Root colonization by the endophytic fungus Piriformospora indica shortens the juvenile phase of Piper nigrum L. by fine tuning the floral promotion pathways.

Piriformospora indica, the mutualistic biotrophic root colonizing endosymbiotic fungus belonging to the order Sebacinales, offers host plants various benefits and enhances its growth and performance. The effect of colonization of P. indica in Piper nigrum L. cv. Panniyur1 on growth advantages, floral induction and evocation was investigated. Growth and yield benefits are credited to the alteration in the phytohormone levels fine-tuned by plants in response to the fungal colonization and perpetuation. The remarkable upregulation in the phytohormone levels, as estimated by LC- MS/MS and quantified by qRT-PCR, revealed the effectual contribution by the endophyte. qRT-PCR results revealed a significant shift in the expression of putative flowering regulatory genes in the photoperiod induction pathway (FLOWERING LOCUS T, LEAFY, APETALA1, AGAMOUS, SUPPRESSOR OF CONSTANS 1, GIGANTEA, PHYTOCHROMEA, and CRYPTOCHROME1) gibberellin biosynthetic pathway genes (GIBBERELLIN 20-OXIDASE2, GIBBERELLIN 2-OXIDASE, DELLA PROTEIN REPRESSOR OF GA1-3 1) autonomous (FLOWERING LOCUS C, FLOWERING LOCUS VE, FLOWERING LOCUS CA), and age pathway (SQUAMOSA PROMOTER LIKE9, APETALA2). The endophytic colonization had no effect on vernalization (FLOWERING LOCUS C) or biotic stress pathways (SALICYLIC ACID INDUCTION DEFICIENT 2, WRKY family transcription factor 22). The data suggest that P. nigrum responds positively to P. indica colonization, affecting preponement in floral induction as well as evocation, and thereby shortening the juvenile phase of the crop.

De novo sequencing of tree peony (Paeonia suffruticosa) transcriptome to identify critical genes involved in flowering and floral organ development.

BACKGROUND: Tree peony (Paeonia suffruticosa Andrews) is a globally famous ornamental flower, with large and colorful flowers and abundant flower types. However, a relatively short and uniform flowering period hinders the applications and production of ornamental tree peony. Unfortunately, the molecular mechanism of regulating flowering time and floral organ development in tree peony has yet to be elucidated. Because of the absence of genomic information, 454-based transcriptome sequence technology for de novo transcriptomics was used to identify the critical flowering genes using re-blooming, non-re-blooming, and wild species of tree peonies. RESULTS: A total of 29,275 unigenes were obtained from the bud transcriptome, with an N50 of 776 bp. The average length of unigenes was 677.18 bp, and the longest sequence was 5815 bp. Functional annotation showed that 22,823, 17,321, 13,312, 20,041, and 9940 unigenes were annotated by NCBI-NR, Swiss-Prot, COG, GO, and KEGG, respectively. Within the differentially expressed genes (DEGs) 64 flowering-related genes were identified and some important flowering genes were also characterized by bioinformatics methods, reverse transcript polymerase chain reaction (RT-PCR), and rapid-amplification of cDNA ends (RACE). Then, the putative genetic network of flowering induction pathways and a floral organ development model were put forward, according to the comparisons of DEGs in any two samples and expression levels of the important flowering genes in differentiated buds, buds from different developmental stages, and with GA or vernalization treated. In tree peony, five pathways (long day, vernalization, autonomous, age, and gibberellin) regulated flowering, and the floral organ development followed an ABCE model. Moreover, it was also found that the genes PsAP1, PsCOL1, PsCRY1, PsCRY2, PsFT, PsLFY, PsLHY, PsGI, PsSOC1, and PsVIN3 probably regulated re-blooming of tree peony. CONCLUSION: This study provides a comprehensive report on the flowering-related genes in tree peony for the first time and investigated the expression levels of the critical flowering related genes in buds of different cultivars, developmental stages, differentiated primordium, and flower parts. These results could provide valuable insights into the molecular mechanisms of flowering time regulation and floral organ development.

Grafting as a strategy to increase flowering of cassava.

In cassava (Manihot esculenta Crantz), transferring genes via genetic breeding depends on crosses between contrasting progenitors, which is often limited by the low flowering rate of many genotypes. The main purpose of this work was to evaluate the effect of grafting on floral induction of cassava. For this, three genotypes were used: 1) BRS Formosa: a genotype with low flowering rate; 2) BGM0823: a genotype with high flowering rate; and 3) FLA05-02: a genotype of M. esculenta ssp. flabellifolia with high flowering rate. Cleft grafting was performed to generate the following treatments: Self-grafting of: 1) BGM0823 (Self-0823); 2) BRS Formosa (Self-Formosa); and 3) FLA05-02 (Self-FLA); and grafting of the genotypes, with the first being the scion and the second the rootstock: 4) BGM0823 × BRS Formosa; 5) BGM0823 × FLA05-02; 6) FLA05-02 × BRS Formosa; 7) FLA05-02 × BGM0823; 8) BRS Formosa × BGM0823; 9) BRS Formosa × FLA05-02; and also ungrafted treatments: 10) BGM0823; 11) BRS Formosa; and 12) FLA05-02. The results showed a 201% increase in the production of male flowers, 560% of female flowers and 400% of fruits in BRS Formosa grafted on BGM0823. BGM0823 (rootstock) also increased fruit production by 190% of FLA05-02. The grafted cassava plants exhibited an increase on the shoot production, although there was no change in the fresh root yield. The grafting of genotypes with high flowering rates can induce flowering in genotypes with low flowering rates.

Cys2/His2 Zinc-Finger Proteins in Transcriptional Regulation of Flower Development.

Flower development is the core of higher-plant ontogenesis and is controlled by complex gene regulatory networks. Cys2/His2 zinc-finger proteins (C2H2-ZFPs) constitute one of the largest transcription factor families and are highly involved in transcriptional regulation of flowering induction, floral organ morphogenesis, and pollen and pistil maturation. Nevertheless, the molecular mechanism of C2H2-ZFPs has been gradually revealed only in recent years. During flowering induction, C2H2-ZFPs can modify the chromatin of FLOWERING LOCUS C, thereby providing additional insights into the quantification of transcriptional regulation caused by chromatin regulation. C2H2-ZFPs are involved in cell division and proliferation in floral organ development and are associated with hormonal regulation, thereby revealing how a flower is partitioned into four developmentally distinct whorls. The studies reviewed in this work integrate the information from the endogenous, hormonal, and environmental regulation of flower development. The structure of C2H2-ZFPs determines their function as transcriptional regulators. The findings indicate that C2H2-ZFPs play a crucial role in flower development. In this review, we summarize the current understanding of the structure, expression, and function of C2H2-ZFPs and discuss their molecular mechanism in flower development.

Experimental evidence of warming-induced flowering in the Mediterranean seagrass Posidonia oceanica.

Sexual reproduction in predominantly clonal marine plants increases recombination favoring adaptation and enhancing species resilience to environmental change. Recent studies of the seagrass Posidonia oceanica suggest that flowering intensity and frequency are correlated with warming events associated with global climate change, but these studies have been observational without direct experimental support. We used controlled experiments to test if warming can effectively trigger flowering in P. oceanica. A six-week heat wave was simulated under laboratory mesocosm conditions. Heating negatively impacted leaf growth rates, but by the end of the experiment most of the heated plants flowered, while controls plants did not. Heated and control plants were not genetically distinct and flowering intensity was significantly correlated with allelic richness and heterozygosity. This is an unprecedented finding, showing that the response of seagrasses to warming will be more plastic, more complex and potentially more resilient than previously imagined.

Flowering of Woody Bamboo in Tissue Culture Systems.

Flowering and subsequent seed set are not only normal activities in the life of most plants, but constitute the very reason for their existence. Woody bamboos can take a long time to flower, even over 100 years. This makes it difficult to breed bamboo, since flowering time cannot be predicted and passing through each generation takes too long. Another unique characteristic of woody bamboo is that a bamboo stand will often flower synchronously, both disrupting the supply chain within the bamboo industry and affecting local ecology. Therefore, an understanding of the mechanism that initiates bamboo flowering is important not only for biology research, but also for the bamboo industry. Induction of flowering in vitro is an effective way to both shorten the flowering period and control the flowering time, and has been shown for several species of bamboo. The use of controlled tissue culture systems allows investigation into the mechanism of bamboo flowering and facilitates selective breeding. Here, after a brief introduction of flowering in bamboo, we review the research on in vitro flowering of bamboo, including our current understanding of the effects of plant growth regulators and medium components on flower induction and how in vitro bamboo flowers can be used in research.

Analysis of global gene expression profiles during the flowering initiation process of Lilium × formolongi.

The onset of flowering is critical for the reproductive development of plants. Lilium × formolongi is a lily hybrid that flowers within a year after sowing. We successfully identified four important stages during vegetative growth and flowering initiation of L. × formolongi under long day conditions. The plant tissues from the four stages were used in a genome-wide transcriptional analysis to investigate stage-specific changes of gene expression in L. × formolongi. In total, the sequence reads of the four RNA-sequencing libraries were assembled into 52,824 unigenes, of which 37,031 (70.10%) were differentially expressed. The global expression dynamics of the differentially expressed genes were predominant in flowering induction phase I and the floral differentiation stage, but down-regulated in flowering induction phase II. Various transcription factor families relevant to flowering were elucidated, and the members of the MADS-box, SBP and CO-like transcription factor families were the most represented. There were 85 differentially expressed genes relevant to flowering. CONSTANS-LIKE, FLOWERING LOCUS T, TREHALOSE-6-PHOSPHATE SYNTHASE and SQUAMOSA PROMOTER BINDING PROTEIN-LIKE homologs were discovered and may play significant roles in the flowering induction and transition process of L. × formolongi. A putative gene regulatory network, including photoperiod, age-dependent and trehalose-6-phosphate flowering pathways, was constructed. This is the first expression dataset obtained from a transcriptome analysis of photoperiod-mediated flowering pathway in lily, and it is valuable for the exploration of the molecular mechanisms of flowering initiation and the short vegetative stage of L. × formolongi.

Adventitious rooting declines with the vegetative to reproductive switch and involves a changed auxin homeostasis.

Adventitious rooting, whereby roots form from non-root tissues, is critical to the forestry and horticultural industries that depend on propagating plants from cuttings. A major problem is that age of the tissue affects the ability of the cutting to form adventitious roots. Here, a model system has been developed using Pisum sativum to differentiate between different interpretations of ageing. It is shown that the decline in adventitious rooting is linked to the ontogenetic switch from vegetative to floral and is mainly attributed to the cutting base. Using rms mutants it is demonstrated that the decline is not a result of increased strigolactones inhibiting adventitious root formation. Monitoring endogenous levels of a range of other hormones including a range of cytokinins in the rooting zone revealed that a peak in jasmonic acid is delayed in cuttings from floral plants. Additionally, there is an early peak in indole-3-acetic acid levels 6h post excision in cuttings from vegetative plants, which is absent in cuttings from floral plants. These results were confirmed using DR5:GUS expression. Exogenous supplementation of young cuttings with either jasmonic acid or indole-3-acetic acid promoted adventitious rooting, but neither of these hormones was able to promote adventitious rooting in mature cuttings. DR5:GUS expression was observed to increase in juvenile cuttings with increasing auxin treatment but not in the mature cuttings. Therefore, it seems the vegetative to floral ontogenetic switch involves an alteration in the tissue's auxin homeostasis that significantly reduces the indole-3-acetic acid pool and ultimately results in a decline in adventitious root formation.

Evidence of genetic change in the flowering phenology of sea beets along a latitudinal cline within two decades.

Sea beets grown from seeds collected in 1989 and 2009 along the coasts of France and adjacent regions were compared for flowering date under controlled conditions. Seeds from both collection years were sown simultaneously and cultivated under the same glasshouse conditions. Date of flowering onset and year of first flowering were recorded. There was an overall northward shift in flowering time of about 0.35° latitude (i.e. 39 km) over the 20-year period. The southern portion of the latitudinal gradient--that is, from 44.7°N to 47.28°N--flowered significantly later by a mean of 1.78 days, equivalent to a 43.2-km northward shift of phenotypes. In the northern latitudes between 48.6°N and 52°N, flowering date was significantly earlier by a mean of 4.04 days, corresponding to a mean northward shift of 104.9 km, and this shift was apparently due to a diminished requirement of exposure to cold temperatures (i.e. vernalization), for which we found direct and indirect evidence. As all plants were grown from seed under identical conditions, we conclude that genetic changes occurred in the sensitivity to environmental cues that mediate the onset of flowering in both the northern and the southern latitudes of the gradient. Microevolution and gene flow may have contributed to this change. There was no significant change in the frequency of plants that flowered without vernalization. The lack of vernalization requirement may be associated with environmental instability rather than with climate conditions.

Análise química da folha "D" de abacaxizeiro cv. Smooth Cayenne antes e após a indução floral em função de doses e parcelamentos de nitrogênio / Chemical analysis of " D " leaf of cv. Smooth Cayenne pineaple before and after the flowering induction as a function of doses and splitting of nitrogen

A cultura do abacaxi é exigente em fertilidade do solo, neste sentido a realização da análise química da folha "D" é muito importante para verificar o seu estado nutricional. O objetivo deste trabalho foi avaliar os teores foliares nutricionais antes e após a indução floral em abacaxizeiro Smooth Cayenne, submetidos a doses e parcelamentos de nitrogênio. O delineamento experimental adotado foi de blocos ao acaso com quatro repetições. Para a 1ª época de análise apenas o efeito de dose foi analisado, já para a 2ª época de análise, foram avaliados dezesseis tratamentos em um esquema fatorial 4x4 (doses e parcelamentos de N). A aplicação de nitrogênio antes da indução floral seja de maneira parcelada ou não proporcionou maiores comprimentos, diâmetros e teores de N, K e S nas folhas 'D', e consequentemente uma maior produtividade de frutos. No entanto a aplicação do N, 2/3 antes e 1/3 após a indução floral superou a produção de frutos em 2 t ha-1, comparada a aplicação total de N antes da indução floral, cabendo ao produtor analisar se o parcelamento seria rentável ou não. O incremento das doses de N proporcionou decréscimo apenas para os teores foliares de K antes e após a indução floral, para os outros macronutrientes houve ajuste de equações do tipo linear positiva e/ou quadrática.

The pineapple plant is demanding in soil fertility, so the accomplishment of chemical analysis of "D" leaf is very important to verify its nutritional state. The objective of this work was to evaluate the leaf nutrient content before and after the flowering induction in pineapple cv. Smooth Cayenne, submitted to doses and splitting of nitrogen. A randomized completely blocks design in four repetitions was used. To first analysis time only the dose effect was just analyzed, already to second analysis time, they were appraised sixteen treatments in a factorial scheme 4x4 (doses and splitting of N). The application of nitrogen before of flowering induction parceled or non increase length, diameter and contents of N, K and S in the leaves "D", presenting positive reflexes in the productivity of the fruits. However the application of N, 2/3 before and 1/3 after of flowering induction exceed the fruit production in 2 t ha -1, comparing tothe application of all the dose of N before of flowering induction, belong the producer analyze of the profitability of parceled or not the nitrogen fertilization. The increment on nitrogen doses provided decreasing on K leaf content before and after of flowering induction, for the other macronutrients were fitted to positive linear and/or quadratic equations.

Florescimento em cana-de-açúcar / Flowering in sugarcane

O florescimento da cana-de-açúcar é um processo fisiológico complexo formado por vários estádios de desenvolvimento, e cada estádio tem a sua própria necessidade ambiental e fisiológica. Os fatores externos relacionados com o florescimento são: fotoperíodo, temperatura, umidade e radiação solar, além da fertilidade do solo. Por outro lado, os fatores internos envolvem fitocromo, hormônios, florígeno, ácidos nucleicos, dentre outros. A intensidade do processo de florescimento e as consequências na qualidade da cana-de-açúcar variam com a variedade e com o clima. A redução do volume de caldo é o principal fator no qual o florescimento interfere, resultante do aumento do teor de fibras. Como as demais Poaceae, a cana-de-açúcar floresce, frutifica e morre, garantindo a perpetuação da espécie. Dessa forma, o homem procura interferir na natureza tentando evitar o florescimento da cana-de-açúcar, seja por meio de melhoramento genético ou por meio de reguladores vegetais. Em áreas comerciais de produção de cana-de-açúcar, onde há condições ideais para o florescimento da cultura, é recomendado o uso de variedade com potencial menos florífero. E, quando não é possível esse manejo varietal, o uso de inibidores do florescimento é a melhor alternativa para evitar mais perdas no conteúdo de sacarose.

The sugarcane flowering is a complex physiological process that consists of several stages of development, each stage has its physiological and environmental requisition. The external factors related to flowering are: photoperiod, temperature, humidity, solar radiation in addition to soil fertility. Already the internal factors involved are: phytochrome, hormones, florigene, nucleic acids, among others. The intensity of the flowering and the consequences on the quality of sugarcane vary with the variety and the climate. The reduction of the sugarcane juice is the main factor which affected by the flowering, resulting from due to the increased fiber content. As other Poaceae, the sugarcane flowers, fruit and dies, ensuring the perpetuation of the species. Thus, the man tries to interfere in nature, trying to prevent the flowering sugarcane, either through breeding or through plant growth regulators. In areas of sugarcane commercial production, where there are ideal conditions for the flowering culture, it is recommended the se of variety with lower potential of flowering. And when this varietal management is more difficult, the use of inhibitors of flowering is the best alternative to avoid more losses of sucrose content.

Effects of paclbbutrazol and kno3 over flowerin and fruit quality in two cultiivars of mango manila / Efecto del pclobbutrazol y kno3 sobre la floración y calidadde fruto en doss cultivares de mangomaanila / Efeit do paclobuutrazol e kno3 sobre a floração e qualidade de fruto em dois cultivares de manga manila

Different doses of Paclobutrazol (PBZ) combined with KNO3 were evaluated in order to determine their effect on flowering and fruit quality on two mango clones. The experiment was carried out at the INIFAP’s Cotaxtla Experimental Station in Veracruz, Mexico. A 14-year old orchard of Manila Cotaxtla 1 and Manila Cotaxtla 2 clones planted in 8×8m plots without irrigation was used. The experimental design was of random blocks in split plots. The eight treatments applied were: a) 0.0, b) 0.5, c) 1.0, d) 1.5, e) 2.0g a.i. PBZ per meter of canopy diameter, all combined with the application of 2% KNO3, f) 4% KNO3 without PBZ, g) 1.5g. a.i. PBZ, without KNO3, and h) control with neither product added. PBZ was applied on the soil and KNO3 in two applications on the foliage. The variables considered were number of panicles, fruit weight, fruit weight loss, total soluble solids (TSS), titratable acidity (TA) and firmness. PBZ and KNO3 application induced a larger number of advanced panicles in relation to the control, with higher values observed as PBZ dose increased. However, in total flowering there was no significant difference between treatments (p<0.05). PBZ did not have negative effects in the quality of fruit of neither cultivar. The treatments with higher doses of PBZ had higher content of TSS, less TA, less firmness and greater weight loss. Both cultivars were different in TA of the ripe fruits.

Se evaluaron diferentes dosis de paclobutrazol (PBZ) combinadas con KNO3 para determinar su efecto sobre floración y calidad de fruta en los clones de mango Manila Cotaxtla-1 y Manila Cotaxtla-2. El experimento fue realizado en el Campo Experimental Cotaxtla del INIFAP, en Veracruz, México. Ambos clones, de 14 años de edad, fueron plantados a 8×8m, sin riego. El diseño experimental utilizado fue de bloques al azar en parcelas divididas. Se aplicaron ocho tratamientos: a) 0,0; b) 0,5; c) 1,0; d) 1,5; y e) 2,0g i.a. por metro de diámetro de copa de PBZ, todos junto con aplicación de KNO3 al 2%; f) 4% KNO3 sin PBZ; g) 1,5g i.a. PBZ sin KNO3; y h) testigo sin PBZ ni KNO3. El PBZ fue aplicado al suelo y el KNO3 al follaje en dos aplicaciones. Las variables consideradas fueron número de panículas, peso de fruto, pérdida de peso del fruto, sólidos solubles totales (SST), acidez titulable (AT) y firmeza. La aplicación de PBZ y KNO3 promovió mayor número de panículas adelantadas con relación al testigo, con mayores valores al incrementar la dosis de PBZ; aunque en floración total no hubo diferencia significativa entre tratamientos (p<0,05). Los niveles de PBZ no tuvieron efecto negativo en la calidad de fruto en ambos cultivares. A mayor dosis de PBZ, hubo mayor contenido de SST, menor AT, menor firmeza y mayor pérdida de peso. Los cultivares mostraron diferencias en AT de los frutos maduros para consumo.

Avaliaram-se diferentes doses de paclobutrazol (PBZ) combinadas com KNO3 para determinar seu efeito sobre floração e qualidade de fruta nos clones de manga Manila Cotaxtla-1 e Manila Cotaxtla-2. O experimento foi realizado no Campo Experimental Cotaxtla do INIFAP, em Veracruz, México. Ambos os clones, de 14 anos de idade, foram plantados a 8×8m, sem regar. O desenho experimental utilizado foi de blocos aleatórios em parcelas divididas. Aplicaram-se oito tratamentos: a) 0,0; b) 0,5; c) 1,0; d) 1,5; e e) 2,0g i.a. por metro de diâmetro de copa de PBZ, todos junto com aplicação de KNO3 a 2%; f) 4% KNO3 sem PBZ; g) 1,5g i.a. PBZ sem KNO3; e h) testemunha sem PBZ nem KNO3. O PBZ foi aplicado ao solo e o KNO3 na folhagem em duas aplicações. As variáveis consideradas foram; número de panículas, peso do fruto, perda de peso do fruto, sólidos solúveis totais (SST), acidez titulável (AT) e firmeza. A aplicação de PBZ e KNO3 promoveu maior número de panículas adiantadas em relação à testemunha, com maiores valores ao incrementar a dose de PBZ; embora em floração total não houvesse diferença significativa entre tratamentos (p<0,05). Os níveis de PBZ não tiveram efeito negativo na qualidade do fruto em ambos os cultivares. Com maior dose de PBZ, houve maior conteúdo de SST, menor AT, menor firmeza e maior perda de peso. Os cultivares mostraram diferenças em AT dos frutos maduros para consumo.

Leaf carbohydrate status in Lolium temulentum during the induction of flowering.

Unifoliated plants of Lolium temulentum L. ev. Ceres, a qualitative long-day grass, were induced to flower by one 24-h long day (LD) or by one 8-h short day (SD) advanced by 1 2 h in the normal regime, so-called 'displaced short day' (DSD). Standard light for SD and DSD was a mixture of fluorescence and incandescence at 400 µmol m-2 s-1 whereas the extension period of the 24-h LD was solely incandescence at 10-15 µmol m-2 s-1 . The DSD system was first characterized by the timings of floral induction, stimulus translocation and apical development. Carbohydrates in the blade tissues and in leaf exudate were analysed comparatively in vegetative and induced plants. Fructans were not detected in the leaf tissues whereas sucrose and starch were found to be present in similar amounts. In SD, their contents exhibited a diurnal fluctuation and were not in large excess. The common change observed during the two inductive treatments was that starch remained at a high level during the LD extension, even though the lighting was unsuitable for photosynthesis, and increased transiently in DSD. Sucrose was the major sugar contained in the leaf exudate. Its content increased when flowering was induced, but not at the same time in the two systems. In LD, sucrose exudation rose when plants were returned to standard light after the inductive cycle, i.e. after the LD stimulus had left the leaf blade. By contrast, during the DSD, sucrose was transported at the same time as the floral stimulus. Results are discussed together with the methods used to time stimulus translocation and their implications.

The influence of photoperiod on incorporation of precursors into tocopherols and plastoquinone in Xanthium strumarium L.

Radioactivity from tyrosine applied to leaves of Xanthium strumarium L. was incorporated into α- and γ-tocopherol and plastoquinone. Time-course studies on vegetative plants showed that γ-tocopherol was rapidly labelled and turned over, while α-tocopherol showed no sign of turnover. The same pattern was observed in the light and in darkness. Plastoquinone synthesis was rapid in the light but it was greatly reduced in the dark. Following floral induction the accumulation of radioactivity in γ-tocopherol was at first slower, but it later readied higher levels than in the vegetative plants. Total incorporation into α-tocopherol and plastoquinone was greatly reduced.