Plant Direct最新文献

Cassava production in sub-Saharan Africa is severely impacted by diseases. Most pathogens require interaction with host susceptibility factors to complete their life cycles and cause disease. Targeted DNA methylation is an epigenetic strategy to alter gene expression in plants, and we previously reported that a zinc-finger fused to DMS3 could establish methylation at the promoter of MeSWEET10a, a bacterial susceptibility gene, and this resulted in decreased disease. Here, we attempt a similar strategy for cassava brown streak disease. This disease is caused by the ipomoviruses CBSV and UCBSV. These viruses belong to the family Potyviridae, which has been shown extensively to require host eIF4E-family proteins to infect plants and cause disease. We previously found that cassava plants with simultaneous knockout mutations in two eIF4E genes, nCBP-1 and nCBP-2, resulted in decreased susceptibility to CBSD. Here, we report successful simultaneous targeting of both promoters with methylation using a dCas9-DRMcd-SunTag system. However, in contrast to our previous work with MeSWEET10a, controls indicate that CRISPR interference is occurring in these lines and is sufficient for the reduction of gene expression. Future research will use genetic crosses to segregate away the DNA methylation reagents and, if DNA methylation proves heritable, assess whether methylation alone is sufficient to increase resistance to CBSD.

Drought has emerged as one of the most severe and widespread environmental stresses affecting plants. Crops exposed to varying levels of drought, ranging from moderate to severe, often experience notable declines in yield or reduced harvest quality. Investigating the molecular mechanisms and cellular factors involved in plant defense against drought is crucial-not only for advancing our understanding of these processes but also for ensuring sustainable food production and supporting humanity's survival. Our previous work identified the small intrinsically disordered protein DSS1 (deleted in split-hand/split-foot) as a key factor in the stress defense mechanisms of Arabidopsis thaliana. The absence of DSS1(V) led to increased sensitivity of plants to oxidative stress induced by hydrogen peroxide or methyl viologen. As drought can induce oxidative stress in plant cells, we investigated if DSS1(V) protein can mitigate stress caused by mild to moderate drought. Alongside the wild-type (WT) strain, the analysis included knockout plants lacking the DSS1(V) gene and plants overexpressing this gene. Various stress-related parameters, including lipid peroxidation, total phenol content, chlorophyll levels, and protein oxidation, were measured. Results indicated that the DSS1(V) knockout line displayed significantly higher sensitivity to drought compared to WT plants. However, elevated levels of DSS1(V) transcripts in the overexpressing lines did not confer a protective effect, as these lines did not exhibit reduced drought sensitivity. These findings provide compelling evidence highlighting the critical involvement of the DSS1(V) protein in the mechanisms underlying plant responses to environmental stress, particularly water deficiency. This protein appears to enable plants to cope with the challenges posed by drought conditions, emphasizing its importance in maintaining cellular homeostasis and mitigating the adverse effects of water scarcity.

Faba bean (Vicia faba L.) is a key crop for sustainable agriculture in temperate cropping systems due to its nitrogen-fixing ability and high protein content, but its productivity is increasingly threatened by drought stress driven by climate change. Precise phenotyping under semicontrolled conditions is crucial for understanding drought responses. High-throughput precision phenotyping enables efficient evaluation of many genotypes, revealing detailed water-use patterns as a basis for breeding productive, drought-resilient cultivars. In this study, faba bean genotypes were grown in a precision phenotyping facility comprising 120-L containers filled with mineral soil to simulate field-like growth conditions. Each container was placed on a high-precision gravimetric scale to record water use in real time in relation to 3-D spectral image information. Precise measurement of genotype-specific transpiration behavior using gravimetric methods enabled detailed insights into the transpiration patterns of different genotypes in response to ambient temperature and humidity fluctuations throughout the day and night, and across the whole-life cycle. The results showed that total water use, water-use efficiency, and consequently yield were particularly influenced by specific transpiration parameters, such as the maximum transpiration rate and the vapor pressure deficit threshold at which stomatal conductance was declined. The results revealed genetically determined variation for transpiration responses to drought stress. Genotypes that reduced water loss earlier tended to achieve higher grain yields and use water more efficiently. The findings show that precise automated phenotyping can identify previously undiscovered genetic variation for breeding drought-tolerant faba bean varieties, which are crucial for ensuring productivity under increasingly water-limited conditions.

Arabidopsis thaliana gene At2g44130 encodes a Kelch-like domain F-box protein designated KFB39 and was previously shown to be specifically expressed on exposure to the oxylipin cis-jasmone. In order to better understand the regulation of At2g44130, a forward genetic screen was carried out to identify mutants in which a promoter-GUS fusion was expressed in the absence of the inducer, cis-jasmone. Two mutants were recovered, showing misexpression of the promoter-GUS fusion, and surprisingly, both were found to be in components (SAC3B, THP1) of the TREX-2 nuclear pore complex. Genetic analysis of sac3 mutants in Arabidopsis revealed additive impairments to growth and development as well as reduced capacity for nuclear export. Promoter-GUS fusions of the Arabidopsis SAC3 and THP1 genes revealed a discrete expression pattern that was non-overlapping with KFB39. A link between the expression of KFB39 and the TREX-2 complex is not obvious, but we note that previously, unrelated forward genetic screens using promoter-reporter fusions have also recovered sac3b and thp1 mutants. We consider some possible explanations for these shared occurrences.

Despite being one of the few bona fide plant tyrosine phosphatases, the Arabidopsis thaliana Rhizobiales-like phosphatase 2 (RLPH2) has no known substrates. Utilizing phospho-proteomics, we identified the activation loop phospho-tyrosine of several A. thaliana D-group mitogen-activated protein kinases (MPKs) as potential RLPH2 substrates. All Arabidopsis D-group MPKs possess a TDY activation loop phosphorylation motif, whereas other MPKs (Groups A, B, and C) contain a TEY motif. Our findings reveal that RLPH2 has a strong preference for aspartate (D) in the TXY motif, providing specificity for RLPH2 to exclusively target and dephosphorylate the D-group MPKs. Additionally, D-group MPKs contain a unique activation loop insertion that conforms to a protein phosphatase one (PP1) binding motif, with findings presented here confirming Arabidopsis PP1 phosphatases dock at this site. Intriguingly, only D-group MPKs among all identified Arabidopsis protein kinases possess this PP1 recruiting motif. Using multiple RLPH2-deficient plant lines, we demonstrate that RLPH2 represses seed dormancy release. Overall, this work highlights the power of phospho-proteomics in identifying substrates of this novel plant tyrosine phosphatase while also revealing new complexities in the interactions between MPK activation loops and multiple phospho-mediated cell signaling events.

The loss of yield due to cold stress during the early reproductive phase poses challenges to the expansion of sorghum cultivation into temperate regions. A better understanding of the physiological mechanisms is crucial for rapid progress in breeding cold-tolerant sorghum varieties. To identify the floral phytohormones responsible for reproductive cold tolerance, a cold-tolerant and a cold-sensitive genotype were subjected to cold stress at various developmental stages during the early reproductive phase. In addition to abscisic acid and its derivatives, including abscisic acid glucose ester, dihydrophaseic acid, and phaseic acid, various gibberellins as well as jasmonic acid and its bioactive form jasmonic acid isoleucine were examined. We found that cold-tolerant sorghum is capable of downregulating abscisic acid concentration under cold stress. While existing literature primarily attributes increased abscisic acid concentration, combined with an insufficient pool of bioactive gibberellins, in sensitive plants as a result of abnormal pollen development, this study shows that this is not the case in sorghum. Additionally, an antagonistic interaction between gibberellins and jasmonic acid was observed regardless of genotype and environmental conditions. These findings contribute to a better understanding of the physiological mechanisms behind cold tolerance in sorghum and could provide important insights for future breeding efforts aiming to accelerate the expansion of cold-tolerant sorghum varieties into temperate climates.

Southern blight, caused by the soil-borne fungus Sclerotium rolfsii (S. rolfsii), poses a significant threat to pepper (Capsicum annuum L.) production, necessitating the development of effective chemical control strategies. This study investigated the physiological responses of pepper plants to S. rolfsii infection and evaluated the efficacy of the fungicides hexaconazole and azoxystrobin. The results demonstrated that hexaconazole, applied at 50 μg·mL^-1, provided outstanding protective activity (97.56%). In contrast, azoxystrobin, at a higher concentration of 100 μg·mL^-1, exhibited optimal overall control, with 88.62% protective and 49.06% curative activity. Beyond direct pathogen suppression, both fungicides mitigated disease impact by safeguarding host plant growth, promoting root system development, and enhancing defense responses through the induction of key antioxidant enzymes, namely, peroxidase (POD) and catalase (CAT). Consequently, the application of hexaconazole and azoxystrobin significantly reduced disease progression and protected normal plant growth. These findings provide a scientific basis for effective management of southern blight in pepper and elucidate how fungicides with distinct modes of action can enhance plant resistance by modulating the antioxidant system.

In vascular plants, genes in the plastid genome are transcribed by two types of RNA polymerases, namely, phage-type nuclear-encoded and bacterial-type plastid-encoded plastid RNA polymerases (NEP and PEP, respectively). Eudicots, including Arabidopsis, carry two isoforms of NEP, RPOTp and RPOTmp. NEPs transcribe multiple plastid-encoded genes including subunits of PEP and translocon and are thus indispensable for the maintenance of plastids. However, regulatory mechanisms of NEPs are largely unknown. RPOTmp transcribes the 16S rRNA gene from a specific promoter in the seeds during vernalization, and its mutation in Arabidopsis retards chloroplast development. As interacting partners of RPOTmp, two NEP-INTERACTING PROTEINs (NIP1 and NIP2) have been identified and suggested to suppress RPOTmp activity by tethering RPOTmp to the thylakoid membrane during chloroplast development in the presence of light, but their precise roles in transcriptional regulation remain to be addressed. From these previous reports, we hypothesize that the functions of RPOTmp would depend on the light conditions and expression of NIPs. To gain insight into how RPOTmp is controlled, we performed a functional analysis of RPOTmp and NIPs using Arabidopsis mutants during germination in the dark and de-etiolation processes under light. We found that RPOTmp-dependent transcription of 16S rRNA is active in imbibed seeds and remains at a basal level throughout the postgermination processes, regardless of light conditions. We also demonstrated a limited impact of NIPs on RPOTmp function during these processes. Our phylogenetic analysis indicates that NIPs have distinct evolutionary profiles compared with RPOTmp, and Arabidopsis is unlikely to have additional NIP-like proteins in plastids. Based on these findings, we propose a modified model of RPOTmp regulation during chloroplast development: RPOTmp activity remains stable throughout the process of chloroplast differentiation and is unaffected by light and NIPs.

Rice straw is a key source of lignocellulosic biomass. GWAS can be used to identify genetic loci controlling stem morphological traits that influence biomass. This study aimed to investigate the genotypic diversity of rice straw internodes through GWAS, using 34,232 single-nucleotide polymorphic sites with a minor allelic frequency (MAF) greater than 0.05. Morphological traits (32) were evaluated in 149 rice accessions at the heading stage. Among the 32 measured traits, 26 were found to be significant. GWAS identified 173 significant SNPs located within 64 QTLs with a putative function in biomass production. Among all the putative genes identified, 21 were selected as candidate genes, including WAK 53a and DUF (248, 295, 309, 1740, 3444, 3464, 3475). In general, the identified candidate genes were grouped into five categories: cytoskeletal and transport of cell wall components, growth and development, cell wall biosynthesis, wall-modifying genes, and regulatory genes. The three major TF groups were WRKY, ERF, and MYB. Haplotype analysis identified seven haplogroups, with five being significant. Path analysis revealed that panicle dry weight (0.64) and internode 3 dry weight (0.57) had the highest positive correlation with biomass. Our findings can be implemented in genome editing methodologies for functional characterization of the candidate genes. This study represents the first comprehensive GWAS of various stem-related morphological traits in Oryza sativa, aiming to identify candidate genes involved in lignocellulosic biomass production and to inform targeted breeding approaches.

Sulfate deprivation (-S) results in numerous metabolic and phenotypic alterations in plants. Kinases are often key players in transducing nutrient status signals to molecular components involved in metabolic and developmental program regulation, but despite the physiological importance of sulfur, to date, no signaling kinases have been identified in sulfur-deficiency signaling response programs. Here, we show that the serine/threonine protein kinase CIPK14/SNRK3.15 plays a regulatory role in the -S response in Arabidopsis thaliana seedlings. Multiple molecular and physiological responses to -S are attenuated in snrk3.15 mutants, including both early adaptive responses and later emergency salvage processes including nutrient deficiency induced senescence. When grown in soil with sufficient sulfur supply, snrk3.15 mutants showed no clear phenotypes, including no difference in seed sulfur content. Lastly, the proteome dataset generated from Col-0 and snrk3.15.1 Arabidopsis seedlings under -S conditions for this project is the first of its kind and will be a valuable research resource.