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With the increasing penetration of distributed generation (DG) in the distribution network, the original network structure of the distribution network has been changed. In addition, the randomness and intermittency of renewable power generation will also have an impact on the voltage and power flow of the distribution network. To solve this problem, this paper proposes a reactive power optimization control method for distribution network with DGs based on second-order oscillating particle swarm optimization (PSO) algorithm with a constriction factor. Considering the economic operation of the distribution network, the proposed control method realizes the coordinated operation of the DGs and battery group with the conventional static reactive power compensation device, so as to improve the voltage quality of the distribution network and reduce the system network loss. At the same time, an improved second-order oscillating PSO algorithm is proposed to improve the speed and convergence of the multiobjective algorithm. Finally, the effectiveness of the proposed control method is verified by using MATLAB/Simulink on IEEE 33 bus distribution network with DGs in both static and dynamic situations.

As one of the most popular bulbous plant with high ornamental value, Lilium spp. has been used as cut flower or green plants in urban landscapes and home gardening. We noticed a cultivar ‘Elodie’ show weak double-flowered phenotype, by which whole 3 can be classified into three different types including stamen, partially petaloid stamen (PPetSta) and totally petaloid stamen (TPetSta). To understand the molecular basis of this homeotically conversion variation, quantitative RNA-Seq analysis was conducted to screen the important unigenes underlying this phenomenon. Meanwhile, endogenous hormone contents including auxin, cytokinin, GA and ABA were detected at the same time. In total, we assembled and annotated 53,182 unigenes. 8453, 21,281 and 7646 DEGs (differentially expressed genes) were identified from PPetSta vs Stamen, TPetSta vs Stamen, and TPetSta vs PPetSta comparisons, in which 2241 unigenes were shared DEGs. 20 transcription factors in MADS-box and MYB families, 43 unigenes in signaling and synthesis pathways of auxin, cytokinin, GA, ABA and ethylene were differentially expressed. Meanwhile, endogenous hormone contents including auxin, cytokinin, GA and ABA were declined in partially petaloidy flower and totally petaloidy flower when compared with the normal stamen. The expression of GA20ox3 and CYP735A2 encode the biosynthesis genes of GA and cytokinin, respectively were downregulated, which was consistent with the hormone determination results. The expression of SAUR50, SLR5, PYL9, ERF4/27 involved in the signaling pathways of IAA, GA, ABA, ethylene and transcription factors MYB44/108, AG2, AGL104, MGS1 had the same expression profiles corresponding with the endogenous hormone content, indicating that they may play a positive role during the process of stamen petalization. This work will help us to unravel several specific genes and provide a theoretical basis for double flower breeding of Lilium species.

Lycoris species have great ornamental and medicinal values; however, their low regeneration efficiency significantly restricts their commercial production. Exogenous hormone application is an effective way to promote bulblet development, but their effect on Lycoris radiata has not been verified to date. In the present study, we examined the effect of different exogenous hormones on bulblet development in L. radiata, and found that gibberellic acid (GA) significantly inhibited, whereas paclobutrazol (PBZ), abscisic acid (ABA), and ethrel promoted bulblet development, especially PBZ, a GA biosynthesis inhibitor. Furthermore, GA reduced endogenous cytokinin (CK) content, as well as the activities of carbohydrate metabolism enzymes, including sucrose synthase (SUS) and glucose-1-phosphate adenylyltransferase (AGPase), by downregulating the expression levels of LrSUS1, LrSUS2, and genes encoding AGPase large and small subunits. This resulted in the decrease in carbohydrate accumulation in the bulblets, thus hindering their development. PBZ had the opposite effect to GA on carbohydrate metabolism; it decreased endogenous GA15 and GA24, thereby promoting bulblet development. ABA promoted endogenous auxin content and the activities of starch synthesis enzymes, especially soluble starch synthase (SSS) and granule-bound SS (GBSS), through the up-regulation of the expression levels of LrSS1, LrSS2, and LrGBSS1 genes, which could also result in the accumulation of carbohydrates in the bulblets and promote their development. In addition, ethrel application partly promoted bulblet development by promoting endogenous CK content. Although the accumulation of carbohydrates and the activity of starch enzymes were increased by ethrel treatment, we hypothesized that the effect of ethrel on regulating carbohydrate metabolism may be indirect. Our results could provide a basis for improving the propagation efficiency of L. radiata for production, as well as propose some directions for future research.

Lycoris longituba is a traditional medicinal plant containing the bioactive compound galanthamine (Gal), a type of amaryllidaceous alkaloid and can be used to treat Alzheimer’s disease. However, research on its genome or transcriptome and associated genes in the biosynthetic pathway is incomplete. In this study, we estimated the nuclear genome size of this species to be 29.47 Gb by flow cytometry. Then, RNA sequencing of the leaves, roots, and bulbs of L. longituba was carried out. After de novo assembly, 4,74,589 all-transcripts and 3,33,440 all-unigenes were finally generated. In addition, the differentially expressed genes (DEGs) were identified, and genes involved in the galanthamine metabolic pathway encoding tyrosine decarboxylase (TYDC), phenylalanine ammonia-lyase (PAL), cinnamate 4-hydroxylase (C4H), p-coumarate 3-hydroxylase (C3H), norbelladine synthase (NBS), norbelladine 4'-O-methyltransferase (OMT), noroxomaritidine synthase (CYP96T1), and N-methyltransferase (NMT) were detected and validated by real-time quantitative PCR analysis. One candidate gene, Lycoris longituba O-Methyltransferase (LlOMT), was identified in the proposed galanthamine biosynthetic pathway. Sequence analysis showed that LlOMT is a class I OMT. LlOMT is localized in the cytoplasm, and biochemical analysis indicated that the recombinant LlOMT catalyzes norbelladine to generate 4′-O-methylnorbelladine. The protoplast transformation result showed that the overexpression of LlOMT could increase the Gal content. Our results indicate that LlOMT may play a role in galanthamine biosynthesis in L. longituba. This work provides a useful resource for the metabolic engineering of amaryllidaceous alkaloids.