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Cold stress is one of the main abiotic stresses that affect the development and growth of kiwifruit (Actinidia arguta). Herein, we analyzed the transcriptomic data of A. arguta dormant shoots in response to low-temperature treatment, identified 52 MYB genes, and constructed a phylogenetic tree based on the encoded protein sequences. Then, the effect of one MYB gene on cold tolerance was analyzed. This gene had an open reading frame of 837 bp long and encoded 279 amino acids. Sequence alignment and phylogenetic analysis revealed that this gene belongs to the R2R3-MYB family and was named AaMYB44 based on its homology to other MYB family members. Quantitative real-time PCR revealed that AaMYB44 expression was significantly induced by low temperatures but exhibited the opposite trend in cold-tolerant genotypes. Subcellular localization assays revealed the nuclear localization of the AaMYB44 protein. Furthermore, AaMYB44 was transformed into Arabidopsis thaliana (A. thaliana) via inflorescence infection, and physiological and biochemical tests revealed that the cold resistance and antioxidant capacity of the transgenic A. thaliana were lower than those of wild-type plants. Overall, AaMYB44 might play a negative regulatory role in response to cold stress, providing new insight into the mechanism of cold tolerance. [ABSTRACT FROM AUTHOR]

Proanthocyanidins (PAs) are important metabolites that enhance freezing tolerance of plants. Actinidia arguta, especially freezing‐tolerant germplasms, accumulate abundant PAs in dormant shoots and thereby enhance freezing tolerance, but the underlying mechanism is unknown. In this study, we used two A. arguta with contrasting cold‐resistant phenotypes, KL and RB, to explore the mechanisms in response to cold tolerance. We determined that a leucoanthocyanidin reductase gene (AaLAR1) was more highly expressed in freezing‐tolerant KL than in freezing‐sensitive RB. Moreover, overexpressing AaLAR1 in kiwifruit promoted PAs biosynthesis and enhanced cold tolerance. The AaLAR1 promoters of various A. arguta germplasms differ due to the presence of a 60‐bp deletion in cold‐tolerant genotypes that forms a functional binding site for MYC‐type transcription factor. Yeast one‐hybrid and two‐hybrid, dual‐luciferase reporter, bimolecular fluorescence complementation and coimmunoprecipitation assays indicated that the AaMYC2a binds to the MYC‐core cis‐element in the AaLAR1 promoter with the assistance of AaMYB5a, thereby promoting PAs accumulation in the shoots of cold‐tolerant kiwifruit. We conclude that the variation in the AaLAR1 promoter and the AaMYC2a–AaMYB5a–AaLAR1 module shape freezing tolerance in A. arguta. The identification of a key structural variation in the AaLAR1 promoter offers a new target for resistance breeding of kiwifruit. Summary statement: A 60‐bp deletion in the AaLAR1 promoter leads to an additional MYC‐core motif that plays a major role in freezing tolerance in kiwifruit (Actinidia arguta). AaMYC2a binds to the MYC motif of AaLAR1 promoter with the assistance of AaMYB5a, promoting proanthocyanidins accumulation and enhancing freezing tolerance. [ABSTRACT FROM AUTHOR]

Efficient diagnosis of apple diseases and pests is crucial to the healthy development of the apple industry. However, the existing single-source image-based classification methods have limitations due to the constraints of single-source input image information, resulting in low classification accuracy and poor stability. Therefore, a classification method for apple disease and pest areas based on multi-source image fusion is proposed in this paper. Firstly, RGB images and multispectral images are obtained using drones to construct an apple diseases and pests canopy multi-source image dataset. Secondly, a vegetation index selection method based on saliency attention is proposed, which uses a multi-label ReliefF feature selection algorithm to obtain the importance scores of vegetation indices, enabling the automatic selection of vegetation indices. Finally, an apple disease and pest area multi-label classification model named AMMFNet is constructed, which effectively combines the advantages of RGB and multispectral multi-source images, performs data-level fusion of multi-source image data, and combines channel attention mechanisms to exploit the complementary aspects between multi-source data. The experimental results demonstrated that the proposed AMMFNet achieves a significant subset accuracy of 92.92%, a sample accuracy of 85.43%, and an F1 value of 86.21% on the apple disease and pest multi-source image dataset, representing improvements of 8.93% and 10.9% compared to prediction methods using only RGB or multispectral images. The experimental results also proved that the proposed method can provide technical support for the coarse-grained positioning of diseases and pests in apple orchards and has good application potential in the apple planting industry. [ABSTRACT FROM AUTHOR]

Ion transport is crucial for salt tolerance in plants. Under salt stress, the high-affinity K+ transporter (HKT) family is mainly responsible for the long-distance transport of salt ions which help to reduce the deleterious effects of high concentrations of ions accumulated within plants. Kiwifruit is well known for its susceptibility to salt stress. Therefore, a current study was designed to decipher the molecular regulatory role of kiwifruit HKT members in the face of salt stress. The transcriptome data from Actinidia valvata revealed that salt stress significantly induced the expression of AvHKT1. A multiple sequence alignment analysis indicated that the AvHKT1 protein contains three conserved amino acid sites for the HKT family. According to subcellular localization analysis, the protein was primarily present in the cell membrane and nucleus. Additionally, we tested the AvHKT1 overexpression in 'Hongyang' kiwifruit, and the results showed that the transgenic lines exhibited less leaf damage and improved plant growth compared to the control plants. The transgenic lines displayed significantly higher SPAD and Fv/Fm values than the control plants. The MDA contents of transgenic lines were also lower than that of the control plants. Furthermore, the transgenic lines accumulated lower Na+ and K+ contents, proving this protein involvement in the transport of Na+ and K+ and classification as a type II HKT transporter. Further research showed that the peroxidase (POD) activity in the transgenic lines was significantly higher, indicating that the salt-induced overexpression of AvHKT1 also scavenged POD. The promoter of AvHKT1 contained phytohormone and abiotic stress-responsive cis-elements. In a nutshell, AvHKT1 improved kiwifruit tolerance to salinity by facilitating ion transport under salt stress conditions. [ABSTRACT FROM AUTHOR]

Secrecy capacity is usually employed as the performance metric of the physical layer security in fiber-optic wiretap channels. However, secrecy capacity can only qualitatively evaluate the physical layer security, and it cannot quantitatively evaluate the physical layer security of an imperfect security system. Furthermore, secrecy capacity cannot quantitatively evaluate the amount of information leakage to the eavesdropper. Based on the channel model of an optical CDMA network using wiretap code, the information leakage rate is analyzed to evaluate the physical layer security. The numerical results show that the information leakage rate can quantitatively evaluate the physical layer security of an optical CDMA wiretap channel, and it is related to transmission distance, eavesdropping position, confidential information rate and optical code. [ABSTRACT FROM AUTHOR]

The ethylene-responsive VII (ERF-VII) transcription factors are crucial in regulating plant waterlogging tolerance. However, the positive role of ERF-VII genes in kiwifruit waterlogging tolerance is rarely reported. In this study, we cloned the AvERF75 gene from the waterlogging-tolerant genotype KR5 (Actinidia valvata) and explored its roles in response to waterlogging stress. Subcellular localization showed AvERF75 protein was localized in cytoplasm and nucleus, and transactivation assays indicated it exhibited transactivation activity. Overexpression of AvERF75 significantly improved the waterlogging tolerance of transgenic plants (both tobacco and kiwifruit) by scavenging ROS. furthermore, we identified AvLOB41 as an interacting partner of AvERF75 protein by Y2H screening and BiFC assay. Taken together, this study confirms the positive role of AvERF75 in regulating waterlogging tolerance and reveals a new regulatory network in response to waterlogging stress. • This study proposes a putative model of AvERF75 and AvLOB4 in modulating waterlogging tolerance in kiwifruit. • Overexpression of AvERF75 enhanced waterlogging tolerance of transgenic plants. • AvLOB41 is involved in the waterlogging tolerance mediated by AvERF75. [ABSTRACT FROM AUTHOR]

Actinidia arguta possesses different colors in the fruit skin and flesh, but the underlying mechanism has not yet been clarified. In this study, we conducted 36 samples RNA-seq to investigate the phenotypic expression of different fruit tissues (skin and flesh) in red and green A. arguta varieties during different coloring phases. GO and KEGG enrichment results of differentially expressed genes (DEGs) suggested that the red color of the skin and flesh was derived from anthocyanin transport and flesh softening, respectively. Weighted gene co-expression network analysis (WGCNA) revealed MEyellow and MEblack modules significantly correlated with skin and flesh coloration, and two genes, Glutathione S-transferases (AaGST) and β-galactosidases (AaBGAL), were identified as hub genes involved in different tissue-specific coloration. Transient overexpression in apples and kiwifruits confirmed the role of AaGST and AaBGAL in color formation. Our results preliminarily explore the mechanism of red color formation in different A. arguta fruit tissues and provide novel insights into red color formation., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 Elsevier B.V. All rights reserved.)

Kiwifruit (Actinidia spp) is a woody, perennial and deciduous vine. In this genus, there are multiple ploidy levels but the main cultivated cultivars are polyploid. Despite the availability of many genomic resources in kiwifruit, SNP genotyping is still a challenge given these different levels of polyploidy. Recent advances in SNP array technologies have offered a high-throughput genotyping platform for genome-wide DNA polymorphisms. In this study, we developed a high-density SNP genotyping array to facilitate genetic studies and breeding applications in kiwifruit. SNP discovery was performed by genome-wide DNA sequencing of 40 kiwifruit genotypes. The identified SNPs were stringently filtered for sequence quality, predicted conversion performance and distribution over the available Actinidia chinensis genome. A total of 134 729 unique SNPs were put on the array. The array was evaluated by genotyping 400 kiwifruit individuals. We performed a multidimensional scaling analysis to assess the diversity of kiwifruit germplasm, showing that the array was effective to distinguish kiwifruit accessions. Using a tetraploid F1 population, we constructed an integrated linkage map covering 3060.9 cM across 29 linkage groups and performed QTL analysis for the sex locus that has been identified on Linkage Group 3 (LG3) in Actinidia arguta. Finally, our dataset presented evidence of tetrasomic inheritance with partial preferential pairing in A. arguta. In conclusion, we developed and evaluated a 135K SNP genotyping array for kiwifruit. It has the advantage of a comprehensive design that can be an effective tool in genetic studies and breeding applications in this high-value crop., (© 2022 The Authors. Plant Biotechnology Journal published by Society for Experimental Biology and The Association of Applied Biologists and John Wiley & Sons Ltd.)