The Plant Journal

Journal: The Plant Journal

Abbreviation

Plant j.

Publisher

Wiley

ISSN

0960-7412
1365-313X

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Publications 1 - 10 of 21

Genome-wide scans of selection highlight the impact of biotic and abiotic constraints in natural populations of the model grass Brachypodium distachyon
Bourgeois, Yann; Stritt, Christoph; Walser, Jean-Claude; et al. (2018)
The Plant Journal
Metabolic profiles of six African cultivars of cassava (Manihot esculenta Crantz) highlight bottlenecks of root yield
Obata, Toshihiro; Klemens, Patrick A.W.; Rosado‐Souza, Laise; et al. (2020)
The Plant Journal
Cassava is an important staple crop in sub‐Saharan Africa, due to its high productivity even on nutrient poor soils. The metabolic characteristics underlying this high productivity are poorly understood including the mode of photosynthesis, reasons for the high rate of photosynthesis, the extent of source/sink limitation, the impact of environment, and the extent of variation between cultivars. Six commercial African cassava cultivars were grown in a greenhouse in Erlangen, Germany, and in the field in Ibadan, Nigeria. Source leaves, sink leaves, stems and storage roots were harvested during storage root bulking and analyzed for sugars, organic acids, amino acids, phosphorylated intermediates, minerals, starch, protein, activities of enzymes in central metabolism and yield traits. High ratios of RuBisCO:phosphoenol pyruvate carboxylase activity support a C3 mode of photosynthesis. The high rate of photosynthesis is likely to be attributed to high activities of enzymes in the Calvin–Benson cycle and pathways for sucrose and starch synthesis. Nevertheless, source limitation is indicated because root yield traits correlated with metabolic traits in leaves rather than in the stem or storage roots. This situation was especially so in greenhouse‐grown plants, where irradiance will have been low. In the field, plants produced more storage roots. This was associated with higher AGPase activity and lower sucrose in the roots, indicating that feedforward loops enhanced sink capacity in the high light and low nitrogen environment in the field. Overall, these results indicated that carbon assimilation rate, the K battery, root starch synthesis, trehalose, and chlorogenic acid accumulation are potential target traits for genetic improvement.
Gene duplication and transposition of mobile elements drive evolution of the Rpv3 resistance locus in grapevine
Foria, Serena; Copetti, Dario; Eisenmann, Birgit; et al. (2020)
The Plant Journal
Reciprocal allopolyploid grasses (Festuca × Lolium) display stable patterns of genome dominance
Glombik, Marek; Copetti, Dario; Bartoš, Jan; et al. (2021)
The Plant Journal
Allopolyploidization entailing the merger of two distinct genomes in a single hybrid organism, is an important process in plant evolution and a valuable tool in breeding programs. Newly established hybrids often experience massive genomic perturbations, including karyotype reshuffling and gene expression modifications. These phenomena may be asymmetric with respect to the two progenitors, with one of the parental genomes being ‘dominant’. Such ‘genome dominance’ can manifest in several ways, including biased homoeolog gene expression and expression level dominance. Here we employed a k-mer based approach to study gene expression in reciprocal Festuca pratensis Huds. × Lolium multiflorum Lam. allopolyploid grasses. Our study revealed significantly more genes where expression mimicked that of the Lolium parent compared to the Festuca parent. This genome dominance was heritable to successive generation and its direction was only slightly modified by environmental conditions and plant age. Our results suggest that Lolium genome dominance was at least partially caused by its more efficient trans-acting gene expression regulatory factors. Unraveling the mechanisms responsible for propagation of parent-specific traits in hybrid crops contributes to our understanding of allopolyploid genome evolution and opens a way to targeted breeding strategies.
Enhancement of vitamin B6 levels in rice expressing Arabidopsis vitamin B6 biosynthesis de novo genes
Mangel, Nathalie; Fudge, Jared B.; Li, Kuan-Te; et al. (2019)
The Plant Journal
Vitamin B6 (pyridoxine) is vital for key metabolic reactions and reported to have antioxidant properties in planta. Therefore, enhancement of vitamin B6 content has been hypothesized to be a route to improve resistance to biotic and abiotic stresses. Most of the current studies on vitamin B6 in plants are on eudicot species, with monocots remaining largely unexplored. In this study, we investigated vitamin B6 biosynthesis in rice, with a view to examining the feasibility and impact of enhancing vitamin B6 levels. Constitutive expression in rice of two Arabidopsis thaliana genes from the vitamin B6 biosynthesis de novo pathway, AtPDX1.1 and AtPDX2, resulted in a considerable increase in vitamin B6 in leaves (up to 28.3‐fold) and roots (up to 12‐fold), with minimal impact on general growth. Rice lines accumulating high levels of vitamin B6 did not display enhanced tolerance to abiotic stress (salt) or biotic stress (resistance to Xanthomonas oryzae infection). While a significant increase in vitamin B6 content could also be achieved in rice seeds (up to 3.1‐fold), the increase was largely due to its accumulation in seed coat and embryo tissues, with little enhancement observed in the endosperm. However, seed yield was affected in some vitamin B6‐enhanced lines. Notably, expression of the transgenes did not affect the expression of the endogenous rice PDX genes. Intriguingly, despite transgene expression in leaves and seeds, the corresponding proteins were only detectable in leaves and could not be observed in seeds, possibly pointing to a mode of regulation in this organ.
A pectin acetyl‐transferase facilitates secondary plasmodesmata formation and RNA silencing movement between plant cells
Jay, Florence; Brioudes, Florian; Novaković, Lazar; et al. (2025)
The Plant Journal
Some silencing small (s)RNAs, comprising micro (mi)RNAs and small-interfering (si)RNAs, move between plant cells to orchestrate gene expression and defense. Besides possible redundancy or embryo lethality, a prevalent challenge in genetic studies of mobile silencing is to discriminate bona fide alterations to sRNA movement from impaired cell-autonomous sRNA activity within silencing-recipient cells. Without such clarifications, cell-to-cell mobility factors are yet to be unequivocally identified. Consequently, known properties of sRNA movement, including contextuality and directionality, remain poorly explained. Circumstantial evidence and synthetic biology pinpoint plasmodesmata (PDs) – the pores traversing plant cell walls (CWs) – as the likely channels involved. Yet, how plants control the number of primary and secondary PDs developing respectively before and after CW formation remains largely unknown. Here, we address these intertwined issues in Arabidopsis using a forward screen for compromised epidermis-to-mesophyll movement of an artificial (a)miRNA. We identify a pectin acetyl-transferase mutation that, we demonstrate, reduces amiRNA physical trafficking but also impedes siRNA, GFP, and viral movement by decreasing the frequency of leaf secondary PDs. sRNA movement at leaf interfaces involving primary PDs remains unaffected, however, as does miRNA and GFP cell-to-cell mobility in roots, hinting at how movement's contextuality and directionality might be achieved. We also show that reducing de-esterified pectin depolymerization decreases leaves' symplasmic connectivity, whereas defective pectin biogenesis increases PD number. Combining genetics with antibody-based pectin probing and atomic force microscopy helps delineate a mechanistically coherent framework whereby pectin esterification and/or abundance impact CW loosening, a process required for CW extension during which secondary PDs form to enable macromolecular trafficking.
CELLULOSE SYNTHASE INTERACTING 1 is required for wood mechanics and leaf morphology in aspen
Bunder, Anne; Sundman, Ola; Mahboubi, Amir; et al. (2020)
The Plant Journal
Cellulose microfibrils synthesized by CELLULOSE SYNTHASE COMPLEXES (CSCs) are the main load-bearing polymers in wood. CELLULOSE SYNTHASE INTERACTING1 (CSI1) connects CSCs with cortical microtubules, which align with cellulose microfibrils. Mechanical properties of wood are dependent on cellulose microfibril alignment and structure in the cell walls, but the molecular mechanism(s) defining these features is unknown. Herein, we investigated the role of CSI1 in hybrid aspen (Populus tremula x Populus tremuloides) by characterizing transgenic lines with significantly reducedCSI1transcript abundance. Reduction in leaves (50-80%) caused leaf twisting and misshaped pavement cells, while reduction (70-90%) in developing xylem led to impaired mechanical wood properties evident as a decrease in the elastic modulus and rupture. X-ray diffraction measurements indicate that microfibril angle was not impacted by the alteredCSI1abundance in developing wood fibres. Instead, the augmented wood phenotype of the transgenic trees was associated with a reduced cellulose degree of polymerization. These findings establish a function for CSI1 in wood mechanics and in defining leaf cell shape. Furthermore, the results imply that the microfibril angle in wood is defined by CSI1 independent mechanism(s).
Lipid kinases PIP5K7 and PIP5K9 are required for polyamine‐triggered K+ efflux in Arabidopsis roots
Zarza, Xavier; Van Wijk, Ringo; Shabala, Lana; et al. (2020)
The Plant Journal
Polyamines, such as putrescine, spermidine and spermine (Spm), are low‐molecular‐weight polycationic molecules present in all living organisms. Despite their implication in plant cellular processes, little is known about their molecular mode of action. Here, we demonstrate that polyamines trigger a rapid increase in the regulatory membrane lipid, phosphatidylinositol‐4,5‐bisphosphate (PIP2), and that this increase is required for polyamine effects on K+ efflux in Arabidopsis roots. Using in vivo 32Pi‐labelling of Arabidopsis seedlings, low physiological (μM) concentrations of Spm were found to promote a rapid PIP2 increase in roots that was time‐ and dose‐dependent. Confocal imaging of a genetically encoded‐PIP2 biosensor revealed that this increase was triggered at the plasma membrane. Differential 32Pi‐labelling suggested that the increase in PIP2 was generated through activation of phosphatidylinositol‐4‐phosphate 5‐kinase (PIP5K) activity rather than inhibition of a phospholipase C or PIP2 5‐phosphatase activity. Systematic analysis of T‐DNA insertion mutants identified PIP5K7 and PIP5K9 as the main candidates involved in the Spm induced‐PIP2 response. Using non‐invasive microelectrode ion‐flux estimation (MIFE), we discovered that the Spm‐triggered K+‐efflux response was strongly reduced in pip5k7 pip5k9 seedlings. Together, our results provide biochemical‐ and genetic evidence for a physiological role of PIP2 in polyamine‐mediated signalling controlling K+ flux in plants.
Introduction of glucan synthase into the cytosol in wheat endosperm causes massive maltose accumulation and represses starch synthesis
Schreier, Tina B.; Fahy, Brendan; David, Laure C.; et al. (2021)
The Plant Journal
We expressed a bacterial glucan synthase (Agrobacterium GlgA) in the cytosol of developing endosperm cells in wheat grains, to discover whether it could generate a glucan from cytosolic ADP-glucose. Transgenic lines had high glucan synthase activity during grain filling, but did not accumulate glucan. Instead, grains accumulated very high concentrations of maltose. They had large volumes during development due to high water content, and very shrivelled grains at maturity. Starch synthesis was severely reduced. We propose that cytosolic glucan synthesized by the glucan synthase was immediately hydrolysed to maltose by cytosolic β-amylase(s). Maltose accumulation resulted in a high osmotic potential in developing grain, drawing in excess water that stretched the seed coat and pericarp. Loss of water during grain maturation then led to shrinkage when the grains matured. Maltose accumulation is likely to account for the reduced starch synthesis in transgenic grains, through signalling and toxic effects. Using bioinformatics, we identify an isoform of β-amylase likely to be responsible for maltose accumulation. Removal of this isoform through identification of TILLING mutants or genome editing, combined with co-expression of heterologous glucan synthase and a glucan branching enzyme, may in future enable elevated yields of carbohydrate through simultaneous accumulation of starch and cytosolic glucan.
Genome‐wide association identifies candidate genes for drought tolerance in coast redwood and giant sequoia
De La Torre, Amanda R.; Sekhwal, Manoj K.; Puiu, Daniela; et al. (2022)
The Plant Journal
Drought is a major limitation for survival and growth in plants. With more frequent and severe drought episodes occurring due to climate change, it is imperative to understand the genomic and physiological basis of drought tolerance to be able to predict how species will respond in the future. In this study, univariate and multitrait multivariate genome-wide association study methods were used to identify candidate genes in two iconic and ecosystem-dominating species of the western USA, coast redwood and giant sequoia, using 10 drought-related physiological and anatomical traits and genome-wide sequence-capture single nucleotide polymorphisms. Population-level phenotypic variation was found in carbon isotope discrimination, osmotic pressure at full turgor, xylem hydraulic diameter, and total area of transporting fibers in both species. Our study identified new 78 new marker × trait associations in coast redwood and six in giant sequoia, with genes involved in a range of metabolic, stress, and signaling pathways, among other functions. This study contributes to a better understanding of the genomic basis of drought tolerance in long-generation conifers and helps guide current and future conservation efforts in the species.

Publications 1 - 10 of 21

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