Gibberellins: extending the Green Revolution

Abstract

The Green Revolution more than doubled crop yields and food production in crop species such as wheat and rice. This was primarily accomplished by altering the gibberellin (GA) signaling pathway to reduce plant height and prevent plants from falling over when growth was promoted with fertilizer application. Similar approaches have not been successfully accomplished in other grass crop species, such as maize, due to pleiotropic deleterious traits that arise from altering the GA pathway. This review highlights new findings in GA research across grass crop species. We have primarily focused on the developmental role of GAs in plant architecture and growth. We discuss how alteration of GA effects could be used to alter plant morphology and development of ideal plant ideotypes for grass crop species. To further extend the Green Revolution and improve food production from cereal crop species, targeted and tissue-specific regulation of the GA pathway will have to be undertaken.

Keywords: Development; gibberellins; maize; plant architecture; rice; wheat.

Fig. 1.

GA-mediated regulation of grass crop architecture. (A–D) Generalized GA metabolism and signaling pathways in plants. (E–L) Examples of GA-mediated mechanisms regulating grass crop architecture: (E, F) internode length (Fang et al., 2024; Mei et al., 2024); (G, H) leaf growth (Nelissen et al., 2015; Zhang et al., 2018) and leaf angle (Tong et al., 2014; Best et al., 2016; Kong et al., 2017); (I, J) tassel and panicle branching (Ashikari et al., 2002; Su et al., 2021; Best and Dilkes, 2022; Wang et al., 2022; Xiao et al., 2022); (K) tiller development in rice (Wu et al., 2020; Huang et al., 2021); and (L) nutrient-use efficiency in rice (Gao et al., 2020; Li et al., 2018; Lu et al., 2021; Sun et al., 2023; Zhang et al., 2020c). Abbreviations: GGPP, trans-geranylgeranyl diphosphate; CPP, ent-copalyl diphosphate; CPS, ent-copalyl diphosphate synthase; KS, ent-kaurene synthase; KO, ent-kaurene oxidase; KAO, ent-kaurenoic acid oxidase; GA, gibberellin; GA13OX, GA 13-oxidase; GA20OX, GA 20-oxidase; GA3OX, GA 3-oxidase; GA2OX, GA 2-oxidase; DELLA, DELLA domain protein; GID1, GA-insensitive1 receptor; TF, transcription factor; SCF^GID2, Skp, Cullin, F-box^GID2; Ub, ubiquitin.

Fig. 2.

Maize and rice ideotypes based on targeted regulation of the GA pathway. Each ideotype silhouette is compared with a typical breeding line. (A) The maize ideotype exhibits short stature with thicker shorter internodes and distinctive leaf traits, including broad lower leaves and shorter, narrower upper leaves. Reproductive traits are characterized by a smaller tassel and a larger ear. (B) The rice ideotype exhibits a lower, densely branched panicle with larger grains. It features a sturdier culm with flood-responsive stem internodes and longer, narrower, and more upright leaves. It produces fewer but more productive tillers promoting efficient nutrient allocation. Both maize and rice ideotypes possess root systems optimized for enhanced nutrient-use efficiency.