TANG1, Encoding a Symplekin_C Domain-Contained Protein, Influences Sugar Responses in Arabidopsis

Abstract

Sugars not only serve as energy and cellular carbon skeleton but also function as signaling molecules regulating growth and development in plants. Understanding the molecular mechanisms in sugar signaling pathways will provide more information for improving plant growth and development. Here, we describe a sugar-hypersensitive recessive mutant, tang1. Light-grown tang1 mutants have short roots and increased starch and anthocyanin contents when grown on high-sugar concentration medium. Dark-grown tang1 plants exhibit sugar-hypersensitive hypocotyl elongation and enhanced dark development. The tang1 mutants also show an enhanced response to abscisic acid but reduced response to ethylene. Thus, tang1 displays a range of alterations in sugar signaling-related responses. The TANG1 gene was isolated by a map-based cloning approach and encodes a previously uncharacterized unique protein with a predicted Symplekin tight-junction protein C terminus. Expression analysis indicates that TANG1 is ubiquitously expressed at moderate levels in different organs and throughout the Arabidopsis (Arabidopsis thaliana) life cycle; however, its expression is not affected by high-sugar treatment. Genetic analysis shows that PRL1 and TANG1 have additive effects on sugar-related responses. Furthermore, the mutation of TANG1 does not affect the expression of genes involved in known sugar signaling pathways. Taken together, these results suggest that TANG1, a unique gene, plays an important role in sugar responses in Arabidopsis.

BRI1 and BAK1 interact with G proteins and regulate sugar-responsive growth and development in Arabidopsis

“…The glucose-induced dark development of Arabidopsis seedlings was not a result of an osmotic effect, because seedlings never developed beyond the expansion of cotyledons on medium containing 1% mannitol (Supplementary Fig. 1a ), consistent with previous reports 32 – 34 . As shown in Fig.…”

“…In dark-grown Col-0 seedlings, hypocotyl length increased in response to low concentrations of glucose, and elongation was progressively inhibited at high concentrations of glucose (Supplementary Fig. 2 ) 33 , 34 . Hypocotyl elongation of dark-grown bri1-301 and bak1-4 seedlings was insensitive to exogenous glucose (Supplementary Fig.…”

“…Dark-grown Arabidopsis seedlings develop leaf-like organs on vertical Petri dishes with even very low concentrations of sugars, suggesting that the dark development phenotype of Arabidopsis seedlings is a sensitive indicator of the effects of sugars on plant growth and development 32 – 34 . To understand how brassinosteroids (BRs) influence sugar responses, we investigated the dark development phenotype of 19-d-old Col-0, bri1-301 , and bak1-4 seedlings.…”

“…As shown in Fig. 1a , the development of dark-grown Arabidopsis seedlings grown on MS medium with glucose was classified into four different stages 32 – 34 . At the stage 1, seedlings did not show the expansion of cotyledons.…”

MOS1 Negatively Regulates Sugar Responses and Anthocyanin Biosynthesis in Arabidopsis

“…Sugars not only serve as energy sources in plants but also as hormone-like molecules in regulating many important physiological processes, including metabolism [ 1 , 2 ], seed germination [ 3 ], and biotic and abiotic stress responses [ 4 , 5 ]. Many sucrose-insensitive or -hypersensitive mutants have been screened to identify genes involved in sugar signaling [ 6 , 7 , 8 , 9 ]. By studying these mutants, it has been recognized that sugars have crosstalk with other signals, such as light [ 10 ], hormones [ 11 , 12 ], stresses [ 12 ], and nutrients [ 13 , 14 ].…”