Sucrose control of phytochrome A signaling in Arabidopsis.

Abstract

The expression of the Arabidopsis plastocyanin (PC) gene is developmentally controlled and regulated by light. During seedling development, PC gene expression is transiently induced, and this induction can be repressed by sucrose. In transgenic seedlings carrying a PC promoter-luciferase fusion gene, the luciferase-induced in vivo luminescence was similarly repressed by sucrose. From a mutagenized population of such transgenic seedlings, we selected for mutant seedlings that displayed a high luminescence leve1 when grown on a medium with 3% sucrose. This screening of mutants resulted in the isolation of several sucrose-uncoupled (sun) mutants showing reduced repression of luminescence by sucrose. Analysis of the sun mutants revealed that the accumulation of PC and chlorophyll a/b binding protein (CAB) mRNA was also sucrose uncoupled, although the extent of uncoupling varied. The effect of sucrose on far-red light high-irradiance responses was studied in wild-type, sunl, sun6, and sun7 seedlings. In wild-type seedlings, sucrose repressed the far-red light-induced cotyledon opening and inhibition of hypocotyl elongation. sun7 seedlings showed reduced repression of these responses. Sucrose also repressed the far-red light-induced block of greening in wild-type seedlings, and both sun6 and sun7 were affected in this response. The results provide evidence for a close interaction between sucrose and light signaling pathways. Moreover, the sun6 and sun7 mutants genetically identify separate branches of phytochrome A-dependent signal transduction pathways.

Sugar effects on early seedling development in Arabidopsis

“…The latter include screens based on transgenic lines containing fusions of sugar-responsive promoters to reporter genes or selection markers. For instance, sucrose uncoupled mutants contain a luciferase reporter gene driven by the plastocyanin promoter (Dijkwel et al 1997); the impaired sucrose induction (isi) mutants contain the ApL3 promoter fused to a negative selection marker, the bacterial cytochrome P 450 gene (Rook et al 2001); the reduced sucrose response (rsr) mutants contain the potato patatin promoter combined with the b-glucoronidase gene (Martin et al 1997). These distinct approaches based on the effects of high sugar media on seedling development or on changes in the activity/expression of sugar-responsive genes, yielded overlapping mutants.…”

Calcium is essential for fructan synthesis induction mediated by sucrose in wheat

“…A number of growth and developmental processes have been found to depend on sucrose signaling (Dijkwel et al 1997;Chiou and Bush 1998;Roldan et al 1999). In wheat and other cool temperate grasses, conditions that favor sucrose accumulation such as low temperatures or illumination of detached leaves lead to the induction of fructan synthesis (Pontis 1989;Wagner et al 1986;Müller et al 2000;Nagaraj et al 2001).…”

Tissue-Specific Expression Profiling of Seedling Stage in Early-Maturity Mutant Induced by Carbon Ion Beam in Sweet Sorghum

“…Interestingly, the PHYA is tissue-specific expressed in KFJT-1. Previous study on Arabidopsis suggested that sucrose could depress expression of PHYA (Dijkwel et al, 1997). Thus, we conferred that the down-regulated PHYA in young stem in KFJT-1 was due to high content of sucrose which mutual adjusted by the gene 3.2.1.26 and 2.4.1.13.…”