Normal Flowers Research Articles

Genetic analysis of a DROOPING LEAF mutant allele dl-6 associated with a twisted and folded leaf base caused by a deficiency in midrib development in rice

The failure of midrib formation in rice leaf blades results in the drooping leaf (dl) phenotype. A normal DROOPING LEAF (DL) gene is necessary for leaf homeotic transformation, which affects midrib and pistil development. Genetic analysis was performed on a new drooping leaf (dl) mutant named dl-6 in rice. The dl-6 allelic mutant exhibited drooping leaves that were severely folded and twisted at the base but had normal flower structure. The dl-6 allele is a nuclear recessive trait that fits a 3:1 Mendelian segregation ratio. The dl-6 mutant leaves displayed an abnormal main vein (midrib-less) with undeveloped aerenchyma and vascular bundles, resulting in severe leaf drooping. The lack of a midrib in dl-6 caused weak mechanical support, which resulted in folding at the collar junction of the leaf base and downward bending. Through genetic mapping, the dl-6 allele was identified at approximately 28.2 cM on rice chromosome 3. The allele was caused by mutations within the DL (LOC_Os03g11600.1) gene, with specific amino acid substitutions and additions in the encoded protein of the YABBY transcription factor. The dl-6 mutant is a recessive allele encoding a dysfunctional YABBY transcription factor that regulates leaf midrib development and aerenchymatous clear cell structures, leading to a drooping leaf phenotype in rice.

Effects of Different Regulating Measures on the Floral and Nutritional Physiology of Lemon

Lemon is an important economic crop in the world and can bloom several times each year. The Dehong prefecture of Yunnan province is one of the main lemon-producing areas in China, and is a suitable area for planting high-quality lemons in China. However, the hot and rainy summers in Yunnan are not conducive to flower bud differentiation, which leads to low lemon yield. Therefore, normal flower bud differentiation is important to guarantee lemon production and quality. In this study, we selected some lemon trees for a pot experiment, and we sprayed the lemon leaves with gibberellin and paclobutrazol to regulate lemon flower formation. We set four separate concentration gradients for each regulator: 50, 100, 150, and 200 mg/L. The PBZ concentration gradients were 200, 400, 600, and 1200 mg/L. After the experiment, we determined and analyzed the morphological index and fruit quality of the lemon trees. The results showed that under the same cultivation and management conditions, spraying paclobutrazol substantially inhibited the growth of lemon shoots, increased the fruit setting rate, and improved the fruit yield. However, gibberellin considerably reduced the number of lemon flowering branches and promoted the vegetative growth of the lemons. When the concentration of paclobutrazol was 600 mg/L, the amount of lemon fruits reached the maximum, which remarkably increased the titratable acid and soluble solids contents of the fruit and ultimately increased the fruit quality compared with the control. Altogether, selecting the appropriate concentration of regulators to control the flowering and fruit setting of fruit trees is important and has value in guiding actual production.

Correlation between Inflorescence Architecture and Floral Asymmetry-Evidence from Aberrant Flowers in Canna L. (Cannaceae).

Floral symmetry studies often focus on the development of monosymmetric and polysymmetric flowers, whereas asymmetric flowers and their position and function within the inflorescence structure are largely neglected. Cannaceae is one of the few families that possesses truly asymmetric flowers, serving as a model to study the characters and mechanisms involved in the development of floral asymmetry and its context within the developing and mature inflorescence. In this study, inflorescence structure and floral morphology of normal asymmetric flowers and 16 aberrant flower collections from Canna indica L. and C. glauca L. were photographed, analyzed, and compared with attention to stamen petaloidy, floral symmetry, and inflorescence branching patterns anterior and posterior to the aberrant flower. In comparison with normal flowers, the aberrant flowers are arranged into abnormal partial florescences, and vary in floral symmetry, orientation, and degree of androecial petaloidy. The appendage of the fertile stamen is universally located distal from the higher order bract, indicating an underlying influence of inflorescence architecture. A synthetic model is proposed to explain the relationship between floral symmetry and inflorescence structure. Data from the observation of aberrant phenotypes strongly support the hypothesis that irregular petaloidy of the stamens is correlated with an asymmetric morphogenetic field within the inflorescence that contributes to the overall floral asymmetry in Canna flowers.

The spatiotemporal regulations of epicatechin biosynthesis under normal flowering and the continuous inflorescence removal treatment in Fagopyrum dibotrys

BackgroundFlowering is a critical physiological change that interferes with not only biomass yield but also secondary metabolism, such as the biosynthesis of flavonoids, in rhizome/root plants. The continuous inflorescence removal (CIR) treatment is frequently conducted to weaken this effect. Fagopyrum dibotrys (D.Don) H.Hara (Golden buckwheat) is a kind of rhizome medicinal plant rich in flavonoids and is widely used for the treatment of lung diseases. The CIR treatment is usually conducted in F. dibotrys because of its excessive reproductive growth. To uncover the molecular mechanisms, comprehensive analysis was performed using metabolome and transcriptome data obtained from normally bloomed and the CIR treated plants.ResultsMetabolome results demonstrated that in the rhizomes of F. dibotrys, its bioactive compound called epicatechin has higher amount than most of the detected precursors. Compared with the normally bloomed plants, the level of epicatechin in the rhizomes of the CIR group increased by 25% at the withering stage. Based on 96 samples of the control and the CIR groups at 4 flowering stages for 4 tissues, RNA-Seq results revealed a 3 ~ 5 times upregulations of all the key enzyme genes involved in the biosynthesis of epicatechin in both time (from the bud stage to the withering stage) and spatial dimensions (from the top of branch to rhizome) under the CIR treatment compared to normal flowering. Integrated analysis of LC–MS/MS and transcriptome revealed the key roles of several key enzyme genes besides anthocyanidin reductase (ANR). A total of 93 transcription factors were identified to co-expressed with the genes in epicatechin biosynthetic pathway. The flowering activator SQUAMOSA promoter-binding protein like (SPLs) exhibited opposite spatiotemporal expression patterns to that of the epicatechin pathway genes; SPL3 could significantly co-express with all the key enzyme genes rather than the flowering repressor DELLA. Weighted gene co-expression network analysis (WGCNA) further confirmed the correlations among chalcone synthases (CHSs), chalcone isomerases (CHIs), ANRs, SPLs and other transcription factors.ConclusionsSPL3 might dominantly mediate the effect of normal flowering and the CIR treatment on the biosynthesis of epicatechin in rhizomes mainly through the negative regulations of its key enzyme genes including CHS, CHI and ANR.

Christolea pterosperma (Brassicaceae), a new species from Tibet (China)

During research in the late 1990s on the account of Brassicaceae for the flora of China (Zhou et al., 2001), the present author examined thousands of specimens from the major herbaria richest in Chinese plants, including A, B, BM, E, GH, IBSC, K, KUN, LE, NAS, P, PE, S, US, W, and WU. As a result, several novelties were described (e.g., Al-Shehbaz & Yang, 1998, 2000; Al-Shehbaz et al., 2000a–c). A few others were represented by incomplete material and remained undescribed with the hope of re-collecting them in southwestern and western China, including Sichuan and Yunnan provinces and Xinjiang and Xizang (Tibet) autonomous regions. Among such incomplete material is a collection by Victor Jacquemont from western Tibet [as India] with a few late-season aborted flowers. The plants are easily identified to the genus Christolea Cambessedes in Jacquemont (1844: 17, t. 17) using the Flora of China (Zhou et al., 2001) and Flora Pan-Himalaya (Al-Shehbaz, 2015). However, a close comparison of with the generic type, C. crassifolia Cambess., and the more recently recognized C. niyaensis An (1995: 376), shows that it differs from them in many significant ways (see below) that support its recognition as a novelty despite lacking normal flowers. Unfortunately, no additional collections of the species are known.

Characterization of Okra Species, Their Hybrids and Crossability Relationships among Abelmoschus Species of the Western Ghats Region

Wild relatives of okra represent a good source of variation for breeding programs, particularly for traits related to biotic and abiotic stresses and fruit quality. However, wild species remain largely unexploited for okra breeding. The cultivated okra accession Abelmoschus esculentus cv. ‘Arka Anamika’ was crossed with three wild accessions: Abelmoschus manihot, Abelmoschus ficulens and Abelmoschus moschatus. The crossability was estimated based on fruit set, seed set and germination rate. The results of cross compatibility studies revealed that the crosses are compatible only when cultivated A. esculentus is used as a female, and reciprocal crosses were not successful in any of the three wild species. Higher fruit set (87.2%) and seed germination (92%) were obtained from the crosses ‘Arka Anamika’ × Abelmoschus manihot. The interspecific F1s exhibited normal growth, flowering and fruit formation, but the hybrids were completely sterile on selfing due to abnormal meiosis. Characterization of the parents and interspecific hybrids revealed that the interspecific hybrids were generally more vigorous than the parents and displayed greater alliance towards their wild parent. The sterile F1s were further treated with 0.1% colchicine to restore fertility. The three interspecific crosses showed considerable differences in mean performance and heterosis over mid parent and better parent. The cross ‘A. Anamika’ × A. manihot displayed positive heterosis over mid parent and better parent for the yield traits, viz., fruit yield per plant, number of fruits per plant, number of primary branches per plant and plant height. The information obtained in the study on crossability relationship, phenotypic characterization and heterosis in interspecific hybrids will assist breeders in the development of prebreeding material.

Intraspecific variations in flowering phenology of African pear (Dacryodes edulis (g. Don) H.J. Lam) flowering in south east Nigeria

A survey was carried out in two states, six locations of south east Nigeria during the normal flowering period for three (3) consecutive years to evaluate the intraspecific variations in flowering phenology of African pear flowering. The different types of the species growing in the forest, distant and nearby farms, including homesteads were used. 60 trees and 180 flowered branches were sampled for the survey. Parameters collected include time for flowering, number of flower per inflorescence, inflorescence length and number of inflorescence per panicle. Data collected were analysed using analysis of variance, regression and correlation. Standard errors and percentages were calculated where appropriate. Based on the observed floral nature, three distinct African pear tree species were identified – female, male and hermaphrodite trees. The time of flowering varied within and between locations. This ranged from December to March 2013 to 2015 for the period of study. Strong positive relationship exist between inflorescence length and flower per inflorescence. Significant (p<0.05) differences were observed in mean flower per inflorescence and mean inflorescence per panicle in 2015 in Abia state. The mean inflorescence length, inflorescence per panicle and flower per inflorescence were statistically (p<0.05) the same for 2014 and 2015 in Imo State. These ranged from 14.79cm to 18.74cm,13.81cm to 18.60cm; 4.16 to 5.66; 5.75 to 6.61, 21.40 to 92.71 and 45.66 to 110.18 respectively.Inflorescence length and inflorescence per panicle were significantly (p<0.05) different in 2013in Imo State. In terms of the trees flowering circle, African pear can be seen as an annual since57% to 77% of the trees flower annually, while 23% to 43% flower biennially and triennially. Therefore the survey study discovered that there are variations in floral natures, inflorescence length, inflorescence per panicle, flowering circle, and time of flowering in African pear. This study will be useful for breeding purposes in African pear.

Insights Into the Molecular Mechanisms of Late Flowering in Prunus sibirica by Whole-Genome and Transcriptome Analyses.

Freezing during the flowering of Prunus sibirica is detrimental to fruit production. The late flowering (LF) type, which is delayed by 7–15 days compared with the normal flowering (NF) type, avoids damages at low temperature, but the molecular mechanism of LF remains unclear. Therefore, this study was conducted to comprehensively characterize floral bud differentiation. A histological analysis showed that initial floral bud differentiation was delayed in the LF type compared to the NF type. Genome-wide associated studies (GWAS) showed that a candidate gene (PaF106G0600023738.01) was significantly associated with LF type. It was identified as trehalose-6-phosphate phosphatase (PsTPPF), which is involved in trehalose-6-phosphate (Tre6P) signaling pathway and acts on floral transition. A whole-transcriptome RNA sequencing analysis was conducted, and a total of 6,110 differential expression (DE) mRNAs, 1,351 DE lncRNAs, and 148 DE miRNAs were identified. In addition, 24 DE mRNAs related with floral transition were predicted, and these involved the following: three interactions between DE lncRNAs and DE mRNAs of photoperiod pathway with two mRNAs (COP1, PaF106G0400018289.01 and CO3, MXLOC_025744) and three lncRNAs (CCLR, LTCONS_00031803, COCLR1, LTCONS_00046726, and COCLR2, LTCONS_00046731); one interaction between DE miRNAs and DE mRNAs with one mRNA, encoding trehalose-6-phosphate synthase (PsTPS1, PaF106G0100001132.01), and one miRNA (miRNA167h). Combined with the expression profiles and Tre6P levels, functions of PsTPPF and PsTPS1 in Tre6P regulation were considered to be associated with flowering time. A new network of ceRNAs correlated with LF was constructed, and it consisted of one mRNA (PsTPS1), one lncRNA (TCLR, LTCONS_00034157), and one miRNA (miR167h). This study provided insight into the molecular regulatory mechanism of LF in Prunus sibirica.

Global Lysine Acetylome Analysis of Flower bud Development in Catalpa bungei

Lysine acetylation, a reversible and dynamic post-translational modification, plays pivotal roles in regulating many biological processes in plants. However, the information of lysine acetylation during flower development of woody angiosperm remains unclear. Herein, we identified a total of 667 lysine acetylation sites in 467 proteins in flower buds of Catalpa Bungei. The acetylated proteins were mainly involved in the pathways of carbon metabolism, glycometabolism and oxidative phosphorylation. Using functional enrichment analysis, 61 and 13 acetylated proteins were involved in the glycometabolism and oxidative phosphorylation pathways, respectively. This suggests that lysine acetylated proteins play critical roles in the energy metabolism pathways. Accordingly, the protein–protein interactions were also highly enriched in the carbon metabolic pathway. Integrative analysis of lysine acetylome and transcriptome showed that transcript level changes of seven key lysine-acetylated proteins/genes involved in energy metabolism were significant different during floral transition. Importantly, compared with the normal flowering variety, the expression levels of phosphoribulokinase, phosphoenolpyruvate carboxykinase, ATP synthase and pyruvate dehydrogenase complex genes were significantly up-regulated at the stages of vegetative and transition buds during early flowering of C. bungei. These data represent the first lysine acetylome in the C. bungei flowers, and can serve as an essential basis for exploring the function of lysine acetylated proteins in the flower bud development of plants.

Microstructural observation on pistil abortion of ‘Li Guang’ apricot and transcriptome reveal the mechanism of endogenous hormones involved in pistil abortion

‘Li Guang’ apricot, a famous local variety, originated in Dunhuang city, Gansu Province, China. The fruit quality of 'Li Guang' apricot is excellent and It will generate greater financial returns. However, due to the change of natural environment and planting structure, pistil abortion has become an important factor affecting fruit setting rate, yield and quality. It seriously affects the economic benefits of this geographical indication product.The distribution and regulation of hormones play an important role in signal molecules of flower abortion. In order to elucidate the key molecular mechanism of apricot flower hormone abortion. Using normal and abortive buds as materials, the pistil abortion of apricot was observed, and the genes related to flowering regulation were identified by RNA sequencing. As compared with normal flowers, the pistil appearance of abortive flower is normal, but the ovary development is abnormal. Microstructure showed that the pollen grains of abortive flowers were decreased sharply, the ovaries shrunk and the ovule primordia developed stagnately. The hormone levels of ZR, IAA and CTK in abortive flowers decreased significantly. But the content of ABA and GA was significantly higher than normal flowers. Through RNA-Seq, it revealed that AUX1, TIR1, ARF, GH3 and SAUR, vital genes displayed identical differential expression profiles to auxin transduction pathway, and ABF, SnRK2, PP2C to abscisic acid, JAZ, MYC2 to jasmonic acid. Mutations in ARF, which encodes auxin response factor, can lead to serious defects in pistils. ARF promotes ovary formation mainly by inhibiting the expression of SPT in this domain. AG regulates early pistil development through CTK-AUXIN, and directly or indirectly affects these hormone pathways at different levels. Once the pistil begins to develop, SPT and ind connect CTK and AUXIN to realize the development of pistil structure. Other factors affecting hormone transport also showed apical and basal hyperplasia and ovary development.

Comparative transcriptome analysis identified important genes and regulatory pathways for flower color variation in Paphiopedilum hirsutissimum

BackgroundPaphiopedilum hirsutissimum is a member of Orchidaceae family that is famous for its ornamental value around the globe, it is vulnerable due to over-exploitation and was listed in Appendix I of the Convention on International Trade in Endangered Species of Wild Fauna and Flora, which prevents its trade across borders. Variation in flower color that gives rise to different flower patterns is a major trait contributing to its high ornamental value. However, the molecular mechanism underlying color formation in P. hirsutissimum still remains unexplored. In the present study, we exploited natural variation in petal and labellum color of Paphiopedilum plants and used comparative transcriptome analysis as well as pigment measurements to explore the important genes, metabolites and regulatory pathways linked to flower color variation in P. hirsutissimum.ResultWe observed that reduced anthocyanin and flavonoid contents along with slightly higher carotenoids are responsible for albino flower phenotype. Comparative transcriptome analysis identified 3287 differentially expressed genes (DEGs) among normal and albino labellum, and 3634 DEGs between normal and albino petals. Two genes encoding for flavanone 3-hydroxylase (F3H) and one gene encoding for chalcone synthase (CHS) were strongly downregulated in albino labellum and petals compared to normal flowers. As both F3H and CHS catalyze essentially important steps in anthocyanin biosynthesis pathway, downregulation of these genes is probably leading to albino flower phenotype via down-accumulation of anthocyanins. However, we observed the downregulation of major carotenoid biosynthesis genes including VDE, NCED and ABA2 which was inconsistent with the increased carotenoid accumulation in albino flowers, suggesting that carotenoid accumulation was probably controlled at post-transcriptional or translational level. In addition, we identified several key transcription factors (MYB73, MYB61, bHLH14, bHLH106, MADS-SOC1, AP2/ERF1, ERF26 and ERF87) that may regulate structural genes involved in flower color formation in P. hirsutissimum. Importantly, over-expression of some of these candidate TFs increased anthocyanin accumulation in tobacco leaves which provided important evidence for the role of these TFs in flower color formation probably via regulating key structural genes of the anthocyanin pathway.ConclusionThe genes identified here could be potential targets for breeding P. hirsutissimum with different flower color patterns by manipulating the anthocyanin and carotenoid biosynthesis pathways.

Analyzing a phenological anomaly in Yucca of the southwestern United States

Yucca in the American desert Southwest typically flowers in early spring, but a well-documented anomalous bloom event occurred during an unusually cold and wet late fall and early winter 2018–2019. We used community science photographs to generate flowering presence and absence data. We fit phenoclimatic models to determine which climate variables are explanatory for normal flowering, and then we tested if the same conditions that drive normal blooming also drove the anomalous blooming event. Flowering for Yucca brevifolia (Joshua tree) and Yucca schidigera (Mojave yucca) is driven by complex, nonlinear interactions between daylength, temperature, and precipitation. To our surprise, early-season flowering odds are highest in colder and drier conditions, especially for Joshua trees, but increase with precipitation late-season. However, the models used to fit normal blooming overpredicted the number of anomalous blooms compared to what was actually observed. Thus, predicting anomalous flowering events remains a challenge for quantitative phenological models. Because our model overpredicted the number of anomalous blooms, there are likely other factors, such as biotic interactions or other seasonal factors, which may be especially important in controlling what is presumed to be rare, out-of-season flowering in desert-adapted Yucca.

Global Survey of Alternative Splicing in Rice by Direct RNA Sequencing During Reproductive Development: Landscape and Genetic Regulation

Alternative splicing is a widespread phenomenon, which generates multiple isoforms of the gene product. Reproductive development is the key process for crop production. Although numerous forms of alternative splicing have been identified in model plants, large-scale study of alternative splicing dynamics during reproductive development in rice has not been conducted. Here, we investigated alternative splicing of reproductive development of young panicles (YP), unfertilized florets (UF) and fertilized florets (F) in rice using direct RNA sequencing, small RNA sequencing, and degradome sequencing. We identified a total of 35,317 alternative splicing (AS) events, among which 67.2% splicing events were identified as novel alternative splicing events. Intron retention (IR) was the most abundant alternative splicing subtype. Splicing factors that differentially expressed and alternatively spliced could result in global alternative splicing. Global analysis of miRNAs-targets prediction revealed that alternative spliced transcripts affected miRNAs’ targets during development. Degradome sequencing detected only 6.8% of the differentially alternative splicing transcripts, suggesting a productive transcripts generation during development. In addition, alternative splicing isoforms of Co-like, a transcription factor, interacted with Casein kinase 1-like protein HD1 (CKI) examined in luciferase assay, which could modulate normal male-floral organs development and flowering time. These results reveal that alternative splicing is intensely associated with developmental stages, and a high complexity of gene regulation.

RNAi Suppression of LEAFY Gives Stable Floral Sterility, and Reduced Growth Rate and Leaf Size, in Field-Grown Poplars

The central floral development gene LEAFY (LFY), whose mutation leads to striking changes in flowering and often sterility, is commonly expressed in non-floral structures; however, its role in vegetative development is poorly understood. Sterility associated with suppression of LFY expression is an attractive means for mitigating gene flow by both seeds and pollen in vegetatively propagated forest trees, but the consequences of its suppression for tree form and wood production are unclear. To study the vegetative effects of RNAi suppression of LFY, we created a randomized, multiple-year field study with 30–40 trees (ramets) in each of two sterile gene insertion events, three transgenic control events, and a wild-type control population. We found that floral knock-down phenotypes were stable across years and propagation cycles, but that several leaf morphology and productivity traits were statistically and often substantially different in sterile vs. normal flowering RNAi-LFY trees. Though trees with suppressed LEAFY expression looked visibly normal, they appear to have reduced growth and altered leaf traits. LFY appears to have a significant role in vegetative meristem development, and evaluation of vegetative impacts from LFY suppression would be prudent prior to large-scale use for genetic containment.

Cut Flower Characteristics and Growth Traits under Salt Stress in Lily Cultivars.

Salt stress is a major constraint of crop productivity because it reduces yield and limits the expansion of agriculture. This study investigated salt tolerance in 26 cultivars of cut lilies (Lilium hybrids) by examining the effect of salt stress on the growth and morphological characteristics of flowers and leaves and their physiological properties (chlorophyll a fluorescence). Salt stress significantly affected the growth and development of cut lilies. Canonical discriminant analysis indicates that the middle leaf width, number of flowers, first flower diameter, petal width, and chlorophyll a fluorescence were correlated with salt stress, whereas plant height, the middle leaf length, days to flowering, and sepal width were less affected by the stress. The cultivars examined were divided into three groups: Group 1 included the salt-sensitive cultivars, which failed to develop normal flowers; Group 2 included cultivars sensitive to salt stress but tolerant to osmotic stress; and Group 3 was the salt-tolerant group, which developed commercially valuable flowers. In conclusion, the cultivars contained a variable range of cut flower characteristics and growth traits that can be employed for lily breeding programs and as material for molecular mechanisms and signaling networks under salt stress.

Manipulation of Flowering Time to Mitigate High Temperature Stress in Rice (Oryza sativa L.)

Background: High temperature is an important abiotic stress affecting the productivity of rice. Early morning flowering trait is an escape mechanism from heat. This trait is present in wild rice cultivars. Here we tried to induce early morning flowering trait by the application of methyl jasmonate.Methods: A pot culture experiment was conducted during Rabi, 2017 and 2018 to study the effect of foliar application of methyl jasmonate on high temperature stress (more than 35°C) mitigation in rice was conducted in the Department of Plant Physiology, College of Agriculture, Vellayani during 2017-2019. The variety used was Uma (MO 16). Methyl jasmonate was applied as foliar spray to the spikelet in varying concentration with different time. Physiological observations were taken at 50% flowering stage and yield parameters were taken at harvest stage. Conclusion: There was significant variation for physiological and yield components among treatments. 4mM L-1 methyl jasmonate at 7am treatment exhibited increase in pollen viability, spikelet fertility percentage, yield per plant and 1000 grain weight. Hence, it is found that methyl jasmonate can advance anthesis time and thereby plants can escape from the severity of temperature experiencing at the normal flowering time in rice.

Inducible expression of human papillomavirus-16 L1 capsomeres in the plastomes of Nicotiana tabacum: Transplastomic plants develop normal flowers and pollen.

Human papillomavirus type-16 (HPV-16) is the major HPV type involved in causing cervical cancer among women. The disease burden is high in developing and underdeveloped countries. Previously, the constitutive expression of HPV-16 L1 protein led to male sterility in transplastomic tobacco plants. Here, the HPV-16 L1 gene was expressed in chloroplasts of Nicotiana tabacum under the control of an ethanol-inducible promoter, trans-activated by nucleus-derived signal peptide. Plants containing nuclear component were transformed with transformation vector pEXP-T7-L1 by biolistic gun. The transformation and homoplasmic status of transformed plants was verified by polymerase chain reaction and Southern blotting, respectively. Protein was induced by spraying 5% ethanol for 7 consecutive days. The correct folding of L1 protein was confirmed by antigen-capture ELISA using a conformation-specific antibody. The L1 protein accumulated up to 3μg/g of fresh plant material. The L1 protein was further purified using affinity chromatography. All transplastomic plants developed normal flowers and produced viable seeds upon self-pollination. Pollens also showed completely normal structure under light microscope and scanning electron microscopy. These data confirm the use of the inducible expression as plant-safe approach for expressing transgenes in plants, especially those genes that cause detrimental effects on plant growth and morphology.

RNAi-mediated repression of dormancy-related genes results in evergrowing apple trees

DORMANCY ASSOCIATED MADS-box (DAM) and SHORT VEGETATIVE PHASE (SVP) genes have been implicated in the regulation of winter dormancy in perennials. Ectopic expression of apple (Malus ×domestica 'Royal Gala') DAM and SVP genes delays budbreak and constrains lateral shoot outgrowth. In this study, we used RNAi interference (RNAi) to simultaneously target all apple DAM and SVP genes to study their role and mode of action in the regulation of bud dormancy, budbreak and flowering. A synthetic construct carrying a hairpin fragment assembled from sequences specific to coding regions of three DAM and two SVP genes was used to generate transgenic lines. Reduced expression of DAM/SVP genes resulted in delayed leaf senescence and abscission in autumn, failure to enter bud dormancy in winter, and continual growth of new leaves regardless of the season for over 3years. Precocious flowering but normal flower morphology, fertility and fruit development were observed. The non-dormant phenotype was associated with modified phytohormone composition. The content of gibberellins (GAs) and jasmonates (JAs) was significantly increased in terminal buds of RNAi lines compared to wildtype plants, accompanied by elevated expression of the key GA biosynthesis pathway gene GIBBERELLIN 20 OXIDASE-2 (MdGA20ox-2) along with the FLOWERING LOCUS T gene MdFT2. The key mediator of plasmodesmatal closure, MdCALLOSE SYNTHASE 1 (MdCALS1) was repressed in RNAi lines. This study provides functional evidence for the role of DAM/SVP genes in vegetative phenology of apple, and paves the way for production of low-chill varieties suitable for growth in warming climates.

수국의 꽃눈분화 발달과 환경 조절에 따른 개화시기 조절

<italic>Hydrangea macrophylla</italic> ‘Verena’ and ‘Moonstar’ were tested in the heated and the non-heated greenhouses to accelerate the flowering period. Compared to ‘Verena’ that have been continuously grown in the bare ground, ‘Verenas’ moved to the non-heated greenhouse have bloomed about a month earlier. Compared to the ‘Moonstar’ that has been left in the bare ground, the ‘Moonstar’ moved to the heated greenhouse, bloomed about two months earlier. Applying this, it seems that if the farmhouse installs a separate facility and warms it up, it will be able to help the farmhouse economy by harvesting flowers during the off-season. ‘Moonstar’ and ‘Moonlight’ grown in the heated greenhouse, where the conditions for flowering buds do not fit, were moved to the bare ground, the heated greenhouse, and the non-heated greenhouse, respectively. Although all individuals bloomed, deformed were shown in ‘Moonlight’ kept in the heated greenhouse, and deformed flower buds formed in ‘Moonlight’ moved to the bare ground. This was not a normal flower bud differentiation condition, so it appears that deformed flower buds were formed. Looking at the results of differentiation between ‘Moonstar’ and ‘Moonlight’, it is expected that ‘Moonlight’ has a slower flowering period than ‘Moonstar’ due to the nature of the species.

Phenotypic plasticity in resource allocation to sexual trait of alligatorweed in wetland and terrestrial habitats

Environmental heterogeneity in resource availability affects invasive plant reproductive strategies and resource allocation to reproduction. Here, we conducted two field surveys to examine the effect of wetland and terrestrial habitats on inflorescence production and resource allocation to inflorescence of the amphibious invasive plant Alternanthera philoxeroides in its invasive range (China). We also specifically examined the effects of water availability, fertilizer application, and plant density (space) in a greenhouse experiment. In field surveys, inflorescence biomass, normal monoclinous flowers and ratio of inflorescences to shoots of plants from wetlands were about 2.4-, 0.8- and 1.3-fold higher than those from terrestrial habitats, respectively. In greenhouse experiment, plants with higher fertilizer application and lower competition conditions produced more inflorescences, and had a lower ratio of roots to shoots and a comparable ratio of inflorescences to shoot and root. Furthermore, water availability had a significant interactive effect when combined with fertilizer level or plant density on inflorescence production and resource allocation. Together, our results indicate that high resources, such as those found in wetland habitats, favor both vegetative growth and sexual trait in A. philoxeroides. However, in terrestrial habitats where resources are relatively poor, the invader can adapt to the environment by allocating more resources to vegetative growth for clonal reproduction and less resources for sexual trait. This phenotypic plasticity in resource allocation likely facilitates the plant to invade heterogeneous wetlands and terrestrial environments.