Physiological and Transcriptomic Responses of Growth in Neolamarckia cadamba Stimulated by Exogenous Gibberellins

Abstract

(1) The phytohormones gibberellins (GAs) play a crucial role in plant growth and development, such as seed germination, flowering, fruiting, and stem elongation. Although many biological roles of GAs have been studied intensively, the molecular mechanisms of GAs in woody plants are still unclear. (2) In this study, we investigated the effects of exogenous application of GAs on Neolamarckia cadamba. (3) The height and biomass of N. cadamba increased after 7 days of GA treatment, especially on the second internode. Transcriptome analysis showed that although the majority of genes involved in the GA signaling pathway were up-regulated, the expression of GA20 oxidase (GA20ox) and GA3 oxidase (GA3ox) was down-regulated in the 3 days GA-treated group compared to the CK group. The expression of the cell elongation-related basic helix-loop-helix genes bHLH74 and bHLH49 was up-regulated in the GA-treated group compared with the CK group. Transcriptional expression levels of transcription factors involved in hormone signaling were changed, mainly including bHLH, ethylene response factor (ERF), and WRKY families. In addition, the transcriptional expression level of the key enzymes engaged in the phenylalanine pathway was downregulated after GA treatment. (4) In brief, our findings reveal the physiological and molecular mechanisms of exogenous GA treatment stimulation in N. cadamba.

Integrated Transcriptomic and Metabolomic Analysis Reveals the Mechanism of Gibberellic Acid Regulates the Growth and Flavonoid Synthesis in Phellodendron chinense Schneid Seedlings

“…GA 3 plays crucial roles in the processes of growth, seed germination, physicochemical properties, nutrient uptake, secondary metabolism, and stress response in plants [30,31]. The previous results showed that exogenous GA 3 promoted the growth of Neolamarckia cadamba and Camellia sinensis seedlings and increased the biomass [7,32]. At the same time, GA 3 enhanced the chlorophyll content but reduced carotenoid content in the leaves of Valencia oranges, suggesting that GA 3 promoted growth by improving chlorophyll content in plants [33].…”

“…Previous studies have demonstrated that exogenous GA 3 significantly improves the photosynthetic pigment content, photosynthetic efficiency, soluble substance content, and antioxidase activities. Concurrently, it increases the fresh weight and plant height, subsequently promoting plant growth [2,[7][8][9][10][11].…”

“…In previous studies, it was demonstrated that exogenous GA 3 reduces the relative expression levels of ZmGA20 OXIDASE7 (GA20ox7) and ZmGA3 OXIDASE1/3 (GA3ox1/3) genes, and enhances the levels of ZmGA2 OXIDASE1/4 (GA2ox1/4) and ZmGA20 OXIDASE2 (GA20ox2) genes in GA biosynthesis in maize [17]. Meanwhile, exogenous GA 3 elevates the relative expression levels of major genes in GA signal pathway while decreasing the levels of NcGA20ox and NcGA3ox genes in biosynthesis after 3 days, ultimately promoting the growth of Neolamarckia cadamba [7]. In addition, exogenous GA 3 impacts the biosynthesis and accumulation of other phytohormones, such as ABA, auxin, and cytokinin (CTKs), to balance the plant growth [12,18].…”

Integrated morphological, metabolome, and transcriptome analyses revealed the mechanism of exogenous gibberellin promoting petiole elongation in Oenanthe javanica

“…GAs is a common plant hormone first identified from fungus Gibberella fujikuroi , which was investigated to promote the stem elongation in many plants ( Eriksson et al., 2000 ; Claeys et al., 2014 ). The cell length in the second internode of Neolamarckia cadamba was also significantly increased after exogenous application of GAs ( Li et al., 2022 ). The GA-deficient mutant with dwarf phenotype further proved the roles of GAs in regulating the plant height ( Ashikari et al., 1999 ; Sakamoto et al., 2004 ).…”

Transcriptome Analysis Reveals the Stress Tolerance Mechanisms of Cadmium in Zoysia japonica

“…bHLH74 is required for leaf and root development in Arabidopsis [59]. In Neolamarckia cadamba, bHLH74 has been reported to function in cell elongation and is upregulated after gibberellin treatment [60]. In tomatoes, SlbHLH96 interacts with SlERF4 and represses the expression of ABA catabolic genes, thereby promoting drought tolerance [61].…”