Plant Molecular Biology最新文献

Although self-incompatibility in apples (Malus × domestica Borkh.) is regulated by a single S-locus with multiple S-haplotypes that comprise pistil S (S-RNase) and pollen S genes, it is not desirable in commercial orchards because it requires cross-pollination to achieve stable fruit production. Therefore, it is important to identify and characterize self-compatible apple cultivars. However, little is known about self-compatibility (SC) and its underlying molecular mechanisms in apples. In this study, we discovered that 'Vered', an early maturing and low chilling-requiring apple cultivar, exhibits stable SC, which was evaluated via self-pollination tests. The S-genotype of 'Vered' was designated as S₂₄S₃₉^sm. Results of genetic analysis of selfed progeny of 'Vered' revealed that SC is associated with the S₃₉^sm-haplotype, and molecular analyses indicated that it is caused by alternative splicing and a 205-bp deletion in S₃₉^sm-RNase. These events induce frameshifts and ultimately produce the defective S₃₉^sm-RNase isoforms that lack their C-terminal half. These results enabled us to develop a 117-bp DNA marker that can be used to assist in the selection of self-compatible apples with the dysfunctional S₃₉^sm-RNase. Thus, analysis of 'Vered' provided insights into the molecular mechanism of the very rare trait of natural stylar-part SC. Moreover, 'Vered' is a valuable genetic resource for breeding cultivars with SC and/or low chilling requirement in apple. Our findings contribute to a better understanding of self-compatible molecular mechanisms in apple and provide for the accelerated breeding of self-compatible apple cultivars.

Elaeagnus mollis is an important newly developing woody oil plant species and the vitamin E (VitE) content in its kernel oil is relatively high. In the present study, the VitE component content and functional genes involving in VitE biosynthesis in E. mollis kernel at different developmental stage were investigated. The VitE content increased with kernel development, reaching up to ~ 7.96 mg/g oil in kernel mature stage. The content of tocopherol was much higher than that of tocotrienol and γ-tocopherol became the dominant component. E. mollis kernel extracts had relatively strong antioxidant capacity. We identified 17 genes (16 VTEs and 1 homogentisic acid geranylgeranyl transferase (HGGT)) directly involving in VitE biosynthesis in RNA-Seq data. Phylogenetic and qRT-PCR results indicated that the annotation and reliability of the RNA-Seq were accurate. Transient overexpression of EmVTE3 and EmWRKY13 in tobacoo leaves increased and decreased the VitE content to 192.18 and 118.29 µg/g, respectively. Weighted gene co-expression analysis elucidated that the blue module showed significant correlation with tocopherol content. Co-expression network analysis revealed that 2-methyl-6-phytobenzoquinone methyltransferase (MPBQ-MT/VTE3) played a vital role and EmWRKY13 may be a key negative regulator in E. mollis VitE biosynthesis. This study not only revealed the traditional VitE biosynthesis pathway in E. mollis, but also set a solid foundation for future genetic breeding of this species.

Genome mining has revealed the halotolerant cyanobacterium Halothece sp. PCC7418 harbors considerable enrichment in the ion transport gene family for putative Na⁺/H⁺ antiporters. Here, we compared transcriptomic profiles of these encoding genes under various abiotic stresses and discovered that Halothece NhaC (hnhaC) was one of 24 genes drastically upregulated under salt stress. Critical roles of HnhaC in salt-stress protection and response were identified by a complementation assay using the salt-sensitive mutant Escherichia coli strain TO114. Expression of HnhaC rendered this mutant more tolerant to high concentrations of NaCl and LiCl. Antiporter activity assays showed that HnhaC protein predominantly exhibited Na⁺/H⁺ and Li⁺/H⁺ antiporter activities under neutral or alkaline pH conditions. Furthermore, expression of HnhaC conferred adaptive benefits onto E. coli by enabling a conditional filamentation phenotype. Dissecting the molecular mechanism of this phenotype revealed that differentially expressed genes were associated with clusters of SOS-cell division inhibitor, SOS response repair, and Z-associated proteins. Together, these results strongly indicate that HnhaC is an Na⁺/H⁺ antiporter that contributes to salt tolerance. The ubiquitous existence of several Na⁺/H⁺ antiporters represents a complex molecular system in halotolerant cyanobacteria, which can be deployed differently in response to growth and to environmental stresses.

Jasmonic acid (JA), an important plant hormone, plays a crucial role in defending against herbivorous insects. In this study, we have identified a new Bowman-Birk type protease inhibitor (BBTI) protein in maize that is regulated by the JA pathway and exhibits significant antifeedant activity, which is notably induced by exogenous Methyl Jasmonate and Ostrinia furnacalis feeding treatments. Bioinformatics analysis revealed significant differences in the BBTI protein among different maize inbred lines, except for the conserved domain. Prokaryotic and eukaryotic expression systems were constructed and expressed, and combined with bioassays, it was demonstrated that the antifeedant activity of BBTI is determined by protein modifications and conserved domains. Through RT-qPCR detection of BBTI and JA regulatory pathway-related genes' temporal expression in different maize inbred lines, we identified the regulatory mechanism of BBTI synthesis under the JA pathway. This study successfully cloned and identified the MeJA-induced anti-feedant activity gene BBTI and conducted functional validation in different maize inbred lines, providing valuable insights into the response mechanism of insect resistance induced by the plant JA pathway. The increased expression of the anti-feedant activity gene BBTI through exogenous MeJA induction may offer a potential new strategy for mediating plant defense against Lepidoptan insects.

In this paper, we have performed an in-depth study of the complete set of the satellite DNA (satDNA) families (i.e. the satellitomes) in the genome of two barley species of agronomic value in a breeding framework, H. chilense (H1 and H7 accessions) and H. vulgare (H106 accession), which can be useful tools for studying chromosome associations during meiosis. The study has led to the analysis of a total of 18 satDNA families in H. vulgare, 25 satDNA families in H. chilense (accession H1) and 27 satDNA families in H. chilense (accession H7) that constitute 46 different satDNA families forming 36 homology groups. Our study highlights different important contributions of evolutionary and applied interests. Thus, both barley species show very divergent satDNA profiles, which could be partly explained by the differential effects of domestication versus wildlife. Divergence derives from the differential amplification of different common ancestral satellites and the emergence of new satellites in H. chilense, usually from pre-existing ones but also random sequences. There are also differences between the two H. chilense accessions, which support genetically distinct groups. The fluorescence in situ hybridization (FISH) patterns of some satDNAs yield distinctive genetic markers for the identification of specific H. chilense or H. vulgare chromosomes. Some of the satellites have peculiar structures or are related to transposable elements which provide information about their origin and expansion. Among these, we discuss the existence of different (peri)centromeric satellites that supply this region with some plasticity important for centromere evolution. These peri(centromeric) satDNAs and the set of subtelomeric satDNAs (a total of 38 different families) are analyzed in the framework of breeding as the high diversity found in the subtelomeric regions might support their putative implication in chromosome recognition and pairing during meiosis, a key point in the production of addition/substitution lines and hybrids.

Stevioside (5-10%) and rebaudioside-A (2-4%) are well-characterized diterpene glycosides found in leaves of Stevia rebaudiana known to have natural sweetening properties with zero glycaemic index. Stevioside has after-taste bitterness, whereas rebaudioside-A is sweet in taste. The ratio of rebaudioside-A to stevioside needs to be changed in order to increase the effectiveness and palatability of this natural sweetener. Plant-specific miRNAs play a significant role in the regulation of metabolic pathways for the biosynthesis of economically important secondary metabolites. In this study inhibition of miRNA through antisense technology was employed to antagonize the repressive action of miRstv_7 on its target mRNAs involved in the steviol glycosides (SGs) biosynthesis pathway. In transgenic plants expressing anti-miRstv_7, reduced expression level of endogenous miRstv_7 was observed than the non-transformed plants. As a result, enhanced expression of target genes, viz. KO (Kaurene oxidase), KAH (Kaurenoic acid-13-hydroxylase), and UGT76G1 (UDP-glycosyltransferase 76G1) led to a significant increase in the rebaudioside-A to stevioside ratio. Furthermore, metabolome analysis revealed a significant increase in total steviol glycosides content as well as total flavonoids content. Thus, our study can be utilized to generate more palatable varieties of Stevia with improved nutraceutical values including better organoleptic and antioxidant properties.

Cucumber (Cucumis sativus L.) is a major vegetable crop grown globally, with a cultivation history of more than 3000 years. The limited genetic diversity, low rate of intraspecific variation, and extended periods of traditional breeding have resulted in slow progress in their genetic research and the development of new varieties. Gamma (γ)-ray irradiation potentially accelerates the breeding progress; however, the biological and molecular effects of γ-ray irradiation on cucumbers are unknown. Exposing cucumber seeds to 0, 50, 100, 150, 200, and 250 Gy doses of ⁶⁰Co-γ-ray irradiation, this study aimed to investigate the resulting phenotype and physiological characteristics of seedling treatment to determine the optimal irradiation dose. The results showed that low irradiation doses (50-100 Gy) enhanced root growth, hypocotyl elongation, and lateral root numbers, promoting seedling growth. However, high irradiation doses (150-250 Gy) significantly inhibited seed germination and growth, decreasing the survival rate of seedlings. More than 100 Gy irradiation significantly decreased the total chlorophyll content while increasing the malondialdehyde (MDA) and H₂O₂ content in cucumber. Transcriptome sequencing analysis at 0, 50, 100, 150, 200, and 250 Gy doses showed that gene expression significantly differed between low and high irradiation doses. Gene Ontology enrichment and functional pathway enrichment analyses revealed that the auxin response pathway played a crucial role in seedling growth under low irradiation doses. Further, gene function analysis revealed that small auxin up-regulated gene CsSAUR37 was a key gene that was overexpressed in response to low irradiation doses, promoting primary root elongation and enhancing lateral root numbers by regulating the expression of protein phosphatase 2Cs (PP2Cs) and auxin synthesis genes.

MicroRNAs (miRNAs) are short, non-coding RNAs that regulate gene expression at the post-transcriptional level. In plants, miRNAs participate in diverse developmental processes and adaptive responses to biotic and abiotic stress. MiR827 has long been recognized to be involved in plant responses to phosphate starvation. In rice, the miR827 regulates the expression of OsSPX-MFS1 and OsSPX-MFS2, these genes encoding vacuolar phosphate transporters. In this study, we demonstrated that miR827 plays a role in resistance to infection by the fungus Magnaporthe oryzae in rice. We show that MIR827 overexpression enhances susceptibility to infection by M. oryzae which is associated to a weaker induction of defense gene expression during pathogen infection. Conversely, CRISPR/Cas9-induced mutations in the MIR827 gene completely abolish miR827 production and confer resistance to M. oryzae infection. This resistance is accompanied by a reduction of leaf Pi content compared to wild-type plants, whereas Pi levels increase in leaves of the blast-susceptible miR827 overexpressor plants. In wild-type plants, miR827 accumulation in leaves decreases during the biotrophic phase of the infection process. Taken together, our data indicates that silencing MIR827 confers resistance to M. oryzae infection in rice while further supporting interconnections between Pi signaling and immune signaling in plants. Unravelling the role of miR827 during M. oryzae infection provides knowledge to improve blast resistance in rice by CRISPR/Cas9-editing of MIR827.

Australian wild limes occur in highly diverse range of environments and are a unique genetic resource within the genus Citrus. Here we compare the haplotype-resolved genome assemblies of six Australian native limes, including four new assemblies generated using PacBio HiFi and Hi-C sequencing data. The size of the genomes was between 315 and 391 Mb with contig N50s from 29.5 to 35 Mb. Gene completeness of the assemblies was estimated to be from 98.4 to 99.3% and the annotations from 97.7 to 98.9% based upon BUSCO, confirming the high contiguity and completeness of the assembled genomes. High collinearity was observed among the genomes and the two haplotype assemblies for each species. Gene duplication and evolutionary analysis demonstrated that the Australian citrus have undergone only one ancient whole-genome triplication event during evolution. The highest number of species-specific and expanded gene families were found in C. glauca and they were primarily enriched in purine, thiamine metabolism, amino acids and aromatic amino acids metabolism which might help C. glauca to mitigate drought, salinity, and pathogen attacks in the drier environments in which this species is found. Unique genes related to terpene biosynthesis, glutathione metabolism, and toll-like receptors in C. australasica, and starch and sucrose metabolism genes in both C. australis and C. australasica might be important candidate genes for HLB tolerance in these species. Expanded gene families were not lineage specific, however, a greater number of genes related to plant-pathogen interactions, predominantly disease resistant protein, was found in C. australasica and C. australis.

Members of the glycosyltransferase 8 (GT8) family play an important role in regulating gene expression in response to many kinds of biotic and abiotic stress. In this study, 56 members of the apple GT8 family were identified, and their gene structure, phylogenetic relationships, chromosomal localization, and promoter cis-acting elements were comprehensively analyzed. Subsequently, 20 genes were randomly selected from the evolutionary tree for qRT-PCR detection, and it was found that MhGolS2 was significantly overexpressed under stress conditions. MhGolS2 was isolated from M.halliana and transgenic Arabidopsis thaliana, tobacco and apple callus tissues were successfully obtained. The transgenic plants grew better under stress conditions with higher polysaccharide, chlorophyll and proline content, lower conductivity and MDA content, significant increase in antioxidant enzyme activities (SOD, POD, CAT) and maintenance of low Na⁺/K⁺ as compared to the wild type. Meanwhile, the expression levels of reactive oxygen species-related genes (AtSOD, AtPOD, and AtCAT), Na⁺ transporter genes (AtCAX5, AtSOS1, and AtHKT1), H⁺-ATPase genes (AtAHA2 and AtAHA8), and raffinose synthesis-related genes (AtSTS, AtRFS1, and AtMIPS) were significantly up-regulated, while the expression levels of K⁺ transporter genes (AtSKOR, AtHAK5) were reduced. Finally, the Y2H experiment confirmed the interaction between MhGolS2 and MhbZIP23, MhMYB1R1, MhbHLH60, and MhNAC1 proteins. The above results indicate that MhGolS2 can improve plant saline-alkali tolerance by promoting polysaccharide synthesis, scavenging reactive oxygen species, and increasing the activity of antioxidant enzymes. This provides excellent stress resistance genes for the stress response regulatory network in apple.