Strigolactones are involved in sugar signaling to modulate early seedling development in <i>Arabidopsis</i>

Abstract

Strigolactones are a novel class of plant hormones that interact with multiple signaling molecules, including auxin, abscisic acid, ethylene, and brassinosteroid, to regulate plant growth and development. Recently, researchers have shown that sugars are involved in bud outgrowth control, suggesting a potential interaction between sugars and strigolactone signaling. To better understand the relationship between strigolactones and sugar in plant development, the sugar sensitivity of strigolactone biosynthesis and signaling mutants (max1 and max2) was evaluated in early seedling development with a low-glucose assay. Both max1 and max2 displayed obvious hyposensitivity to glucose repression, as do gin mutants, but they were hypersensitive like the wild type to the high-glucose conditions used for gin mutant screening. The strigolactones acted synergistically with glucose in repressing seedling establishment. A further comparative transcriptomic analysis indicated that the expression of stress-related genes in the max2 mutant is impaired by glucose, and a carbohydrate analysis revealed a reduced hexose content in the max mutants. Our results suggest that the roles of strigolactones in the regulation of early seedling development are probably independent of the HXK1 signaling pathway. Taken together, these findings provide evidence that strigolactones are involved in sugar signaling, thus modulating early seedling development.

Sugar availability suppresses the auxin-induced strigolactone pathway to promote bud outgrowth

“…Moreover, rms3 , a strigolactone-perception pea mutant, exhibits a reduced inhibition with decreasing sucrose concentration. This holds also true for seedling development of max2, a strigolactone signaling mutant, which displayed a reduced response to sugar (Li et al , 2016). This effect of sugar on bud outgrowth through strigolactone pathway matches with the sucrose-mediated repression of MAX2 expression in rose buds (Barbier et al , 2015b) and the downregulation of MAX2 in response to defoliation and shade in sorghum (Kebrom et al , 2010).…”

“…Interestingly, sugars have been reported to have an opposite effect to auxin on cytokinins and strigolactones in different developmental processes (Arrom & Munne-Bosch, 2012; Li et al , 2016; Tian et al , 2018) including in bud outgrowth (Barbier et al , 2015b; Barbier et al , 2019). In our previous study on rose isolated nodal segments grown without auxin (Barbier et al , 2015b), we highlighted that sucrose stimulated bud outgrowth, and that this growth was preceded by down-regulated strigolactone signaling gene expression and increased cytokinin synthesis.…”

Strigolactones positively regulate chilling tolerance in pea and in Arabidopsis

“…However, SL are involved in sugar metabolism and sugar signalling pathways that modulate early seedling development (Li et al, ). The max seedlings are hyposensitive to sugar‐induced growth arrest (Li et al, ). The results presented here may indicate that SL signalling interacts with sugar signalling in the expression of cold tolerance in A. thaliana .…”

“…However, SL are involved in sugar metabolism and sugar signalling pathways that modulate early seedling development (Li et al, 2016). The max seedlings are hyposensitive to sugar-induced growth arrest (Li et al, 2016).…”

Chemical regulators of plant hormones and their applications in basic research and agriculture*

“…SLs were finally recognized as plant hormones following the finding that SL inhibits shoot branching in rice and Arabidopsis [319,320]. In addition, studies have indicated that SLs also play roles in enhancing lateral root formation and root hair elongation [321], inhibiting adventitious root formation [322], stimulating cambial activity [323], accelerating leaf senescence [324], counteracting temperature-induced seed dormancy [325], and playing a synergistic role in sugar-induced suppression of seedling establishment [326]. Application of SLs can be expected to contribute to agriculture.…”