Seasonal fluctuations in day length regulate important aspects of plant development such as the flowering transition or, in potato (Solanum tuberosum), the formation of tubers. Day length is sensed ...by the leaves, which produce a mobile signal transported to the shoot apex or underground stems to induce a flowering transition or, respectively, a tuberization transition. Work in Arabidopsis, tomato and rice (Oryza sativa) identified the mobile FLOWERING LOCUS T (FT) protein as a main component of the long-range 'florigen', or flowering hormone, signal. Here we show that expression of the Hd3a gene, the FT orthologue in rice, induces strict short-day potato types to tuberize in long days. Tuber induction is graft transmissible and the Hd3a-GFP protein is detected in the stolons of grafted plants, transport of the fusion protein thus correlating with tuber formation. We provide evidence showing that the potato floral and tuberization transitions are controlled by two different FT-like paralogues (StSP3D and StSP6A) that respond to independent environmental cues, and show that an autorelay mechanism involving CONSTANS modulates expression of the tuberization-control StSP6A gene.
SUMMARY
Plants regulate their reproductive cycles under the influence of environmental cues, such as day length, temperature and water availability. In Solanum tuberosum (potato), vegetative ...reproduction via tuberization is known to be regulated by photoperiod, in a very similar way to flowering. The central clock output transcription factor CYCLING DOF FACTOR 1 (StCDF1) was shown to regulate tuberization. We now show that StCDF1, together with a long non‐coding RNA (lncRNA) counterpart, named StFLORE, also regulates water loss through affecting stomatal growth and diurnal opening. Both natural and CRISPR‐Cas9 mutations in the StFLORE transcript produce plants with increased sensitivity to water‐limiting conditions. Conversely, elevated expression of StFLORE, both by the overexpression of StFLORE or by the downregulation of StCDF1, results in an increased tolerance to drought through reducing water loss. Although StFLORE appears to act as a natural antisense transcript, it is in turn regulated by the StCDF1 transcription factor. We further show that StCDF1 is a non‐redundant regulator of tuberization that affects the expression of two other members of the potato StCDF gene family, as well as StCO genes, through binding to a canonical sequence motif. Taken together, we demonstrate that the StCDF1–StFLORE locus is important for vegetative reproduction and water homeostasis, both of which are important traits for potato plant breeding.
Significance Statement
Plants can regulate their water uptake through adapting the aperture of the stomata. Here, we show that mutual regulation of a long non‐coding RNA and a clock output transcription factor together influence water homeostasis, providing a possible new approach to understand drought tolerance.
Summary
In potato, maturity is assessed by leaf senescence, which, in turn, affects yield and tuber quality traits. Previously, we showed that the CYCLING DOF FACTOR1 (StCDF1) locus controls leaf ...maturity in addition to the timing of tuberization. Here, we provide evidence that StCDF1 controls senescence onset separately from senescence progression and the total life cycle duration.
We used molecular–biological approaches (DNA‐Affinity Purification Sequencing) to identify a direct downstream target of StCDF1, named ORESARA1 (StORE1S02), which is a NAC transcription factor acting as a positive senescence regulator.
By overexpressing StORE1S02 in the long life cycle genotype, early onset of senescence was shown, but the total life cycle remained long. At the same time, StORE1S02 knockdown lines have a delayed senescence onset. Furthermore, we show that StORE1 proteins play an indirect role in sugar transport from source to sink by regulating expression of SWEET sugar efflux transporters during leaf senescence.
This study clarifies the important link between tuber formation and senescence and provides insight into the molecular regulatory network of potato leaf senescence onset. We propose a complex role of StCDF1 in the regulation of potato plant senescence.
See also the Commentary on this article by Tai, 242: 2385–2387.
SUMMARY
Potato (Solanum tuberosum L.) is one of the world's most important crops, but it is facing major challenges due to climatic changes. To investigate the effects of intermittent drought on the ...natural variability of plant morphology and tuber metabolism in a novel potato association panel comprising 258 varieties we performed an augmented block design field study under normal irrigation and under water‐deficit and recovery conditions in Ica, Peru. All potato genotypes were profiled for 45 morphological traits and 42 central metabolites via nuclear magnetic resonance. Statistical tests and norm of reaction analysis revealed that the observed variations were trait specific, that is, genotypic versus environmental. Principal component analysis showed a separation of samples as a result of conditional changes. To explore the relational ties between morphological traits and metabolites, correlation‐based network analysis was employed, constructing one network for normal irrigation and one network for water‐recovery samples. Community detection and difference network analysis highlighted the differences between the two networks, revealing a significant correlational link between fumarate and plant vigor. A genome‐wide association study was performed for each metabolic trait. Eleven single nucleotide polymorphism (SNP) markers were associated with fumarate. Gene Ontology analysis of quantitative trait loci regions associated with fumarate revealed an enrichment of genes regulating metabolic processes. Three of the 11 SNPs were located within genes, coding for a protein of unknown function, a RING domain protein and a zinc finger protein ZAT2. Our findings have important implications for future potato breeding regimes, especially in countries suffering from climate change.
Significance Statement
Potato is one of the world's most important crops but it is facing major challenges due to climatic changes. We conducted an augmented block field study with a tropical climate‐adapted potato association panel under normal and water‐deficit conditions. We assessed all plants for 45 morphological traits and measured 42 central metabolites in the tuber. Correlation‐based network analysis highlighted a connection between fumarate and plant vigor, traced back to a zinc finger protein and a RING domain protein.
Gibberellins (GAs; tetracyclic di-terpenoid carboxylic acids) are endogenous plant growth regulators responsible for stimulating plant growth and development from seed germination to plant maturity. ...In potato (
Solanum tuberosum
L.), GA levels are known to be crucial in the complex process of tuberization. Gibberellin 2-oxidases (GA2oxs) inactivate bioactive GAs during stolon swelling and early stages of tuberization as evident from the predominant expression of a member of this gene family namely
GA2ox1
. We isolated and characterized a 1105-bp cDNA clone encoding a 340-aa GA2ox1 form, designated St-GA2ox1, using total RNA from growing tuber of a potato (
Solanum tuberosum
L.) cultivar, Kufri Chipsona-1 (KC-1) based on RT-PCR approach. A total of 26 GA2ox sequences were also retrieved from potato genome database and analysed. Multiple sequence alignment revealed sequence relatedness between the GA2oxs. Crucial protein motifs were identified. Phylogenetic analysis revealed the evolutionary relationships between the GA2oxs. Three-dimensional structure of St-GA2ox1 was predicted by using AlphaFold tool, validated by the predicted local-distance difference test and Ramachandran Plot. Structural analysis and molecular docking were carried out to identify domains, binding sites and affinity for the ligand. The STRING database and hydropathy analysis revealed the presence of a putative interaction site for other enzymes. Expression Atlas database and semi-quantitative RT-PCR revealed the expression patterns of various GA2ox forms in different potato organs. This comprehensive report would be useful in providing new insights into possible underlying mechanisms involved in tuber development, and could facilitate the targeted alteration of genes responsible to combat the stress and enhance tuber production.
New promising manganese-containing nanobiocomposites (NCs) based on natural polysaccharides, arabinogalactan (AG), arabinogalactan sulfate (AGS), and
-carrageenan (
-CG) were studied to develop novel ...multi-purpose trophic low-dose organomineral fertilizers. The general toxicological effects of manganese (Mn) on the vegetation of potatoes (
L.) was evaluated in this study. The essential physicochemical properties of this trace element in plant tissues, such as its elemental analysis and its spectroscopic parameters in electron paramagnetic resonance (EPR), were determined. Potato plants grown in an NC-containing medium demonstrated better biometric parameters than in the control medium, and no Mn accumulated in plant tissues. In addition, the synthesized NCs demonstrated a pronounced antibacterial effect against the phytopathogenic bacterium
(
) and were proved to be safe for natural soil microflora.
Maintenance of plant physiological functions under drought stress is normally considered a positive feature as it indicates sustained plant health and growth. This study was conducted to investigate ...whether plant growth-promoting rhizobacteria (PGPR) Bacillus subtilis HAS31 has potential to maintain potato growth and yield under drought stress. We analyzed trends of chlorophyll concentration, photosynthesis process, relative water content, osmolytes, antioxidants enzymes and oxidative stress, relative growth rate, tuber and aboveground biomass production in two potato varieties, Santae (drought-tolerant) and PRI-Red (drought-sensitive). Plants of both genotypes were treated with 100 g of HAS31 inoculant at 10 days after germination and exposed to different soil relative water contents (SRWC), including 80 ± 5% (well watered), 60 ± 5% (moderate stress) and 40 ± 5% SRWC (severe stress) for 7 days at tuber initiation stage (30 days after germination). The drought stress reduced plant relative growth rate, biomass production, leaf area, number of leaves and tubers, tuber weight, and final yield. The drought-stressed plants showed decline in chlorophyll contents, membrane stability, leaf relative water contents and photosynthetic rate. Under drought stress, enzymatic activity of catalase (CAT), peroxidase (POD) and superoxide dismutase (SOD), contents of total soluble sugars, soluble proteins and proline increased. The application of PGPR reduced the impact of drought and maintained higher growth and physio-chemical traits of the plants. The plants with PGPR application showed higher relative growth rate, dry matter production, leaf area, number of tubers, tuber weight and yield as compared to plants without PGPR. The PGPR-HAS31 treated plants maintained higher photosynthetic process, contents of chlorophyll, soluble proteins, total soluble sugars, and enzymatic activities of CAT, POD and SOD as compared to plants without PGPR. The results of the study suggest that plant growth regulators have ability to sustain growth and yield of potato under drought stress by maintaining physiological functions of the plants.
Photoperiod-regulated flowering and potato tuber formation involve leaf-produced mobile signals, florigen and tuberigen, respectively. The major protein component of florigen has been identified as ...the FLOWERING LOCUS T (FT) protein. In rice, an FT-like protein, Heading date 3a (Hd3a), induces flowering by making the florigen activation complex (FAC) through interactions with 14-3-3 and OsFD1, a rice FD-like protein. In potato, StSP6A, an FT-like protein, was identified as a major component of tuberigen. However, the molecular mechanism of how StSP6A triggers tuber formation remains elusive. Here we analyzed the significance of the formation of a complex including StSP6A, 14-3-3 and FD-like proteins in tuberization. Yeast two-hybrid, bimolecular fluorescence complementation and in vitro pull-down assays showed that StSP6A and StFDL1, a potato FD-like protein, interact with St14-3-3s. StSP6A overexpression induced early tuberization in a 14-3-3-dependent manner, and suppression of StFDL1 delayed tuberization. These results strongly suggest that an FAC-like complex, the tuberigen activation complex (TAC), comprised of StSP6A, St14-3-3s and StFDL1, regulates potato tuber formation.
NRAMP family genes participate in the absorption and transport of heavy metals such as cadmium (Cd), zinc (Zn), copper (Cu), lead (Pb), iron (Fe) and manganese (Mn) and play an important role in the ...response to heavy metal stress. There is an abundance of research on these genes in bacteria, plants and fungi, although not in S. tuberosum. A total of 48 members(potato(5), Arabidopsis(7), Tomato(9), pepper(9), rice(12) and tobacco(6)) were identified from 6 species (potato (Solanum tuberosum), Arabidopsis thaliana, Tomato (Solanum lycopersicum), pepper (Capsicum annuum), rice (Oryza sativa) and tobacco (Nicotiana attenuate)) and were classified into four subgroups. Across NRAMP gene family members, there are 15 highly conserved motifs that have similar genetic structures and characteristics. In addition, a total of 16 pairs of colinear genes were found in eight species. Analysis of cis-elements indicated that, in response to abiotic stress, NRAMPs are mainly regulated by phytohormones and transcription factors. In addition, analysis of expression profiles indicated that StNRAMP4 is mainly expressed in the roots. According to a qRT-PCR-based analysis of the StNRAMP family, with the exception of Pb2+ stress, StNRAMPs positively responded to stress from Cu2+, Cd2+, Zn2+ and Ni2+ and The expression patterns is similar of StNRAMP2, under Pb2+, and Cu2+ treatment, the relative expression peaked at 24 h. the relative expression peaked at 12 h and was upregulated 428-fold in the roots under Ni2+ stress. Under Cd2+ stress, StNRAMP3 was upregulated 28-fold in the leaves. StNRAMP1, StNRAMP4 and StNRAMP5 showed significant upregulation under Cu2+, Cd2+ and Zn2+ stress, respectively. Expression of StNRAMPs could be specifically induced by heavy metals, implying their possible role in the transport and absorption of heavy metals. This research explains the colinear characteristics of NRAMPs in several food crop species, which is useful for providing important genetic resources for cultivating food crop that accumulate low amounts of heavy metals and for explaining the biological functions of NRAMPs in plants.
•Totally five NRAMP genes were firstly genome-widely identified in potato.•The different response pattern of NRAMP genes was performed under 5 heavy metals stress.•Comparative genomics analysis for five NRAMP were indicated for understanding response to heavy metals stress in plant.
Potato (Solanum tuberosum L.) is cultivated worldwide for its underground tubers, which provide an important part of human nutrition and serve as a model system for belowground storage organ ...formation. Similar to flowering, stolon-expressed FLOWERING LOCUS T-like (FT-like) protein SELF-PRUNING 6A (StSP6A) plays an instrumental role in tuberization by binding to the bZIP transcription factors StABI5-like 1 (StABL1) and StFD-like 1 (StFDL1), causing transcriptional reprogramming at the stolon subapical apices. However, the molecular mechanism regulating the widely conserved FT-bZIP interactions remains largely unexplored. Here, we identified a TCP transcription factor StAST1 (StABL1 and StSP6A-associated TCP protein 1) binding to both StSP6A and StABL1. StAST1 is specifically expressed in the vascular tissue of leaves and developing stolons. Silencing of StAST1 leads to accelerated tuberization and a shortened life cycle. Molecular dissection reveals that the interaction of StAST1 with StSP6A and StABL1 attenuates the formation of the alternative tuberigen activation complex (aTAC). We also observed StAST1 directly activates the expression of potato GA 20-oxidase gene (StGA20ox1) to regulate GA responses. These results demonstrate StAST1 functions as a tuberization repressor by regulating plant hormone levels; our findings also suggest a mechanism by which the widely conserved FT-FD genetic module is fine-tuned.
PDF
