Fig. 1 Gibberellin biosynthesis pathways in plants 2ox：GA 2-oxidase. 3ox：GA 3-oxidase. 13ox：GA 13-oxidase. 20ox：GA 20-oxidase. GGDP：geranylgeranyl diphosphate. CPS：ent-copalyl diphosphate synthase. KS：ent-kaurene synthase. KO：ent-kaurene oxidase. KAO：ent-kaurenoic acid oxidase. This figure was modified from Yamaguchi[2]

Fig. 2 Sketch of GA-GID1-DELLAsignal transduction Binding with a bioactive GA results in a conformational change in the GID1 receptor,thus which promotes interaction with DELLA proteins. Recruitment of an F-box protein initiates ubiquitination of DELLA mediated by an SCF E3 ubiquitin ligase targeting the DELLA for proteasomal degradation. Deficiency of DELLA eliminates its growth repression and suppresses other DELLA-mediated reactions

Fig.3 Green Revolution genes in gibberellin biosynthesis and signal transduction a：Mutation sites of the sd1 alleles. sd1 mutations affect the activity of GA20ox,which catalyzes the conversion of GA53 to GA20 in the biosynthetic pathway to the biological active product,GA1. The GA20ox gene consists of three exons and two introns. The mutation in each allele is indicated by either an arrow（single-nucleotide substitution）or a line（internal deletion）. b：GA action results in the degradation of Rht. The mutant forms of Rht（Rht-B1b and Rht-D1b）are not susceptible to GA-induced degradation. The arrow indicates the position of terminal codons in Rht-B1b and Rht-D1b. The C-terminus（light blue）is highly conserved in all related proteins and contains the repressor activity. The N-terminus（green）contains the GA-signalling domain that includes two highly conserved motifs（dark blue）that are required for GA-induced degradation. This figure was modified from Hedden et al[6]and Sasaki et al[9]

Fig. 4 GRF4 increases the efficiency of nitrogen and carbon metabolism in rice a：In Green Revolution varieties（GRVs）,DELLA-like protein SLR1（SLENDER RICE1）inhibits the interaction between OsGIF1 and OsGRF4,which affects the metabolism of nitrogen（N）and carbon（C）. b：In improved GRVs,increased expressions of OsGRF4 overcomes the inhibition of SLR1 to OsGIF1-OsGRF4 interactions. In addition,OsGRF4 efficiently promotes nitrogen and carbon use efficiency by self-promotion and thus resulting in higher yields. This figure was modified from Wang et al[60]

Fig. 5 Mechanism of NGR5 regulating rice tillering The rice transcription factor NGR5 facilitates nitrogen-dependent recruitment of PRC2 to repress expression of tillering genes,thus promoting tillering in response to increasing nitrogen supply. NGR5 can be degraded after binding with the gibberellin receptor GID1,while DELLA accumulation inhibits the GID1-NGR5 interaction via competitively binding with GA-GID1,thus stabilizing. This figure was modified from Wu et al[59]

Fig.e 6 A simplified model for the role of GAs in stress response Different abiotic stresses induce the expression of GA2oxs via specific effectors,which results in the subsequent decrease of GAs synthesis,thus promotes DELLA accumulation. Under pathogen attack,JA-mediated JAZ protein degradation releases its repression to DELLAs and MYC transcription factors. MYC2 in turn also enhances the expression of DELLA. Accumulation of DELLAs leads to growth cessation via inhibition of cell elongation and cell division. Other protective mechanisms include the expression promotion of genes encoding detoxification enzymes to inhibit ROS generation,and promotion of JA response via direct repression of JAZ activity. Arrows and T-bars indicate positive or negative regulation,respectively. This figure was modified from Hedden et al[1]