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Special Issue "Genetic and Morphological Variation in Tropical and Temperate Plant Species"

A special issue of Forests (ISSN 1999-4907). This special issue belongs to the section "Forest Ecophysiology and Biology".

Deadline for manuscript submissions: 15 March 2019

Special Issue Editors

Guest Editor
Dr. W. John Kress

Department of Botany, National Museum of Natural History, Smithsonian Institution, Washington, DC, USA
Website | E-Mail
Interests: systematic biology; evolutionary biology; conservation biology; DNA barcoding
Guest Editor
Dr. Nancai Pei

Research Institute of Tropical Forestry, Chinese Academy of Forestry, Guangzhou, China
Website | E-Mail
Interests: forest biology; plant DNA barcoding; urban forestry

Special Issue Information

Dear Colleagues,

Plants provide the foundation for the structure and function, as well as interactions, among organisms, in both tropical and temperate zone habitats. To date, many investigations have revealed patterns and mechanisms generating plant diversity at various scales and from diverse ecological perspectives. However, in the era of climate change, anthropogenic disturbance, and rapid urbanization new insights are needed to understand how plant species in these forest habitats are changing and adapting. Investigations of plants in both little-disturbed, more natural environments, as well as in urban areas in which crucial green infrastructure is ever more important for sustaining complex human societies are needed. This Special Issue of Forests will focus on plant variation from the perspectives of morphology, genetics, and function, especially plant interactions with biotic and abiotic factors. Research articles may address any aspect of plant evolution and community phylogenetics (explorations of patterns and mechanisms from diverse organismal levels, e.g., molecular, population, species, community, landscape, and ecosystem), plant functional traits (e.g., nutrient traits of leaf, stem, root; reproductive traits of flower, fruit, seed), and/or responses of plant species to changing environments (e.g., water, atmosphere, soil, human activities). Studies providing quantitative evaluation or description of interactions of plants with animals and microbes, both in natural and urban environments, including terrestrial and aquatic systems, are also welcome.

Dr. W. John Kress
Dr. Nancai Pei
Guest Editors

Manuscript Submission Information

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Keywords

  • tree genetics
  • plant morphology
  • forest biodiversity
  • plant traits
  • plant-animal interactions
  • environmental change

Published Papers (12 papers)

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Research

Open AccessArticle Physiological and Transcriptome Analysis of a Yellow-Green Leaf Mutant in Birch (Betula platyphylla × B. Pendula)
Forests 2019, 10(2), 120; https://doi.org/10.3390/f10020120
Received: 19 December 2018 / Revised: 30 January 2019 / Accepted: 1 February 2019 / Published: 2 February 2019
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Abstract
Chlorophyll (Chl)-deficient mutants are ideal materials for the study of Chl biosynthesis, chloroplast development, and photosynthesis. Although the genes encoding key enzymes related to Chl biosynthesis have been well-characterized in herbaceous plants, rice (Oryza sativa L.), Arabidopsis (Arabidopsis thaliana), and maize [...] Read more.
Chlorophyll (Chl)-deficient mutants are ideal materials for the study of Chl biosynthesis, chloroplast development, and photosynthesis. Although the genes encoding key enzymes related to Chl biosynthesis have been well-characterized in herbaceous plants, rice (Oryza sativa L.), Arabidopsis (Arabidopsis thaliana), and maize (Zea mays L.), yellow-green leaf mutants have not yet been fully studied in tree species. In this work, we explored the molecular mechanism of the leaf color formation in a yellow-green leaf mutant (yl). We investigated the differentially expressed genes (DEGs) between yl and control plants (wild type birch (WT) and BpCCR1 overexpression line 11, (C11)) by transcriptome sequencing. Approximately 1163 genes (874 down-regulated and 289 up-regulated) and 930 genes (755 down-regulated and 175 up-regulated) were found to be differentially expressed in yl compared with WT and C11, respectively. Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway enrichment analysis for DEGs revealed that photosynthesis antenna proteins represent the most significant enriched pathway. The expressions of photosynthesis antenna proteins are crucial to the leaf color formation in yl. We also found that Chl accumulate, leaf anatomical structure, photosynthesis, and growth were affected in yl. Taken together, our results not only provide the difference of phenomenal, physiological, and gene expression characteristics in leaves between yl mutant and control plants, but also provide a new insight into the mutation underlying the chlorotic leaf phenotype in birch. Full article
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Open AccessArticle Genome-Wide Analysis and Expression Profiling of the Heat Shock Factor Gene Family in Phyllostachys edulis during Development and in Response to Abiotic Stresses
Forests 2019, 10(2), 100; https://doi.org/10.3390/f10020100
Received: 3 December 2018 / Revised: 22 January 2019 / Accepted: 23 January 2019 / Published: 26 January 2019
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Abstract
Heat shock transcription factors (Hsfs) play crucial roles in regulating plant responses to heat and other stresses, as well as in plant development. As the largest monopodial bamboo species in the world, how to adapt to various stresses under the background of global [...] Read more.
Heat shock transcription factors (Hsfs) play crucial roles in regulating plant responses to heat and other stresses, as well as in plant development. As the largest monopodial bamboo species in the world, how to adapt to various stresses under the background of global climate change is very important for the sustainable development of bamboo forest. However, our understanding of the function of Hsfs in moso bamboo (Phyllostachys edulis) is limited. In this study, a total of 22 non-redundant Hsf genes were identified in the moso bamboo genome. Structural characteristics and phylogenetic analysis revealed that members of the PheHsf family can be clustered into three classes (A, B and C). Furthermore, PheHsfs promoters contained a number of stress-, hormone- and development-related cis-acting elements. Transcriptome analysis indicated that most PheHsfs participate in rapid shoot growth and flower development in moso bamboo. Moreover, the expression patterns of all 12 members of class A were analyzed under various stresses (heat, drought, salt and cold treatment) through Figurereal-time quantitative polymerase chain reaction (qRT-PCR). Within the class A PheHsf members, PheHsfA1a was expressed mainly during moso bamboo development. Expression of four PheHsfA4s and one PheHsfA2 (PheHsfA4a-1, PheHsfA4a-2, PheHsfA4d-1, PheHsfA4d-2, and PheHsfA2a-2) was up-regulated in response to various stresses. PheHsfA2a-2, PheHsfA4d-1 and PheHsfA4d-2 were strongly induced respectively by heat, drought and NaCl stress. Through co-expression analysis we found that two hub genes PheHsfA4a-2 and PheHsfA4a-1 were involved in a complex protein interaction network. Based on the prediction of protein interaction networks, five PheHsfAs (PheHsfA4a-1, PheHsfA4a-2, PheHsfA4d-1, PheHsfA4d-2, and PheHsfA2a-2) were predicted to play an important role in flower and shoot development and abiotic stress response of moso bamboo. This study provides an overview of the complexity of the PheHsf gene family and a basis for analyzing the functions of PheHsf genes of interest. Full article
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Open AccessArticle DNA Barcoding Analysis and Phylogenetic Relation of Mangroves in Guangdong Province, China
Forests 2019, 10(1), 56; https://doi.org/10.3390/f10010056
Received: 9 December 2018 / Revised: 3 January 2019 / Accepted: 4 January 2019 / Published: 12 January 2019
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Abstract
Mangroves are distributed in the transition zone between sea and land, mostly in tropical and subtropical areas. They provide important ecosystem services and are therefore economically valuable. DNA barcoding is a useful tool for species identification and phylogenetic reconstruction. To evaluate the effectiveness [...] Read more.
Mangroves are distributed in the transition zone between sea and land, mostly in tropical and subtropical areas. They provide important ecosystem services and are therefore economically valuable. DNA barcoding is a useful tool for species identification and phylogenetic reconstruction. To evaluate the effectiveness of DNA barcoding in identifying mangrove species, we sampled 135 individuals representing 23 species, 22 genera, and 17 families from Zhanjiang, Shenzhen, Huizhou, and Shantou in the Guangdong province, China. We tested the universality of four DNA barcodes, namely rbcL, matK, trnH-psbA, and the internal transcribed spacer of nuclear ribosomal DNA (ITS), and examined their efficacy for species identification and the phylogenetic reconstruction of mangroves. The success rates for PCR amplification of rbcL, matK, trnH-psbA, and ITS were 100%, 80.29% ± 8.48%, 99.38% ± 1.25%, and 97.18% ± 3.25%, respectively, and the rates of DNA sequencing were 100%, 75.04% ± 6.26%, 94.57% ± 5.06%, and 83.35% ± 4.05%, respectively. These results suggest that both rbcL and trnH–psbA are universal in mangrove species from the Guangdong province. The highest success rate for species identification was 84.48% ± 12.09% with trnH-psbA, followed by rbcL (82.16% ± 9.68%), ITS (66.48% ± 5.97%), and matK (65.09% ± 6.00%), which increased to 91.25% ± 9.78% with the addition of rbcL. Additionally, the identification rate of mangroves was not significantly different between rbcL + trnH-psbA and other random fragment combinations. In conclusion, rbcL and trnH-psbA were the most suitable DNA barcode fragments for species identification in mangrove plants. When the phylogenetic relationships were constructed with random fragment combinations, the optimal evolutionary tree with high supporting values (86.33% ± 4.16%) was established using the combination of matK + rbcL + trnH-psbA + ITS in mangroves. In total, the 476 newly acquired sequences in this study lay the foundation for a DNA barcode database of mangroves. Full article
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Open AccessArticle Drought Impact on Leaf Phenology and Spring Frost Susceptibility in a Quercus robur L. Provenance Trial
Forests 2019, 10(1), 50; https://doi.org/10.3390/f10010050
Received: 20 November 2018 / Revised: 7 January 2019 / Accepted: 8 January 2019 / Published: 11 January 2019
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Abstract
Research highlights: The susceptibility of oaks to late spring and early autumn frosts is directly related to their leaf phenology. Drought may alter the leaf phenology and therefore frost tolerance of oaks. However, the effects of drought on oak leaf phenology and frost [...] Read more.
Research highlights: The susceptibility of oaks to late spring and early autumn frosts is directly related to their leaf phenology. Drought may alter the leaf phenology and therefore frost tolerance of oaks. However, the effects of drought on oak leaf phenology and frost resistance have not been thoroughly studied. Background and objectives: One of the consequences of climate change is an increase in the frequency of dry episodes during the vegetation period. Pedunculate oak (Quercus robur L.) is an economically and ecologically important forest tree species that prefers humid habitats. Therefore, knowledge of the impact of drought on this species is of great importance for the adaptation of forestry strategies and practices to altered environmental conditions. The aim of this study was to determine the impact of drought on leaf phenology and spring frost susceptibility in nine provenances. Materials and methods: One-year-old saplings originating from nine European provenances were used in the trial. The saplings were exposed to experimental drought and then re-watered in two subsequent years. Spring and autumn leaf phenology were scored. The trial was impacted by a late spring frost in the third year, and the resulting leaf frost injury was scored. The effects of drought treatment on the phenology and frost susceptibility of plants from the provenances were analysed. Results: Leaf phenology of plants from most of the studied provenances was significantly influenced by the drought treatment (p < 0.001). Drought induced a carry-over effect on flushing phenology, which was observed as delayed bud burst (from 0.6 to 2.4 days) in the second year and as advanced bud burst (from 0.1 to 6.3 days) in the third year. Therefore, opposite shifts in flushing phenology may be induced as a result of differences in the time span when plants sense water deficits. In contrast to flushing, autumn leaf phenology was unambiguously delayed following the drought treatments for all studied provenances (from 2.1 to 25.8 days). Differences in late frost susceptibility were predominantly caused by among-provenance differences in flushing phenology. However, the drought treatment significantly increased frost susceptibility in the plants (the rate of frost-injured plants per provenance increased from 3% to 78%). This higher susceptibility to spring frost was most likely caused by the advanced flushing phenology that resulted from the drought treatment in the previous year. Full article
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Open AccessArticle Variation in Photosynthetic Traits and Correlation with Growth in Teak (Tectona grandis Linn.) Clones
Forests 2019, 10(1), 44; https://doi.org/10.3390/f10010044
Received: 24 July 2018 / Revised: 6 September 2018 / Accepted: 10 September 2018 / Published: 10 January 2019
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Abstract
In order to interpret the patterns of genetic variation of photosynthesis and the relationships with growth traits within gene resources of teak (Tectona grandis Linn.), gas exchange, and chlorophyll fluorescence parameters, growth traits of plants in nursery and field trials were measured [...] Read more.
In order to interpret the patterns of genetic variation of photosynthesis and the relationships with growth traits within gene resources of teak (Tectona grandis Linn.), gas exchange, and chlorophyll fluorescence parameters, growth traits of plants in nursery and field trials were measured for 20 teak clones originated from different countries. The results show that there was abundant genetic variation in gas exchange, chlorophyll fluorescence, and growth among the teak clones. The measured traits were found to have generally high heritability (h2) except for intercellular concentration of carbon dioxide (CO2) (Ci). The net photosynthetic rate (Pn), seedling height, and individual volume of wood were significantly correlated with each other, and seedling height was significantly correlated with plant height in field trials, suggesting that Pn and seedling height can be useful in teak breeding. Teak clones 7029, 71-5, 7219, 7412, and 7122, and provenances 3070, 3074, and 3071 had higher photosynthetic rates, and can be regarded as a key resource in teak improvement programs. This work provides useful information for teak breeding and germplasm resource management. Full article
Open AccessArticle Diversity Estimation and Antimicrobial Activity of Culturable Endophytic Fungi from Litsea cubeba (Lour.) Pers. in China
Forests 2019, 10(1), 33; https://doi.org/10.3390/f10010033
Received: 6 December 2018 / Revised: 29 December 2018 / Accepted: 31 December 2018 / Published: 6 January 2019
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Abstract
Endophytes are important components of forest ecosystems, and have potential use in the development of medical drugs and the conservation of wild medicinal plants. This study aimed to examine the diversity and antimicrobial activities of endophytic fungi from a medicinal plant, Litsea cubeba [...] Read more.
Endophytes are important components of forest ecosystems, and have potential use in the development of medical drugs and the conservation of wild medicinal plants. This study aimed to examine the diversity and antimicrobial activities of endophytic fungi from a medicinal plant, Litsea cubeba (Lour.) Pers. The results showed that a total of 970 isolates were obtained from root, stem, leaf, and fruit segments of L. cubeba. All the fungal endophytes belonged to the phylum Ascomycota and could be classified into three taxonomic classes, nine orders, twelve families, and seventeen genera. SF15 (Colletotrichum boninense) was the dominant species in L. cubeba. Leaves harbored a greater number of fungal endophytes but lower diversity, while roots harbored the maximum species diversity of endophytic fungi. For the antimicrobial activities, seventeen isolates could inhibit the growth of plant pathogenic fungi, while the extracts of six endophytes showed antimicrobial activity to all the tested pathogenic fungi. Among these endophytes, SF22 (Chaetomium globosum) and SF14 (Penicillium minioluteum) were particularly effective in inhibiting seven plant pathogenic fungi growths and could be further explored for their potential use in biotechnology, medicine, and agriculture. Full article
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Open AccessArticle Morphological Characteristics and Allometric Relationships of Shoot in Two Undergrowth Plants: Polygonatum odoratum and Polygonatum multiflorum
Forests 2018, 9(12), 783; https://doi.org/10.3390/f9120783
Received: 16 November 2018 / Revised: 14 December 2018 / Accepted: 17 December 2018 / Published: 19 December 2018
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Abstract
The main purpose of this investigation was to describe the spatial arrangement of shoot tissues, as seen in transverse section, and allometric relationships in two contrasting species of Polygonatum i.e., Polygonatum odoratum which commonly grows in mixed pine-oak forest with shoots rectangular in [...] Read more.
The main purpose of this investigation was to describe the spatial arrangement of shoot tissues, as seen in transverse section, and allometric relationships in two contrasting species of Polygonatum i.e., Polygonatum odoratum which commonly grows in mixed pine-oak forest with shoots rectangular in shape, and Polygonatum multiflorum found in oak-hornbeam forest with cylindrical shoots. The mass and length of the aerial shoots of each individual plant were measured. The shoot regions of each plant were then categorized as basal (b), central (c) or apical (a). Transverse sections of these shoot regions were subsequently cut, and the following parameters were measured: (1) Diameter of shoots, (2) thickness of the outer and inner zones of parenchyma and (3) thickness of the sclerenchyma zone. Additional allometric relationships between the various measurements were computed and determined as Pearson’s correlation coefficients (r). Both species of Polygonatum differed significantly with respect to the length, diameter and thickness of the outer zone of parenchyma. Shoots of P. multiflorum were taller but narrower than those of P. odoratum, which had a significantly wider zone of outer parenchyma. Allometric relationships were stronger for P. multiflorum, and for both species, they were generally stronger in the basal part of the shoot. We conclude that in P. multiflorum, the strong correlation between the diameter and length of the shoot seems to be important to the growth in shaded environments. Full article
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Open AccessArticle Diversity and Utilization of Edible Plants and Macro-Fungi in Subtropical Guangdong Province, Southern China
Forests 2018, 9(11), 666; https://doi.org/10.3390/f9110666
Received: 17 September 2018 / Revised: 22 October 2018 / Accepted: 22 October 2018 / Published: 25 October 2018
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Abstract
Food supply from forests is a fundamental component of forest ecosystem services, but information relating to suitability for human consumption and sustainable utilization of non-timber forest products (NTFPs) in developing countries is lacking. To address this gap in knowledge, diverse datasets of edible [...] Read more.
Food supply from forests is a fundamental component of forest ecosystem services, but information relating to suitability for human consumption and sustainable utilization of non-timber forest products (NTFPs) in developing countries is lacking. To address this gap in knowledge, diverse datasets of edible plants and macro-fungi were obtained from field collections, historical publications, and community surveys across seven cities in Guangdong Province (GP), southern China. Seven edible parts and five food categories of plant species were classified according to usage and specific nutrient components. Edible plant species were also categorized into different seasons and life forms. Our results show that at least 100 plant species (with 64 plant species producing fruit) and 20 macro-fungi were commonly used as edible forest products in subtropical GP. There were 55 and 57 species providing edible parts in summer and autumn, respectively. Many edible plants had multiple uses. Tree and herbaceous species made up the majority of the total. Our study provides evidence that both edible plants and macro-fungi can enrich the food supply for residents in rural and urban areas by acting as supplemental resources. We therefore suggest that, in spite of the prevalence of imported foods due to modern infrastructure, edible NTFPs from subtropical forests might be leveraged to support the increasing demand for food in an era of rapid urbanization and global change. Full article
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Open AccessArticle Identification of miRNAs Associated with Graft Union Development in Pecan [Carya illinoinensis (Wangenh.) K. Koch]
Forests 2018, 9(8), 472; https://doi.org/10.3390/f9080472
Received: 23 May 2018 / Revised: 14 July 2018 / Accepted: 31 July 2018 / Published: 3 August 2018
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Abstract
Pecan [Carya illinoinensis (Wangenh.) K. Koch] is a high-value fruit tree with a long juvenile period. The fruiting process of pecan seedlings can be largely accelerated through grafting. As non-coding small RNAs, plant miRNAs participate in various biological processes through negative regulation [...] Read more.
Pecan [Carya illinoinensis (Wangenh.) K. Koch] is a high-value fruit tree with a long juvenile period. The fruiting process of pecan seedlings can be largely accelerated through grafting. As non-coding small RNAs, plant miRNAs participate in various biological processes through negative regulation of gene expression. To reveal the roles of miRNAs in the graft union development of pecan, four small RNA libraries were constructed from the graft union at days 0, 8, 15, and 30 after grafting. A total of 47 conserved miRNAs belonging to 31 families and 39 novel miRNAs were identified. For identified miRNAs, 584 target genes were bioinformatically predicted, and 266 of them were annotated; 29 miRNAs (including 16 conserved and 13 novel miRNAs) were differentially expressed during the graft process. The expression profiles of 12 miRNA were further validated by quantitative reverse transcription PCR (qRT-PCR). In addition, qRT-PCR revealed that the expression levels of 3 target genes were negatively correlated with their corresponding miRNAs. We found that miRS26 might be involved in callus formation; miR156, miR160, miR164, miR166, and miRS10 might be associated with vascular bundle formation. These results indicate that the miRNA-mediated gene regulations play important roles in the graft union development of pecan. Full article
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Open AccessArticle Transcriptome Analysis of Bael (Aegle marmelos (L.) Corr.) a Member of Family Rutaceae
Forests 2018, 9(8), 450; https://doi.org/10.3390/f9080450
Received: 13 June 2018 / Revised: 9 July 2018 / Accepted: 10 July 2018 / Published: 26 July 2018
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Abstract
Aegle marmelos (L.) Corr. is a medicinally and horticulturally important tree member of the family Rutaceae. It is native to India, where it is also known as Bael. Despite its importance, the genomic resources of this plant are scarce. This study presented the [...] Read more.
Aegle marmelos (L.) Corr. is a medicinally and horticulturally important tree member of the family Rutaceae. It is native to India, where it is also known as Bael. Despite its importance, the genomic resources of this plant are scarce. This study presented the first-ever report of expressed transcripts in the leaves of Aegle marmelos. A total of 133,616 contigs were assembled to 46,335 unigenes with minimum and maximum lengths of 201 bp and 14,853 bp, respectively. There were 7002 transcription factors and 94,479 simple sequence repeat (SSR) markers. The A. marmelos transcripts were also annotated based on information from other members of Rutaceae; namely Citrus clementina and Citrus sinensis. A total of 482 transcripts were annotated as cytochrome p450s (CYPs), and 314 transcripts were annotated as glucosyltransferases (GTs). In the A. marmelos leaves, the monoterpenoid biosynthesis pathway was predominant. This study provides an important genomic resource along with useful information about A. marmelos. Full article
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Open AccessArticle Genetic Diversity and Structure through Three Cycles of a Eucalyptus urophylla S.T.Blake Breeding Program
Forests 2018, 9(7), 372; https://doi.org/10.3390/f9070372
Received: 17 April 2018 / Revised: 15 June 2018 / Accepted: 15 June 2018 / Published: 21 June 2018
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Abstract
Eucalyptus urophylla S.T.Blake is an important commercial tropical plantation species worldwide. In China, a breeding program for this species has progressed through three cycles but genetic diversity and structure in the breeding populations are uncertain. A sampling of field trials from these populations [...] Read more.
Eucalyptus urophylla S.T.Blake is an important commercial tropical plantation species worldwide. In China, a breeding program for this species has progressed through three cycles but genetic diversity and structure in the breeding populations are uncertain. A sampling of field trials from these populations was carried out to evaluate their genetic diversity and structure using 16 microsatellite loci. Significant deviations from Hardy-Weinberg equilibrium were recorded at all 16 loci in the populations. Overall expected and observed heterozygosity (He and Ho) estimates of 0.87 and 0.59 respectively for the first cycle population, and 0.88 and 0.60 respectively for the third cycle population, revealed reasonably high levels of genetic diversity. The genetic differentiation coefficient (Fst) revealed low differentiation among pairs of provenances (from the species’ native range) comprising the first cycle population (range: 0.012–0.108), and AMOVA results showed that the majority of molecular genetic variation existed among individuals rather than among provenances for the first cycle population and among individuals rather than among field trial sources in the third cycle population. Levels of genetic diversity appeared to remain unchanged from the first to third cycle populations, and the results indicate prospects for maintaining if not increasing diversity through recurrent breeding. Likely effects of artificial directional selection, prior to sampling, on both populations examined are discussed along with implications for future E. urophylla breeding. Full article
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Open AccessArticle Genome-Wide Identification and Characterization of MADS-box Family Genes Related to Floral Organ Development and Stress Resistance in Hevea brasiliensis Müll. Arg.
Forests 2018, 9(6), 304; https://doi.org/10.3390/f9060304
Received: 26 April 2018 / Revised: 26 May 2018 / Accepted: 28 May 2018 / Published: 29 May 2018
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Abstract
Elucidating the genetic mechanisms associated with the transition from the vegetative to reproductive phase in the rubber tree has great importance for both theoretical guidance and practical application to yield genetic improvement. At present, many transcription factors, including those that belong to the [...] Read more.
Elucidating the genetic mechanisms associated with the transition from the vegetative to reproductive phase in the rubber tree has great importance for both theoretical guidance and practical application to yield genetic improvement. At present, many transcription factors, including those that belong to the MADS-box gene family, have been revealed to have roles in regulating the transition from vegetative growth to reproductive growth. However, to the best of our knowledge, the Mad-box gene family from H. brasiliensis Müll. Arg. has not been characterized in detail. To investigate members of the HbMADS-box gene family associated with floral organ and inflorescence development in H. brasiliensis, we performed genome-wide identification and analysis of the MADS-box gene family related to flower development in H. brasiliensis, and a total of 20 MADS-box genes were newly identified in the H. brasiliensis genome. Expression profiling revealed that HbMad-box genes were differentially expressed in various tissues, which indicated that HbMad-box genes may exert different functions throughout the life cycle. Additionally, 12 genes (HbSEP, HbAGL9.1, HbAGL9.2, HbCMB1, HbCMB1-L, HbAGL6, HbAGL8, HbAP1, HbAG, HbDEFL, HbTT16, and HbPADS2) were found to be associated with the differentiation of flower buds and may be involved in flower development in H. brasiliensis. All of these floral-enriched HbMADS-box genes were regulated by hormone, salt, cold, high-temperature, and drought stresses. The present study is the first to carry out the genome-wide identification and analysis of the MADS-box gene family related to flower development in H. brasiliensis, and 20 new HbMad-box genes were identified in H. brasiliensis. Most of the newly identified HbMad-box genes were found to be associated with the differentiation of flower buds and may be involved in flower development in H. brasiliensis. Our results demonstrated that HbMad-box genes may be multifunctional regulators that have roles in distinct aspects of development, and are mainly involved in the maintenance of floral organ and inflorescence development. Full article
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