Horticultural Species Research Articles

Bumblebees sense rootstock-mediated nutrition and fertilization regime in tomato

AimsSince producing more with less is required for increasing agricultural sustainability and reducing its environmental impact, breeding varieties with increased yield stability under reduced fertilizer application is an important goal, particularly in high valued horticultural crops such as tomato (Solanum lycopersicum L.). However, because of the difficulties to conciliate yield and fertilizer use efficiency through breeding, the graft-compatible genetic biodiversity existing in horticultural species offers the possibility to directly approach this objective in high-yielding elite varieties through improving nutrient capture and promoting ecosystem services such as insect pollination. We hypothesized that rootstocks affect pollinator foraging decisions through the nutritional status that impacts yield.MethodsFifteen genetically diverse experimental rootstocks were grafted to a scion tomato variety and cultivated under optimal and reduced (25% of optimal) P and NPK fertilization in the presence of managed bumblebee pollinators (Bombus terrestris).ResultsUp to twofold yield variability between rootstocks was associated with leaf nutrition and photosynthesis of the scion. Interestingly, fertilization regime and the rootstock genotype influenced the pollinator foraging decisions since bumblebees showed feeding preference for plants cultivated under low P, and for the most yielding and nutritious graft combinations under reduced but not under optimal fertilization. Bumblebees can sense plant nutritional status through source-sink relations, as supported by the consistent relationship between pollinator preferences and leaf carbon concentration.ConclusionsThis study opens new perspectives for using pollinators as “phenotypers” to select the most resilient plants under suboptimal conditions and/or genotypes that synergistically increase crop productivity by promoting the ecosystem service provided by the insects.

What modulates the impacts of acid rain on the allelopathy of the two Asteraceae invasives?

Most of the allelopathic studies have focused on the independent allelopathy of one invasive plant, but have ignored the co-allelopathy of the two invasives. The variations in the type of acid rain can modulate the invasiveness of invasives via the changes in the allelopathy. Thus, it is vital to elucidate the allelopathy of invasives, particularly the co-allelopathy of the two invasives, under acid rain with different types, to illuminate the mechanisms driving the co-invasion of two invasives under diversified acid rain. However, little progress has been finished in this aspect presently. This study aimed to evaluate the co-allelopathy of two Asteraceae invasives Solidago canadensis L. and Erigeron annuus L. treated with acid rain with different nitrogen-to-sulfur ratios on seed germination and seedling growth of the horticultural Asteraceae species Lactuca sativa L. via a hydroponic experiment. Aqueous extracts of the two Asteraceae invasives generated obvious allelopathy on L. sativa. S. canadensis aqueous extracts caused stronger allelopathy. There may be an antagonistic effect for the co-allelopathy of the two Asteraceae invasives. Nitric acid at pH 5.6 weakened the allelopathy of the two Asteraceae invasives, but the other types of acid rain strengthened the allelopathy of the two Asteraceae invasives. The allelopathy of the two Asteraceae invasives increases with the increasing acidity of acid rain, but the allelopathy of the two Asteraceae invasives decreases with the increasing nitrogen-to-sulfur ratio of acid rain. Accordingly, the species number of invasives, and the acidity and type of acid rain modulated the impacts of acid rain on the allelopathy of the two Asteraceae invasives.

Direct fluorescence labelling of NO inside plant cells.

Nitric oxide (NO) plays a key role in regulating plant growth, enhances nutrient uptake, and activates disease and stress tolerance mechanisms in most plants. NO is marked as a potential tool for improving the yield and quality of horticultural crop species. Research on NO in plant species can provide an abundance of valuable information regarding this. Hence, we have prepared a simple chemosensor (NPO) for the detection of endogenous NO in chickpea saplings. NPO selectively interacts with NO as determined through a chemodosimetric method to clearly show both the colorimetric and fluorometric changes. After the interaction with NO, the colorless NPO turns yellow as observed by the naked eye and shows bright cyan-blue fluorescence under a UV lamp. The 1 : 1 stoichiometric ratio between NPO and NO is determined from Job's plot resulting in a stable diazeniumdiolate product. The interaction mechanism is well established by absorption, fluorescence titration, NMR titration, HRMS, and DFT calculations. This method has successfully been employed in the plant's root and stem systems to label NO. Confocal microscopy images might help us to understand the endogenous NO generation and the mechanism that happens inside plant tissues.

Two new subspecies of Crocus biflorus L. (Iridaceae) from the Iraqi Kurdistan region using morphological and molecular methods

Species belonging to the Crocus genus are considered among the most attractive horticultural species and valuable economic plants in the world. Crocus plants are present at several locations in the Iraqi Kurdistan region. However, a comprehensive study has not been conducted yet in recognition of the species in this area. In the current work we used Internal Transcribed Spacers of nuclear ribosomal DNA (ITSnr) markers and morphological traits to provide information on this genus. The study revealed two new subspecies within species Crocus biflorus; Crocus biflorus subsp. penjwenii and Crocus biflorus subsp. qaradaghii. In addition, the circumscriptions of Crocus cancellatus and Crocus pallasii, as well as their subspecies ranks (haussknechtii and cancellatus) respectively, are confirmed in Iraq for the first time by using molecular means.

Study on morphological characterization of Citrus macroptera Mont collected from garo hills district Meghalaya, India

The work was undertaken to study the variability in Citrus macroptera from five Garo hills district. Many important horticultural plant species, viz. Citrus are known to have originated from this region. Citrus macroptera Mont. is one of the endangered, semi-wild species which have found to exist in various parts of NE region, including Meghalaya. Thirty accession of Citrus macroptera from five different districts of Garo Hills, Meghalaya were collected to study its variability in quantity and quality parameters. In the study significant to highly significant differences were observed among the genotypes. The analysis of variance for different parameters such as tree height, tree girth, leaf length, leaf width, fruit width, fruit length, fruit weight, number of fruit segment, rind thickness, number of seeds per segment, seed length, and seed width varied significantly among accession. Variability among accession collected from different location shows the great scope for genetically potential genotypes for cultivation and also for their exploitation in plant breeding programme.

Investigation of specific molecular marker and EC50 values of guazatine for Geotrichum citri-aurantii on citrus in China

Geotrichum citri-aurantii is a postharvest fungi disease of citrus which can significantly affect the economy. In this work, two pairs of RPB1 genes primers, 2996-R&F and 4989-R&F, targeting G. citri-aurantii, were successfully developed to distinguish G. citri-aurantii from other Geotrichum species and 27 postharvest pathogens of various horticultural species. In addition, G. citri-aurantii (AY-1, isolated in 2012) used as the positive control, we further isolated 24 G. citri-aurantii isolates (4 from Wuhan, 9 from Guilin and 11 from Ganzhou) in China and investigated the median effective concentration (EC50) values of all isolates to guazatine using a colony diameter approach. The results showed that the EC50 values of 22 isolates from the three cities generally increased compared to AY-1. The isolate SF-9 from Ganzhou showed the highest EC50 value to guazatine (EC50 = 32.3578 mg/L) among all the isolates and the average EC50 of isolates from Ganzhou (EC50 = 10.3313 mg/L) was 182 times higher than that of the control. However, the average EC50 values of the G. citri-aurantii isolates from Guilin (EC50 = 0.0826 mg/L) and Wuhan (EC50 = 0.1295 mg/L) were 2.2 times and 1.4 times higher than that of AY-1, respectively. What's important, 13 isolates (AY-5, G12, SF-1, 2 from Guilin city; SF-3, 4, 5, 6, 7, 9, 13, 15, 16 from Ganzhou city) of all still gave rise to disease with 1 mg/L of guazatine treatment in vivo. Above all, an efficient method to afford a rapid identification of G. citri-aurantii was developed and it provided theoretical basis to control guazatine use.

Genome-Wide Identification and Expression Analysis of the KCS Gene Family in Yellow Horn Reveal Their Putative Function on Abiotic Stress Responses and Wax Accumulation

The β-ketoacyl CoA synthase encoded by the KCS genes is a rate-limiting enzyme for the synthesis of very-long-chain fatty acid (VLCFA), which catalyzes the VLCFA elongation. Yellow horn (Xanthoceras sorbifolium) is a horticultural tree species known for its kernel oil, which has strong resistance to drought, cold, high temperature, and saline-alkali. The conserved domain FAE1-CUT1-RPPA and ACP-syn-III_C of the KCS gene family were used to search the KCS sequences across the whole genomic sequence of yellow horn; a total of 20 XsKCS genes were identified and divided into four subfamilies. The conserved motif and transmembrane structure analysis revealed that most XsKCSs had a conserved transmembrane domain except XsKCS10 and XsKCS20. The prediction of cis-acting elements of XsKCS genes showed that XsKCS genes contained many stress and hormone response elements, such as ABRE, MBS, and LTR. Furthermore, XsKCS genes exhibited differential expression profiles under abiotic stress and stress-related hormone treatment conditions. Transcriptomic data showed that XsKCS1, XsKCS11, and XsKCS17 had higher expression in yellow horn with high leaf cuticular wax, indicating that they may function in the cuticular wax accumulation and drought response. This study laid a foundation for further functional verification of XsKCS genes in yellow horn stress response.

Genome-wide identification and expression analysis of peach multiple organellar RNA editing factors reveals the roles of RNA editing in plant immunity

BackgroundMultiple organellar RNA editing factor (MORF) genes play key roles in chloroplast developmental processes by mediating RNA editing of Cytosine-to-Uracil conversion. However, the function of MORF genes in peach (Prunus persica), a perennial horticultural crop species of Rosaceae, is still not well known, particularly the resistance to biotic and abiotic stresses that threaten peach yield seriously.ResultsIn this study, to reveal the regulatory roles of RNA editing in plant immunity, we implemented genome-wide analysis of peach MORF (PpMORF) genes in response to biotic and abiotic stresses. The chromosomal and subcellular location analysis showed that the identified seven PpMORF genes distributed on three peach chromosomes were mainly localized in the mitochondria and chloroplast. All the PpMORF genes were classified into six groups and one pair of PpMORF genes was tandemly duplicated. Based on the meta-analysis of two types of public RNA-seq data under different treatments (biotic and abiotic stresses), we observed down-regulated expression of PpMORF genes and reduced chloroplast RNA editing, especially the different response of PpMORF2 and PpMORF9 to pathogens infection between resistant and susceptible peach varieties, indicating the roles of MORF genes in stress response by modulating the RNA editing extent in plant immunity. Three upstream transcription factors (MYB3R-1, ZAT10, HSFB3) were identified under both stresses, they may regulate resistance adaption by modulating the PpMORF gene expression.ConclusionThese results provided the foundation for further analyses of the functions of MORF genes, in particular the roles of RNA editing in plant immunity. In addition, our findings will be conducive to clarifying the resistance mechanisms in peaches and open up avenues for breeding new cultivars with high resistance.

Characterization and evaluation of Greek tomato landraces for productivity and fruit quality traits related to sustainable low-input farming systems.

Tomato is one of the most important horticultural species all over the world, having high level of consumption and employing many people, both in the primary sector (farmers) and in the secondary sector (traders, seed companies and processors). Nowadays, the use of commercial tomato F1 hybrids tends to prevail because of high yield potential and homogeneity of fruits which are often characterized by lack of quality and sensory characteristics. In contrast, tomato landraces have outstanding quality traits, such as high concentration of antioxidants and organoleptic compounds, as well as often include desirable genes in their genome for adaptability, plasticity, response to low-input conditions, and high fruit nutritional value. Thus, they are appropriate material in the use of sustainable agricultural management systems or as gene donors for the development of new type of tomato cultivars suitable for low-input farming systems. The present experimental study refers to 22 Greek tomato landraces and two commercial cultivars (cv. Macedonia and the F1 hybrid Formula) used as controls, which were characterized by phenotypical markers and evaluated under low-input sustainable farming conditions. Specifically, during this research, measurements were taken regarding yield potential (early production, number of fruits per plant, fruit weight, total yield) and fruit quality traits, such as physicochemical characteristics (pH, acidity, and soluble solid components - Brixο) also according to nutritional value (content of ascorbic acid, lycopene, total carotenoids, and total phenolics) of tomato fruits. In the most promising landraces (cv. Milo Chalkidiki, cv. Eratiras, cv. Lotos, cv. Aspros lotos, cv. Pantaroza, cv. Karabola and cv. Kardia Vodiou), having comparable yield and fruit quality traits with commercial cultivars, intrapopulation "Pure line selection" method, under low-input farming conditions was applied for two years. Following this approach, we succeed to determine the level of yield potential and provide information for the nutritive value and utilization of typical tomato landraces, improving their yield and fruit quality traits, following a mild intrapopulation selection under low-input farming conditions. This data pipeline is expected to be of interest for organic farmers and processors of high nutritive tomato products, with low carbon footprint for the environment.

Ploidy Levels and DNA Contents of Bougainvillea Accessions Determined by Flow Cytometry Analysis

Bougainvillea Comm. ex Juss. (Nyctaginaceae; Bougainvillea) is a popular ornamental plant with vigorous growth, luxuriant blooming, colorful bracts, and a high tolerance to the stresses of temperature, drought, and soil pollution, and thus is widely cultivated in tropical and subtropical regions. However, the paucity of information on ploidy and the genomic constitution is a significant challenge to genome research and cultivar improvement. We present a flow cytometry method for ploidy detection in bougainvillea based on evaluating different lysates and tissues, identify the ploidy level of a batch of bougainvillea accessions, and infer the genome size of horticultural species Bougainvillea glabra, Bougainvillea spectobilis, and Bougainvillea peruviana. The results show that tender leaves and woody plant buffer (WPB) were optimal for flow cytometry analysis. The 2C nuclear DNA amounts in 176 bougainvillea accessions ranged from 4.66 ± 0.04 to 12.26 ± 0.1 pg, which represents 161 diploids, 13 triploids, 1 tetraploid, and 1 di-tetraploid mixoploid. For B. glabra, B. spectobilis, and B. peruviana, the mean 1C values were 3.201, 3.066, and 2.915 pg, respectively. The genome size of B. glabra was significantly larger than that of B. peruviana (P = 0.0004), but had no significant variation with that of B. spectobilis (P = 0.1061). These results reveal fundamental cytogenetic information for bougainvillea that are beneficial to whole-genome sequencing and hybrid breeding programs.

Improving production and fruit quality of tomato under abiotic stress: Genes for the future of tomato breeding for a sustainable agriculture

Climate change and a rising world population make generation of crops with enhanced abiotic stress tolerance and higher nutritive value a priority objective in agriculture. In this review we have summarized recent advances on tomato ( Solanum lycopersicum ), the most important horticultural species regarding production and nutritional quality. Firstly, the different and complex processes evolved in abiotic stress tolerance are summarized, with special attention on responses to osmotic, oxidative and ionic and nutritional stress, as well as the anatomical changes involved in plant adaptation to abiotic stress. In order to avoid or reduce production loss and improve fruit quality under abiotic stress, it is of utmost importance the identification of tomato key genes involved in abiotic stress long-term tolerance, that is, genes which simple variation determines a significant change not only in vegetative but also in reproductive growth. The functions of the tomato genes known to date affecting fruit yield under abiotic stress are described, including those involved in signal sensing, perception and transduction of abiotic stress, transcription factors and abiotic stress responsive genes. Together with production, fruit quality is crucial in tomato given its so high worldwide consumption per capita . Nutritional compounds as carotenoids and vitamin E are well known antioxidants and abiotic stress induces a secondary oxidative stress to which plants have to react. Although the increased metabolites production under abiotic stress may be due to physiological adaptation processes, advances in this field will go in parallel to the identification of genes improving fruit quality when the plant is grown subjected to stressful conditions. The key genes involved in improvement of nutritional quality of tomato fruit under abiotic stress are reviewed, in particular the main ones involved in accumulation of crucial metabolites in this aspect, such as carotenoids and tocopherols. One of the main bottlenecks in breeding programs nowadays is the strong reduction of phenotypic and genetic diversity in modern germplasm. Therefore, searching of new genetic resources for improvement of abiotic stress tolerance and fruit quality is critical, including sources of natural variation, like wild relatives and traditional varieties or landraces, as well as spontaneous and induced mutants with beneficial effects on these traits. All of them will expand our knowledge on the processes involved in abiotic stress tolerance and fruit quality in tomato. • Adaptation strategies essential to uphold growth through plant life cycle in stress • Long-term stress tolerance genes are critical to reduce yield losses • Increasing fruit quality when growing tomato plants under abiotic stress conditions • Finding new genetic resources for improvement of tomato fruit yield and quality

Morphometric parameters and photosynthetic performance of in vitro propagated pineapple

Pineapple (Ananas comosus) is a horticultural species of the Bromeliaceae family of high socioeconomic interest, widely cultivated around the world. The multiplication of pineapple seedlings in the field can be time-consuming, requiring a significant labor investment. The objective of this study was to evaluate the performance of continuous and temporary immersion systems in the micropropagation scale-up of the species. Shoots were obtained from explants subcultured in flasks with gelled culture medium and without gas exchange. The shoots were transferred to liquid MS medium supplemented with 2mM NAA, and 4mM BAP, and cultivated in four different devices: sealed flasks, flasks with semipermeable gas membranes, RITA®, and twin-flasks. After 45 days of cultivation, plant growth, fresh mass increment, the stomatal density of the abaxial surface of the leaves, the maximum quantum yield of the photosystem II, and contents of chlorophyll and carotenoids were analyzed. Significant differences were observed in plant growth, stomatal density, and contents of chlorophyll and carotenoids. The twin-flasks and RITA® devices revealed better results in morphological parameters, such as plant growth and stomatal density, while the treatments in sealed flasks and with membrane stood out in the chlorophyll content.

Rhus typhina L. triggered greater allelopathic effects than Koelreuteria paniculata Laxm under ammonium fertilization

Most of the allelopathic studies have concentrated on the allelopathic effects of invasive herbaceous plants on the natives, particularly on seed germination and seedling growth (Sge&Sgr), but have ignored the allelopathic effects of invasive trees and the differences in the allelopathic effects of invasive plants (particularly invasive trees) and the natives. Nevertheless, the variations in the ratio of different nitrogen (N) forms in N fertilization can change the differences in the allelopathic effects of the invasive plants and the natives. Thus, it is important to evaluate the differences in the allelopathic effects of invasive plants (particularly invasive trees) and the natives under N fertilization, particularly with different N forms. However, the recent process in this area is limited. This study aimed to estimate the differences in the allelopathic effects (using aqueous leaf extracts) of one of the most destructive invasive trees in China (Rhus typhina L.) and the native tree (Koelreuteria paniculata Laxm) on Sge&Sgr of the horticultural species Lactuca sativa L. under N fertilization with different forms (i.e., N-NH4, N-NO3, urea, and a mixture of the three N forms at a 1:1:1 ratio). The two deciduous Sapindales trees generated significantly allelopathic effects on Sge&Sgr of L. sativa. R. typhina created stronger allelopathic effects on leaf photosynthetic area, plant growth competitiveness, and plant water content of L. sativa than K. paniculate. N solution can intensify the allelopathic effects of the two deciduous Sapindales trees on seedling growth of L. sativa. The allelopathic effects of R. typhina on seedling growth of L. sativa were significantly greater than those of K. paniculata under N-NH4. Thus, the growth competitiveness of R. typhina may be higher than that of K. paniculata under N-NH4 via the stronger allelopathic effects on adjacent species.

Phylogenomics as an effective approach to untangle cross-species hybridization event: A case study in the family Nymphaeaceae

Hybridization is common and considered as an important evolutionary force to increase intraspecific genetic diversity. Detecting hybridization events is crucial for understanding the evolutionary history of species and further improving molecular breeding. The studies on identifying hybridization events through the phylogenomic approach are still limited. We proposed the conception and method of identifying allopolyploidy events by phylogenomics. The reconciliation and summary of nuclear multi-labeled gene family trees were adopted to untangle hybridization events from next-generation data in our novel phylogenomic approach. Given horticulturalists' relatively clear cultivated crossbreeding history, the water lily family is a suitable case for examining recent allopolyploidy events. Here, we reconstructed and confirmed the well-resolved nuclear phylogeny for the Nymphaeales family in the context of geological time as a framework for identifying hybridization signals. We successfully identified two possible allopolyploidy events with the parental lineages for the hybrids in the family Nymphaeaceae based on summarization from multi-labeled gene family trees of Nymphaeales. The lineages where species Nymphaea colorata and Nymphaea caerulea are located may be the progenitors of horticultural cultivated species Nymphaea 'midnight' and Nymphaea 'Woods blue goddess'. The proposed hybridization hypothesis is also supported by horticultural breeding records. Our methodology can be widely applied to identify hybridization events and theoretically facilitate the genome breeding design of hybrid plants.

La quiescencia como estado estratégico del proceso infectivo de especies de Colletotrichum

Colletotrichum, a genus of Ascomycota fungi with a diversity of species grouped into several species complexes, or clades, is associated with diseases known as "Anthracnose". It affects significantly different tropical and subtropical fruit species. Infections occur in the field and postharvest; quiescent stages are mainly responsible for postharvest losses. An analysis of this pre-infective stage is made based on consulted papers. The infective process is modulated by the length of the quiescent period of the fungus during the vegetative or pre-productive stages of trees. Quiescent stage is determined by the host’s biochemical responses and the pathogen’s activity. Once the pathogen is activated, it develops an infectious necrotrophic process. Colletotrichum quiescence has been studied mainly in subtropical fruits and horticultural species, and the studies highlight the role of volatile compounds, metabolites and enzymes involved in the length and breaking of quiescence, as well as the differential responses according to the phenological stage and the genotype of the plant. Transcriptomic and proteomic analysis of the host-fungus interaction have revealed the role of genes in the occurrence and breaking of quiescence. Knowledge about the quiescence of Colletotrichum in tropical fruits is necessary to improve management efficiency. Detection and induction of quiescent infections has been studied and genomics has allowed to understand the occurrence of quiescence in the infective process; however, in crops in the tropics, such as mango, an important crop in Colombia, questions about associated species and biology of their quiescence are still unanswered.

Predicting point-source invasion success in the Queensland fruit fly (Bactrocera tryoni): An individual-based modelling approach

Fruit flies are a major pest worldwide for fruit producing industries. Incursions into fly free areas usually occurs via infested fruit; however, little is reported about the size of a propagule to start a new establishment. Propagule pressure is an important predictor of the probability that an invasive species will establish a breeding population. Recently, individual-based model (IBM) became a valuable modelling tool for exploring invasive species. Here, we developed a spatially-explicit individual-based model (IBM) specifically parameterized for the Queensland fruit fly (Qfly) (Bactrocera tryoni Froggatt), a major horticultural pest species in Australia and a major quarantine concern worldwide. Usually, new establishments or incursions originate from the introduction of infested fruit and larvae must progress through several stages to become sexually mature adults. For a Qfly incursion to establish a breeding population, flies must avoid predators and survive long enough to become reproductively mature, find a mate, and find ripening fruit. Additionally, their offspring must survive and successfully reproduce. The IBM model simulated release of a fixed number of flies into a heterogeneous environment of varying suitability. We conducted simulations to delineate the contributions of demographic stochasticity and Allee effects (finding a mate in a spatial environment) on establishment probability. Our model delineated several key influential factors, especially tree density, extrinsic mortality and mating range. We performed sensitivity analyses to identity which biological and ecological mechanisms strongly affect establishment probability. Integrating the model's findings with information on transport of infested fruit helps explain why Qfly incursions are common, but yet most fail to establish. Our model predicted that circa 16 and 50 flies were required for a 50% and 99% chance of establishment respectively. Additionally, our model predicted the mating distance for Qfly was 16.1 m. The mean daily dispersal distance was 30 m. We discuss how this knowledge might be used to better manage Qfly by alterations in surveillance and male annihilation technique.

Use of the tetrazolium test for estimating the physiological quality of seeds

The tetrazolium test has been developed and improved since the early years of the 20 th century. Hundreds of seed specialists have dedicated their efforts for perfecting the methodology of the test for several species. Among these seeds experts, two of them deserve special recognition, Dr. Georg Lakon and Dr. Robert P. Moore, whose achievements had fundamental importance for the further development of the test. The test relies on the activity of certain dehydrogenase enzymes and indirectly measures the respiration capability of the living tissues of the seeds. The initial objective of the test was to quickly determine seed viability. Later on, it focussed on estimating seed vigour and more recently in diagnosing the possible causes that contribute to reduce the physiological quality of seed lots, such as mechanical damage, weathering damage and insect problems. Nowadays, the methodology of the tetrazolium test has been perfected for seeds of several species, including agricultural, vegetable, horticultural, flower, tree and shrub species. Seed quality control is improved with the use of the tetrazolium test in all phases of seed production such as harvesting, receiving, before and after seed processing and drying, during storage and before sowing. The test can be applied even before harvesting the crop. The methods for determining vigour will be briefly presented for seeds of the following species: cotton, common bean, maize, soybean, wheat, sunflower, peanut, Solanaceae, and tropical forage grass seeds. The utilisation of tetrazolium results, as with any vigour test, can assist the categorisation of vigour levels for different seed lots and for estimating the performance of these lots in the field under optimum and stressful conditions.

Targeted approaches to improve tomato fruit taste.

Tomato (Solanum lycopersicum) is the most valuable fruit and horticultural crop species worldwide. Compared with the fruits of their progenitors, those of modern tomato cultivars are, however, often described as having unsatisfactory taste or lacking flavor. The flavor of a tomato fruit arises from a complex mix of tastes and volatile metabolites, including sugars, acids, amino acids, and various volatiles. However, considerable differences in fruit flavor occur among tomato varieties, resulting in mixed consumer experiences. While tomato breeding has traditionally been driven by the desire for continual increases in yield and the introduction of traits that provide a long shelf-life, consumers are prepared to pay a reasonable premium for taste. Therefore, it is necessary to characterize preferences of tomato flavor and to define its underlying genetic basis. Here, we review recent conceptual and technological advances that have rendered this more feasible, including multi-omics-based QTL and association analyses, along with the use of trained testing panels, and machine learning approaches. This review proposes how the comprehensive datasets compiled to date could allow a precise rational design of tomato germplasm resources with improved organoleptic quality for the future.

The chloroplast genome of the Iris japonica Thunberg (Butterfly flower) reveals the genomic and evolutionary characteristics of Iris species

Iris japonica Thunberg is one of the horticultural species belonging to the Iris genus and Iridaceae family. Previous studies have revealed its hepatoprotective activity and ornamental values. However, little genetic and genomic information about this species is available. Here, to decipher the chloroplast genome and reveal its evolutionary characteristics, we sequenced, de novo assembled, and comprehensively analyzed the chloroplast genome of I. japonica. The genome was 152,453 bp in length and displayed a circular structure with a large single-copy region, a small single-copy region, and two inverted repeat regions. It contained 131 genes, including 85 protein-coding genes, eight ribosomal RNA genes, and 38 transfer RNA genes. We also identified 23 microsatellite repeat sequences, 34 tandem repeat sequences, and 60 dispersed repeat sequences in the chloroplast genome of I. japonica. Sequence divergence analyses of the chloroplast genomes of 20 Iris species revealed that the top four most highly variable regions were ndhC-trnV-UAC, rpl22-rps19, rps16-trnQ-UUG, and trnG-UCC-trnR-UCU. Phylogenetic analysis showed that I. japonica was most closely related to I. tectorum. This study reported a new chloroplast genome of I. japonica and performed comparative analyses of 20 Iris chloroplast genomes. The results would facilitate the evolutionary research and development of molecular markers for Iris species.

Nitrogen Influence to the Independent Invasion and the Co-Invasion of Solidago canadensis and Conyza canadensis via Intensified Allelopathy

The allelopathy of alien plants is critical to their successful invasion. In nature, two alien plants can co-invade the same habitat. Changes in the forms of nitrogen may have the potential to alter the invasion process of alien plants by causing alterations in their allelopathy. This study aimed to evaluate the individual and combined allelopathy of two alien plants from the Asteraceae family, Solidago canadensis L. and Conyza canadensis (L.) Cronq. This study examined the effects of aqueous leaf extracts of the two alien plants with different nitrogen forms (NO3−N, NH4−N, and CO(NH2)2−N, and the mixed nitrogen forms at a 1:1:1 ratio) on the seed germination and seedling growth of the horticultural Asteraceae species Lactuca sativa L. using a germination bioassay. The allelopathy of the two alien plants significantly reduced the seed germination and seedling growth of L. sativa. Extracts from S. canadensis produced stronger allelopathy on the seed germination and seedling growth of L. sativa compared with those from C. canadensis. The mixture of extracts from the two alien plants produced an antagonistic effect when compared with the effects of extracts from each plant species. The addition of nitrogen intensified the allelopathy of the two alien plants on the seed germination and seedling growth of L. sativa. The degree of influence of nitrogen on the individual and combined allelopathy of the two alien plants was similar. Thus, nitrogen deposition may facilitate the independent invasion and co-invasion of the two alien plants via intensified allelopathy.