Current Plant Biology最新文献

Mitonuclear incompatibility results from a breakdown of the coordinated function between co-evolved genes located in nuclear and mitochondrial compartments. Horizontal Gene Transfer (HGT), involving the acquisition of genes from unrelated species, can trigger mitonuclear incompatibilities when foreign gene products interact with native ones, particularly in multisubunit complexes. Recent findings highlighted rampant HGT in the mitochondrial genomes of holoparasitic plants of the genus Lophophytum (Balanophoraceae). In Lophophytum, some mitochondrial genes involved in the Oxidative Phosphorylation (OXPHOS) system were acquired from their legume hosts, unlike the nuclear-encoded OXPHOS subunits, which remain native. This unique configuration of a doubly chimeric OXPHOS, combining native nuclear-encoded subunits with both foreign and native mitochondrial-encoded subunits, raises questions regarding the potential effects of the interactions between native and foreign proteins on mitochondrial respiration activity in Lophophytum. We examined the mitochondrial ultrastructure, evaluated protein expression via Western blots, and analyzed cellular respiration through oxygen consumption rates and adenylate content in these holoparasitic plants. Surprisingly, our results revealed no disruption of the OXPHOS machinery or activity in Lophophytum despite the functional replacement of several native protein subunits by foreign homologs. Furthermore, there was no apparent impact on the OXPHOS system given their parasitic lifestyle and complete loss of photosynthesis.

High soil salinity has an unfavorable consequence on the growth and productivity of rice crop. However, some salt-tolerant plant growth-promoting bacteria (ST-PGPB) regulate specific physiological, biochemical, and molecular properties to promote crop growth while minimizing the detrimental effects of salt stress. In this regard, we isolated ST-PGPB from rhizospheric soil and examined it to mitigate the salinity stress in rice seedlings. The growth of the bacterium at 3 M NaCl demonstrated its halotolerance, and 16S rRNA sequencing identified it as Bacillus siamensis, and the isolated strain was named BW. Further study indicated that biopriming with BW strain helps plant growth promotion-related phenotype and significantly mitigates salinity stress in rice seedlings. Treatment of rice seeds with BW resulted in significantly improved germination of seedlings at 75 mM to 150 mM NaCl, along with better physiology and biochemical parameters than the untreated ones. Furthermore, Bacillus sp. BW efficiently colonizes rice roots and produces auxin and siderophore, via forming biofilm under different salt concentrations. Under 100–200 mM NaCl treatment conditions, the extracellular metabolite profile from BW showed a substantial abundance in specific metabolites, such as osmoprotective chemicals, suggesting the likely protective mechanism against salinity stress damage. This study demonstrates the role and potential of a halotolerant- BW strain in supporting the growth of rice plants under salinity conditions.

Castor is an industrially economic and valuable oilseed crop cultivated worldwide. There is a constant upsurge in demand for its oil. But wilt caused by Fusarium spp. is a devastating disease that severely affects the productivity depending upon the crop stage. Stable high yielding pistillate lines serve as donors in heterosis breeding programme and for further biotechnological advancements. Genetic characterization of wilt resistance indicated the role of duplicate dominant epistasis in YTP 1 × TMV 5, complementary epistasis in DPC 9 × JP 65 and JP 65 × SKI 215, duplicate recessive epistasis in YRCP 1 × DPC 9. Monogenic recessive nature of wilt resistance was reported in other four cross combinations viz., YRCP 2 × JP 65, SKP 84 × JP 65, YRCP 2 × DPC 9 and YRCP 2 × SKP 84. Magnified images taken using LED phase contrast microscope portrayed the presence of microconidia and macroconidia and Scanning Electron Microscope (SEM) image analysis showed the presence of intact internal cell structures in resistant check (48−1) while the cell structures were disturbed with mycelial growth in the susceptible check (JI 35). Among 21 pistillate lines screened, seven viz., DPC 9, DPC 16, SKP 84, JP 96, GEETA, M 574 and M 619–1 were resistant. By screening P1, P2, F1, F2, BC₁F₁ (P1) and BC₁F₁ (P2) generations of eight crosses under field and pot test method, the stable pistillate line DPC 9 was found to be wilt resistant. F₁ generation plants expressed 100% susceptibility indicating the recessive nature of wilt resistance. JP 65 × SKI 215 and YRCP 1 × DPC 9 showed the minimum incidence comparing other F₂ populations. The backcross (YRCP 1 × DPC 9) × DPC 9 was found to possess the lowest wilt incidence compared to other populations under field and green house condition. Hence the identified lines could be better used to develop wilt resistant high yielding hybrid and for further identifying and introgressing genomic regions conferring wilt resistance to high yielding popular variety through linkage/QTL mapping technique.

Drought is one of the important abiotic factors that affect faba bean growth and productivity in the Mediterranean region. In order to study the response of faba bean plant to water-deficit stress, a physiological and proteomic analysis was carried out in leaf tissue. All physiological parameters were affected by drought. The physiological mechanism underlying the response of faba bean leaves to water-deficit was therefore attributed to the alleviation of oxidative stress via the accumulation of proline and to the synergistic action of the antioxidant enzyme system (CAT, SOD, APX and GPOX). Proteomic analysis identified 2000 proteins from faba bean leaves, of which were 81 differentially expressed. Of those, 36 were downregulated and 45 were upregulated under water-deficit treatment. KEGG and GO enrichments indicated differentially abundant proteins (DAPs) related to photosynthesis, antioxidants and ROS detoxifying enzymes, biosynthesis of amino acids and secondary metabolites, molecular chaperones, signal transduction, energy and carbohydrate metabolism and metabolic enzymes. The current results provide evidence for a complex synergetic pathway, in which ROS detoxification mechanisms and photoprotection constituted the major aspect of water-deficit tolerance in faba bean leaves. These results offer a foundational basis regarding the molecular mechanism involved in drought resistance within the faba bean species.

This study tests the hypothesis that a more salt-excluder rootstock can attenuate salt stress in grapevine plants by enhancing photosynthesis and providing ionic and oxidative protection. Plants of ‘BRS Vitória’ variety, grafted with the rootstocks IAC 313 (salt-excluder) and SO4, were subjected to salinity by adding NaCl (0, 50, and 100 mM) for 30 days. Plants with SO4 showed more severe salt toxicity symptoms in leaves and lower chlorophyll content under salinity. Conversely, plants with IAC 313 showed improved photosynthesis and stomatal conductance, along with higher carboxylation efficiency under salt compared to SO4. Under salinity, plants with SO4 showed higher losses of K⁺ in stems, roots, and petioles, as well as increased accumulation of Na⁺ in these organs, relative to IAC 313. Furthermore, plants with IAC 313 had lower leaf Na⁺ content under salinity and reduced leaf Cl⁻ content at 50 mM NaCl, a response associated with a higher Na⁺ allocation in petioles of IAC 313. At 50 mM, IAC 313 exhibited better photochemical activity, as indicated by electron transport rate and non-photochemical quenching. However, at 100 mM, both rootstocks showed similar trends, suggesting that the photosynthetic restriction was primarily due to stomatal disturbances. Plants with IAC 313 showed better APX activity and ascorbate balance under salinity. IAC 313 showed more salt-resistance traits than SO4, although the growth was similarly affected in both rootstocks. This response could be due to the reduced time of salt treatment (30 days). In summary, our data indicate that IAC 313 rootstock possesses better salt tolerance traits than SO4.

Respiratory burst oxidase homolog (RBOH) proteins in plants generate reactive oxygen species (ROS) in the apoplast to regulate developmental processes and stress responses. Herein, a total of 40 TaRBOH genes are identified in the genome of Triticum aestivum by a genome-wide search using the latest database. Phylogenetic analysis separated the RBOH proteins into five clusters and close clustering suggested an evolutionary relationship among them. The presence of duplication events (DEs) and the nature of selection (purifying) during evolutionary analysis revealed their role in the expansion of the TaRBOH gene family. The interaction analyses revealed their extended roles and coordinated functioning with various stress-related signaling pathways, including ABA- and Ca²⁺-signaling. Expression profiling in different tissue developmental stages and under stress conditions disclosed their involvement in growth, development and stress responses. In addition, the presence of assorted groups of cis-regulatory elements, interaction with the diverse nature of transcription factors and miRNA related to plant development, hormones and various stresses further suggested their association with developmental and stress-responsive pathways. This study provides inclusive information related to the functioning of TaRBOH genes in bread wheat and would provide a valuable reference for their functional characterization for crop improvement.

Rice is widely cultivated worldwide, and beneficial bactrial colonization are particularly desirable for sustainable agriculture because they promote growth and production by preventing excessive heavy metal contamination. The present study was conducted with the aim of improving the growth of rice seedlings (MTU1010 variety) under copper (Cu) stress by using Cu-tolerant plant growth promoting bacteria (PGPB) Micrococcus yunnanensis GKSM13. Strain GKSM13 was able to produce plant growth promoting factors (PGPFs) such as indole-3-acetic acid (IAA), gibberellin A3 (GA₃) and ammonia, accumulate proline, fix N₂, and inhibit 2,2-Diphenyl-1-picrylhydrazyl (DPPH). Rice seedlings treated with Cu²⁺ and co-inoculated with GKSM13 significantly improved their growth in morphological and biochemical aspects. When analysed by field emission scanning electron microscope (FE-SEM), GKSM13 was found to be associated with the root cells in the form of large number of coccoid cells. The uptake of Cu²⁺ in rice seedlings was reduced to 57.5% in the presence of GKSM13. Strain GKSM13 treatment also reduced Cu-induced oxidative stress of rice seedlings by activating antioxidant enzymes including superoxide dismutase (SOD), catalase (CAT), ascorbate peroxidase (APOX) and glutathione peroxidase (GPOX), which was supported by DPPH inhibition and reduction of malondialdehyde (MDA) accumulation. Insight into the genome of strain GKSM13 reveals the presence of tryptophan (trp), ent-kaurene, cyanase (cyn), phosphate-specific transport (pst), major facilitator superfamily transporter (MFS), sulphate transporter (cys), proline (pro) and SOD (sod) genes, which are responsible for promoting plant growth and alleviating Cu²⁺ stress. Therefore, the application of strain M. yunnanensis GKSM13 could provide a sustainable agricultural solution for Cu-affected mining areas.

Sub-group 4 R2R3-type MYB transcription factors (TFs) are involved in repression of the phenylpropanoid pathway. In this study, we identified and characterized three MYB transcriptional repressors in common tobacco, named NtMYB1, NtMYB2, and NtMYB4, which belong to sub-group 4 members. Tissue expression properties and specificity of stress-induced expression indicated that the NtMYB1, NtMYB2, and NtMYB4 may perform different functions in tobacco. Overexpression of NtMYB1, NtMYB2, and NtMYB4 reduced phenylpropanoids and flaonoid compounds, such as caffeic acid, chlorogenic acid, neochlorogenic acid, and rutin, respectively. Meanwhile, the expression of the most structural genes involved in phenylpropanoids and flavonoids were reduced in the overexpression transgenic lines. In addition, results based on co-expression and expression analyses revealed possible interactions between NtMYB1, NtMYB2, and NtMYB4 and multiple bHLH TFs. Our results showed that the three sub-group 4 R2R3 members exhibited different expression pattern in various tissues and under abiotic stress conditions. Meanwhile, we hypothesized that the three of them involved in the inhibition of phenylpropanoid and flavonoid biosynthesis might be interaction with bHLH TFs.

Sorghum, also known as great millet, is a major cereal crop that feeds over 500 million people in more than 100 countries, especially in Africa and Asia. It can grow well under harsh environmental conditions, such as drought, heat, salinity, and soils that are nutritionally poor. The crop is water- and nitrogen-efficient with C₄ photosynthesis system and a relatively small genome of about 730 Mb. Its genome has been sequenced and annotated, revealing significant genetic variation and genomics resources. Despite being drought tolerant, there is a great degree of variation among the diverse lines of germplasm for drought and drought associated traits, and hence resilience to drought and other stresses need to be studied through the integration of phenomics and genomics technologies. There is an urgent need to adopt advanced genomics and high-throughput technologies to find candidate genes and alleles for crop traits, develop molecular markers and genomic selection (GS) models, create new genetic variation and design sorghum ideotypes that suit to the changing climate.

Jojoba (Simmondsia chinensis) is a desert shrub with an ability to survive in extremely arid environments. The exceptional drought tolerance of jojoba includes traits that could be useful in developing drought tolerant crop plants. This study characterized changes in gene expression in jojoba under water-stress during a controlled-environment experiment. A large number of transcripts (10,936) were identified as differentially expressed under contrasting water stress conditions. These included transcripts corresponding to antioxidant activity-related genes such as superoxide dismutase, defense response genes such as Pathogenesis-Related 4 (PR4), water molecule bio-channels such as aquaporins, cell membrane protectants such as Late Embryogenesis Abundant (LEA), and growth regulators such as 1-aminocyclopropane-1-carboxylic acid (ACC). A total of 880 novel transcripts were identified as representing possible novel genes associated with jojoba subjected to water stress. There were also many transcripts linked to transcriptional regulation that were expressed in response to water-stress in jojoba. Many male-specific transcripts corresponding to stress-related genes and transcription regulators were differentially expressed under water-stress with 1928 differentially expressed transcripts that aligned to the two Y chromosome-specific regions Y1 and Y2. The water-stress related genes detected may help explain the drought tolerance of jojoba and provide a valuable source of genes for exploitation in providing tolerance to water stress in other species.