Integrated Signals of Jasmonates, Sugars, Cytokinins and Auxin Influence the Initial Growth of the Second Buds of Chrysanthemum after Decapitation

Decapitation is common in horticulture for altering plant architecture. The decapitation of chrysanthemum plants breaks apical dominance and leads to more flowers on lateral branches, resulting in landscape flowers with good coverage. We performed both third- and second-generation transcriptome sequencing of the second buds of chrysanthemum. This third-generation transcriptome is the first sequenced third-generation transcriptome of chrysanthemum, revealing alternative splicing events, lncRNAs, and transcription factors. Aside from the classic hormones, the expression of jasmonate-related genes changed because of this process. Sugars also played an important role in this process, with upregulated expression of sucrose transport-related and TPS genes. We constructed a model of the initial growth of the second buds after decapitation. Auxin export and sugar influx activated the growth of these buds, while the JA-Ile caused by wounding inhibited the expression of CycD genes from 0 h to 6 h. After wound recovery, cytokinins accumulated in the second buds and might have induced ARR12 expression to upregulate CycD gene expression from 6 h to 48 h, together with sugars. Therefore, jasmonates, cytokinins, sugars, and auxin work together to determine the fate of the buds of plants with short internodes, such as chrysanthemum.

A new orange-fruited species of Monstera (Araceae: Monsteroideae) from Panama

Monstera alcirana, endemic to Panamá, is described and illustrated using a color plate based on photographs of the vegetative and reproductive structures of living material. This species is the fourth of the very small species of Monstera in Central America. It is morphologically similar to M. obliqua, M. minima and M. gambensis but differs by has short internodes, thickly coriaceous blade and peduncle longer than the length of the leaf.

Boeica multinervia K.Y. Pan (Gesneriaceae): a new record for India

We present the first record of Boeica multinervia (Gesneriaceae) for India, based on specimens from Sagalee, Arunachal Pradesh, India. The species is easily recognized due to its short internodes, stoloniferous habit, and glandular pubescent rosette leaves and inflorescence. Boeica multinervia is so far known only from (Xizang) China. A brief description along with additional notes and photographs are provided.

Paraphlomis kuankuoshuiensis (Lamiaceae), a new species from the limestone areas of northern Guizhou, China

Paraphlomis kuankuoshuiensis (Lamiaceae), a new species found in the limestone areas of northern Guizhou, China, is described and illustrated in this paper. Based on its tubular-campanulate calyx, this taxon should be a member of sect. Paraphlomis Prain. The new species resembles P. patentisetulosa C.Y. Wu & H. W. Li, P. hispida C.Y. Wu, and P. hirsutissima C.Y. Wu & H.W. Li, but differs from these three taxa in the following aspects: the stems are very short (<7 cm), with one or two short internodes, giving the impression of having a tuft of basal leaves; it has sparsely setose hairs on the outer surface of the calyces and short fruiting calyces. The florescence, fruit period, habitat, and the geographical distribution of P. kuankuoshuiensis are also quite different from the three closely related species.

Notes on the genus Zeravschania (Apiaceae) with description of two new species from Afghanistan and Iran

Two species of Apiaceae are described as new to science: Zeravschania khorasanica from the Khorasan Province, eastern Iran, and Z. podlechii from the Ghor Province, central Afghanistan. Zeravschania khorasanica is related to Z. regeliana and Z. scabrifolia, but differs in rigid remains of petioles and sheaths, deeply laciniate ultimate segments of leaves, and broad-keeled ribs of mericarps. Zeravschania podlechii differs from other species of the genus in multiple stems, short internodes, dichotomous branching, and an unusual life form (сushion plant). In addition, Z. knappii is transferred to the genus Dichoropetalum on the basis of morphological evidence.

Maize brachytic2 (br2) suppresses the elongation of lower internodes for excessive auxin accumulation in the intercalary meristem region

Background Short internodes contribute to plant dwarfism, which is exceedingly beneficial for crop production. However, the underlying mechanisms of internode elongation are complicated and have been not fully understood. Results Here, we report a maize dwarf mutant, dwarf2014 (d2014), which displays shortened lower internodes. Map-based cloning revealed that the d2014 gene is a novel br2 allele with a splicing variation, resulting in a higher expression of BR2-T02 instead of normal BR2-T01. Then, we found that the internode elongation in d2014/br2 exhibited a pattern of inhibition-normality-inhibition (transient for the ear-internode), correspondingly, at the 6-leaf, 12-leaf and 14-leaf stages. Indeed, BR2 encodes a P-glycoprotein1 (PGP1) protein that functions in auxin efflux, and our in situ hybridization assay showed that BR2 was mainly expressed in vascular bundles of the node and internode. Furthermore, significantly higher auxin concentration was detected in the stem apex of d2014 at the 6-leaf stage and strictly in the node region for the ear-internode at the 14-leaf stage. In such context, we propose that BR2/PGP1 transports auxin from node to internode through the vascular bundles, and excessive auxin accumulation in the node (immediately next to the intercalary meristem) region suppresses internode elongation of d2014. Conclusions These findings suggest that low auxin levels mediated by BR2/PGP1 in the intercalary meristem region are crucial for internode elongation.

Transcriptome analysis and identification of genes associated with fruiting branch internode elongation in upland cotton

Background Appropriate plant architecture can improve the amount of cotton boll opening and allow increased planting density, thus increasing the level of cotton mechanical harvesting and cotton yields. The internodes of cotton fruiting branches are an important part of cotton plant architecture. Thus, studying the molecular mechanism of internode elongation in cotton fruiting branches is highly important. Results In this study, we selected internodes of cotton fruiting branches at three different stages from two cultivars whose internode lengths differed significantly. A total of 76,331 genes were detected by transcriptome sequencing. By KEGG pathway analysis, we found that DEGs were significantly enriched in the plant hormone signal transduction pathway. The transcriptional data and qRT-PCR results showed that members of the GH3 gene family, which are involved in auxin signal transduction, and CKX enzymes, which can reduce the level of CKs, were highly expressed in the cultivar XLZ77, which has relatively short internodes. Genes related to ethylene synthase (ACS), EIN2/3 and ERF in the ethylene signal transduction pathway and genes related to JAR1, COI1 and MYC2 in the JA signal transduction pathway were also highly expressed in XLZ77. Plant hormone determination results showed that the IAA and CK contents significantly decreased in cultivar XLZ77 compared with those in cultivar L28, while the ACC (the precursor of ethylene) and JA contents significantly increased. GO enrichment analysis revealed that the GO categories associated with promoting cell elongation, such as cell division, the cell cycle process and cell wall organization, were significantly enriched, and related genes were highly expressed in L28. However, genes related to the sphingolipid metabolic process and lignin biosynthetic process, whose expression can affect cell elongation, were highly expressed in XLZ77. In addition, 2067 TFs were differentially expressed. The WRKY, ERF and bHLH TF families were the top three largest families whose members were active in the two varieties, and the expression levels of most of the genes encoding these TFs were upregulated in XLZ77. Conclusions Auxin and CK are positive regulators of internode elongation in cotton branches. In contrast, ethylene and JA may act as negative regulators of internode elongation in cotton branches. Furthermore, the WRKY, ERF and bHLH TFs were identified as important inhibitors of internode elongation in cotton. In XLZ77(a short-internode variety), the mass synthesis of ethylene and amino acid conjugation of auxin led to the inhibition of plant cell elongation, while an increase in JA content and degradation of CKs led to a slow rate of cell division, which eventually resulted in a phenotype that presented relatively short internodes on the fruiting branches. The results of this study not only provide gene resources for the genetic improvement of cotton plant architecture but also lay a foundation for improved understanding of the molecular mechanism of the internode elongation of cotton branches.

Overexpression of BpCUC2 Influences Leaf Shape and Internode Development in Betula pendula

The CUP-SHAPED COTYLEDON 2 (CUC2) gene, which is negatively regulated by microRNA164 (miR164), has been specifically linked to the regulation of leaf margin serration and the maintenance of phyllotaxy in model plants. However, few studies have investigated these effects in woody plants. In this study, we integrated genomic, transcriptomic, and physiology approaches to explore the function of BpCUC2 gene in Betula pendula growth and development. Our results showed that Betula pendula plants overexpressing BpCUC2, which is targeted by BpmiR164, exhibit shortened internodes and abnormal leaf shapes. Subsequent analysis indicated that the short internodes of BpCUC2 overexpressed transgenic lines and were due to decreased epidermal cell size. Moreover, transcriptome analysis, yeast one-hybrid assays, and ChIP-PCR suggested that BpCUC2 directly binds to the LTRECOREATCOR15 (CCGAC), CAREOSREP1 (CAACTC), and BIHD1OS (TGTCA) motifs of a series of IAA-related and cyclin-related genes to regulate expression. These results may be useful to our understanding of the functional role and genetic regulation of BpCUC2.

Application of biostimulants influences shoot and root characteristics of seedlings of winter pea (Pisum sativum L.)

In the cooler regions of Europe, the success of winter pea cultivation depends strongly on proper plant development before winter. Previous research has suggested that plants need to develop short internodes and at least their first two leaves before the arrival of frost. However, this stage of growth is sometimes not reached in the event of late sowing, due to factors such as unpredictable weather conditions or the delayed harvest of a previous crop. An effective solution may be the application of plant growth regulators before the sowing of seeds. The aim of this study was to assess the seedling developmental characteristics of winter pea dependent on biostimulator applications in low temperature conditions (4°C). Seven different winter pea cultivars were treated with three biostimulants: Asahi SL, Kelpak SL, and Primus B. After 21 days of seedling development, basic biometrical characteristics were measured (length and weight of shoots and roots). It was found that ‘Enduro’ and ‘Aviron’ showed greatest root development, regardless of the applied biostimulants. The highest germination was achieved by ‘Aviron’. The efficiency of biostimulators on the cultivars tested was low, although slightly better results were found for Asahi SL in combination with ‘Enduro’ and ‘Aviron’.

Thin myelin sheaths as the hallmark of remyelination persist over time and preserve axon function

The presence of thin myelin sheaths in the adult CNS is recognized as a marker of remyelination, although the reason there is not a recovery from demyelination to normal myelin sheath thickness remains unknown. Remyelination is the default pathway after myelin loss in all mammalian species, in both naturally occurring and experimental disease. However, there remains uncertainty about whether these thin sheaths thicken with time and whether they remain viable for extended periods. We provide two lines of evidence here that thin myelin sheaths may persist indefinitely in long-lived animal models. In the first, we have followed thin myelin sheaths in a model of delayed myelination during a period of 13 years that we propose results in the same myelin sheath deficiencies as seen in remyelination; that is, thin myelin sheaths and short internodes. We show that the myelin sheaths remain thin and stable on many axons throughout this period with no detrimental effects on axons. In a second model system, in which there is widespread demyelination of the spinal cord and optic nerves, we also show that thinly remyelinated axons with short internodes persist for over the course of 2 y. These studies confirm the persistence and longevity of thin myelin sheaths and the importance of remyelination to the long-term health and function of the CNS.