Plant Reproductive Organs Research Articles

Ecological fitting is a sufficient driver of tight interactions between sunbirds and ornithophilous plants.

Plant–bird pollination interactions evolved independently on different continents. Specific adaptations can lead to their restriction when potential partners from distant evolutionary trajectories come into contact. Alternatively, these interactions can be enabled by convergent evolution and subsequent ecological fitting.We studied the interactions between New World plants from the genus Heliconia, Asian plants of genus Etlingera and African sunbirds on a local farm in Cameroon. Heliconia spp. evolved together with hummingbirds and Etlingera spp. with spiderhunters —an oriental subgroup of the sunbird family.Sunbirds fed on all studied plants and individual plant species were visited by a different sunbird spectrum. We experimentally documented a higher number of germinated pollen grains in sunbird‐visited flowers of Etlingera spp. For Heliconia spp., this experiment was not successful and pollen tubes were rarely observed, even in hand‐pollinated flowers, where enough pollen was deposited. The analyses of contacts with plant reproductive organs nevertheless confirmed that sunbirds are good pollen vectors for both Heliconia and Etlingera species.Our study demonstrated a high ecological fit between actors of distinct evolutionary history and the general validity of bird‐pollination syndrome. We moreover show that trait matching and niche differentiation are important ecological processes also in semi‐artificial plant‐pollinator systems.

POPULATION DYNAMICS OF EUXESTA SPP. (DIPTERA: OTITIDAE) IN MAIZE (Zea Mays L.), WHEAT (Triticum aestivum L.) AND POLYCULTURE

In Brazil there is a great concern about the incidence of insect pests on reproductive organs of plants. In maize, there has been some species of Euxesta (Diptera: Otitidae) flies causing damage, especially in sweet maize. The objective of this study was to evaluate the presence of Euxesta spp. in maize, wheat and polyculture. For this, two experiments were carried out in a savanna area. The first was set in two potential hosts, the high protein white maize and the wheat, the second experiment was carried out in a polyculture system (maize, soybean, sorghum and cotton). The insects were captured weekly until the end of cultivation through McPhail traps with hydrolyzed maize protein randomly distributed in both fields..Two species, Euxesta eluta and Euxesta mazorca, were sampled. There was a greater collection of individuals in maize compared to wheat. Higher number of E. eluta was observed in soybean and cotton, followed by maize 1 and 2 and sorghum. The number of E. maize was found to be higher in the two kinds of maize, soybean, cotton and sorghum. The number of females was higher than males in both crops.

Изменчивость репродуктивной способности Lonicera caerulea (Caprifoliaceae) в сейсмоактивной зоне Горного Алтая (Северо-Чуйский хр., р. Кызыл-Ярык)

Seismically active areas of tectonic faults create specific inhomogeneous living conditions of plant populations and can thereby determine their structure. Studies of the reaction of plant reproductive structures to geoecological anomalies associated with active tectonic processes are practically absent. The aim of this work was to study the variability of the reproductive characteristics of Lonicera caerulea subsp. altaica plants in the local seismic zone of the Altai Mountains. We carried out studies in 2017 in the valley of the Kyzyl-Yaryk river (Altai Republic, Kosh-Agachsky district) (See Fig. 1), which was formed in the junction zone of seismic-generating faults active in the Holocene that are the boundaries of the North Chuy Range, Kurai intermountain basin and Chagan-Uzun massif and separating the Kurai and Chuysky depressions. We isolated 5 micropopulations of the Altai subspecies of blue honeysuckle - L. caerulea subsp. altaica in areas differing in volumetric activity of the radon emanation field (262-1162 Bq / m3) for research. Fifty fruits were selected in each micropopulation of L. caerulea subsp. altaica from 20 plants. We examined the morphometric characteristics and taste of the fruits, the number of full seeds and immature ovules in the fruits, the ratio of the number of full seeds to the total number of seeds and ovules, the correlation between the characters, as well as the seed germination capacity and germination readiness. The taste of the fruits was evaluated by the organoleptic method on a 5-point scale of taste variations based on the degree of bitterness in the fruits. To determine seed germinating capacity and germination readiness, germination was performed in Petri dishes at room temperature. We evaluated germination readiness on the 5th day, where n is the number of seeds and N is the number of seeds germinated during this period. For each micropopulation, we analyzed data for intragroup homogeneity using the χ2 method. Student’s t-test, Fisher’s exact test and one-way ANOVA analysis were used to test statistically significant differences in reproductive characteristics, as well as to assess the correlation between them. The analysis of variance (ANOVA) showed that the values of the Fisher criterion for the length, width, index, weight of the fruit and the number of seeds in them considerably exceed the critical value, which indicates a reliable effect of the place of plant growth on all these parameters at a 95-99% probability level. For individual test micropopulations, significant differences were found in the morphometric characteristics and seed productivity of plant fruits in comparison to the control micropopulation (the area with the lowest level of radon emanation field) (See Fig. 2, 3, 4 and 5). An analysis of the frequency of occurrence of plants with different weight and seed productivity of the fruits from the studied micropopulations showed a shift in the distribution of these parameters towards larger values, compared to the control micropopulation (See Fig. 6). The seeds collected in the control micropopulation were characterized by the least germination (See Fig. 8) and the shortest germination period (See Fig. 9). In the studied population, the average and close degree of correlation between the weight of the fruit and the number of full seeds was established; the reliability of the correlation varied depending on the place of plant growth. Plants in the L. caerulea subsp. altaica in the valley of the Kyzyl-Yaryk river were characterized by high polymorphism of the fruit shape. The frequency of occurrence of plants with oval fruits was significantly lower than in populations of L. caerulea subsp. altaica in other areas of the Altai Mountains. In micropopulations under the influence of a higher level of volumetric activity of subsoil radon, the variety of fruit shapes (See Fig. 3) and their taste variations (See Fig. 7) increased, including an increase in the expression of the recessive trait L. caerulea, the absence of bitter fruits (bitter-free fruits). The correlation between the level of radon emanation and the frequency of occurrence of plants with bitter fruits was significant at p <0.01. The influence of the level of radon emanation on the variability of morphometric characteristics of the fruit, seed productivity, germination and germination energy of the seeds was not significant. The heterogeneity of the population of the L. caerulea subsp. altaica, according to the features of the generative sphere, suggests a possible influence of a complex of factors associated with active tectonic processes on the formation and development of plant reproductive organs.

OPERATIONAL IRRIGATION MANAGEMENT: MODERN CHALLENGES, REALITIES AND VISIONS

Introduction. The current challenges in water and agriculture management in Ukraine wield major influence on the development of reclamation science and practice. These challenges and the realities of irrigated farming require a revision of traditional decision-making methods and criteria to ensure resource-efficient irrigation management. Analytical and experimental studies were conducted to evaluate existing irrigation practices, develop a vision for its development over the next 20-30 years, and evaluate the prospects for the use of certain innovative products that can be implemented for irrigation management under existing economic conditions and in the future. The purpose of the research was to improve the methods of operational irrigation management and support the adoption of appropriate strategic decisions to achieve resource efficiency in irrigated agriculture. The following tasks were solved: to investigate the temporal and spatial variability of the natural and economic conditions of irrigation use; to determine the basic directions of models and algorithms improvement for operational irrigation planning taking into account the spatial and temporal variability of natural and economic conditions of real production; to evaluate perspective directions of development of irrigation planning methods to ensure resource efficiency of management in the current agricultural practice. Methods and methodologies. The research was conducted during 2012-2019 at the farms of Kherson and Zaporizhzhya regions. Testing and pilot implementation of the operational irrigation planning information system “GIS Polyv” has been carried out. The studies were carried out on 306 fields, the total area of which was 9266.09 ha, the main crops were soybean, sunflower, winter wheat, alfalfa and winter rape. Research methods included on-site observations, modelling, remote sensing, and method of system analysis. Results and discussion. The role of on-site and space agro-monitoring for the correction of bioclimatic coefficients of crop water consumption taking into account the space-time variability of the actual biomass has been substantiated and demonstrated. For the adaptation of irrigation management to the conditions of air drought, it is proposed to use an additional criterion for making decisions on crop cooling, which is determined by the maximally permissible temperature duration at the vegetation surface above the physiologically acceptable level. It is established that under conditions of air drought, in addition to slowing the growth of biomass, physiological processes occur in the leaves and reproductive organs of plants, due to the increase in the temperature of the vegetation surface. According to studies of energy transfer processes in crops during periods of atmospheric drought, an increase in the use of a share of thermal energy for turbulent exchange has been found compared to the volumes of energy that is evaporated. The vision of the future development of methods of operational irrigation planning based on modern agricultural information platforms has been presented. It will allow to choose a method of operational irrigation management, based on the capabilities of each farm economy and to provide "on-line" consulting for water user organizations or farm personnel.

문제중심학습(Problem-Based Learning)을 활용한 예비 생물교사 대상의 식물분류학 수업 사례 연구

This study was aimed to investigate the effects of problem-based learning (PBL) applications in plant systematics classes for pre-service biology teachers through two problems about the vegetative and reproductive organs of plants during 8 weeks. The study was conducted with 26 pre-service biology teachers from one college of education. This study reported the first PBL class case in plant systematics classes as a part of botanical education for pre-service biology teachers, and thus, the students’ solutions to the problems were presented. The data for the students’ views about the PBL classes was collected from a questionnaire on the plant teaching efficacy, students’ reflective journals and semi-structured interviews. The students produced diverse solutions through active participation to PBL activities. Plant teaching outcome expectancy was shown to be higher than personal teaching efficacy. Pre-service biology teachers expressed satisfaction with the PBL activities for creating plant teaching materials. They were found to have enjoyed the process of communicating with their members, forming good relationship and solving problems with collaborative learning in PBL classes. Although expressing lack of time, they also had opportunity for self-directed learning and indirect experience in teaching. In conclusion, PBL needs to be applied to other biological subjects for educating pre-service teachers.

Determination of the post-anthesis nitrogen status using ear critical nitrogen dilution curve and its implications for nitrogen management in maize and wheat

Abstract Nitrogen (N) accumulation in plant reproductive organs during the post-anthesis growth phase of maize and wheat plays a crucial role in the formation of grain yield and quality. However, little is known about the effect of crop pre-anthesis and post-anthesis N status on ear N accumulation (NAE). This study endeavored to extend the crop N dilution theory already developed for vegetative growth period to determine ear critical N concentration (%NcE) during post-anthesis period of crop growth for analyzing the difference of NAE under various N levels. The data including the weight of dry mass (W) and N concentration of entire plant and ear, post-anthesis plant N uptake (PANU) from soil, grain number (GN), and grain weight (GW) were collected on wheat (two cultivars) and maize (three cultivars) from eight N rates (0–300 kg N ha−1) field experiments. The results revealed that the process of %N dilution exists in ear and it is plausible to extend the concept of %NcE curve till crop post-anthesis period. The %NcE curves as function of ear dry mass (WE) of wheat (%NcE = 2.85WE-0.17) and maize (%NcE = 2.22WE-0.26) were lower than those developed in maize and wheat on whole plant basis. This study revealed that the ear has the potential to diagnose ear N status under different N conditions and the increases in ear N nutrition index (NNIE) during the post-anthesis period with increasing N rate were well synchronized with plant NNI (NNIp) at anthesis. GN and GW of maize and wheat showed significantly positive correlation with NNIp at anthesis and NNIE at maturity under N-limiting treatments, and GN and GW could keep relatively stable under non-N limiting treatments. NNIp and NNIE showed the potential capacity to predict GN and GW of maize and wheat under N limiting condition. Ear critical N accumulation (NAcE) was calculated using ear Nc curve to investigate the differences mechanism of NAE under different N conditions. The difference of NAcE under different N treatments was deduced from the pre-anthesis N status of maize and wheat by determining GN. The ear N deficiency (NDE) between NAcE and NAE was co-regulated by plant pre-anthesis and post-anthesis N status, which in turn have potential to explain the variance of GW at maturity in both crops. The significantly attenuated effect of pre-anthesis N deficiency on ear potential N demand in maize and wheat indicated that the post-anthesis N management must consider the pre-anthesis N status and the corresponding reduction of the post-anthesis N input to prevent N loss under N limiting treatment in both crops. Maize was more dependent on post-anthesis N status while wheat was more reliant on pre-anthesis N status for satisfying ear growth and producing optimum GN owing to the differential values of PANU/NAE in maize and wheat during post-anthesis period. This study provides a new viewpoint on post-anthesis N management of maize and wheat for enhancing N use efficiency and grain yield.

Nitrogen-fixing bacteria and Oxalis \u2013 evidence for a vertically inherited bacterial symbiosis

BackgroundPlant-endophyte symbioses often revolve around nitrogen metabolism, and involve varying degrees of intimacy. Although evidence for vertical inheritance of nitrogen-fixing endophytic bacteria is increasing, it is confined mostly to crop plants, and to date no such system has been reported for geophytes.MethodsBacterial endophytes associated with Oxalis, the most species-rich geophytic genus form the Cape Flora in southern Africa was studied. Culturable endophytes were isolated from surface-sterilized vegetative and reproductive plant organs for six host species at three locations. Colonies of microbes on various artificial media were morphotyped, enumerated and identified using sequence data. Filter exclusion experiments were conducted to determine if endophytes were vertically transmitted to seeds, determine if mucilage plays a role to actively attract microbes from the soil and to assess microbial richness isolated from the mucilage of Oxalis seedlings. Fluorescent microscopy was implemented in order to visualize endophytic bacteria in cryo-sectioned seeds.ResultsEvidence for a novel, vertically transmitted symbiosis was reported. Communities of nitrogen-fixing and plant growth-promoting Bacillus endophytes were found to associate with selected Oxalis hosts from nitrogen-deficient environments of the Cape. Bacillus endophytes were ubiquitous and diverse across species and plant bodies, and were prominent in seeds. Three common nitrogen-fixing Bacillus have known oxalotrophic properties and appear to be housed inside specialised cavities (containing oxalates) within the plant body and seeds.ConclusionsThe discovery of vertical transmission and potential benefits to both host and endophyte suggest a particularly tight mutualism in the Oxalis-endophyte system. This discovery suggests unexpected ways in which geophytes might avoid nitrogen deficiency, and suggest that such symbioses are more common than previously expected.

MORPHOFUNCTIONAL CHARACTERISTICS OF LEAVES AND FRUITS IN MALOIDEAE (ROSACEAE): b. THE ROLE OF SURFACE TISSUES IN THE FORMATION OF RESISTANCE TO FUNGAL DISEASES

Background. Resistance to the effects of plant biotic stressors is determined by a set of factors. Among them, the leading protective role is often assigned to the physiological and biochemical characteristics of the surface tissues. However, one cannot ignore the specificity of the microstructural organization of the plant surface, since the nature of interactions in phytopathogenic organisms is more complex than the chemical impact. Meanwhile, the information accumulated to date about the structure of the surface tissues of the vegetative and reproductive organs of plants, and the interface of mycobiota, is fragmentary.Objective. Mature leaves and fruits taken from representatives of the subfamily Maloideae Werber (Malus domestica Borkh., Pyrus communis L., Cydonia oblonga Mill. and Mespilus germanica L.) were selected for the study.Materials and methods. Samples for the research were taken from the middle part of the crown of model trees in 3 replications. In recent years, scanning electron microscopy (SEM) with cryofixation is considered the most promising technique and is used to analyze the surface of biological organisms and identification of species. It is particularly informative in the case of organisms with complex surface micromorphology and for studying the biodiversity of pathogens. However, in this work we combined the methods of light, electron (SEM, TEM) and confocal microscopy. The samples were also studied using phytopathological and histochemical techniques. Condensed polyphenols were detected using K2Cr2O7 and FeCl3 as well as 4-(Dimethylamino)cinnamaldehyde (DMACA, Sigma-Aldrich).Results. On the basis of the obtained phytopathological materials and published data an overview of fungal diseases afflicting leaves and fruits of M. domestica, P. communis, C. oblonga and M. germanica was made. It has been established that a common feature of the Maloideae fruits is the accumulation of condensed polyphenols, which play an important protective role against biotic stressors, in the cells of the pericarp’s outer tissues. Anatomical and morphological characteristics of passive immunity, or horizontal resistance to fungal pathogens, include the specific nature of waxy and cuticular deposits, features of the formation of cuticular folds and peristomatic rings in the stomata area and microstrands at the base of trichomes, thickness of the cuticle and cork tissue, and the development of lenticels on fruits.Conclusion. The studied model plants suffer from a sufficiently wide range of diseases with different etiologies; among them, the most widespread and harmful are mycoses. In view of this, their resistance to fungal pathogens correlates with the specificity of the leaf and fruit surface microstructure and the content of phenolic substances (polyphenols) in the cells of the pericarp’s surface tissues.

Reproductive Ontogeny and the Evolution of Morphological Diversity in Conifers and Other Plants.

Biologists often study morphological evolution through form and function relationships. But biological structures can perform multiple functional roles, complicating efforts to understand the evolutionary significance of any one relationship. Plant reproductive organs perform multiple roles in a sequence, however, which provides a unique opportunity to understand how structures evolve to meet multiple functional demands. Using conifers as a study group, we discuss how a shared developmental trajectory links the performance of sequential functional roles. Variation in development among lineages can underlie morphological diversity; pollination-stage seed cones in Pinaceae conifers function similarly but show diverse forms reflecting differences in developmental rate. As cones develop further, the morphologies that they use to perform later functional roles are influenced by the specific developmental patterns used to meet earlier demands, which may ultimately limit morphological diversity. However, we also show how selective pressures relating to the final functional stage (seed dispersal) may influence cone anatomy and morphology over all previous stages, highlighting the complex linkages among form, function, and development. We end by discussing the potential relationships between functional ontogeny and morphological disparity in plant reproductive structures more broadly, suggesting that the complex functional roles associated with seed plant reproduction probably underlie the high disparity in this group.

Evaluation of plant seed DNA and botanical evidence for potential forensic applications

Seeds, the reproductive organs of plants, are common as trace evidence from crime scenes. Seed evidence could be grouped into several categories based on the types of crimes they are associated with, including child abuse, homicides and drugs. Most commonly, seeds are examined microscopically and identified to the plant species level to show a linkage between persons and places. More recently, forensic researchers have evaluated the potential for extracting and typing DNA from seeds to further individualize the samples. As a model system, tomato seeds were examined microscopically after different cooking treatments and assessed for the potential to DNA type seeds for variety identification. A sufficient quantity and quality of DNA were recovered from uncooked, digested and undigested tomato seeds for amplified fragment length polymorphism (AFLP) analysis; however, any form of cooking destroyed the seed DNA. A simple microscopic analysis was able to distinguish between a cooked tomato seed versus an uncooked seed. This article is intended to provide an overview of case examples and current techniques for the forensic examination of seeds as plant-derived evidence.

The plant social network: Volatiles and their release

Plants have exploited the language of small chemicals for interacting with their environment more extensively than any other types of living organisms. An amazing diversity of volatile organic compounds (VOCs) released by plants play essential roles in their reproduction, defense, and communication, and influence atmospheric chemistry and climate. Plant VOCs are also used by humans as flavors, fragrances, biofuels, insecticides and pharmaceuticals. To date, the chemistry of plant volatiles is well understood, however, little is known about the biosynthesis of this diverse group of compounds and their release from the cell to the atmosphere. Presented results will show how the integration of metabolic profiling, functional genomic approach, targeted metabolic engineering with metabolic flux analysis and modeling can provide a comprehensive understanding of the regulation of flux through VOC metabolic networks. This presentation will also cover different aspects of volatile emission: from function in protecting plant reproductive organs via natural fumigation to promoting stigma development and seed yield. This presentation will also discuss molecular mechanisms responsible for deploying VOC from plant cells into the atmosphere.Support or Funding InformationThis work was supported by Grant IOS‐16555438 from the National Science Foundation and by the USDA National Institute of Food and Agriculture Hatch project 177845.This abstract is from the Experimental Biology 2019 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.

Flower closure enhances pollen viability in Crocus discolor G. Reuss

Repetitive flower closure (nyctinasty) is influenced by various regulatory mechanisms, but its ultimate function remains unclear. It is hypothesized that closed corolla may protect a plant's reproductive organs against various unfavourable environmental conditions. We investigated if repetitive flower closure enhances pollen viability and prevents pollen loss in an early spring flowering species, Crocus discolor, occurring in open grasslands of submontane to subalpine zones of the Western Carpathian Mountains. Artificially interrupted temporal petal closure resulted in lower pollen viability, but it had no effect on the pollen availability in flowers. The latter result suggests that wind did not cause pollen loss from open flowers, but whether closed corolla may protect reproductive organs from being damaged by hail or rain remains to be tested. Closing corolla may serve as a pollen protection mechanism, particularly in early flowering plants facing harsh environmental conditions.

Diversity, specificity, co-occurrence and hub taxa of the bacterial-fungal pollen microbiome.

Flower pollen represents a unique microbial habitat, however the factors driving microbial assemblages and microbe-microbe interactions remain largely unexplored. Here we compared the structure and diversity of the bacterial-fungal microbiome between eight different pollen species (four wind-pollinated and four insect-pollinated) from close geographical locations, using high-throughput sequencing of the 16S the rRNA gene fragment (bacteria) and the internal transcribed spacer 2 (ITS2, fungi). Proteobacteria and Ascomycota were the most abundant bacterial and fungal phyla, respectively. Pseudomonas (bacterial) and Cladosporium (fungal) were the most abundant genera. Both bacterial and fungal microbiota were significantly influenced by plant species and pollination type, but showed a core microbiome consisting of 12 bacterial and 33 fungal genera. Co-occurrence analysis highlighted significant inter- and intra-kingdom interactions, and the interaction network was shaped by four bacterial hub taxa: Methylobacterium (two OTUs), Friedmanniella and Rosenbergiella. Rosenbergiella prevailed in insect-pollinated pollen and was negatively correlated with the other hubs, indicating habitat complementarity. Inter-kingdom co-occurrence showed a predominant effect of fungal on bacterial taxa. This study enhances our basic knowledge of pollen microbiota, and poses the basis for further inter- and intra-kingdom interaction studies in the plant reproductive organs.

Resource reallocation patterns within Sagittaria trifolia inflorescences following differential pollination

Understanding resource allocation to reproduction, a key factor in life history tradeoffs, has long intrigued plant ecologists. Despite the recognized importance of understanding the movement of resources among flowers following variable pollination, the patterns of resource reallocation to plant reproductive organs have not been thoroughly addressed. In this study, we aimed to empirically explore how resources redistribute within inflorescences in response to differential pollination intensities. Using a common herb, Sagittaria trifolia, we conducted supplemental and controlled pollination for single, some, or all flowers in simple and complex inflorescences, and compared their resulting fruiting probabilities, seed production, and average seed masses. Pollen supplementation of a single flower significantly increased its fruiting probability; however, the same manipulation of an inflorescence did not increase its overall reproduction. Single pollen-supplemented flowers had a higher percentage fruit set than inflorescences receiving supplemental pollination. In complex inflorescences, supplemental pollination had no effect on the reproductive success of flowers on the lateral or main branches. We provided evidence of resource reallocation from controlled to pollen-supplemented flowers in simple inflorescences; however, resources were unlikely to be reallocated between the main and lateral branches in the complex inflorescences, suggesting that flowering branches represent integrated physiological units in S. trifolia. The results also demonstrated that single-flower supplemental pollination would exaggerate pollen limitation and lead to a biased understanding of a plant's reproductive status.

Optimal planting density and sowing date can improve cotton yield by maintaining reproductive organ biomass and enhancing potassium uptake

Cotton is the fifth major oil crop and grown primarily for natural fiber globally. Suitable management practices like planting density (PD) and sowing date (SD) are the major drivers of cotton crop productivity. Cotton production with a normal practice of 3 plants m−2 in Yangtze River Valley China, resulting in an average yield of 1200kgha−1 although, high input costs and low productivity are the two major consequences in cotton production systems. The production costs can be decreased and profits can be increased through optimal PD and adjusting SD. The objectives of this study were to optimize growth, yield, biomass partitioning and potassium (K) distribution of a cotton crop under a short growing season and elevated PD. Experiments were conducted with two sowing dates i.e. early (S1, May 20 and late S2, June 04) as the main plot and three plant densities (D1, low 7.5; D2, moderate; 9.0 and D3, high; 10.5plantsm−2) as the subplot laid out in a split arrangement with four replicates. D3 crops significantly delayed cotton growth period under late sowing date compared with early planted crops. Compared with S2 crops, S1 plants produced 29% and 26% higher seed cotton and lint yield, respectively. Among the PD, D2 plants produced 12%, 15%, 13% and 6% more seed cotton yield and lint yield over D1 and D3 crops respectively. The increment in yield was due to increased plant reproductive organs biomass occasioned by moderate density and longer cropping season which allowed the utilization of available resources. Higher K acquisition i.e. (0.9VMkgha−1d−1), further improved reproductive structures formation in S1 combined with D2 crops. The S1 in combination with D2 crops resulted in the highest average (77VTkgha−1d−1) and maximum (93VMkgha−1d−1) rates of reproductive organs biomass accumulation than other combinations. Conclusively, use of medium density under both sowing dates is an effective strategy for optimal seed cotton and lint yield.

Next-Generation Sequencing Sheds New Light on Small RNAs in Plant Reproductive Development.

Reproductive development is a key step of the plant life cycles and indicates the start of a new life cycle. The reproductive organs including flower, fruit and seed, have diverse and complex structures, which is a syndrome in the evolution of angiosperms. The development of plant reproductive organs depends on the correct spatial and temporal expression of numerous genes acting in concert to form regulatory networks. Small non-coding RNAs (sRNAs) play a key role in the reproductive development through different modes of sequence-specific interaction with their targets. The sRNAs guide transcriptional and post-transcriptional regulation to intensively integrate into the complex process. Next generation sequencing techniques (NGS) has greatly extended scientist's capabilities to identified and quantify sRNAs by supplying a massive of sequences. In turn this has led to a greater understanding of the many complex roles and interactions that sRNAs are involved with during reproductive development. In this review, we provide an overview of the biogenesis and classification of plant sRNAs, and summarize the recent progress in the understanding of plant sRNA in the flower, and fruit/seed development. Also, we discuss NGS approaches to profile global sRNA expression, as well as the application of sRNA-seq/degradome-seq approaches to identify novel sRNAs and verify their targets related to the above development processes.

Arabidopsis Transcription Factors SPL1 and SPL12 Confer Plant Thermotolerance at Reproductive Stage

Plant reproductive organs are vulnerable to heat, but regulation of heat-shock responses in inflorescence is largely uncharacterized. Here, we report that two of the SQUAMOSA PROMOTER BINDING PROTEIN-LIKE (SPL) transcriptional factors in Arabidopsis, SPL1 and SPL12, act redundantly in thermotolerance at the reproductive stage. The spl1-1 spl12-1 inflorescences displayed hypersensitivity to heat stress, whereas overexpression of SPL1 or SPL12 enhanced the thermotolerance in both Arabidopsis and tobacco. RNA sequencing revealed 1939 upregulated and 1479 downregulated genes in wild-type inflorescence upon heat stress, among which one-quarter (1,040) was misregulated in spl1-1 spl12-1, indicating that SPL1 and SPL12 contribute greatly to the heat-triggered transcriptional reprogramming in inflorescence. Notably, heat stress induced a large number of abscisic acid (ABA) responsive genes, of which ∼39% were disturbed in heat induction in spl1-1 spl12-1 inflorescence. Preapplication of ABA and overexpression of SPL1 restored the inflorescence thermotolerance in spl1-1 spl12-1 and in the ABA biosynthesis mutant aba2-1, but not in the pyl sextuple mutant defective in ABA receptors PYR1/PYL1/PYL2/PYL4/PYL5/PYL8. Thus, inflorescence thermotolerance conferred by SPL1 and SPL2 involves PYL-mediated ABA signaling. The molecular network consisting of SPL1 and SPL12 illustrated here shed new light on the mechanisms of plant thermotolerance at the reproductive stage.

Strigolactones affect tomato hormone profile and somatic embryogenesis.

Exogenously applied GR24 affected somatic embryo formation and morphogenesis of strigolactone-deficient tomato mutant through cross-talk with auxins and cytokinins indicating involvement of SLs in the embryogenic process. Strigolactones (SLs) mediate the regulation of plant responses to the environment through cross-talk with other plant hormones, especially auxins. Auxins play a crucial role in coordinating the morphogenesis and development of plant reproductive organs, including the signal-transduction cascade leading to the reprogramming of gene-expression patterns before embryo formation. SLs' role in these processes is unknown, in contrast to their proven involvement in auxin transport and distribution. We used tomato cv. M82 and its SL-deficient mutant SL-ORT1 to study the influence of SLs on hormone profile in tomato roots and shoots, and their involvement in somatic embryogenesis (SE) and morphogenesis (adventitious root formation). The synthetic SL GR24 had different effects on SE of M82 and SL-ORT1, indicating that SLs influence the cytokinin-to-auxin ratio in tomato SE.

Involvement of the Rcs regulon in the persistence of Salmonella Typhimurium in tomatoes.

It is becoming clear that human enteric pathogens, like Salmonella, can efficiently colonize vegetative and reproductive organs of plants. Even though the bacterium's ability to proliferate within plant tissues has been linked to outbreaks of salmonellosis, little is known about regulatory and physiological adaptations of Salmonella, or other human pathogens, to their persistence in plants. A screen of Salmonella deletion mutants in tomatoes identified rcsA and rcsB genes as those under positive selection. In tomato fruits, populations of Salmonella rcsB mutants were as much as 100-fold lower than those of the wild type. In the follow-up experiments, competitive fitness of rcsA and rcsB mutants was strongly reduced in tomatoes. Bioinformatics predictions identified a putative Salmonella RcsAB binding box (TTMGGAWWAABCTYA) and revealed an extensive putative RcsAB regulon, of which many members were differentially fit within tomatoes.

Endophytic bacteria of woody plants as the basis of complex microbial preparations for agriculture and forestry

The literature review focuses on endophytic bacteria inhabiting woody plants. Endophytic bacteria for genera Pseudomonas, Bacillus, Paenibacillus, Burkholderia, and Erwina are shown to be found in almost all woody tissues. In additional, endophytic bacteria have been found in reproductive plant organs. It is shown that endophytic bacteria have functional properties that are useful for host plants: the ability to fix atmospheric nitrogen, produce growth simulating and biocontrol substances, and to induce systemic resistane of plants to biotic and abiotic stresses. Endophytic bacteria are a major part of the microbiome of woody plants, possess valuable functional properties of host plants, and are a promising biotechnological resource for the development of complex microbial preparations for agriculture and forestry.