Background: The genus Zingiber of the Zingiberaceae is distributed in tropical, subtropical, and in Far East Asia. This genus contains about 100–150 species, with many species valued as important agricultural, medicinal and horticultural resources. However, genomic resources and suitable molecular markers for species identification are currently sparse. Results: We conducted comparative genomics and phylogenetic analyses on Zingiber species. The Zingiber chloroplast genome (size range 162,507–163,711 bp) possess typical quadripartite structures that consist of a large single copy (LSC, 86,986–88,200 bp), a small single copy (SSC, 15,498–15,891 bp) and a pair of inverted repeats (IRs, 29,765–29,934 bp). The genomes contain 113 unique genes, including 79 protein coding genes, 30 tRNA and 4 rRNA genes. The genome structures, gene contents, amino acid frequencies, codon usage patterns, RNA editing sites, simple sequence repeats and long repeats are conservative in the genomes of Zingiber. The analysis of sequence divergence indicates that the following genes undergo positive selection (ccsA, ndhA, ndhB, petD, psbA, psbB, psbC, rbcL, rpl12, rpl20, rpl23, rpl33, rpoC2, rps7, rps12 and ycf3). Eight highly variable regions are identified including seven intergenic regions (petA-pabJ, rbcL-accD, rpl32-trnL-UAG, rps16-trnQ-UUG, trnC-GCA-psbM, psbC-trnS-UGA and ndhF-rpl32) and one genic regions (ycf1). The phylogenetic analysis revealed that the sect. Zingiber was sister to sect. Cryptanthium rather than sect. Pleuranthesis. Conclusions: This study reports 14 complete chloroplast genomes of Zingiber species. Overall, this study provided a solid backbone phylogeny of Zingiber. The polymorphisms we have uncovered in the sequencing of the genome offer a rare possibility (for Zingiber) of the generation of DNA markers. These results provide a foundation for future studies that seek to understand the molecular evolutionary dynamics or individual population variation in the genus Zingiber.

Ginger (Zingiber officinale), the type species of Zingiberaceae, is one of the most widespread medicinal plants and spices. Here, we report a high-quality, chromosome-scale reference genome of ginger ‘Zhugen’, a traditionally cultivated ginger in Southwest China used as a fresh vegetable, assembled from PacBio long reads, Illumina short reads, and high-throughput chromosome conformation capture (Hi-C) reads. The ginger genome was phased into two haplotypes, haplotype 1 (1.53 Gb with a contig N50 of 4.68 M) and haplotype 0 (1.51 Gb with a contig N50 of 5.28 M). Homologous ginger chromosomes maintained excellent gene pair collinearity. In 17,226 pairs of allelic genes, 11.9% exhibited differential expression between alleles. Based on the results of ginger genome sequencing, transcriptome analysis, and metabolomic analysis, we proposed a backbone biosynthetic pathway of gingerol analogs, which consists of 12 enzymatic gene families, PAL, C4H, 4CL, CST, C3’H, C3OMT, CCOMT, CSE, PKS, AOR, DHN, and DHT. These analyses also identified the likely transcription factor networks that regulate the synthesis of gingerol analogs. Overall, this study serves as an excellent resource for further research on ginger biology and breeding, lays a foundation for a better understanding of ginger evolution, and presents an intact biosynthetic pathway for species-specific gingerol biosynthesis.

The current differential protection is introduced into active distribution network to improve the selectivity and reliability of protection. However, it is difficult to meet the synchronous requirement of differential protection for distribution networks. Therefore, this paper proposes an impedance differential protection for the active distribution network. The principle and criterion of the impedance differential protection are established according to the significant differences between differential impedance and restraint impedance during normal operation, external fault and internal fault. Furthermore, an auxiliary criterion is constructed by the amplitude characteristic of fault current to cope with the existing dead-zone fault. A complete protection scheme based on the proposed principle is designed. Several major factors are taken full consideration in the scheme including transition resistances, current transformer saturation, unsynchronized data, various penetrations and underground cables. Extensive digital simulations are conducted to verify the principle. Theoretical analyses and simulations demonstrate the effectiveness and advantage of this principle. Compared with current differential protection, the impedance differential protection significantly reduces the requirement of data synchronization and transmission band-width, which plays an important role in adapting to the communication infrastructure of distribution network.

Limited information is available if the application of plant growth promoting bacteria (PGPB) can promote soil nutrient availability and plant growth, especially for fruit crops. This study evaluated PGPB, isolated from a vegetable purple soil in Chongqing, China, to increase soil nitrogen (N), phosphorus (P) and potassium (K) availability; as well as the growth of kiwifruit (Actinidia chinensis). Three out of 17 bacterial isolates with a high capacity for N2-fixation and P- and K-solubilization were identified by phenotypic and 16S rRNA sequencing. The three isolates were identified as Bacillus amyloliquefaciens (XD-N-3), B. pumilus (XD-P-1) and B. circulans (XD-K-2) and then mixed as a complex bacterial inoculant. Four treatments of (1) no-fertilizer and no-bacterial inoculant (Control), (2) no-bacterial inoculant and a full-rate of chemical NPK fertilizer (CF), (3) the complex inoculant (CI), and (4) a half-rate CF and full CI (1/2CF+CI), a pot experiment then evaluated effects of this complex inoculant on soil microflora, kiwifruit growth, soil N2-fixation, and P- and K-solubility. Results indicated that the growth of N2-fixing, P- and K-solubilizing bacteria was ranked from greatest to least as 1/2CF+CI ≈ CI > CF ≈ Control. Though generally without significant treatment differences in soil total N, P or K, significantly greater soil available N, P or K was respectively patterned as 1/2CF+CI ≈ CI > CF ≈ Control, as 1/2CF+CI > CF > CI > Control or as 1/2CF+CI > CF ≈ CI > Control, indicating an improvement of soil fertility through the complex inoculant. In regards to plant growth, greater total plant biomass and total N, P and K accumulation among treatments were ranked as 1/2CF+CI ≈ CI > CF > Control. Additionally, the level of leaf PPO (polyphenol oxidase) activity ranked as CF > 1/2CF+CI ≈ Control ≈ CI, while MDA (malondialdehyde) contents as Control > CI ≈ CF > 1/2CF+CI. In short, the complex inoculant was able to improve available soil N, P and K and kiwifruit growth (CI vs. Control). These results promote a better understanding of the potential of using a complex bacterial inoculant for promoting soil fertility and plant growth.

Kiwifruit (Actinidia chinensis) is a rich nutritious fruit crop owing to a markedly higher content of vitamin C and minerals. To promote fruit set and to increase the yield of kiwifruit, forchlorfenuron (CPPU) has been widely applied. However, the molecular details regarding CPPU controlling kiwifruit development, especially at the fastest fruit growth stage, remain unknown. In the present study, we measured the effect of CPPU on developmental regulation in red-fleshed kiwifruit (Actinidia chinensis ‘Hongyang’). Additionally, a cytological analysis was performed to clarify the precise changes in the cell structure of the CPPU-treated kiwifruits. Moreover, the concentration of endogenous phytohormones, including indoleacetic acid (IAA), zeatin (ZT), gibberellic acid 3 (GA₃), and abscisic acid (ABA), were measured by Enzyme-linked Immunosorbent Assay (ELISA). Furthermore, RNA-Seq was performed to dissect the complicated molecular mechanisms, with a focus on biosynthesis, metabolism, and signaling compounds, such as endogenous hormones, sugars, and L-ascorbic acid. Our results demonstrated that CPPU treatment not only regulates the size and weight of a single fruit but also improves the quality in ‘Hongyang’ kiwifruit through the accumulation of both soluble sugar and vitamin C. It was also seen that CPPU regulates kiwifruit development by enhancing cell expansion of epidermal cells and parenchyma cells, while, promoting cell division of subepidermal cells. Additionally, CPPU significantly increased the gibberellin and cytokinin biosynthetic pathway and signaling, while repressing auxin and ABA biosynthetic pathway; thus, signaling plays an essential role in CPPU controlling kiwifruit development. Notably, transcriptomic analysis revealed that a total of 2244 genes, including 352 unannotated genes, were differentially expressed in kiwifruits because of CPPU treatment, including 127 transcription factors. These genes are mainly enriched in plant hormone signal transduction, photosynthesis, MAPK signaling pathway, starch and sucrose metabolism, and phenylpropanoid biosynthesis. Overall, our results highlight that CPPU regulation of kiwifruit development is mainly associated with an antagonistic and/or synergistic regulatory role of endogenous phytohormones, and enhancing the energy supply. This provides new insights into the molecular details of CPPU controlling kiwifruit development at the fastest fruit growth stage, which is of agricultural importance for kiwifruit breeding and crop improvement.

A substation-area protective relay is proposed to overcome the inherent defects of the traditional backup protection system. The relay performs local backup protective functions for the whole substation and its connected transmission lines. The setting coordination of backup protections will be simplified by this relay with a shorter fixed time-delay. The algorithm of locating the faulted component employs the current differential principle with a self-adaptive restraint characteristic. The current sampled values are obtained by process-level networks inside the smart substation and by wide-area Ethernet between adjacent substations. The relay also works with the breaker states and the tripping generic object oriented substation event (GOOSE) from primary protections. A prototype based on the proposed scheme and IEC61850 standards has been developed by digital signal processor/field programmable gate array. The performance of the prototype was evaluated through the complete digital testing system using real time digital simulator/gigabit transceiver network and a communication simulator. Tests were carried out under different typical scenarios, such as fault transition resistances, inrush currents, current transformer saturations, and abnormal communications.