During the reproductive transition in flowering plants a vegetative apical meristem (SAM) forming leaves, becomes an inflorescence meristem (IM) that forms bracts and flowers. In the monocot model Oryza sativa, the core flowering genetic regulatory network (GRN) relies on early activation of four major promoters, namely Heading date 3a (Hd3a, a FLOWERING LOCUS T-FT), Heading date 1 (Hd1, a CONSTANS-CO), FLOWERING LOCUS D (OsFD1), and 14–3–3 proteins, which form a florigen activation complex (FAC) to regulate the transition from SAM to IM. This is followed by the transcription of OsMADS22, OsMADS47 (an AGAMOUS-like 24/ SHORT VEGETATIVE PHASE-AGL24/SVP), OsMADS50 and OsMADS51 (a SUPPRESSOR OF OVEREXPRESSION OF CONSTANS 1-SOC1) that activate floral meristem identity genes like OsMADS14 and OsMADS15 (FRUITFUL-like-FUL homologs). Other genes like TERMINAL FLOWER LOCUS 1 (TFL1) and OsMADS55 (AGL24/SVP) repress flowering and maintain the vegetative phase. Our goal is to evaluate the flowering GRN in the Orchidaceae (ca. 25,000 species), one of the most diverse groups of ornamental angiosperms. In order to understand the molecular mechanisms that trigger flowering in Orchidaceae, we sequenced 13 reference transcriptomes of neotropical orchid species representing different phylogenetic positions, having ornamental potential and diversity of growth and floral forms. We isolated homologs and performed phylogenetic analyses of all genes from the flowering GRN to understand the evolution of these gene lineages. Our ML results indicate that FT/TFL1, FD, AGL24/SVP, SOC1 and FUL gene lineages have been subject to multiple duplications in monocots as well as in Orchidaceae as a result of recorded whole genome duplication events. In particular, we emphasize the recovery of six subclades of FT, three of FUL-like, three of AGL24/SVP, three of FD and three of SOC1. Conversely, fewer TFL1 homologs are found and some genes like FLC are lost in Orchidaceae, which suggests major changes in the repression of flowering. Our studies also show active expression of many representative genes in Cattleya trianae and Elleanthus aurantiacus in the SAM and in IM indicating important functions in the reproductive transition. We hypothesize that the flowering GRN in orchids has significant variations in copy number and expression patterns when compared to the canonical rice flowering GRN

Plant genetics is more quantitative and analytical than other areas of plant biology. The mathematical descriptions of Mendelian inheritance and population genetics are sometimes discouraging, and students often have serious misconceptions. Innovative strategies in expositive classes can clearly encourage student’s motivation and participation, but laboratories and practical classes are generally the students‘ most favorite academic activities. Genetic practices are usually employed with the aim to teach experimental methods (as PCR, DNA extraction,…). However, the design of lab practices focused on the learning of abstract concepts such as genetic interaction, quantitative inheritance, genetic linkage, genetic recombination, gene mapping, or molecular markers, is a complex task that requires a suitable segregant plant material. The most optimal population for pedagogical purposes is an F₂ population, which results in extremely useful not only to explain different key concepts of genetics (as dominance, epistasis, and linkage) but also to introduce to the student's additional curricular tools, particularly, concerning statistical analysis. Among various model organisms available, barley possesses several unique features for demonstrating genetic principles. Therefore, we have generated a barley F₂ population from the parental lines of the Oregon Wolfe Barley collection (https://barleyworld.org/owb). The objective of this work is to present this F₂ population, composed of more than 300 individuals, as a model to teach Mendelian genetics in a medium-high level Genetics course. We provide an exhaustive phenotypic and genotypic description of this plant material, including qualitative and quantitative traits as well as a set of molecular markers. Examples of genetic interaction (epistasis) and linkage analysis are explored and discussed. The description of the specific methodologies and practical exercises carried out in our Genetics courses can be helpful for transferring our fruitful experience to anyone interested in implementing this educational resource in his/her teaching.

Oaks are one of the most important and most common deciduous tree species in the forests of Central Europe, accounting for 10% of the total area. However, due to progressive global warming, the oak is increasingly exposed to biotic and abiotic stressors. In addition to drought and heat, thermophilic herbivorous insects are also a challenge for the oaks.

During studies on the green oak leaf roller (Tortrix vidiana L.) in North Rhine-Westphalia (Germany), differences in the infestation intensity of individual oaks by this herbivorous moth were found, which led to a definition of tolerant (T-oaks, little defoliated) and susceptible (S-oaks, heavily defoliated) oaks.

To validate results from conducted biochemical and molecular studies, ethological studies were carried out with the specialist Tortrix viridana (2013) and the generalist Lymantria dispar L. (gypsy moth) (2019). The parameters used to determine the performance of these herbivorous insects on the two different oak genotypes were developmental time, amount of fed leaves, and mortality of larvae and pupae during the juvenile phase.

While the overall developmental time of green oak leaf roller larvae did not show a significant difference on S- and T-oaks, especially the female larvae of Lymantria dispar needed a longer developmental time on T-oaks.

On T-oaks, larvae of Tortrix viridana had to consume significantly more leaf material to achieve approximately the same pupal weight as larvae fed on S-oaks. In contrast, larvae of the gypsy moth tended to ate less T-oak than S-oak leaf material without revealing differences in pupal weights.

For the green oak leaf roller the mortality of pupae from T-oaks was significantly higher than from S-oaks. For Lymantria dispar no significant differences in mortality was observed.

Basically, T-oaks seem to offer a poorer nutritional and developmental basis for both kinds of leaf-eating insects.

Common bean (Phaseolus vulgaris L.) is a major grain legume consumed worldwide with high nutritional value. Seed-borne pathogens represent a serious problem for seeds, causing losses of yield and quality reduction.

Basilicata Region (southern Italy) is a traditional, vocational area of bean production, in particular for "Fagioli di Sarconi" common beans, including different ecotypes protected by the European Union with the mark PGI (Protected Geographical Indication).

The study aimed to determine the presence of seed-borne pathogens isolated from seeds of two ecotypes of "Fagioli di Sarconi" common beans, "Ciuoto" and "Cannellino rosso", collected from three different cultivation areas of Basilicata Region during the years 2018 and 2019, for identifying genotypes resistant to seed-borne pathogens and well adapted to climatic changes.

The seeds were preliminary evaluated for their purity and germinability and treated or not with sodium hypochlorite for seed-borne pathogens screening, by using three validated seed health testing methods, according to the 2020 International Rules for seed testing: washing, blotter and between paper tests.

The washing test identified 17 fungal pathogens, different for ecotype and year of observation. Furthermore, the 1% sodium hypochlorite treatment strongly reduced the contaminants maintaining the Rhizoctonia solani, Colletotrichum lindemuthianum, Fusarium oxysporum, Fusarium solani pathogens; instead, using the blotter test, Aspergillus spp., Cladosporium spp., Botrytis spp., Mucor spp., Rhizophus spp. saprophyte pathogens resulted.

Finally, between paper test, specific for detecting the C. lindemuthianum, revealed the presence of this pathogen for the both ecotypes and years, in all areas. This assay individuated some bacteria, too.

Crop growth in acidic soils is generally limited by low soil fertility [low phosphorus (P) levels] and Al and Mn toxicity. Adequate P nutrition is normally supplied through soil P fertilizers that are obtained from mined phosphorite found mainly in Morocco. Unfortunately, the scarcity of this non-renewable mineral resource is already feared, which led some of the largest global fertilizer producers to cease exports¹. Arbuscular mycorrhizal fungi (AMF) are known to improve the host resistance to biotic and abiotic stress as well as water and nutrient acquisition, particularly P. When colonization is initiated from a pre-established intact extraradical mycelium (ERM), shoot P levels can increase almost 1.7-fold, depending on the plant species associated to ERM development (Developer)². In the present study, wheat (Triticum aestivum L.), one of the most widely produced cereal crops, was grown in acidic soil where intact ERM of AMF associated to native stress adapted Developers was previously grown. The non-mycotrophic Silene gallica L. (SIL), was compared to strongly mycotrophic Lolium rigidum L. (LOL) and Ornithopus compressus (ORN), whose role as ERM Developers have previously shown wheat growth promoting properties². After 3 weeks, wheat shoots P levels and subcellular redistribution were analysed through inductively coupled plasma mass spectrometry (ICP-MS)³.

Mycotrophic Developers established ERMs that promoted wheat shoot P accumulation (1.7 and 1.6-fold for LOL and ORN, respectively). Wheat P redistribution was determined after shoot sample fractionation through differential centrifugation. One fraction contained cell wall debris and metal granules (apoplastic fraction) and the other the organelles and vacuole contents (symplastic fraction). Shoots of wheat grown after SIL showed 40% of P at the apoplastic fraction while after LOL or ORN this proportion was approx. 50%.

Intact ERM from mycotrophic Developers adapted to acidic soils seems to influence crop growth by increasing P uptake and managing its subcellular distribution. This knowledge is important in the development of sustainable agricultural practices in the framework of net carbon zero-emission agriculture.

1. Campos, P. et al. Phosphorus Acquisition Efficiency Related to Root Traits: Is Mycorrhizal Symbiosis a Key Factor to Wheat and Barley Cropping? Front. Plant Sci. 9, 1–21 (2018).

2. Brito, I., Carvalho, M., Alho, L. & Goss, M. J. Managing arbuscular mycorrhizal fungi for bioprotection: Mn toxicity. Soil Biol. Biochem. 68, 78–84 (2014).

3. Faria, J. M. S. et al. Toxic levels of manganese in an acidic Cambisol alters antioxidant enzymes activity, element uptake and subcellular distribution in Triticum aestivum. Ecotoxicol. Environ. Saf. 193, 110355 (2020).

The use of natural enemies against crop pests has been promoted during the last decades. Among natural enemies, spiders are efficient generalist predators. An efficient pest limitation relies on the overlap of the predator and the pest in time and space. In Portugal, the cultivation of the olive tree (Olea europaea L.) represents a key economic and cultural activity. Previous works highlighted the ground hunter spider Haplodrassus rufipes (Lucas, 1846) (Araneae: Gnaphosidae) as a promising natural enemy against the olive fruit fly Bactrocera oleae (Rossi, 1790), the main pest of the olive tree in northeastern Portugal. The objectives of this work were (1) to approximate the distribution of H. rufipes throughout the whole Iberian Peninsula using the climatic suitability as surrogate of its potential distribution, and (2) compare it with the distribution of O. europaea to assess the match between the distributions of both species. The probability of occurrence of H. rufipes was approximated using a maxent (maximum entropy) algorithm based on presence-only data. Bioclimatic data was obtained from the WorldClim database at a 1 km resolution. The optimal model was selected using the checkerboard method for data partitioning. The distribution of O. europaea was visualized using a chorological map. The most contributing bioclimatic variables to the maxent model were the mean diurnal range, the temperature annual range, and the precipitation of the driest month. The distribution of O. europaea fairly overlapped the highest values of the bioclimatic suitability of H. rufipes (p > 0.6) throughout the Iberian Peninsula. Our results support further studies on the role of H. rufipes as a potential natural enemy in the olive grove agroecosystem.

The authors are grateful to the Foundation for Science and Technology (FCT, Portugal), for financial support through the project “Gestão dos serviços de ecossistema no olival utilizando modelos espaciais avançados - OLIVESIM” PTDC/ASP-PLA/30003/2017.

Rice blast is one of the most widespread diseases threatening rice production and crop damage accounts for a major loss to rice farmers worldwide. To identify genetic regions associated with leaf blast resistance, a genome-wide association study was performed with 391 MAGIC indica plus rice accessions developed at IRRI, Philippines. Evaluation of leaf blast severity was performed in the uniform blast nursery (UBN) during 2016 and 2017 at ICAR-IIRR, Hyderabad, India. Genome-Wide Association Study was performed using six different statistical models with GBS data on 27041 single nucleotide polymorphisms (SNPs) distributed on all 12 rice chromosomes. A total of 130 associated SNP were detected and only seven common SNPs were identified with all the models on chromosome 3, 8, and 12. Farm CPU and Blink gave similar results and detected 31 associated SNPs on chromosome 3, 8, and 12. The highest number of annotated genes were identified on chromosome 12 followed by 8 and 3. Chromosome 12 harboring a major cluster of blast resistant genes and at least 20 blast resistant genes were mapped on this chromosome. Candidate genes identified in associated SNP regions on chromosome 12 in our study are encoding disease resistance genes; stripe rust resistance protein, MLA12, NBS-LRR disease resistance protein, NB-ARC domain-containing protein, CC-NBS-LRR resistance protein MLA13, indicating the possibility of developing casual SNPs/QTNs for leaf blast resistance in rice from these regions.

Many natural control agents of olive pests need pollen and nectar from non-crop plants in order to complete their life cycles. However, a deep knowledge about the occurring plant species in the agroecosystem is necessary to select the plant species to be maintained or enhanced from a conservation biological control approach. Thus, in this study the goal was to increase the understanding about the plants biodiversity in Mirandela, an important olive producing region in the northeast of Portugal. For that, in a weekly basis during spring and every other week in summer and autumn blooming plant inventories were accomplished in three olive orchards with spontaneous vegetation and its surroundings (woody and herbaceous vegetation areas) from April to December of 2012 and 2013. The percentage ground cover for each flowering plant species was recorded following the Daubenmire cover scale modified by Bailey. From total of 258 plant species belonging to 47 families, 172, 169 and 180 species were identified in the herbaceous, olive and woody plots respectively. The most abundant family was Asteraceae followed by Poaceae, Fabaceae and Brassicaceae and the most abundant species was Coleostephus myconis (L.) Rchb.f. followed by Echium plantagineum L. (Boraginaceae), Chamaemelum mixtum (L.) All. (Asteraceae) and Crepis capillaris (L.) Wallr. (Asteraceae). Several species were specific of each land use and presented different flowering periods, representing a potential variety of food sources across the seasons. Additionally, some of the identified species, such as Foeniculum vulgare L. (Apiaceae), are known for their implications as providers of key requisites for natural control agents. These result provided with valuable information for the implementation of conservation biological control measures.

The plant cell wall (PCW) is a multidimensional structure composed of a cellulose microfibril net embedded in a soluble matrix of pectic polysaccharides, hemicelluloses, and a small proportion of glycoproteins, phenolic components and ions ¹. Understanding the contribution of cell wall components to the mechanical and biological properties of cell walls as a whole is challenging, due to the heterogeneity of plant tissues/organs and the ability of plants to adapt and modify cell wall composition in response to environmental stimuli ².

Different approaches have been developed to study the mechanics of the cell wall or the interaction between polysaccharides. For example: Atomic Force microscopy or Brillouin scattering. These methods are difficult to set-up, rely in highly qualified experts and expensive equipment which can limit their routine application in regular labs. Therefore, in this publication a method is presented to analyse the properties and interactions of PCW individual components by mimicking the cell wall tri-dimensional matrix using a simplified model of composite macro-hydrogels & alcogels and a texture analyser. The analysis of cellulose-xylan hydrogels using a Texture Analyser will be reported for first time here. The results confirm the applicability of this method in the screening of interactions between cell walls polymers. We also applied the method to study the properties of cellulose extracted from tomato as these are unused products in the food industry. Results are compared and correlated with material composition offering a new approach for the screening of agricultural waste available for exploitation in new materials.

Unravel the mechanical properties of the cell wall and/or individual cell wall glycans is now a priority, in order to act in advance to the imminent global change and look for new bio-degradable low cost materials derived from renewable sources that can be used as an alternative to environmentally hazardous plastic. Additionally, texture analysis of the cell wall polysaccharides could be relevant for other disciplines as a food industry ³ or medical engineering to develop scaffolds ⁴or drug delivery ⁵.

References:

1. Jamet, E. & Dunand, C. Plant Cell Wall Proteins and Development. Int J Mol Sci21, doi:10.3390/ijms21082731 (2020).
2. Lopez-Sanchez, P.et al. Cellulose-pectin composite hydrogels: Intermolecular interactions and material properties depend on order of assembly. Carbohydr Polym 162, 71-81, doi:10.1016/j.carbpol.2017.01.049 (2017).
3. Riaz, A.et al. Preparation and characterization of chitosan-based antimicrobial active food packaging film incorporated with apple peel polyphenols. Int J Biol Macromol 114, 547-555, doi:10.1016/j.ijbiomac.2018.03.126 (2018).
4. Gershlak, J. R.et al. Crossing kingdoms: Using decellularized plants as perfusable tissue engineering scaffolds. Biomaterials 125, 13-22, doi:10.1016/j.biomaterials.2017.02.011 (2017).
5. Xiao, Y.et al. Low cost delivery of proteins bioencapsulated in plant cells to human non-immune or immune modulatory cells. Biomaterials 80, 68-79, doi:10.1016/j.biomaterials.2015.11.051 (2016).

Tomato, Solanum lycopersicum, is one of the most cultivated vegetable worldwide with more than two hundred million tonnes of fruit produced in 2018 worldwide. However, between one quarter and half of the production is lost due to uncontrolled conditions during transport and storage. Understanding the biological components and processes that affect the physical properties and structure of tomato fruits during the post-harvest is essential to design new strategies to reduce these losses. The aim of this project is to determine whether the callose metabolism has an indirect or direct positive impact on the shelf-life of the tomato fruit. Callose synthesis is catalysed by a multi-subunit enzyme complex with a catalytic subunit known as Callose Synthases (Cals), whereas callose degradation is mediated by β-1,3- glucanases (BGs).

In this publication, we will present the first objective of the project: “The selection of specific tomato BG genes via an in-silico approach”¹. In this regard, 50 callose degrading enzymes (beta-1,3-glucanases) were identified in-silico using bioinformatic tools. Phylogenetic analysis revealed tomato genes being distributed in three cluster (α, b and γ) with evolutionary relations with previously characterized Arabidopsis thaliana BG enzymes². Expression data revealed different expression patterns across tissues and organs. Interestingly, microarray expression analysis showed two trends in the BG temporal expression in fruit flesh: expression of enzymes in cluster α (which comprises all previously localized plasmodesmata proteins) decreased during the ripening, while enzymes in clusters β and γ (including pathogenesis-induced proteins) increased. To verify correlations between expression and function, two enzymes were selected, one from cluster a, which is repressed during ripening, and one from cluster b, which is induced during ripening. qRT-PCR will be used to confirm the expression of the selected genes. Transient overexpression of the selected genes driven by a 35 S CaMV (Cauliflower Mosaic Virus) promoter in tomato fruit will be performed via infiltration of tomato fruit with Agrobacterium tumefaciens. Preliminary experimental data will be presented.

References:

¹Gaudioso-Pedraza, Rocio, and Yoselin Benitez-Alfonso. ‘A Phylogenetic Approach to Study the Origin and Evolution of Plasmodesmata-Localized Glycosyl Hydrolases Family 17’. Frontiers in Plant Science 5 (23 May 2014). https://doi.org/10.3389/fpls.2014.00212

²Doxey, A.C., Yaish, M.W.F., Moffatt, B.A., Griffith, M., McConkey, B.J. Functional Divergence in the Arabidopsis -1,3- Glucanase Gene Family Inferred by Phylogenetic Reconstruction of Expression States. Molecular Biology and Evolution 24,(2007): 1045–1055. https://doi.org/10.1093/molbev/msm024

This project has received funding from the European Union’s Horizon 2020 research and innovation programme under the Marie Skłodowska-Curie