Loss of function of the AP2/ERF transcription factor StGAME9 abolishes activation and induction of steroidal glycoalkaloid biosynthesis in potato plants.
Jul 2026· Plant physiology and biochemistry : PPB· Vol 237, pp.
111561
· 0 citations· 47 references
Medicine
TL;DR
Integrated transcriptomic and metabolomic characterization of knockout mutants (Stgame9) revealed extensive reprogramming of gene expression and metabolism, affecting not only SGA and sterol pathways but also a broader range of metabolic processes, with stress-related metabolic responses being attenuated in Stgame9 tubers.
Abstract
Steroidal glycoalkaloids (SGAs) are toxic defense substances present in certain species of the Solanaceae, including major crops such as eggplant, tomato, and potato. GLYCOALKALOID METABOLISM 9 (GAME9) was first identified in tomato and potato as an APETALA 2/ETHYLENE RESPONSE FACTOR (AP2/ERF) transcription factor regulating key genes in SGA biosynthesis. However, the spatial effects of endogenous GAME9 in potato remain largely unexplored, particularly in tubers, highlighting a knowledge gap in understanding activation and induction of SGA biosynthesis in this important staple food crop. Here, we generated StGAME9 knockout mutants in potato via DNA-free CRISPR/Cas9. Compared to the wild type, knockout mutants contained significantly reduced SGA levels in leaves, and were almost free of SGAs in tubers. Notably, SGA accumulation remained minimal in the mutant tubers even under two SGA-inducing conditions; wounding and light exposure, indicating a loss of inducible SGA biosynthesis. Integrated transcriptomic and metabolomic characterization of knockout mutants (Stgame9) revealed extensive reprogramming of gene expression and metabolism, affecting not only SGA and sterol pathways but also a broader range of metabolic processes, with stress-related metabolic responses being attenuated in Stgame9 tubers. Despite these changes, Stgame9 plants displayed a normal growth phenotype under both greenhouse and field conditions. Our findings substantiate a pivotal role of GAME9 in potato for the regulation of basal and induced SGA biosynthesis. The results further indicate that StGAME9 is involved in the regulation of a broader, complex, and interconnected network along biosynthetic pathways, where potato metabolism exhibits substantial robustness and compensatory capacity to buffer the loss of StGAME9.
These findings uncover a modularly coordinated control of SGAs accumulation and chlorophyll biosynthesis by bifurcation of StCRY1-StHY5 axis, providing a promising strategy to concurrently curb light-induced tuber greening and glycoalkaloids accumulation.
Jun Qin, S. Jing, Shengxuan Liu et al.· The Plant Cell· 0 citations
An integrated multi-omics analysis of dwarf and normal-height red tangerine × trifoliate orange hybrid seedlings revealed a PtARF6/8-PtGH3.1 transcriptional module that regulates auxin homeostasis through IAA conjugation, providing genetic insights into GH3.1-mediated dwarfism.
Soil salinization limits the yield and quality of Dendrobium officinale. The molecular mechanisms linking methyl jasmonate (MeJA) signaling to the biosynthesis of glucomannans (GMs) under salinity remain unclear. In the WGCNA of MeJA- and salinity-treated D. officinale transcriptome, an R2R3-MYB transcription factor was identified, DoMYB41, which was highly expressed in stems and induced by both treatments. Overexpression of DoMYB41 in PLBs increased GMs and anthocyanin, enhanced the activities of antioxidant enzymes, reduced oxidative damage, and elevated relative water content, whereas CRISPR/Cas9 knockout lines showed opposite phenotypes. Transcriptomic analysis identified DoTIP1–1 as a key downstream target, and biochemical assays (dual-LUC, Y1H, EMSA) confirmed that DoMYB41 activates DoTIP1–1 transcription by directly targeting the MBS motif present in its promoter. Furthermore, DoMYB41 physically interacted with the bHLH transcription factor DoMYC2, which alone bound to and activated the promoters of both DoTIP1–1 and DoMYB41, forming a positive feedback loop. Intriguingly, DoMYB41 and DoMYC2 synergistically activated DoTIP1–1. These findings uncovered a MeJA-responsive DoMYB41-DoMYC2 cascade that iteratively activates DoTIP1–1 expression and promotes the biosynthesis of GMs, thereby enhancing salinity tolerance in D. officinale. This study also provides genetic targets for salinity tolerance in breeding programs for this horticultural orchid.
Evidence is provided suggesting that StFKF1 influences the timing of flowering and tuber initiation, as well as the expression patterns of key regulatory genes, under long-day conditions, thereby contributing to a theoretical foundation for understanding developmental transitions in this specific environmental context.
Zefeng Zhai, Yongguang Liu, Haicai Li et al.· Molecular breeding· 0 citations
Together, these findings provide a foundation for functional characterization and useful information for future research on the role of SlPHD family members in plant abiotic stress tolerance.
Tayeb Muhammad, Tao Yang, Haitao Yang et al.· Planta· 0 citations
Male sterility is a vital trait for hybrid seed production. However, the synergistic coordination between sugar metabolism and reactive oxygen species (ROS) during pollen development remains poorly understood. Here, we identified a plastid-localized hexokinase, CsHXK3, that participates in both processes in cucumber (Cucumis sativus L.). CsHXK3 is localized to the tapetum, microspores, and vascular tissues of the anther. The significant downregulation of CsHXK3 expression in cell wall invertase 3-silenced (CsCWIN3-RNAi) lines supports its essential role in downstream hexose utilization. Biochemical analysis confirmed that CsHXK3 is a glucose-preferring enzyme that is essential for hexose phosphorylation. The CRISPR/Cas9-mediated knockout of CsHXK3 resulted in severe male sterility, characterized by defective tapetal programmed cell death, collapsed pollen grains, and severely impaired pollen germination. Loss of CsHXK3 led to reduced accumulation of sugars (glucose, fructose, and sucrose) and starch in the anthers, accompanied by substantially downregulated expression of sugar transporter genes, including Sugars Will Eventually be Exported Transporters (CsSWEETs) and Sugar Transport Protein 13 (CsSTP13). CsHXK3 deficiency disrupted ROS homeostasis by reducing hydrogen peroxide (H2O2) levels, which was accompanied by the downregulated expression of the ROS-generating gene Respiratory Burst Oxidase Homolog B (CsRBOHB) and upregulated expression of genes encoding ROS-scavenging peroxidases. Our findings indicate that CsHXK3 may coordinate carbohydrate metabolism with ROS homeostasis during pollen development, offering insights into the metabolic regulation of male reproductive success in plants.
Lijun Lv, Lidong Zhang, Hujian Li et al.· The Plant Journal· 0 citations
