Short Internodes Research Articles

A novel maize dwarf mutant generated by Ty1-copia LTR-retrotransposon insertion in Brachytic2 after spaceflight.

Retrotransposon insertion in Brachytic2 generated a new incomplete recessive dwarf allele after spaceflight can moderately reduce plant height in heterozygous and potentially improve maize yield. Plant height and ear height are two important agronomic traits in maize breeding. In this study, two dwarf mutants short internode length1 (sil1) and short internode length2 (sil2) were obtained from two of 398 spaceflighted seeds of inbred line 18-599. The decrease in longitudinal cell number and cell length led to the shortened internodes of sil1 and sil2. A Ty1-copia LTR-retrotransposon, termed ZmRE-1, inserted in the fifth exon of Brachytic2 (Br2) was identified in sil1 and sil2 at exactly the same site, which indicated the transposition of ZmRE-1 probably correlated with the spaceflight. This new dwarf mutant allele was named as br2-sil in this study. The insertion of ZmRE-1 not only led to the loss of normal transcript of Br2 allele, but also reduced the transcript expression of br2-sil allele. Chop-qPCR displayed that the promoter region DNA methylation level of br2-sil allele in sil1 was higher than that of Br2 allele in WT-sil1. We speculated that the increased methylation level might downregulate the br2-sil expression. There was no difference in the seed-setting rate between sil1 and WT-sil1. Meanwhile, br2-sil could reduce plant and ear height effectively in Br2/br2-sil genotype without negative effects on grain yield. Therefore, the application of br2-sil in breeding has the potential to improve the grain yield per unit area through increasing the planting density.

<p><strong>Notes on the genus <em>Zeravschania </em>(Apiaceae) with description of two new species from Afghanistan and Iran</strong></p>

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.

Analyses of Plastome Sequences Improve Phylogenetic Resolution and Provide New Insight Into the Evolutionary History of Asian Sonerileae/Dissochaeteae.

Sonerileae/Dissochaeteae (Melastomataceae) comprises ca. 50 genera, two thirds of which occur in Southeast Asia. Phylogenetic relationships within this clade remain largely unclear, which hampers our understanding of its origin, evolution, and biogeography. Here, we explored the use of chloroplast genomes in phylogenetic reconstruction of Sonerileae/Dissochaeteae, by sampling 138 species and 23 genera in this clade. A total of 151 complete plastid genomes were assembled for this study. Plastid genomic data provided better support for the backbone of the Sonerileae/Dissochaeteae phylogeny, and also for relationships among most closely related species, but failed to resolve the short internodes likely resulted from rapid radiation. Trees inferred from plastid genome and nrITS sequences were largely congruent regarding the major lineages of Sonerileae/Dissochaeteae. The present analyses recovered 15 major lineages well recognized in both nrITS and plastid phylogeny. Molecular dating and biogeographical analyses indicated a South American origin for Sonerileae/Dissochaeteae during late Eocene (stem age: 34.78 Mya). Two dispersal events from South America to the Old World were detected in late Eocene (33.96 Mya) and Mid Oligocene (28.33 Mya) respectively. The core Asian clade began to diversify around early Miocene in Indo-Burma and dispersed subsequently to Malesia and Sino-Japanese regions, possibly promoted by global temperature changes and East Asian monsoon activity. Our analyses supported previous hypothesis that Medinilla reached Madagascar by transoceanic dispersal in Miocene. In addition, generic limits of some genera concerned were discussed.

Identification of a Sidwf1 gene controlling short internode length trait in the sesame dwarf mutant dw607.

SiDWF1 encodes a gibberellin receptor GID1B-like protein controlling the internode length and plant height in sesame. Sesame is a high-height crop. Here we systematically analyzed the morphological and genetic characters of the sesame dwarf mutant dw607 (dwf1 type). The plant height and the internode length of dw607 significantly declined, while the thousand seed weight (TSW) significantly increased (P < 0.01). The cell size of stem parenchyma and pith tissue reduced, and vascular bundle cells and parenchyma tissue arranged much tighter in the dwarf mutant. Based on the cross-population association mapping of a RIL population of the cross 'dw607 (dwf1) × 15N41 (wt type),' the target interval linked to the short internode length was located on C9.scaffold2 of SiChr.4 in sesame. We further screened the 58 variants using the genomic variant data of 824 germplasm and BSA DNA pools and determined the target gene Sidwf1. The SNP mutation of C1057 to T1057 resulted in the amino acid change of P150 (proline) to S150 (serine) in SiDWF1. SiDWF1 gene allele is 1,638bp and encodes a gibberellin receptor GID1B-like protein. Transcription profile assay reflected that Sidwf1 is highly expressed in leaf, stem, bud, and capsule tissues. The dynamic variation in endogenous GA3 content in dw607 and the wild type was also monitored in this study. The results revealed the molecular genetic mechanism of the internode length and plant height trait in sesame for the first time. The findings supply the theoretical and material basis for developing the marker-assisted selection (MAS) breeding in sesame.

Reineckea flava (Liliaceae), a New Species from Guangxi Province, China

The new species Reineckea flava J. Z. Dong (Liliaceae) is described and illustrated from Guangxi, China. It differs from R. carnea (Andrews) Kunth in having slanting rhizomes with short oblate internodes (shorter axis 4–6 mm × longer axis 8–14 mm), with thick and short adventitious roots at nodes, narrowly lanceolate leaves (5–10 mm broad), and yellow-orange fruits.

First detection of “Candidatus Phytoplasma asteris” ‐ and “Candidatus Phytoplasma solani”‐related strains in fig trees

AbstractIn July 2017, a survey was conducted in a fig collection plot at Locorotondo (south of Italy) to investigate the possible presence of phytoplasmas in plants showing yellowing, deformed leaves, short internodes, mottling and mosaic. Samples were collected from symptomatic plants and tested by nested PCR assays using universal and specific primers to amplify the 16S rDNA of these prokaryotes. PCR results detected the presence of phytoplasma sequences in twenty plant samples that resulted clustering two phylogenetically distinct phytoplasmas, i.e., “Candidatus Phytoplasma asteris” and “Candidatus Phytoplasma solani” affiliated to 16SrI and 16SrXII ribosomal groups, respectively. The presence of phytoplasmas belonging to both ribosomal groups was confirmed with group specific quantitative PCR and RFLP assays on 16S ribosomal amplicons. Results of this study indicate for the first time the occurrence of phytoplasmas in fig; however, more work should be carried out to verify their association with the symptoms observed on diseased fig plants.

Multilocus phylogeny of a cryptic radiation of Afrotropical long‐fingered bats (Chiroptera, Miniopteridae)

AbstractThe Old World bat family Miniopteridae comprises only the genus Miniopterus, which includes 20 currently recognized species from the Afrotropical realm and 15 species from Eurasia and Australasia. Since 2003, the number of recognized Miniopterus species has grown from 19 to 35, with most newly described species endemic to Madagascar and the Comoros Archipelago. We investigated genetic variation, phylogenetic relationships and clade membership in Miniopterus focusing on Afrotropical taxa. We generated mitochondrial cytochrome‐b (cyt‐b) and nuclear intron data (five genes) from 352 vouchered individuals collected at 78 georeferenced localities. Including 99 additional mitochondrial sequences from GenBank, we analysed a total of 25 recognized species. Mitochondrial genetic distances among cyt‐b‐supported clades averaged 9.3%, representing as many as five undescribed species. Multilocus coalescent delimitation strongly supported the genetic isolation of eight of nine tested unnamed clades. A large number of sampled clades in sub‐Saharan Africa are distributed wholly or partly in East Africa (nine of 13 clades), suggesting that Miniopterus diversity has been grossly underestimated. Although 25 of 27 cyt‐b and 23 of 25 nuclear gene tree lineages from the Afrotropics were strongly supported as monophyletic, a majority of deep nodes were poorly resolved in phylogenetic analyses. Long terminal branches subtending short backbone internodes in the phylogenetic analyses suggest a rapid radiation model of diversification. This hypothesis needs to be tested using more phylogenetically informative data.

Uncovering the inflorescence evolution of Eleusininae (Cynodonteae: Chloridoideae: Poaceae)

AbstractInflorescence forms in grasses lead to a general assumption that their evolution is random. We reconstructed the ancestral inflorescence for Poaceae subtribe Eleusininae and outlined possible evolutionary pathways to test the hypotheses of (1) non-directionality in grass inflorescence evolution and (2) an evolutionary direction from complex to simpler inflorescence architectures in this lineage. By studying early stages of inflorescence and spikelet development, we investigated ontogenetic changes that may correlate with evolutionary pathways identified. The approach presented here indicates that the current diversity of inflorescences found in Eleusininae is probably a result of two distinct evolutionary pathways. The main path involves a multi-staged course with shortening of main axis internodes first, followed by a decrease in number of primary branches and florets per spikelet. We postulate that reduced elongation of the internodes may affect the apical and axillary meristems performance, which in turn promotes a decrease in the number of primary branches and floret per spikelet. Current diversity in inflorescences of Eleusininae may be a consequence of a reductive evolution. We found that the evolutionary directionality of inflorescences in Eleusininae may be associated with developmental events that affected inflorescence morphology at early stages.

GENETIC SOURCES FOR BREEDING BUSHY AND SHORT-VINE WATERMELON CULTIVARS

Background. When studying the collection of watermelon, it is important to disclose its genetic potential by identifying spontaneous mutations, using its accessions in crosses, and analyzing inheritance of its main traits in hybrids. One of the priorities in watermelon breeding is to develop and produce genetic sources of bushy and short-vine forms with stable manifestation of their morpho-biological characters under various environmental conditions.Material and methods. Accessions from the watermelon collection (local landraces, commercialized and promising cultivars, hybrids and lines obtained in the process of work) of diverse ecogeographic groups served as the material for this research. Description of morphological characters and assessment of economically useful ones were based on the guidelines for studying and maintaining the cucurbit collection and the guidelines for cucurbit crop breeding, both developed by VIR.Results. Variability and inheritance of the bushiness and short vine characters were studied in watermelon accessions according to the features of their growth and development. The habitus of the bushy forms is shaped by the length of stems (0.8– 1.2 m) and very short (2–3 cm) internodes. Short-vine plant stems are 1.3–1.5 m long. Short-vine plants in the early period of development distinctly stand out for their compact bush, if compared with long-vine forms. Short vines are developed due to short internodes (4–5 cm) and a smaller number of lateral shoots.Conclusion. Many years of studying the watermelon collection in the field resulted in identification of promising genetic sources for the breeding of bushy and short-vine cultivars: bushy dissected-leaf lines (KRL) – KRL 694, KRL 656, KRL 376 and KRL 394; bushy entire-leaf lines (KTsL) – KTsL 760/13; yellow-green bushy dissectedleaf lines (ZhZKRL) – ZhZKRL; short-vine watermelon lines (KPL) – KPL 774 and KPL 368. The developed lines differ in morpho-biological and economically useful characters (yield,fruit quality, growing season duration, etc.). They possess resistance to diseases (fusarium wilt and anthracnose) and environmental stressors. The lines are offered for use in the breeding of new bushy and short-vine cultivars and improvement of the existing ones, with various combinations of morpho-biological and economic traits. Brief descriptions of main economically valuable characters of the breeding lines are presented.

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

BackgroundAppropriate 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.ResultsIn 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.ConclusionsAuxin 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.

Morphological, transcriptomics and phytohormone analysis shed light on the development of a novel dwarf mutant of cabbage (Brassica oleracea)

Plant dwarf mutants generally exhibit delayed growth, delayed development, short internodes, and abnormal leaves and flowers and are ideal materials to explore the molecular mechanism of plant growth and development. In the current study, we first discovered a spontaneous cabbage (Brassica oleracea) dwarf mutant 99–198dw, which exhibits a dwarf stature, wrinkled leaves, non-heading, and substantially reduced self-fertility compared with the wild-type 99–198; however, the underlying molecular mechanism of its dwarfism is unknown. Here, we performed comparative phenotype, transcriptome and phytohormone analyses between 99–198 and 99–198dw. Cytological analysis showed that an increase in cell size, a reduction in cell layers, chloroplast degradation and a reduction in mitochondria were observed in 99–198dw. RNA-Seq showed that a total of 3801 differentially expressed genes (DEGs) were identified, including 2203 upregulated and 1598 downregulated genes in the dwarf mutant. Key genes in stress-resistant pathways were mostly upregulated, including salicylic acid (SA), jasmonic acid (JA), abscisic acid (ABA), ethylene (ET), etc., while the DEGs reported to be related to plant height, such as those involved in the gibberellin (GA), brassinolide (BR), indole-3-acetic acid (IAA), and strigolactone (SL) pathways were mostly downregulated. In addition, the DEGs in the cell division pathway were all downregulated, which is consistent with the cytokinesis defects detected by cytological analysis. The changes in the GA4, JA, ET, SA and ABA contents measured by liquid chromatography coupled with tandem mass spectrometry (LC–MS/MS) absolute quantification were consistent with the transcriptome analysis. Further hormone treatment tests showed that the exogenous application of GA, BR, 6BA, paclobutrazol (PC), etc. did not rescue the phenotype, implying that the change in phytohormones is due to but not the cause of the dwarf trait. It was speculated that mutation of certain DEG related to cell division or participating in signalling pathway of phytohormones like GA, BR, IAA, and SL were the cause of dwarf. These results are informative for the elucidation of the underlying regulatory network in 99–198dw and enrich our understanding of plant dwarf traits at the molecular level.

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.

A phylogenomic framework for pelagiarian fishes (Acanthomorpha: Percomorpha) highlights mosaic radiation in the open ocean.

The fish clade Pelagiaria, which includes tunas as its most famous members, evolved remarkable morphological and ecological variety in a setting not generally considered conducive to diversification: the open ocean. Relationships within Pelagiaria have proven elusive due to short internodes subtending major lineages suggestive of rapid early divergences. Using a novel sequence dataset of over 1000 ultraconserved DNA elements (UCEs) for 94 of the 286 species of Pelagiaria (more than 70% of genera), we provide a time-calibrated phylogeny for this widely distributed clade. Some inferred relationships have clear precedents (e.g. the monophyly of 'core' Stromateoidei, and a clade comprising 'Gempylidae' and Trichiuridae), but others are unexpected despite strong support (e.g. Chiasmodontidae + Tetragonurus). Relaxed molecular clock analysis using node-based fossil calibrations estimates a latest Cretaceous origin for Pelagiaria, with crown-group families restricted to the Cenozoic. Estimated mean speciation rates decline from the origin of the group in the latest Cretaceous, although credible intervals for root and tip rates are broad and overlap in most cases, and there is higher-than-expected partitioning of body shape diversity (measured as fineness ratio) between clades concentrated during the Palaeocene-Eocene. By contrast, more direct measures of ecology show either no substantial deviation from a null model of diversification (diet) or patterns consistent with evolutionary constraint or high rates of recent change (depth habitat). Collectively, these results indicate a mosaic model of diversification. Pelagiarians show high morphological disparity and modest species richness compared to better-studied fish radiations in contrasting environments. However, this pattern is also apparent in other clades in open-ocean or deep-sea habitats, and suggests that comparative study of such groups might provide a more inclusive model of the evolution of diversity in fishes.

Peach witches’-broom, an emerging disease associated with ‘Candidatus Phytoplasma phoenicium’ and ‘Candidatus Phytoplasma aurantifolia’ in Iran

During field surveys carried out from 2013 to 2017 in the eight main peach producing provinces of Iran, symptoms of a phytoplasma-like peach witches'-broom disease (PWIB), inducing severe yellowing, little leaf, internode shortening, crown and stem witches’-broom, decline, and death, were observed. The aim of this work was to identify and characterize the agent(s) associated with PWIB by biological assays and molecular analyses. PWIB agents were successfully transmitted under controlled conditions from scions of in field-affected peach trees, exhibiting severe or mild symptoms, to peach and bitter almond seedlings inducing phytoplasma-like symptoms. A 16S rDNA fragment of 1250 bp was amplified by nested-PCR from all PWIB-affected trees and grafted seedlings. Nucleotide sequence identity, presence of species-specific signature sequences, in silico RFLP, single nucleotide polymorphisms, and phylogenetic analyses of 16S rDNA allowed the assignation of the phytoplasma strains identified in seven Iranian provinces in peach trees with severe PWIB symptoms to four SNP genetic lineages of ‘Ca. P. phoenicium’ (subgroup 16SrIX-B and its variant). PWIB phytoplasma strains identified in Abarkooh (Yazd province) in peach trees with mild symptoms were attributed to the species ‘Ca. P. aurantifolia’ (subgroup 16SrII-C). This report of a wide spread of ‘Ca. P. phoenicium’ in association with PWIB in Iran supported its capability of adaptation to a broad range of fruit tree species, such as peach, nectarine, and apricot. As ‘Ca. P. phoenicium’ and ‘Ca. P. aurantifolia’ are the etiological agents of other important plant diseases in Iran and neighbouring countries, further investigations are needed to determine the role played by peach in their epidemiological pathways.

Bulked-segregant Analysis Identified a Putative Region Related to Short Internode Length in Melon

Short internode length (SIL) is one of the most commercially and important traits in melon varieties (Cucumis melo L.). SIL can result in a compact vining type that promotes concentrated fruit in high-density crops, leading to greater use of light resources for photosynthesis and greater yield per unit area. In our study, two parental melon lines ‘M1-32’ (P1, standard vine) and ‘X090’ (P2, short internodes), and their F1, F2, BC1P1, and BC1P2 progenies were evaluated after being grown in plastic greenhouse conditions in 2017 and 2018. Main stem length (MSL) and internode length (IL) of six melon generations indicated that a single recessive gene (MD7) controlled dwarfism in the ‘X090’ melon line. Whole-genome analysis revealed a genomic region harboring the candidate dwarfism gene on chromosome 7. Six polymorphic cleaved amplified polymorphic sequence (CAPS) markers from chromosome 7 were used to construct a genetic linkage that spanned 30.28 cM. The melon dwarfing locus MD7 responsible for SIL was positioned between markers M7-4 and M7-5, with 3.16 cM of flanking distance. The CAPS markers M7-4 and M7-5 developed have the potential to accelerate the development of dwarf melon varieties, especially in situations when dwarf genotypes are an important breeding goal using marker-assisted selection.

Basal internode elongation of rice as affected by light intensity and leaf area

Short basal internodes are important for lodging resistance of rice (Oryza sativa L.). Several canopy indices affect the elongation of basal internodes, but uncertainty as to the key factors determining elongation of basal internodes persists. The objectives of this study were (1) to identify key factors affecting the elongation of basal internodes and (2) to establish a quantitative relationship between basal internode length and canopy indices. An inbred rice cultivar, Yinjingruanzhan, was grown in two split-plot field experiments with three N rates (0, 75, and 150 kg N ha−1 in early season and 0, 90, and 180 kg N ha−1 in late season) as main plots, three seedling densities (16.7, 75.0, and 187.5 seedlings m−2) as subplots, and three replications in the 2015 early and late seasons in Guangzhou, China. Light intensity at base of canopy (Lb), light quality as determined from red/far-red light ratio (R/FR), light transmission ratio (LTR), leaf area index (LAI), leaf N concentration (NLV) and final length of second internode (counted from soil surface upward) (FIL) were recorded. Higher N rate and seedling density resulted in significantly longer FIL. FIL was negatively correlated with Lb, LTR, and R/FR (P < 0.01) and positively correlated with LAI (P < 0.01), but not correlated with NLV (P > 0.05). Stepwise linear regression analysis showed that FIL was strongly associated with Lb and LAI (R2 = 0.82). Heavy N application to pot-grown rice at the beginning of first internode elongation did not change FIL. We conclude that FIL is determined mainly by Lb and LAI at jointing stage. NLV has no direct effect on the elongation of basal internodes. N application indirectly affects FIL by changing LAI and light conditions in the rice canopy. Reducing LAI and improving canopy light transmission at jointing stage can shorten the basal internodes and increase the lodging resistance of rice.

Rubus stunt: a review of an important phytoplasma disease in Rubus spp.

Phytoplasmas are cell wall-less plant pathogenic bacteria that colonize the phloem of their host plants and can be transferred by plant sap-sucking hemipteran insects or by vegetative propagation. In Rubus species such as red raspberry (Rubus idaeus) and blackberry (Rubus subgenus Rubus), phytoplasmas cause a disease which is referred to as Rubus stunt. Disease symptoms of Rubus stunt include stunting, witches’ broom, small leaves, short internodes, enlarged sepals, phyllody, flower proliferation, and fruit malformations. Rubus stunt is widely spread geographically and has been reported to be present throughout Europe, the former Soviet Union, the USA, Pakistan, and Turkey. As the incubation period of Rubus stunt can be up to 1 year and Rubus plants are usually produced by vegetative propagation, there is a high risk of spreading this disease in planting material. In addition, Rubus stunt is commonly overlooked because disease symptoms are often inconspicuous. Therefore, Rubus stunt has a high economic importance in these high-input crops with large initial investments. Here, we review the current state of knowledge on the causative agents of Rubus stunt, their spread, and control measures.

Updating Ceramium (Rhodophyta, Ceramiales) biodiversity in the North Adriatic Sea (Mediterranean): Ceramium rothianum sp. nov. and rediscovery of three forgotten species

ABSTRACTThe cosmopolitan genus Ceramium Roth (Ceramiaceae), with over 200 currently accepted species, is one of the largest in the Rhodophyta. The genus is characterized by cylindrical or slightly compressed thalli, with axial cells incompletely to completely covered by cortical cells, alternate to pseudo-dichotomous branching and straight to inrolled apices. Despite recent studies, the nomenclature and taxonomy of this genus are still very problematic, linked to the high degree of variation in morphological characters, small thallus sizes, epiphytic habit and the existence of cryptic species. The Mediterranean Sea is reported to have a particularly high diversity of Ceramium species: the North Adriatic Sea, in particular Venice and nearby coasts, was a favourite classical collecting area from where several species were described. In this study we characterize Ceramium sampled from transitional waters of the Venice Lagoon (Italy) by molecular and morphological approaches. Through phylogenetic analyses, using the plastid ribulose-1,5-bisphosphate carboxylase/oxygenase gene (rbcL) as molecular marker, we identify six distinct taxonomic entities, of which four represent taxa not currently recognized in the Venice Lagoon or the wider Mediterranean Sea. One of these is the poorly known species Ceramium connivens Zanardini, which is non-spiny and fully corticated when mature with short naked internodes developing in older axes. Two entities with erect partially corticated thalli without spines, probably misidentified up to now as Ceramium diaphanum (Lightfoot) Roth, correspond to the new species Ceramium rothianum Wolf et al. and to the forgotten species Ceramium nodosum (Kützing) A.W. Griffiths & Harvey. The last entity, characterized by prostrate axes giving rise to narrow erect incompletely corticated, non-spiny axes, is identified as the rare, poorly known species Ceramium incospicuum Zanardini.

Genetic characterization of novel and CRISPR-Cas9 gene edited maize brachytic 2 alleles

Maize plants with mutations at brachytic 2 (br2) reduce plant height through internode shortening while maintaining the rest of the plant's relative size. The gene product of Br2 encodes an ATP binding cassette type B (ABCB) auxin transporter. Several br2 mutations have been previously reported, notably independent characterizations of 8 bp and 241 bp deletions (br2-23 and br2-qpa1, respectively), a single missense mutation (br2-qph1), and a MITE transposon insertion (br2-NC238). Two new br2 mutations (designated br2-7081 and br2-7861) have now been characterized with different genetic mechanisms than prior reports providing further examples of functional genetic variation in maize. A gene edited br2 allele (designated br2-1005) has also been generated through use of CRISPR-Cas9 technology. Both novel br2 transposon mutants in this report (br2-7081, br2-7861) arose spontaneously, independently and were identified in proprietary maize germplasm; both contain insertions that result in frameshifts with presence of premature stop codons. The br2-7081 allele contains a 4.7 kb insertion in exon 5, which is identified as a Ty1-copia family long terminal repeat (LTR) retrotransposon. The br2-7861 allele contains a 579 bp insertion in intron 4, which is identified as a partial Sirevirus LTR retrotransposon, and encodes a transcribed exon of 190 bp. A gene edit in br2 (br2-1005) was generated when a CRISPR-Cas9-induced double strand break was repaired by the plant via non-homologous end joining, causing a 1 bp frameshift resulting in a premature stop codon in exon 5. Also, of note in this study is the 8 bp deletion reportedly characterizing the br2-23 mutant allele was unexpectedly found in wild-type Br2 (non-brachytic) germplasm indicating the 8 bp deletion by itself likely does not result in a brachytic phenotype. The novel mutant alleles reported here provide further examples of functional genetic variation in maize br2, either through inherent genetic variation mechanisms or generated using site-directed nuclease technology. The br2-1005 allele highlights the utility of gene editing to phenocopy naturally occurring mutations, and all three alleles in this report provide additional opportunities to research the brachytic semi-dwarf phenotype in maize.

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’.