The utilization of stabilized DELLA proteins Rht-B1b and Rht-D1b was crucial for increasing wheat (Triticum aestivum) productivity during the Green Revolution. However, the underlying mechanisms remain to be clarified. Here, we cloned a gain-of-function allele of the GSK3/SHAGGY-like kinase-encoding gene GSK3 by characterizing a dwarf wheat mutant. Furthermore, we determined that GSK3 interacts with and phosphorylates the Green Revolution protein Rht-B1b to promote it to reduce plant height in wheat. Specifically, phosphorylation by GSK3 may enhance the activity and stability of Rht-B1b, allowing it to inhibit the activities of its target transcription factors. Taken together, we reveal a positive regulatory mechanism for the Green Revolution protein Rht-B1b by GSK3, which might have contributed to the Green Revolution in wheat.

Brassinosteroids (BRs) play an essential role in promoting skotomorphogenesis, yet the underlying mechanisms remain unknown. Here we report that a plant-specific BLISTER (BLI) protein functions as a positive regulator of both BR signaling and skotomorphogenesis in Arabidopsis (Arabidopsis thaliana). We found that the glycogen synthase kinase 3 (GSK3)-like kinase BRASSINOSTEROID INSENSITIVE2 (BIN2) interacts with and phosphorylates BLI at four phosphorylation sites (Ser70, Ser146, Thr256 and Ser267) for degradation; in turn, BR inhibits degradation of BLI. Specifically, BLI cooperates with the BRASSINAZOLE RESISTANT1 (BZR1) transcription factor to facilitate the transcriptional activation of BR-responsive genes. Genetic analyses indicated that BLI is essentially required for BZR1-mediated hypocotyl elongation in the dark. Intriguingly, we reveal that BLI and BZR1 orchestrate the transcriptional expression of gibberellin (GA) biosynthetic genes to promote the production of bioactive GAs. Our results demonstrate that BLI acts as an essential regulator of Arabidopsis skotomorphogenesis through promoting BR signaling and GA biosynthesis.

Tryptophan decarboxylase (TDC) plays an important role in plant hormonal balance and secondary metabolite synthesis by catalyzing the conversion of tryptophan to tryptamine. Prior research has indicated that AevTDC from Aegilops variabilis, a relative of wheat (Triticum aestivum L.), enhances wheat resistance to the pathogen cereal cyst nematode by influencing salicylic acid and flavonoid pathways. Expanding on these findings, this study demonstrates that AevTDC promotes both serotonin and flavonoid synthesis, resulting in altered wheat grain color. Furthermore, we observed that AevTDC overexpression induces the expression of TaMYB310, which is closely associated with flavonoid biosynthesis. TaMYB310 activates the expression of CHS (encoding chalcone synthase) and FLS (encoding flavonol synthase) by directly binding to the MYB binding site (MBS), thereby promoting flavonoid biosynthesis. Additionally, overexpression of AevTDC reduced wheat seed sensitivity to abscisic acid (ABA), providing an explanation for the accelerated seed germination. In summary, this study reveals the critical role of AevTDC in regulating wheat metabolism, emphasizing its importance in promoting serotonin and flavonoid synthesis, altering grain color, and accelerating seed germination. These findings offer insights into plant metabolic regulation mechanisms and their applications in agricultural improvement.