Florigen governs shoot regeneration.
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ABSTRACT:
SUBMITTER: Kutsher Y
PROVIDER: S-EPMC8249374 | biostudies-literature |
REPOSITORIES: biostudies-literature
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Project description:The superiority of hybrids has long been exploited in agriculture, and although many models explaining "heterosis" have been put forth, direct empirical support is limited. Particularly elusive have been cases of heterozygosity for single gene mutations causing heterosis under a genetic model known as overdominance. In tomato (Solanum lycopersicum), plants carrying mutations in SINGLE FLOWER TRUSS (SFT) encoding the flowering hormone florigen are severely delayed in flowering, become extremely large, and produce few flowers and fruits, but when heterozygous, yields are dramatically increased. Curiously, this overdominance is evident only in the background of "determinate" plants, in which the continuous production of side shoots and inflorescences gradually halts due to a defect in the flowering repressor SELF PRUNING (SP). How sp facilitates sft overdominance is unclear, but is thought to relate to the opposing functions these genes have on flowering time and shoot architecture. We show that sft mutant heterozygosity (sft/+) causes weak semi-dominant delays in flowering of both primary and side shoots. Using transcriptome sequencing of shoot meristems, we demonstrate that this delay begins before seedling meristems become reproductive, followed by delays in subsequent side shoot meristems that, in turn, postpone the arrest of shoot and inflorescence production. Reducing SFT levels in sp plants by artificial microRNAs recapitulates the dose-dependent modification of shoot and inflorescence production of sft/+ heterozygotes, confirming that fine-tuning levels of functional SFT transcripts provides a foundation for higher yields. Finally, we show that although flowering delays by florigen mutant heterozygosity are conserved in Arabidopsis, increased yield is not, likely because cyclical flowering is absent. We suggest sft heterozygosity triggers a yield improvement by optimizing plant architecture via its dosage response in the florigen pathway. Exploiting dosage sensitivity of florigen and its family members therefore provides a path to enhance productivity in other crops, but species-specific tuning will be required.
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Project description:Shoot regeneration is a key tool of modern plant biotechnology. While many researchers use this process empirically, very little is known about the early molecular genetic factors and signaling events that lead to shoot regeneration. Using tobacco as a model system, we found that the inductive events required for shoot regeneration occur in the first 4-5 days following incubation on regeneration medium. Leaf segments placed on regeneration medium did not produce shoots if removed from the medium before four days indicating this time frame is crucial for the induction of shoot regeneration. Leaf segments placed on regeneration medium for longer than five days maintain the capacity to produce shoots when removed from the regeneration medium. Analysis of gene expression during the early days of incubation on regeneration medium revealed many changes occurring with no single expression pattern evident among major gene families previously implicated in developmental processes. For example, expression of Knotted gene family members increased during the induction period, whereas transcription factors from the Wuschel gene family were unaltered during shoot induction. Expression levels of genes involved in cell cycle regulation increased steadily on regeneration medium while expression of NAC genes varied. No obvious possible candidate genes or developmental processes could be identified as a target for the early events (first few days) in the induction of shoot regeneration. On the other hand, observations during the early stages of regeneration pointed out that regeneration does not occur from a single cell but a group of cells. We observed that while cell division starts just as leaf segments are placed on regeneration medium, only a group of cells could become shoot primordia. Still, these primordia are not identifiable during the first days.
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Project description:Diploid strawberry (Fragaria vesca 'Baiguo') is a model plant for studying functional genomics in Rosaceae. Adventitious shoot regeneration is essential for functional genomics by Agrobacterium tumefaciens-mediated transformation. An efficient shoot regeneration method using diploid strawberry leaf explants was conducted on 1/2MS?+?1/2B5 medium that contained 2.0?mg?L-1 TDZ over 14 days of dark culture; this induced the maximum percentage of shoot regeneration (96.44?±?1.60%) and the highest number of shoots per explant (23.46?±?2.14) after 11 weeks of culture. The explants considerably enlarged after 12 days; then, turned greenish brown after 30 days, yellowish brown after 36 days, and completely brown and necrotic after 48 days. Large numbers of adventitious shoots were produced from 48 to 66 days, and the shoots elongated from 66 to 78 days; this represents a critical period of reinvigoration, which included 30 days for leaf explant chlorosis, 36 days for adventitious shoot appearance, and 48 days for generation of numerous shoots. During the reinvigoration process, higher expressions of the hormone synthesis-related genes Ciszog1, CKX2, CKX3, CKX7, YUC2, YUC6, YUC10, YUC9, and GA2ox were detected from 30 to 48 days. Our results indicate that these genes may regulate reinvigoration of shoot regeneration.
| S-EPMC6736952 | biostudies-literature
Project description:Potato (Solanum tuberosum L.) is the third most economically important crop in the world and has a high nutritional value. In this study, the in vitro culture response of four widely grown in Kazakhstan potato cultivars, Astanalyk, Monument Kunaev, Tokhtar, and Aksor, was investigated using stem and leaf explants. Published protocols were evaluated and optimized to develop a more efficient protocol for the regeneration of plants from local potato cultivars in tissue culture, which is a prerequisite to facilitate potato genome modification. The explants were cultured on solid Murashige and Skoog medium supplemented with different concentrations and combinations of zeatin, 6-benzylaminopurine (BAP), gibberellic acid (GA3), 1-naphthaleneacetic acid (NAA) and indole-3-acetic acid (IAA). The maximum regeneration was induced from the stem internodal explants. A significant effect of the explant source on direct regeneration was confirmed with statistical analysis. The number of shoots obtained from the internode was 10.0 from cv. Aksor followed by cvs. Tokhtar and Astanalyk. The medium DRM-VIII with 1 mg/l zeatin, 0.1 mg/l IAA and 7.0 mg/l GA3 was considered the best for direct shoot regeneration and multiple shoot formation from all cultivars. To conclude, we outline a protocol for direct plant regeneration from four potato cultivars. Our findings suggest commercial cultivars Astanalyk and Aksor are good candidates for developing the genome-edited plants through direct shoot regeneration.
| S-EPMC7365135 | biostudies-literature
Project description:We used mutant analysis, protein–protein interaction assays and DNA affinity purification (DAP) sequencing coupled to in silico prediction of binding syntaxes to study several bZIP proteins that assemble into florigen activation/repressor complexes (FACs/FRCs).
2022-07-10 | GSE207402 | GEO
Project description:Plants can regenerate from a variety of tissues on culturing in appropriate media. However, the metabolic shifts involved in callus formation and shoot regeneration are largely unknown. The metabolic profiles of callus generated from tomato (Solanum lycopersicum) cotyledons and that of shoot regenerated from callus were compared with the pct1-2 mutant that exhibits enhanced polar auxin transport and the shr mutant that exhibits elevated nitric oxide levels. The transformation from cotyledon to callus involved a major shift in metabolite profiles with denser metabolic networks in the callus. In contrast, the transformation from callus to shoot involved minor changes in the networks. The metabolic networks in pct1-2 and shr mutants were distinct from wild type and were rewired with shifts in endogenous hormones and metabolite interactions. The callus formation was accompanied by a reduction in the levels of metabolites involved in cell wall lignification and cellular immunity. On the contrary, the levels of monoamines were upregulated in the callus and regenerated shoot. The callus formation and shoot regeneration were accompanied by an increase in salicylic acid in wild type and mutants. The transformation to the callus and also to the shoot downregulated LST8 and upregulated TOR transcript levels indicating a putative linkage between metabolic shift and TOR signalling pathway. The network analysis indicates that shift in metabolite profiles during callus formation and shoot regeneration is governed by a complex interaction between metabolites and endogenous hormones.
| S-EPMC5421760 | biostudies-literature
Project description:Shoot regeneration involves reprogramming of somatic cells and de novo organization of shoot apical meristems (SAMs). In the best-studied model system of shoot regeneration using Arabidopsis, regeneration is mediated by the auxin-responsive pluripotent callus formation from pericycle or pericycle-like tissues according to the lateral root development pathway. In contrast, shoot regeneration can be induced directly from fully differentiated epidermal cells of stem explants of Torenia fournieri (Torenia), without intervening the callus mass formation in culture with cytokinin; yet, its molecular mechanisms remain unaddressed. Here, we characterized this direct shoot regeneration by cytological observation and transcriptome analyses. The results showed that the gene expression profile rapidly changes upon culture to acquire a mixed signature of multiple organs/tissues, possibly associated with epidermal reprogramming. Comparison of transcriptomes between three different callus-inducing cultures (callus induction by auxin, callus induction by wounding and protoplast culture) of Arabidopsis and the Torenia stem culture identified genes upregulated in all the four culture systems as candidates of common factors of cell reprogramming. These initial changes proceeded independently of cytokinin, followed by cytokinin-dependent, transcriptional activations of nucleolar development and cell cycle. Later, SAM regulatory genes became highly expressed, leading to SAM organization in the foci of proliferating cells in the epidermal layer. Our findings revealed three distinct phases with different transcriptomic and regulatory features during direct shoot regeneration from the epidermis in Torenia, which provides a basis for further investigation of shoot regeneration in this unique culture system.
| S-EPMC8579340 | biostudies-literature
Project description:Sesamum indicum is an ancient oilseed crop known for its high quality edible oil and its medicinally important lignans. The crop is said to be recalcitrant to plant tissue culture thus limiting the use of modern biotechnology for its genetic improvement. We present here a protocol describing plant regeneration through adventitious shoot formation from cotyledons dissected from sesame seeds soaked for four hours in water. Subculturing of the cotyledons after two weeks of culture on to a fresh Murashige and Skoog medium leads to differentiation of adventitious shoots from the proximal cut end of the explant. Culture of cotyledons on a medium containing 9% sucrose for a couple of weeks prior to transfer to MS medium supplemented with 3% sucrose induced a higher frequency of shoot regeneration. The highest frequency of 25% adventitious shoot regeneration was observed for S. indicum variety UMA. This variety also turned out to be the best among the ten genotypes tested for shoot regeneration through tissue culture. While addition of IAA marginally improved regeneration, silver nitrate was found essential for enhancing the frequency of shoot regeneration. The regenerated shoots formed roots on full strength MS medium supplemented with 1 mg/l IBA and the rooted plants were established in soil.
| S-EPMC6296652 | biostudies-other
Project description:BACKGROUND:LEAFY COTYLEDON 2 (LEC2) acts throughout embryo morphogenesis and maturation phase to maintain embryogenic identity. Our previous study stated that Arabidopsis thaliana LEC2 (AtLEC2) driven by glucocorticoid receptor-dexamethasone (GR-DEX) inducible system (AtLEC2-GR) triggers embryogenic callus formation in tobacco (Nicotiana tabacum). RESULTS:In this study, the adenosine phosphate isopentenyltransferase genes AtIPT3, AtIPT7 and the tRNA isopentenyltransferase gene AtIPT9 were overexpressed in the AtLEC2-GR transgenic background. In the AtIPT7-OE AtLEC2-GR and AtIPT9-OE AtLEC2-GR seedlings, high-quality embryogenic callus was obtained under the DEX condition, and the shoot regeneration efficiency was 2 to 3.5 folds higher than AtLEC2-GR alone on hormone free medium without DEX. Transcriptome analyses showed that up-regulated BBM, L1L, ABI3, and FUS3 might function during embryogenic callus formation. However, at the shoot regeneration stage, BBM, L1L, ABI3, and FUS3 were down-regulated and Type-B ARRs were up-regulated, which might contribute to the increased shoot regeneration rate. CONCLUSIONS:A novel system for inducing shoot regeneration in tobacco has been developed using the GR-DEX system. Induced expression of AtLEC2 triggers embryogenic callus formation and overexpression of AtIPT7 or AtIPT9 improves shoot regeneration without exogenous cytokinin.
| S-EPMC6633698 | biostudies-literature
Project description:In the present study, an efficient system for the in vitro regeneration of adventitious shoots from the peach rootstock Hansen 536 leaves has been established. Twenty regeneration media containing McCown Woody Plant Medium (WPM) as a basal salt supplemented with different concentrations and combinations of plant growth regulators (PGRs) were tested. Expanded leaves along with their petiole from 3-week-old elongated in vitro shoot cultures were used as starting explants. The highest regeneration rate (up to 53%) was obtained on WPM basal medium enriched with 15.5 ?M N6-benzylaminopurine (BAP). The influences on leaf regeneration of the ethylene inhibitor silver thiosulphate (STS) and of different combinations of antibiotics added to the optimized regeneration medium were also investigated. The use of 10 ?M STS or carbenicillin (238 ?M) combined with cefotaxime (210 ?M) significantly increased the average number of regenerating shoots per leaf compared to the control. In vitro shoots were finally elongated, rooted and successfully acclimatized in the greenhouse. The results achieved in this study advances the knowledge on factors affecting leaf organogenesis in Prunus spp., and the regeneration protocol described looks promising for the optimization of new genetic transformation procedures in Hansen 536 and other peach rootstocks and cultivars.
| S-EPMC7357001 | biostudies-literature