Increase In Number Of Flowers Research Articles

A SEPALLATA MADS-Box Transcription Factor, SlMBP21, Functions as a Negative Regulator of Flower Number and Fruit Yields in Tomato.

MADS-box transcription factors act as the crucial regulators in plant organ differentiation. Crop yields are highly influenced by the flower number and fruit growth. However, flower identification is a very complex biological process, which involves many cascade regulations. The molecular mechanisms underlying the genetic regulation of flower identification in cultivated plants, such as tomato, are intricate and require further exploration. In this study, we investigated the vital function of a SEPALLATA (SEP) MADS-box gene, SlMBP21, in tomato sympodial inflorescence meristem (SIM) development for the conversion from SIMs to floral meristems (FMs). SlMBP21 transcripts were primarily accumulated in young inflorescence meristem, flowers, sepals, and abscission zones. The Ailsa Craig (AC++) tomato plants with suppressed SlMBP21 mRNA levels using RNAi exhibited a large increase in flower number and fruit yields in addition to enlarged sepals and inhibited abscission zone development. Scanning electron microscopy (SEM) revealed that the maturation of inflorescence meristems (IMs) was repressed in SlMBP21-RNAi lines. RNA-seq and qRT-PCR analyses showed that numerous genes related to the flower development, plant hormone signal transduction, cell cycle, and cell proliferation et al. were dramatically changed in SlMBP21-RNAi lines. Yeast two-hybrid assay exhibited that SlMBP21 can respectively interact with SlCMB1, SFT, JOINTLESS, and MC, which play key roles in inflorescence meristems or FM development. In summary, our data demonstrate that SlMBP21 functions as a key regulator in SIM development and the conversion from SIMs to FMs, through interacting with other regulatory proteins to control the expression of related genes.

Elucidating the flower, seed yield and phytochemical variability of marigold (Calendula officinalis L.) in response to winter sowing at different harvest intervals and dates

Marigold is a plant native to the Mediterranean region, belonging to the Asteraceae family, and has been cultivated as a medicinal and ornamental plant all over the world for centuries. Due to its long flowering period, it is important to determine the appropriate harvest interval and date. This study was performed in the Research Area of Çukurova University in the 2019–2020 and 2020–2021 growing seasons, with an aim to investigate the influence of different harvest intervals (4-, 8-, and 12-day harvest intervals for the flowers) and harvest dates (8-day interval for the seeds) on the flower and seed yield and quality traits of marigold. The highest total flower yield (7519.8 kg/ha; harvest at 4-day intervals) and seed yield (595.6 kg/ha; 1st harvest) were obtained in the 1st growing season. The highest seed fixed oil ratio (12.86 %) was obtained in June, and the highest flower essential oil ratio (0.18 %) was obtained in May. Of the 38 components in the essential oil, α-Cadinol (22.59 %–30.10 %), δ-Cadinene (9.88 %–13.79 %), τ-Muurolol (6.58 %–8.20 %), γ-Cadinene (4.80 %–7.15 %), and γ-Muurolene (4.15 %–4.82 %) were determined as the main components. Six fatty acids were detected in the fixed oil and the main components were determined as α-calendic acid (22.07 %–49.41 %), linoleic acid (28.31 %–37.85 %), and oleic acid (7.18 %–30.06 %). The highest α-calendic acid ratios were detected in June and decreased as the harvests were delayed. Consequently, the application of harvesting at 4-day intervals for increased flower number and harvesting seeds early due to the high α-calendic acid rate can be considered as a feasible approach.

Deficit irrigation strategies (PRD, SDI) and titanium nanoparticles improve water use efficiency and flower quality in greenhouse-grown cut roses

This study explored the use of deficit irrigation techniques for water management in the hydroponic greenhouse cultivation of cut roses. A factorial experiment was conducted using three irrigation treatments: full irrigation (FI), partial root drying (PRD), and sustained deficit irrigation (SDI), and three doses of titanium dioxide nanoparticle foliar application (0, 15, and 30 ppm) as stress alleviation. Results showed that drought stress increased biochemical parameters such as the plants' proline and total phenol content. Compared to SDI treatment, the PRD treatments have an increase in flower number by 40%. The PRD strategy has positive effects on drought tolerance by increasing osmotic and elastic adjustment. Therefore, higher relative water content and longer root length in PRD treatments were observed. Thus, Biomass water use efficiency significantly increased in PRD treatments compared to others. In the PRD treatment, yield WUE increases by 26% and 61% compared to FI and SDI, respectively. The results showed TiO2-NPs positively affected mitigating and even improving some traits in drought stress conditions. These results suggest the superiority of the PRD strategy, which improves growth characteristics and water use efficiency, leading to increased sustainability, reduced environmental impact of greenhouse toxic wastewater, and total profitability of the greenhouse.

Efficient Utilization of Agro-industrial Waste through Vermicomposting and its Impact on Growth and Yield of Brinjal (Solanum melongena L.)

Background: Application of vermicompost produced from diverse organic wastes could be one of the most economical and attractive methods of solving waste disposal problem and increasing the nutrient contents of soil simultaneously. Vermicompost is used as an organic fertilizer, the effects of vermicompost obtained from different organic wastes on plant growth and yield. Methods: The vermicomposting of sugarcane trash and bagasse waste was carried out during (January-March) and by using the vermicompost a field culture experiment was conducted in brinjal for three months from April-June, 2019. There are 6 treatments namely T1-T6 and control. Vegetative parameters such as shoot length, root length, number of leaves, fresh weight, and dry weight at different stages (30, 60 and 90 DAS), number of flowers and number of branches on 60 and 90 DAS. On 90th day yield characters like number of fruits, diameter of fruits, fruit length, single fruit weight, fruit yield per plant and fruit yield per plot were analyzed. Results: A significant increase in shoot length (32.9, 55.3 and 98.5), root length (17.85, 25.10 and 33.30), number of leaves (21.33, 50.00 and 77.00), fresh weight (31.10, 48.30 and 55.55) and dry weight (7.10, 7.95 and 9.30) was observed in T5 - C5 (Predecomposted Sugarcane bagasse, Trichoderma asperelloids and earthworm (Eudrilus eugeniae) 5t/h) treatment, followed by T2 - C2 (Predecomposted Sugarcane trash, Trichoderma asperelloids and earthworm (Eudrilus eugeniae) 5t/h) treatment on 30, 60 and 90 DAS. A significant increase in number of flowers (27.50 and 55.50) and number of branches (22.50 and 27.50) was observed in T5 treatment followed by other treatments on 60 and 90 DAS. The maximum amount in number of fruits (22.00), fruit length (15.70), single fruit weight (93.15), fruit yield per plant (10.35) and fruit yield per plot (37.25) were noted in T5 treatment, followed by T2 treatment on 90 DAS and minimum amount were reported in control (soil). The results of the study clearly indicated that treatment T5 significantly increased the vegetative parameters and yield characters in brinjal.

Effect of Composted Sugarcane Trash and Bagasse on the Growth and Yield of Tomato (Solanum lycopersicum L.)

Background: Organic farming proves many advantages for recycling regenerates the waste matter into wealth and can wipe out the use of chemical fertilizers and pesticides. Sustainable agriculture can be ensured in future with the help of organic farming which includes various processes of biological origin such as compost and vermicompost. Methods: The study was conducted at Alanthurai, Coimbatore, Tamil Nadu. Agro-industrial waste of sugarcane trash and bagasse were collected and were used for biocomposting process using Pleurotus florida, Trichoderma asperelloides, microbial consortium and Eudrillus eugeniae. Six different treatments were incorporated in the present study. Vegetative parameters such as shoot length, root length, number of leaves, fresh weight and dry weight at different stages (30, 60 and 90 DAS), number of flowers and number of branches on 60 and 90 DAS. On 90th day yield characters like number of fruits, diameter of fruits, single fruit weight, fruit yield per plant and fruit yield per plot were analyzed. Result: A significant increase in shoot length, root length, number of leaves, fresh weight and dry weight was observed in T3 - C3 (Predecomposted sugarcane trash + Trichoderma asperelloids and Microbial consortium 5 t/h) treatment, followed by T1 - C1 (Predecomposted sugarcane trash Pleurotus florida and earthworm (Eudrilus eugeniae) 5 t/h) treatment on 30, 60 and 90 DAS. A significant increase in number of flowers and number of branches was observed in T3 treatment followed by other treatment on 60 and 90 DAS. The maximum amount in number of fruits, diameter of fruit, single fruit weight, fruit yield per plant and fruit yield per plot were noted in T3 treatment, followed by T1 treatment on 90 DAS and minimum amount were reported in control (soil). The results of the study clearly indicated that treatment T3 significantly increased the vegetative parameters and yield characters in tomato.

Leaf photosynthesis and yield response of winter green gram (Vigna radiata) to high temperature and elevated CO2 in the soil plant atmosphere research (SPAR)

Legumes play an important role in India’s food security, inflation rate and export values. Climate variability might significantly affect the growth, development and yield of legume crops in various regions of the globe. The present study investigated the long episodes effect of high temperature and CO2 and ambient conditions on leaf photosynthesis and yield attributes of green gram (Vigna radiata) using soil plant atmospheric research (SPAR). Green gram was grown under high day temperature (HDT) (day maximum temperature + 3oC) and elevated CO2 (600ppm) (HDT and eCO2), high day and night temperature (HDNT) (day maximum temperature + 3oC) and elevated CO2 (600ppm) (HDNT and eCO2) and ambient conditions. Leaf photosynthesis, stomatal conductance, transpiration rate and chlorophyll index were significantly (p=0.05) increased by 25%, 24.1%, 23% and 4.6%, respectively, under HDT and eCO2 from 30 to 45 DAS (days after sowing) in comparison with ambient and HDNT and eCO2. The significant increase in number of flowers shed per plant increased under HDNT and eCO2 by 13% during 45 to 60 DAS. The increase in the number of pods per plant and grain yield per plant under HDT and eCO2 during 45 to 60 DAS by 26.9% and 25.7%, respectively. However, the biomass of the green gram was increased under HDNT and eCO2 during 30 to 45 DAS. These studies indicated a significant increase in leaf photosynthesis and yield of green gram under HDT and eCO2 at flower initiation to pod development stage (30 to 60 DAS) followed by HDNT and eCO2 and ambient condition. Overall study indicated that increasing temperature and CO2 would increase the biomass and yield of the green gram.

Shifting season of fire and its interaction with fire severity: Impacts on reproductive effort in resprouting plants.

Fire regimes shape plant communities but are shifting with changing climate. More frequent fires of increasing intensity are burning across a broader range of seasons. Despite this, impacts that changes in fire season have on plant populations, or how they interact with other fire regime elements, are still relatively understudied. We asked (a) how does the season of fire affect plant vigor, including vegetative growth and flowering after a fire event, and (b) do different functional resprouting groups respond differently to the effects of season of fire? We sampled a total of 887 plants across 36 sites using a space‐for‐time design to assess resprouting vigor and reproductive output for five plant species. Sites represented either a spring or autumn burn, aged one to three years old. Season of fire had the clearest impacts on flowering in Lambertia formosa with a 152% increase in the number of plants flowering and a 45% increase in number of flowers per plant after autumn compared with spring fires. There were also season × severity interactions for total flowers produced for Leptospermum polygalifolium and L. trinervium with both species producing greater flowering in autumn, but only after lower severity fires. Severity of fire was a more important driver in vegetative growth than fire season. Season of fire impacts have previously been seen as synonymous with the effects of fire severity; however, we found that fire season and severity can have clear and independent, as well as interacting, impacts on post‐fire vegetative growth and reproductive response of resprouting species. Overall, we observed that there were positive effects of autumn fires on reproductive traits, while vegetative growth was positively related to fire severity and pre‐fire plant size.

Evaluation of the effect of compensatory behavior of planting density, mother corm weight and planting depth on vegetative characteristics and yield of saffron (Crocus.sativus L.)

In order to investigate the effect of compensatory behavior of planting density, corm weight and planting depth on vegetative characteristics and yield of saffron stigma (Crocus. Sativus L.), a factorial split plot experiment with a randomized complete block design with three replications in the research center and Agricultural education and natural resources of Khorasan Razavi (Gonabad Research Station) was conducted in the cropping years 2018-2020. In this study, planting density treatment (in four levels of 60, 90, 120 and 150 corms per square meter) in the main plot and factorial planting depth (in two levels of 15±2 and 25±2 cm from the soil surface) and corm weight (in two Levels 4± 1 and 8 ± 1 gr) were located in the subplot. The results showed that increasing the density from 60 to 150 corms per square meter caused a significant increase in flower number, flower fresh weight and stigma dry weight, number of plants, number of leaves per plant, average length of a leaf and total leaf length per square meter. Accordingly, increasing the weight of coriander from 4 to 8 gr significantly increases flower number, flower fresh weight, stigma dry weight, number of plants, number of leaves per plant, average length of a leaf, total leaf length per square meter and total Leaf length per plant in the first and second years and reduced flower number, flower fresh weight and stigma dry weight in the third year. The results also showed that increasing the planting depth from 15 to 25 cm caused a significant decrease in all studied traits of saffron. The effect of dual and triple interactions on the studied traits was mainly significant. Overall, the results showed that the use of larger mother corms has a relative priority only in the early years and the importance of its effect decreases with increasing farm age. Based on this, it seems that it is possible to have a different strateg and with a combination of less depth and especially more density to compensate for the effect of corm weight and achieved more overall performance.

Effect of silicon and gibberellic acid on growth and flowering of gladiolus

Effect of silicon and gibberellic acid on growth and flowering of gladiolus

Saffron-pumpkin/watermelon: A clean and sustainable strategy for increasing economic land equivalent ratio under limited irrigation

Generally, from the onset of dormancy to flowering, saffron farms are free of vegetation. Therefore, nutrients loss due to soil erosion, increased soil temperature and reduced land use efficiency are the most obvious problems of sole saffron cultivation, occurring over this period. Herein the intercropping advantage of saffron with watermelon or pumpkin and its effects on growth, yield and economic land equivalent ratio under limited irrigation were evaluated as a three-year field experiment (2014–2017) with a randomized complete blocks design arranged in factorial with three replicates. In this study, limited irrigation regimes on pumpkin and watermelon (14 and 28 days intervals) and cropping systems (saffron, pumpkin, watermelon, saffron + pumpkin and saffron + watermelon) were considered as the first and the second factors, respectively. Except for 2014, the individual effects of irrigation scheme and cropping systems on flower number and dried stigma yield were significant. In 2015, 2016, in comparison to saffron monoculture, intercropping significantly increased flower number and dried stigma yield. Moreover, in these years, increase in irrigation interval from 14 to 28 days significantly reduced average fruit weight in pumpkin and watermelon. The maximum land equivalent ratio and economic land equivalent ratio of saffron were found in saffron-pumpkin intercropping system with 14 days irrigation interval. Intercropping could positively affect saffron corms growth and N and P concentrations in the corms. In sum, considering the water shortage in arid and semi-arid regions, saffron-pumpkin or saffron-watermelon intercropping increases land efficiency and improves farmers’ income during perennial life cycle of saffron.

BIFURCATE FLOWER TRUSS: a novel locus controlling inflorescence branching in tomato contains a defective MAP kinase gene.

A mutant line, bifurcate flower truss (bif), was recovered from a tomato genetics programme. Plants from the control line produced a mean of 0.16 branches per truss, whereas the value for bif plants was 4.1. This increase in branching was accompanied by a 3.3-fold increase in flower number and showed a significant interaction with exposure to low temperature during truss development. The control line and bif genomes were resequenced and the bif gene was mapped to a 2.01 Mbp interval on chromosome 12; all coding region polymorphisms in the interval were surveyed, and five candidate genes displaying altered protein sequences were detected. One of these genes, SlMAPK1, encoding a mitogen-activated protein (MAP) kinase, contained a leucine to stop codon mutation predicted to disrupt kinase function. SlMAPK1 is an excellent candidate for bif because knock-out mutations of an Arabidopsis orthologue MPK6 were reported to have increased flower number. An introgression browser was used to demonstrate that the origin of the bif genomic DNA at the BIF locus was Solanum galapagense and that the SlMAPK1 null mutant is a naturally occurring allele widespread only on the Galápagos Islands. This work strongly implicates SlMAPK1 as part of the network of genes controlling inflorescence branching in tomato.

Interactions of Salinity Stress and Flower Thinning on Tomato Growth, Yield, and Water Use Efficiency

ABSTRACTThis study was conducted to investigate the effects of salinity stress and flower number on growth, yield, water use efficiency (WUE), and fruit quality of cherry tomatoes cultivated under soilless conditions. The experiment was conducted in a plastic house (5-m wide × 11-m long) located in Gifu University. The seedlings were transplanted in a randomized complete block design with six plants per treatment (NT1 and ST1 were with four plants), giving a total of 44 plants in 22 pots (two plants per pot). Two different salinity levels [no-salinity and salinity with electrical conductivity: 0.8 and 3.0 dS m−1, respectively] and four flower number treatments (8, 13, 18, and free per truss) were investigated in the experiment. The results showed that salinity stress negatively affected tomato growth, yield, and marketable yield, but improved tomato fruit quality. The number of flowers had no effect on tomato growth variables and WUE, but the yield significantly increased with increasing flower number. However, the fruit quality was decreased with increased flower number. A reasonable control for fruit load can increase marketable yield in commercial cultivation. Under salinity stress conditions, properly increasing the number of flowers can avoid yield reduction.

Saline soil microbiome: A rich source of halotolerant PGPR

Twenty halotolerant free-living, nitrogen-fixing bacterial strains were isolated from the Lonar Soda Lake and screened for growth at different NaCl concentrations. Out of 20, only Four isolates DL2, DL3, and DL6 showed optimum growth at 4% NaCl, and DL11 showed optimum growth at 6% NaCl concentration and tolerated 10% NaCl concentration. Biochemical and 16S rRNA sequencing identified DL2 as P. mendocina, DL3 as A. beijerinckii, DL6 as P. stutzeri, and DL11 as B. subtilis. Further, these four isolates were characterized for plant growth-promoting traits and all are indole acetic acid and ammonia producers and they also solubilize the phosphate under 4% NaCl concentration. The salt tolerance of these isolates was also increased from 10 to 14% by using a physical mutagen like UV and mutant strains were also screened for PGP traits. To determine the efficacy of these isolates as plant growth-promoting bacteria, Bioinoculum I (mixed culture of wild strains) and Bioinoculum II (mixed culture of mutant strains) were prepared and tested on Catharanthus roseus at 4% NaCl concentration. Plants treated with Bioinoculum II showed 12.61 and 82.35% increase in shoot and root length, respectively, and 71.42% increase in number of flowers as compared to control plants under saline conditions. These results indicate that halotolerant bacteria isolated from saline environments have the potential to enhance plant growth under saline stress through direct or indirect mechanisms and would be most appropriate as bioinoculants under such conditions.

Domestication-driven Gossypium profilin 1 (GhPRF1) gene transduces early flowering phenotype in tobacco by spatial alteration of apical/floral-meristem related gene expression.

BackgroundPlant profilin genes encode core cell-wall structural proteins and are evidenced for their up-regulation under cotton domestication. Notwithstanding striking discoveries in the genetics of cell-wall organization in plants, little is explicit about the manner in which profilin-mediated molecular interplay and corresponding networks are altered, especially during cellular signalling of apical meristem determinacy and flower development.ResultsHere we show that the ectopic expression of GhPRF1 gene in tobacco resulted in the hyperactivation of apical meristem and early flowering phenotype with increased flower number in comparison to the control plants. Spatial expression alteration in CLV1, a key meristem-determinacy gene, is induced by the GhPRF1 overexpression in a WUS-dependent manner and mediates cell signalling to promote flowering. But no such expression alterations are recorded in the GhPRF1-RNAi lines. The GhPRF1 transduces key positive flowering regulator AP1 gene via coordinated expression of FT4, SOC1, FLC1 and FT1 genes involved in the apical-to-floral meristem signalling cascade which is consistent with our in silico profilin interaction data. Remarkably, these positive and negative flowering regulators are spatially controlled by the Actin-Related Protein (ARP) genes, specifically ARP4 and ARP6 in proximate association with profilins. This study provides a novel and systematic link between GhPRF1 gene expression and the flower primordium initiation via up-regulation of the ARP genes, and an insight into the functional characterization of GhPRF1 gene acting upstream to the flowering mechanism. Also, the transgenic plants expressing GhPRF1 gene show an increase in the plant height, internode length, leaf size and plant vigor.ConclusionsOverexpression of GhPRF1 gene induced early and increased flowering in tobacco with enhanced plant vigor. During apical meristem determinacy and flower development, the GhPRF1 gene directly influences key flowering regulators through ARP-genes, indicating for its role upstream in the apical-to-floral meristem signalling cascade.Electronic supplementary materialThe online version of this article (doi:10.1186/s12870-016-0798-0) contains supplementary material, which is available to authorized users.

Effects of Seaweed Extract Application Rate and Method on Post-production Life of Petunia and Tomato Transplants

Seaweed extracts are widely used as plant growth regulators in agriculture and horticulture for improvement of plant growth and development. This study investigated the effects of rockweed (Ascophyllum nodosum) extract application method (foliar spray or substrate drench) and rate on growth and postharvest drought tolerance of petunia (Petunia hybrida) and tomato (Solanum lycopersicum) transplants grown in a commercial peat/perlite substrate. Foliar sprays significantly affected growth of petunia and tomato, but did not improve drought tolerance of petunia and tomato. Whereas, substrate drenches significantly improved drought tolerance of petunia and tomato compared with the control. Shoot fresh weight (FW), shoot dry weight (DW), root index (RI), and chlorophyll index (SPAD) of petunia and tomato increased significantly with increasing concentration of foliar spray rate up to 5 mL·L−1, but did not change significantly with further higher foliar spray rates. Weekly substrate drenches at 20 mL·L−1 significantly decreased FW, DW, RI, and SPAD values of petunia and tomato. In this study, substrate drench at 5–10 mL·L−1 significantly increased flower number of petunia and tomato. The results of this study suggested that substrate drenches at 5–10 mL·L−1 are appropriate for the improvement of postharvest life of petunia and tomato transplants, and that foliar applications can increase plant growth.

Pyramiding of AtEDT1/HDG11 and Cry2Aa2 into pepper (Capsicum annuum L.) enhances drought tolerance and insect resistance without yield decrease

Improvement of biotic and abiotic stress tolerance without yield decrease has been a great challenge in vegetable breeding. Functional stacking of multiple resistant genes could potentially be an effective strategy against more different stress. Here, we report that constitutive co-expression of Arabidopsis thaliana homodomain-leucine zipper transcription factor Enhanced Drought Tolerance/HOMEODOMAIN GLABROUS11 (AtEDT1/HDG11) and Bacillus thuringiensis Cry2Aa2 was able to increase pepper drought tolerance and insect resistance. More importantly, fruit yield was improved under both normal and drought stress conditions. The improved tolerance to drought stress was associated with improved root system and reduced stomatal density. Compared to the non-transgenic control, the transgenic pepper plants also had higher levels of chlorophyll content, chlorophyll fluorescence (Fm/Fv), proline, soluble sugar, abscisic acid, and ROS scavenging capacity under dehydration stress conditions. The increased flower number, elevated fruit weight, and improved fruit number all contributed to the increased yield of transgenic pepper. In addition, bioassays showed that the transgenic plants were effective to control the Prodenia litura, producing a mortality rate of 81.3 % after 5 days of infection. Therefore, our study indicates that stacking of AtEDT1/HDG11 and Cry2Aa2 in pepper plants can improve drought tolerance and insect resistance, demonstrating application of AtEDT1/HDG11 and Cry2Aa2 has the potential to enhance drought tolerance and insect resistance.

Effect of elevated CO2on growth and yield of French bean (Phaseolus vulgarisL.) genotypes

The elevated CO2 levels are known to increase crop growth. French bean (Phaseolus vulgaris L.) being an important cool season legume vegetable, with C3 CO2 fixation mechanism, is likely to be benefitted by higher CO2 level. Hence, a study was initiated to quantify the response of two promising French bean cultivars, viz., Arka Komal and Arka Anoop to elevated CO2 concentrations of 550 ppm as compared to ambient levels of 380 ppm in open top chambers (OTCs). Significantly higher leaf area, root dry weight and total dry matter accumulation was recorded at 550 ppm elevated CO2 which was translated into significant increase in number of flowers and subsequently pod yield in cv. Arka Anoop compared to Arka Komal.

Transcriptome of the inflorescence meristems of the biofuel plant Jatropha curcas treated with cytokinin.

BackgroundJatropha curcas, whose seed content is approximately 30–40% oil, is an ideal feedstock for producing biodiesel and bio-jet fuels. However, Jatropha plants have a low number of female flowers, which results in low seed yield that cannot meet the needs of the biofuel industry. Thus, increasing the number of female flowers is critical for the improvement of Jatropha seed yield. Our previous findings showed that cytokinin treatment can increase the flower number and female to male ratio and also induce bisexual flowers in Jatropha. The mechanisms underlying the influence of cytokinin on Jatropha flower development and sex determination, however, have not been clarified.ResultsThis study examined the transcriptional levels of genes involved in the response to cytokinin in Jatropha inflorescence meristems at different time points after cytokinin treatment by 454 sequencing, which gave rise to a total of 294.6 Mb of transcript sequences. Up-regulated and down-regulated annotated and novel genes were identified, and the expression levels of the genes of interest were confirmed by qRT-PCR. The identified transcripts include those encoding genes involved in the biosynthesis, metabolism, and signaling of cytokinin and other plant hormones, flower development and cell division, which may be related to phenotypic changes of Jatropha in response to cytokinin treatment. Our analysis indicated that Jatropha orthologs of the floral organ identity genes known as ABCE model genes, JcAP1,2, JcPI, JcAG, and JcSEP1,2,3, were all significantly repressed, with an exception of one B-function gene JcAP3 that was shown to be up-regulated by BA treatment, indicating different mechanisms to be involved in the floral organ development of unisexual flowers of Jatropha and bisexual flowers of Arabidopsis. Several cell division-related genes, including JcCycA3;2, JcCycD3;1, JcCycD3;2 and JcTSO1, were up-regulated, which may contribute to the increased flower number after cytokinin treatment.ConclusionsThis study presents the first report of global expression patterns of cytokinin-regulated transcripts in Jatropha inflorescence meristems. This report laid the foundation for further mechanistic studies on Jatropha and other non-model plants responding to cytokinin. Moreover, the identification of functional candidate genes will be useful for generating superior varieties of high-yielding transgenic Jatropha.Electronic supplementary materialThe online version of this article (doi:10.1186/1471-2164-15-974) contains supplementary material, which is available to authorized users.

Mean Daily Temperature Regulates Plant Quality Attributes of Annual Ornamental Plants

In protected environments, temperature is often regulated to produce ornamental crops for specific market dates. Temperature primarily controls plant developmental rate and thus production time, but it can also interact with light quantity to affect crop quality attributes such as flower number, branching, and biomass accumulation. We quantified how mean daily temperature (MDT) between 14 and 26 °C influenced quality characteristics of 15 common bedding plant crops. American marigold (Tagetes erecta), cup flower (Nierembergia caerulea), diascia (Diascia barberae), flowering tobacco (Nicotiana alata), geranium (Pelargonium ×hortorum), globe amaranth (Gomphrena globosa), heliotrope (Heliotropium arborescens), nemesia (Nemesia foetans), New Guinea impatiens (Impatiens hawkeri), osteospermum (Osteospermum ecklonis), pot marigold (Calendula officinalis), snapdragon (Antirrhinum majus), stock (Matthiola incana), and torenia (Torenia fournieri) were grown under two mean daily light integrals (9.0 and 18.0 mol·m−2·d−1) in five environmentally controlled greenhouse compartments with a 16-h photoperiod. As MDT increased from 14 to 26 °C, flower or inflorescence number decreased for nearly all crops. In six crops, flower or inflorescence size decreased as MDT increased, whereas in five crops, there was an initial increase in flower size with an increase in MDT and then a subsequent decrease at MDT greater than 20 °C. In 10 of the crops, shoot weight at flowering decreased linearly or quadratically with an increase in MDT. Branch number was inversely related with MDT in eight crops and was positively correlated with an increase in flower number. We conclude that in a majority of the crops studied, plant quality decreased as the MDT increased, which can at least partially be attributed to earlier flowering at the higher MDTs. Therefore, there is often a tradeoff between faster crop timing and higher plant quality, especially for plants with a low estimated base temperature (Tmin) for development.

The Effects of Gibberellic Acid on Sex Expression and Secondary Sexual Characteristics in Papaya

The vegetative forms of male (XY), female (XX), and hermaphrodite (XYh) papaya (Carica papaya L.) plants are phenotypically identical. However, the flower and inflorescence morphology of each sex type is unique. Gynodioecious varieties SunUp, SunUp Diminutive mutant, and dioecious AU9 were used to test the response of papaya to gibberellic acid (GA3). Exogenous applications of GA3 on female and hermaphrodite flowers of papaya did not yield any sex reversal phenotype but caused a significant increase in peduncle elongation and inflorescence branch number in all treated plants. An increase in flower number was seen in females but not hermaphrodites or males. There was an increase in plant height for all treated plants except SunUp Diminutive mutant, suggesting that the mechanism causing the dwarf phenotype is independent of gibberellins. Gibberellin metabolism genes were identified in the papaya genome, none of which mapped to the sex-determining region of either the male- or hermaphrodite-specific region of papaya Y or Yh chromosome. We hypothesize that a transacting regulatory element that enhances gibberellin biosynthesis plays a role in the extreme length of the male papaya peduncle.