In the melon exotic accession PI 161375, the gene cmv1, confers recessive resistance to Cucumber mosaic virus (CMV) strains of subgroup II. cmv1 prevents the systemic infection by restricting the ...virus to the bundle sheath cells and impeding viral loading to the phloem. Here we report the fine mapping and cloning of cmv1. Screening of an F2 population reduced the cmv1 region to a 132 Kb interval that includes a Vacuolar Protein Sorting 41 gene. CmVPS41 is conserved among plants, animals and yeast and is required for post-Golgi vesicle trafficking towards the vacuole. We have validated CmVPS41 as the gene responsible for the resistance, both by generating CMV susceptible transgenic melon plants, expressing the susceptible allele in the resistant cultivar and by characterizing CmVPS41 TILLING mutants with reduced susceptibility to CMV. Finally, a core collection of 52 melon accessions allowed us to identify a single amino acid substitution (L348R) as the only polymorphism associated with the resistant phenotype. CmVPS41 is the first natural recessive resistance gene found to be involved in viral transport and its cellular function suggests that CMV might use CmVPS41 for its own transport towards the phloem.
SUMMARY
KARRIKIN INSENSITIVE2 (KAI2) is an α/β‐hydrolase required for plant responses to karrikins, which are abiotic butenolides that can influence seed germination and seedling growth. Although ...represented by four angiosperm species, loss‐of‐function kai2 mutants are phenotypically inconsistent and incompletely characterised, resulting in uncertainties about the core functions of KAI2 in plant development. Here we characterised the developmental functions of KAI2 in the grass Brachypodium distachyon using molecular, physiological and biochemical approaches. Bdkai2 mutants exhibit increased internode elongation and reduced leaf chlorophyll levels, but only a modest increase in water loss from detached leaves. Bdkai2 shows increased numbers of lateral roots and reduced root hair growth, and fails to support normal root colonisation by arbuscular‐mycorrhizal (AM) fungi. The karrikins KAR1 and KAR2, and the strigolactone (SL) analogue rac‐GR24, each elicit overlapping but distinct changes to the shoot transcriptome via BdKAI2. Finally, we show that BdKAI2 exhibits a clear ligand preference for desmethyl butenolides and weak responses to methyl‐substituted SL analogues such as GR24. Our findings suggest that KAI2 has multiple roles in shoot development, root system development and transcriptional regulation in grasses. Although KAI2‐dependent AM symbiosis is likely conserved within monocots, the magnitude of the effect of KAI2 on water relations may vary across angiosperms.
Significance Statement
KAI2 is an α/β‐hydrolase receptor for abiotic karrikins and yet elusive plant hormones. The roles of KAI2 have been extensively studied in the dicotyledon Arabidopsis. Here we provide a comprehensive characterisation of the roles of KAI2 in the monocotyledon Brachypodium distachyon.
Among a set of genes in pea (Pisum sativum L.) that were induced under drought-stress growth conditions, one encoded a protein with significant similarity to a regulator of chlorophyll catabolism, ...SGR. This gene, SGRL, is distinct from SGR in genomic location, encoded carboxy-terminal motif, and expression through plant and seed development. Divergence of the two encoded proteins is associated with a loss of similarity in intron/exon gene structure. Transient expression of SGRL in leaves of Nicotiana benthamiana promoted the degradation of chlorophyll, in a manner that was distinct from that shown by SGR. Removal of a predicted transmembrane domain from SGRL reduced its activity in transient expression assays, although variants with and without this domain reduced SGR-induced chlorophyll degradation, indicating that the effects of the two proteins are not additive. The combined data suggest that the function of SGRL during growth and development is in chlorophyll re-cycling, and its mode of action is distinct from that of SGR. Studies of pea sgrL mutants revealed that plants had significantly lower stature and yield, a likely consequence of reduced photosynthetic efficiencies in mutant compared with control plants under conditions of high light intensity.
Summary
The isolation of the nematode‐resistance gene Gpa2 in potato is described, and it is demonstrated that highly homologous resistance genes of a single resistance‐gene cluster can confer ...resistance to distinct pathogen species. Molecular analysis of the Gpa2 locus resulted in the identification of an R‐gene cluster of four highly homologous genes in a region of approximately 115 kb. At least two of these genes are active: one corresponds to the previously isolated Rx1 gene that confers resistance to potato virus X, while the other corresponds to the Gpa2 gene that confers resistance to the potato cyst nematode Globodera pallida. The proteins encoded by the Gpa2 and the Rx1 genes share an overall homology of over 88% (amino‐acid identity) and belong to the leucine‐zipper, nucleotide‐binding site, leucine‐rich repeat (LZ‐NBS‐LRR)‐containing class of plant resistance genes. From the sequence conservation between Gpa2 and Rx1 it is clear that there is a direct evolutionary relationship between the two proteins. Sequence diversity is concentrated in the LRR region and in the C‐terminus. The putative effector domains are more conserved suggesting that, at least in this case, nematode and virus resistance cascades could share common components. These findings underline the potential of protein breeding for engineering new resistance specificities against plant pathogens in vitro.
The pepper (Capsicum annuum) Bs3 gene confers resistance to avrBs3-expressing strains of the bacterial spot pathogen Xanthomonas campestris pv. vesicatoria. To physically delimit Bs3, a pepper YAC ...library was screened with two flanking DNA markers that are separated from Bs3 by 1.0 and 1.2 cM, respectively resulting in the identification of three YAC clones. Genetic mapping of the corresponding YACends revealed however, that these YACs do not cover Bs3 and subsequent screens with newly developed YACend markers failed to identify new YAC clones. Marker saturation at the Bs3 locus was carried out by amplified fragment length polymorphism (AFLP). The analysis of 1,024 primer combinations resulted in the identification of 47 new Bs3-linked AFLPs. High-resolution linkage mapping of Bs3 was accomplished by inspecting more than 4,000 F2 segregants resulting in a genetic resolution of 0.01 cM. Using tightly Bs3-linked YACend- and AFLP-derived markers we established a Bs3-spanning BAC contig and physically delimited the target gene within one BAC clone. The analysis of the Bs3-containing genomic region revealed substantial local variation in the correlation of genetic and physical distances.
The ease of usage and the convenience of cloud computing come with considerable responsibility. The latter, consists of carefully addressing different security aspects of this technology. The ...integrity and availability of the outsourced data constitute essential considerations for adopters' final decisions. However, the most critical factor is the efficiency of integrity checks, which must prioritize restricted-resource data owners without affecting the performance of the Cloud Service Provider. This paper proposes a secure scheme, called Proof of Exponentiation of Dynamic Data Possession <inline-formula> <tex-math notation="LaTeX">{ \mathsf {PoEDDP} } </tex-math></inline-formula> based on <inline-formula> <tex-math notation="LaTeX">{ \mathsf {RSA} } </tex-math></inline-formula>-Accumulators. The proof of concept demonstrates that this scheme is 20 times faster compared to other <inline-formula> <tex-math notation="LaTeX">{ \mathsf {RSA} } </tex-math></inline-formula>-based cryptographic accumulator schemes. It could be improved to achieve great results with proper optimizations on the larger integer multiplication side.
Proof of Retrievability (PoR) is a technique used to ensure the authenticity of data on outsourced storage services. It improves the soundness and the robustness of the data integrity scheme and ...allows clients to recover the remote data. Under the circumstance of considering untrusted parties including the Cloud Storage Provider (CSP) and Third Party Authenticator (TPA), incorporating PoR and zero-knowledge Proofs, which is another technique used to allow a prover to convince a verifier that a secret exists without revealing the secret itself, will ensure client integrity verification, strengthen privacy, and improve fairness to both sides. In this paper, we present, on one hand, the state-of-the-art of PoR under zero-knowledge constructs following an existing data integrity scheme taxonomy of cloud storage. We analyze the PoR scheme formalism and its similarities with zero-knowledge concepts, in addition to the techniques used to settle robustness and zero-knowledge proofs methods. On the other hand, we propose our improved taxonomy of proofs of retrievability enriched by the zero-knowledge, the cryptography model, and the cryptographic setup. The proposed taxonomy equips researchers with a tool to think about the PoR scheme from those perspectives. In the end, we state some fruitful lines of works that PoR can take advantage of; i.e Bulletproofs, Interactive Oracle Proofs, and Interactive Oracle Proofs of Proximity For Reed-Solomon.
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