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.
Abstract
Potato, the fourth largest food crop in the world, stores nutrients in underground tubers. However, light exposure induces tuber accumulation of chlorophyll and toxic steroidal glycoalkaloids (SGAs), an unwanted trait called tuber greening causes potato quality decline and parts of tuber inedible. Despite progress in enzymatic cascades governing SGAs biosynthesis, the regulatory scheme of SGAs and chlorophyll metabolism in light-exposed tubers persists as a critical knowledge gap. Here, we identify the blue light receptor StCRY1 plays a predominant role in light-induced tuber greening and SGAs elevation, which functions as a light-controlled transcriptional switch for genes involved in SGAs and chlorophyll biosynthesis. We show that transcription factor StHY5 acts downstream of StCRY1 to co-regulates both chlorophyll and SGAs metabolism. However, StMYB4, a transcription factor regulated by StHY5, promotes SGAs synthesis by directly binding to SGA biosynthetic genes without affecting chlorophyll homeostasis. Furthermore, StCRY1 employs a dual strategy by modulating StMYB4 expression and physically interaction with StMYB4 to regulate its transcriptional activity. Collectively, 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.
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.
Ying Liu, Irene Merino, Lizel Potgieter et al.· Plant physiology and biochem...· 0 citations
Accumulation of steroidal glycoalkaloids (SGAs) drives postharvest potato tuber greening and poses food-safety risks, yet the temporal dynamics and regulatory basis of light induction remain unclear.
We compared a storage-tolerant cultivar (XS) and a storage-sensitive cultivar (JZ). Under continuous light for 0, 2, 10, and 30 d, we quantified α-solanine and α-chaconine and performed integrated metabolomic and transcriptomic analyses in JZ. SGAs increased more sharply in JZ than in XS. Metabolomics detected 616 differentially accumulated metabolites: steroid-related metabolites (diosgenin) rose rapidly at 2 d, whereas phenolic acids, flavonoids, and SGAs accumulated at 30 d. Transcriptome profiling indicated early activation of sterol/cholesterol biosynthesis and late enhancement of phenylpropanoid and phytosterol pathways. WGCNA identified candidate genes including CYP72A54, MYB185, HY5, and PIF3.
We propose an “early steroid remodeling–late co-amplification of phenolics and SGAs” model, providing evidence for postharvest light-exclusion management and low-SGA breeding, and supporting risk assessment during storage and transport.
Yuru Lv, Yongyu Fang, Qi Zhao et al.· Chemical and Biological Tech...· 0 citations
BBX transcription factors can respond to UV-B signals, promote plant photomorphogenesis, and regulate plant anthocyanin biosynthesis. Based on transcriptome sequencing analysis, this study analyzed the transcription factors of StBBXs under UV-B treatment and identified two differentially expressed genes, StBBX19 and StBBX24. We explored the protein structures, promoters, and phylogenetics of StBBX19 and StBBX24, speculating that they respond to UV-B treatment and regulate anthocyanin biosynthesis. We constructed overexpression vectors, YFP, and bimolecular fluorescence complementation vectors for the transient transformation of tobacco. The results suggest that StBBX19 and StBBX24 may not function as direct regulators of anthocyanin biosynthesis, but rather enhance anthocyanin accumulation through interaction with StMYB308. Still, after interacting with StMYB308, purple spots appeared on tobacco leaves, suggesting that the interaction between StBBX19, StBBX24, and StMYB308 increases anthocyanin content in tobacco leaves. This study provides significant evidence for the adaptation mechanism of plants under UV-B treatment and offers new insights for molecular plant breeding of pigmented potatoes.
Quiju Dong, Xinyu Liu, Jun Li et al.· BMC Plant Biology· 0 citations
Aeroponics is an important approach for the production of virus-free seed potatoes. The propagation efficiency of aeroponically grown potatoes is affected by light conditions. However, the effects of different supplemental light conditions on potato yield and their underlying mechanisms remain unclear. Here, multiple light conditions are applied to investigate their influences on potato minituber production. The results show that red–blue light supplementation significantly increases plant yield. Physiologically, it enhances chlorophyll and carotenoid contents, thereby increasing net photosynthetic rate and CO2 utilization efficiency. Red–blue light temporally regulates hormone balance by increasing the GA/ABA ratio at the early stage to promote vegetative growth, and maintaining higher trans-zeatin content at the late stage, potentially sustaining cell division. These synergistic effects may enhance yield by delaying senescence and prolonging the tuberization period. Transcriptomic analysis reveals that red–blue light treatment enriches pathways related to hormone signaling, senescence-associated, and zeatin biosynthesis at the late growth stage, and upregulates key tuberization genes (StSP6A, StSP3D, StFTL1), which may be associated with tuber formation. Red–blue light treatment optimizes photosynthesis, remodels hormone networks, and induces temporal transcriptional reprogramming, while also increasing the yield of virus-free seed potatoes in aeroponic culture. This study provides theoretical and technical support for the efficient aeroponic breeding of virus-free seed potatoes.
Tetrapyrrole biosynthesis is an absolute essential metabolic pathway in plants that predominantly gives rise to chlorophyll, heme, and phytochromobilin. Dysregulation of tetrapyrrole biosynthesis severely impairs plant growth and development when heme and chlorophyll synthesis are not adjusted to the needs in the respective plant organ and when excessive accumulation of light-absorbing tetrapyrrole intermediates cause oxidative damage. However, how chlorophyll and heme synthesis are properly balanced during early development of greening seedlings remains largely elusive. In this study, we performed a suppressor screen on the photosensitive Arabidopsis thaliana pif1 pif3 (for phytochrome-interacting factors) double mutant, which exhibits excessive singlet oxygen (1O₂) accumulation, and identified four different point mutants of the GENOMES UNCOUPLED 3 (GUN3, also known as HY2) gene encoding phytochromobilin synthase. Further genetic analysis revealed that either mutation of GUN3 or also GUN2 (encoding heme oxygenase, also known as HY1/HO1), but not FC1 (encoding ferrochelatase), rescues the cell death phenotype of pif1 pif3, lowers 1O₂ levels, and suppresses 1O₂-responsive gene expression. Furthermore, gun2 and gun3 mutations lead to heme-mediated feedback inhibition of 5-aminolevulinic acid synthesis and consequently reduced protochlorophyllide accumulation in the pif1 pif3 background. Notably, GUN2 and GUN3 physically interact with GUN4, while their mutations markedly correspond with decreased content of GUN4 and GUN5, which are involved in Mg chelation at the beginning of chlorophyll biosynthesis. Our studies point to an important regulatory role of GUN2 and GUN3 for the mutual link of heme and chlorophyll synthesis.
Huafan Zhu, Yuhong Li, Wenqiang Yang et al.· Plant and Cell Physiology· 0 citations
Apical dominance is a key determinant of plant architecture and yield formation in crops. Auxin and jasmonic acid are crucial endogenous regulators of this process, yet their functions in the above‐ground shoots and underground modified stems (tubers) of asexually propagated potato plants remain largely unclear. Here, we demonstrate that the jasmonate pathway component
StJAZ1‐like
promotes the release of apical dominance in potato.
StJAZ1‐like
overexpression enhanced axillary bud outgrowth, increased shoot branching and triggered multi‐bud sprouting from individual tuber eyes. Transcriptome profiling of dormant axillary buds revealed pronounced alterations in hormone‐related pathways, including marked upregulation of the auxin efflux carrier
StPIN3
, accompanied by reduced indole‐3‐acetic acid (IAA) and abscisic acid (ABA) levels in axillary buds. Consistently, functional analyses demonstrated that
StPIN3
positively regulates lateral branching and tuber sprouting, indicating that
StPIN3
acts downstream of StJAZ1‐like. Mechanistically, StJAZ1‐like physically interacts with StPIF02, a bHLH transcription factor. StPIF02 directly binds the
StPIN3
promoter and activates its transcription. Collectively, our results suggest a StJAZ1‐like–StPIF02–StPIN3 regulatory module that links jasmonate with auxin to modulate apical dominance in potato, providing candidate pathways for designing an ideal multi‐branched plant architecture in potato.
Enshuang Wang, Shahnewaz Begum, S. Jing et al.· Plant, Cell and Environment· 0 citations
