Journal of Plant Research最新文献

We have previously suggested that in rice (Oryza sativa L.) leaves of different ages and N nutrition statuses, photosystems II and I (PSII and PSI, respectively) are regulated depending on N partitioning to Rubisco, which can determine the magnitude of unutilized light energy. The robustness of this mechanism was tested using Rubisco-antisense transgenic rice plants, in which reduced N partitioning to Rubisco markedly increases unutilized light energy. In wild-type plants, N partitioning to Rubisco tended to be smaller in the leaves at lower positions owing to leaf senescence. In the transgenic plants, N partitioning to Rubisco was generally smaller than in the wild-type plants and was relatively constant among leaf positions. The quantum efficiency of PSII [Y(II)] and quantum yield of non-photochemical quenching [Y(NPQ)] correlated positively and negatively, respectively, with N partitioning to Rubisco irrespective of leaf position or genotype. The oxidation levels of the reaction center chlorophyll of PSI (P700) [Y(ND)] negatively correlated with N partitioning to Rubisco. However, in mature and early senescent leaves of the transgenic plants, Y(ND) was markedly lower than expected from N partitioning to Rubisco. These results suggest that in the transgenic plants, the regulation depending on N partitioning to Rubisco is robust for PSII but fails for PSI in mature and early senescing leaves. In these leaves, the magnitudes of P700 oxidation were found to be less than expected from the Y(II) and Y(NPQ) values. The mechanistic reasons and physiological implications of these phenomena are discussed.

The Khanka Lowland forest-steppe is the most eastern outpost of the Eurasian steppe biome. It includes unique grassland plant communities with rare steppe species. These coenosis have changed under the influence of anthropogenic activity, especially during the last 100 years and included both typical steppe species and nemoral mesophytic species. To distinguish these ecological groups of plants the random forest method with three datasets of environmental variables was applied. Specifically, a model of classification with the most important bioindices to predict a mesophytic ecological group of plants with a sensitivity greater than 80% was constructed. The data demonstrated the presence of steppe species that arrived at different times in the Primorye Territory. Most of these species are associated with the Mongolian-Daurian relict steppe complex and habit in the Khanka Lowland. Other species occur only in mountains in Primorye Territory and do not persist in the Khanka Lowland. These findings emphasize the presence of relict steppe communities with a complex of true steppe species in the Khanka Lowland. Steppe communities exhibit features of anthropogenic influence definitely through the long land use period but are not anthropogenic in origin. The most steppe species are located at the eastern border of distribution in the Khanka Lowlands and are valuable in terms of conservation and sources of information about steppe species origin and the emergence of the steppe biome as a whole.

A perennial pseudometallophyte Arabidopsis halleri is frequently infected with cucumber mosaic virus (CMV) in its natural habitat. The purpose of this study was to characterize the effect of CMV infection on the environmental adaptation of its natural host A. halleri. The CMV(Ho) strain isolated from A. halleri was inoculated into clonal virus-free A. halleri plants, and a unique plant-virus system consisting of CMV(Ho) and its natural wild plant host was established. In a control environment with ambient zinc supplementation, CMV(Ho) infection retarded growth in the above-ground part of host plants but conferred strong drought tolerance. On the other hand, in an excess zinc environment, simulating a natural edaphic environment of A halleri, host plants hyperaccumulated zinc and CMV(Ho) infection did not cause any symptoms to host plants while conferring mild drought tolerance. We also demonstrated in Nicotiana benthamiana as another host that similar effects were induced by the combination of excess zinc and CMV(Ho) infection. Transcriptomic analysis indicated that the host plant recognized CMV(Ho) as a mutualistic symbiont rather than a parasitic pathogen. These results suggest a resilient mutualistic interaction between CMV(Ho) and its natural host A. halleri in its natural habitat.

Soil salinization has been considered as a major environmental threat to plant growth. Different types of salt in saline soil have different effects on germination and seedling growth. Effect of NaCl on germination and seedling establishment in Suaeda liaotungensis have been reported, but its response to alkali stress remains unclear. Our results showed that brown seeds had higher germination rate, however, black seeds had higher germination recovery percentage under alkali stress. Na₂CO₃ had stronger inhibitory effect on germination and seedling growth than NaHCO₃. As the concentration of alkali stress increased, the ROS level of brown seeds gradually ascended, while that of black seeds decreased first and then ascended. MDA content of dimorphic seeds significantly increased under alkali stress. The trend of SOD, POD and CAT activity between dimorphic seeds was similar under the same type of alkali stress. Alkali stress enhanced proline content of dimorphic seeds, and dimorphic seeds in NaHCO₃ solution had higher proline content than Na₂CO₃ solution. Moreover, radicle and shoot tolerance indexes of seedlings in NaHCO₃ solution were significantly higher than that of Na₂CO₃ solution. Under strong alkali stress, seedlings in NaHCO₃ solution had significantly lower ROS level and MDA content as well as higher antioxidant enzyme activity than Na₂CO₃ solution. This study comprehensively compared the morphological and physiological characteristics in germination and seedlings to better reveal the saline-alkali tolerance mechanisms in S. liaotungensis.

The widespread use of antibiotics in intensive animal husbandry, and the agricultural utilization of manure from such farms, imposes a significant burden on the environment. Consequently, the effects of antibiotics should be studied not only in animals and humans but also in all components of biocenoses and agrocenoses. In our study, we analyze the impact of four different concentrations of tetracycline present in soil (0, 5, 50, and 500 mg/kg of soil) on the growth and key photosynthesis parameters of pea seedlings: chlorophyll concentration, aminolevulinic acid concentration, aminolevulinic acid dehydrogenase activity, and ribulose bisphosphate carboxylase-oxygenase (RuBisCO) activity. At the lowest tetracycline concentration, chlorophyll content decreased by 13% compared to the control (0 tetracycline), while at the highest antibiotic concentration, it decreased by as much as 27%. Similarly, the decrease in aminolevulinic acid (a chlorophyll precursor) concentration was significant, amounting to 34%. However, the activity of the dehydrogenase enzyme, which consumes this precursor, decreased even more drastically by 51%, indicating significant disturbances in the light phase of photosynthesis. However, the activity of RuBisCO in pea plants subjected to tetracycline was even more severely affected, dropping by 58%, 69%, and 70% in soils with increasing concentrations of tetracycline. The reduction in enzyme activity could only partially be explained by a less pronounced decrease in the quantity of RuBisCO (large subunit) protein, which amounted to 6.5%, 11%, and 35% for tetracycline concentrations of 5, 50, and 500 mg/kg of soil, respectively.

The vascular bundle in the ear-internode of maize is a key conduit for transporting photosynthetic materials between "source" and "sink", making it critically important to examine its micro-phenotypes and genetic architecture to identify advantageous characteristics and cultivate high-yielding and high-quality varieties. Unfortunately, the limited observation methods and scope of study precludes any comprehensive and systematic investigations into the microscopic phenotypes and genetic mechanisms of vascular bundle in maize ear-internode. In this study, 47 phenotypic traits were extracted in 495 maize inbred lines using micro computed tomography (Micro-CT) scanning technology and a deep learning-based phenotype acquisition method for stem vascular bundle, which included stem slice-related, epidermis zone-related, periphery zone-related, inner zone-related and vascular bundles-related traits. Phenotypic analysis indicated that there was extensive phenotypic variation of vascular bundle traits in ear-internode, especially that in the inner zone. Of these, 30 phenotypic traits with heritability greater than 0.70 were conducted for GWAS, and a total of 4,225 significant SNPs and 416 candidate genes with detailed functional annotations were identified. Furthermore, 20 genes were highly expressed in stem-related tissues, especially in maize internodes. Functional analysis of candidate genes indicated that the pathways obtained for candidate genes of different trait groups were distinct, mainly involved in vitamin synthesis and metabolism, transport of substances, carbohydrate derivative catabolic process, protein transport and localization, and anatomical structure development. The results of this study will help to further understand the phenotypic traits of stem vascular bundles and provide a reference for revealing the genetic mechanism of maize ear-internode vascular bundles.

The rice albumin (RAG) gene family belongs to the Tryp_alpha_amyl family. RAG2, specifically expressed in 14-21 DAP (days after pollination) seeds, regulates grain yield and quality. In this study, we identified another RAG family gene, RAL6, which exhibits specific expression in developing seeds, particularly in 7, 10, and 15 DAP seeds. Employing the CRISPR/Cas9 system, we analyzed functions of RAL6 and found that the ral6 lines (ral6-1, ral6-2, ral6-3, and ral6-4) displayed thinner seeds with significantly decreased 1000-grain weight and grain thickness compared to ZH11. Additionally, the cell width of spikelet cells, total protein and glutelin contents were significantly reduced in ral6. The germination assay and 1% TTC staining revealed a significant decrease in seed vigor among the ral6 lines. The alpha-amylase activity in ral6 mutant seeds was also markedly lower than in ZH11 seeds after 2 days of imbibition. Furthermore, co-expression analysis and GO annotation showed that co-expressed genes were involved in immune response, oligopeptide transport, and the glucan biosynthetic process. Collectively, our findings suggest that RAL6 plays a coordinating role in regulating grain weight and seed germination in rice.

Land plants have evolved many systems to adapt to a wide range of environmental stresses. In seed plants, oligogalactolipid synthesis is involved in tolerance to freezing and dehydration, but it has not been analyzed in non-vascular plants. Here we analyzed trigalactosyldiacylglycerol (TGDG) synthesis in Marchantia polymorpha. TGDG is synthesized by galactolipid: galactolipid galactosyltransferase [GGGT; SENSITIVE TO FREEZING2 (SFR2) in Arabidopsis]. We analyzed the subcellular localization and GGGT activity of two M. polymorpha SFR2 homologs (MpGGGT1 and MpGGGT2, each as a GFP-fusion protein) using a transient expression system in Nicotiana benthamiana leaves and found that MpGGGT1-GFP localized in the chloroplast envelope membrane. We produced mutants Mpgggt1 and Mpgggt2 and found that TGDG did not accumulate in Mpgggt1 upon treatment of the thallus with acetic acid. Moreover, growth of Mpgggt1 mutants was impaired by acetic acid treatment. Microscopy revealed that the acetic acid treatment of M. polymorpha plants damaged intracellular membranes. The fact that the effect was similar for wild-type and Mpgggt1 plants suggested that MpGGGT has a role in recovery from damage. These results indicate that MpGGGT plays a crucial role in M. polymorpha growth under conditions of acid stress, which may have been encountered during the ancient terrestrial colonization of plants.

Plants defend themselves against herbivores by recognizing herbivore-derived elicitors and activating intracellular signaling. In Arabidopsis, the receptor-like kinase HAK1 recognizes the poly-saccharide elicitor (FrA) from Spodoptera litura larvae, leading to the expression of defense-related genes such as PDF1.2. During this process, the cytoplasmic kinase CRK2 phosphorylates PBL27, triggers the ERF13 expression via ethylene signaling and subsequently leads to PDF1.2 expression. Herein, we investigated four cytoplasmic kinases from the same receptor-like cytoplasmic kinase (RLCK) VII family as PBL27 that interacts with CRK2. Among them, PBL11, like PBL27, is phosphorylated by CRK2 and induces PDF1.2 expression but does not affect ERF13 expression. The weight gain of S. litura larvae on PBL11-deficient mutant plants was only slightly higher than that of wild-type plants, suggesting that PBL11 may function as a minor RLCK that supports the defense response.

Analysis of the sex expression in 10 'Lemon' (mmff) cucumber plants (Cucumis sativus L.), known to be andromonoecious, revealed that 3 plants produced female flowers with short ovaries, resembling bisexual flowers, after producing male and bisexual flowers. To investigate the heredity pattern governing these aberrant female flowers with short ovaries, F₁ hybrid plants (MmFf) were generated through a cross between 'Dokanari-sennari' (MMFF) and 'Lemon' (mmff), and #4 (mmff) and #45 (mmFF) were meticulously selected from a pool of 45 F₂ segregants. Analysis of the sex expression in both 10 F₅ plants (mmff) derived from the #4 (mmff) and 10 F₄ plants (mmFF) derived from the #45 (mmFF) revealed that 8-9 plants produced female flowers with short ovaries after producing male and bisexual flowers. Notably, no female flowers with short ovaries were produced in the plants carrying the M gene, such as 'Dokanari-sennari' (MMFF), 8 F₁ hybrid plants (MmFf), and the 29 F₂ segregants (M-F-,M-ff). Thus, female flowers with short ovaries may be produced in some 'Lemon' (mmff) cucumber plants and their progeny, particularly those carrying the mm genotype (CS-ACS2 genes with c.97G > T mutations), after the production of male and bisexual flowers. However, no clear genetic rules governing the occurrence of these female flowers with short ovaries were observed. This is the first report on trimonoecious cucumber plants displaying male flowers, bisexual flowers with short ovaries, and female flowers with short ovaries, all on the same plant, under the influence of the mm genotype (CS-ACS2 genes with c.97G > T mutations).