found that whereas AtIDD8-deficient idd8 mutants exhibit delayed flowering under long days, AtIDD8-overexpressing plants (35S:IDD8) show early flowering. In addition, the sucrose synthase genes SUS1 and SUS4 were upregulated in 35S:IDD8 plants but downregulated in idd8 mutants, in which endogenous sugar levels were altered. AtIDD8 activates the SUS4 gene by binding directly to its promoter, resulting in promoted flowering in SUS4-overexpressing plants. SUS4 expression also responds to photoperiodic signals. Notably, the AtIDD8 gene is suppressed by sugar deprivation. Therefore, we conclude that AtIDD8 regulation of sugar transport and metabolism is linked to photoperiodic flowering.

Loose Plant Architecture1, an INDETERMINATE DOMAIN Protein Involved in Shoot Gravitropism, Regulates Plant Architecture in Rice

“…We further demonstrated that this motif was responsible for the major transcriptional repression activity of LPA1. In Arabidopsis, AtIDD8 is a transcriptional activator, and its activation domains also locate to the C terminus (Seo et al, 2011b). Our result for LPA1 not only revealed the diversity of transcriptional activities of IDD proteins but also implied that such activities are mainly conferred by their C termini.…”

“…However, yeast two-hybrid analyses did not give a meaningful result. Additionally, LPA1 also possesses putative DNA-binding activity, because the highly conserved ID domain has been shown to recognize DNA sequences (Kozaki et al, 2004;Seo et al, 2011b). Therefore, LPA1 may be part of a complicated transcriptional and proteinprotein interaction network that regulates rice shoot gravitropism.…”

“…In Arabidopsis, AtIDD3/MAGPIE, AtIDD10/JACKDAW, and AtIDD8/NUTCRACKER are involved in root development with the GRAS transcription factors SHOOT-ROOT and SCARECROW (Levesque et al, 2006;Welch et al, 2007). AtIDD8 also regulates photoperiodic flowering by modulating sugar transport and metabolism (Seo et al, 2011b). Recently, AtIDD1/ENHYDROUS was shown to promote germination by regulating light and hormonal signaling during seed maturation (Feurtado et al, 2011).…”

TheArabidopsisC2H2 Zinc Finger INDETERMINATE DOMAIN1/ENHYDROUS Promotes the Transition to Germination by Regulating Light and Hormonal Signaling during Seed Maturation

“…SHR has been shown to directly regulate NUT and MAG expression, while MAG and JKD have been shown to physically interact with SHR and SCR (Levesque et al, 2006;Cui et al, 2007;Welch et al, 2007). Recently, Seo et al (2011) found that NUT/IDD8 regulates the transition to flowering through its regulation of sugar metabolism. SHOOT GRAVI-TROPISM5/IDD15 (SGR5) has been linked to gravity perception and starch accumulation in inflorescence stems (Tanimoto (A) Germination sensitivity to applied (+)-ABA at 1 mM concentration in Columbia wild type (wt), overexpression ENY-ME and RAB18:ENY lines, and knockdown RAB18:ENYami lines.…”

The control of developmental phase transitions in plants

“…Genetic analyses, mostly conducted in Arabidopsis and rice, have identified numerous genes that participate in the regulation of flowering. Endogenous factors that regulate reproductive phase change include hormones and carbohydrate assimilates, such as gibberellins and sugars (Corbesier et al, 1998;Moon et al, 2003;Ohto et al, 2001;Seo et al, 2011). Among the environmental factors that may affect plant growth, only a few seem to be specifically monitored to control flowering (Amasino, 2010;Srikanth and Schmid, 2011).…”