Pollen viability and incompatibility in indigenous rice bean (Vigna umbellata (Thunb.) Ohwi & Ohashi)

Pollen viability, germination and compatibility are essential in determining the success of pollination and seed setting of high-valued crops. Rice bean (Vigna umbellata (Thunb.) Ohwi & Ohashi) is an underutilized and unexplored indigenous legume with high potential for commercial production. In this study, pollen quality, viability, germination rate and incompatibility among selected six rice bean (V. umbellata) accessions from Barili, Cebu, Philippines were evaluated to determine the barriers and effective pollination habit for increased productivity while retaining the important traits, including high tolerance in poor soils, superior climatic resilience and resistance to pest and diseases. Results of acetocarmine calorimetric assay showed that rice beans’ (V. umbellata) pollens are highly viable, with accessions VU 004 (56.33 ± 4.91%) and VU 007 (54.34 ± 4.53%) having the optimum viability rate. Brewbaker and Kwack medium treated with 0.2 g.l-1 and 0.3 g.l-1 boric acid (H3BO4) enhanced the germination rate in vitro (11.56 ± 5.53% and 9.47 ± 6.50% respectively). Bud (14.96 ± 1.53%) and post-anthesis pollens (10.28 ± 0.94%) have optimum germination rate in 0.2 g.l-1 boric acid media, while anthesis pollens are suitable in media supplemented with sucrose and boric acid alone (12.20 ± 1.50%) and with 0.1 g.l-1 myo-inositol supplementation (8.49 ± 1.86%). Pollination test revealed that rice bean accessions have high self-compatibility (50.76 + 3.45%) and low cross-compatibility (26.57 + 2.49%). The findings provide an important background in understanding the pollen quality and intraspecific interaction among indigenous rice bean (V. umbellata) accessions in Barili, Cebu to improve production and hybridization.

Seed Paternity Analysis Using SSR Markers to Assess Successful Pollen Donors in Mixed Olive Orchards

The olive tree (Olea europaea L.) is a wind-pollinated crop that exhibits an extreme alternate bearing habit. To improve fruit set, several methods have been used to determine the most successful compatible combinations of cultivars. In this study, priority is given to seed paternity analysis based on simple sequence repeats (SSRs), microsatellite markers used for the identification of potential pollen donors of cultivar ‘Oblica’ in a mixed olive orchard during two consecutive years. Seven microsatellite primers were successfully used to examine the paternity of olive embryos from ‘Oblica’ mother trees. Embryos were considered as a product of self-fertilization if only maternal alleles were present, but not a single case of self-fertilization was found among all the embryos analyzed. Two dominant pollen donors were not the closest nor the cultivars with the highest number of trees in the orchard, suggesting that cross-compatibility may have a key role in determining pollen donor success. In our earlier studies, pollen tube growth and fertilization success correlated with fruit set when controlled crosses between cultivars were performed; however, some discrepancy might appear compared to paternity analyses when mother trees have a free choice among different pollen sources from cultivars growing in their surroundings.

Web-Based Tool for Algebraic Modeling and Mathematical Optimization

In this article, we present a new open-source tool for algebraic modeling and mathematical optimization. We begin by distilling the main gaps within the existing algebraic modeling languages and tools (varying performance, limited cross-compatibility, complex syntax, and different solver, feature, and problem type support). Later, we propose a state-of-the-art web-based tool (WebAML and Optimization System) for algebraic modeling languages and mathematical optimization. The tool does not require specific algebraic language knowledge, allows solving problems using different solvers, and utilizes the best characteristics of existing algebraic modeling languages. We also provide clear extension points and ideas on how we could further improve such a tool.

Engineering a thixotropic and biochemically tunable hyaluronan and collagen bioink for biofabrication of multiple tissue construct types

The field of three-dimensional (3D) bioprinting has advanced rapidly in recent years. Significant reduction in the costs associated with obtaining functional 3D bioprinting hardware platforms is both a cause and a result of these advances. As such, there are more laboratories than ever integrating bioprinting methodologies into their research. However, there is a lack of standards in the field of biofabrication governing any requirements or characteristics to support cross-compatibility with biomaterial bioinks, hardware, and different tissue types. Here we describe a modular extracellular matrix (ECM) inspired bioink comprised of collagen and hyaluronic acid base components that: 1) employ reversible internal hydrogen bonding forces to generate thixotropic materials that dynamically reduce their elastic moduli in response to increased shear stress, thus enabling increased compatibility with printing hardware; and 2) modular addons in the form of chemically-modified fibronectin and laminin that when covalently bound within the bioink support a variety of tissue types, including liver, neural, muscle, pancreatic islet, and adipose tissue. These features aim to accelerate the deployment of such bioinks for tissue engineering of functional constructs in the hands of various end users.

Genome-Wide Analysis of Almond Skp1 Family Members And Identification of Self-Incompatibility-Related PsdSSK1

S-phase kinase-associated protein 1 ( Skp1 ) is a component of the SKP1-Cullin1-F-box (SCF) complex, which facilitates ubiquitin-mediated protein degradation in eukaryotes. SLF interacting Skp1-like 1 ( SSK1 ), which is located outside the S-site, is a newly discovered type of self-incompatibility-related pollen-specific gene whose product interacts with pollen determinants. In this study, we identified 18 members of the Prunus dulcis Skp1 (PsdSkp1) family that were unevenly distributed across six chromosomes of the almond genome. The phylogenetic tree revealed that the PsdSkp1 members could divided into four groups: I, II, III, and IV. The conserved motifs, conserved domains, and motif structures of the PsdSSK1 and PsdSkp1-12 proteins are similar. There were three pairs of fragment duplication genes and one pair of tandem repeat genes, and their functions were highly evolutionarily conserved. Transcriptome data showed that PsdSkp1 was expressed in almond flower tissues, that its expression was affected by freezing stress, and that its expression changed significantly in cross-pollination. Molecular experiments proved that PsdSSK1 and PsdSkp1-12 had the same protein sequence, and the genes were significantly highly expressed mainly in the pollen or throughout pollen cells, with subcellular localization in the cytoplasm. PsdSkp1-12 is an ssk1 gene in almond, and it may be involved in the SCF complex to regulate the almond pollen response via SI and cross-compatibility. In conclusion, our research lays a foundation for future functional research on PsdSkp1 members, especially for exploring the mechanism of almond SI.

Cross-compatibility of cultivated cowpea varieties and their wild relatives: Implications for crop improvement

Hybridization programmes that potentially exploit the variability existing in the wild germplasm of Vigna unguiculata L. Walpers could be of great potential for the future of plant breeding. Bearing this in mind, four cultivated cowpea varieties (Achi shuru, Ife Brown, Kanannado and Zebra bean) were crossed to two of their wild relatives: subsp. dekindtiana var. pubescens and subsp. unguiculata var. spontanea to ascertain the cross compatibility, reproductive potential and possible heterosis in the F1 generations. Results showed that the cultivated varieties hybridized relatively well with their wild relatives showing pod set range of 42.9% to 52.3% in crosses with subsp. dekindtiana var. pubescens and 40.0% to 52.0% in crosses with subsp. unguiculata var. spontanea. The F1 hybrid plants showed high heterosis in plant height, number of leaves per plant, number of flowers per plant, number of pods per plant and percentage pod set. They also produced viable seeds for F2 generations. These results are indications of a good reproductive potential of the hybrids thus making the wild relatives, good sources of important gene pool for the improvement of the cultivated populations.

Genome-Wide Association Studies for Sex Determination and Cross-Compatibility in Water Yam (Dioscorea alata L.)

Yam (Dioscorea spp.) species are predominantly dioecious, with male and female flowers borne on separate individuals. Cross-pollination is, therefore, essential for gene flow among and within yam species to achieve breeding objectives. Understanding genetic mechanisms underlying sex determination and cross-compatibility is crucial for planning a successful hybridization program. This study used the genome-wide association study (GWAS) approach for identifying genomic regions linked to sex and cross-compatibility in water yam (Dioscorea alata L.). We identified 54 markers linked to flower sex determination, among which 53 markers were on chromosome 6 and one on chromosome 11. Our result ascertained that D. alata is characterized by the male heterogametic sex determination system (XX/XY). The cross-compatibility indices, average crossability rate (ACR) and percentage high crossability (PHC), were controlled by loci on chromosomes 1, 6 and 17. Of the significant loci, SNPs located on chromosomes 1 and 17 were the most promising for ACR and PHC, respectively, and should be validated for use in D. alata hybridization activities to predict cross-compatibility success. A total of 61 putative gene/protein families with direct or indirect influence on plant reproduction were annotated in chromosomic regions controlling the target traits. This study provides valuable insights into the genetic control of D. alata sexual reproduction. It opens an avenue for developing genomic tools for predicting hybridization success in water yam breeding programs.

Growing Environment and Heat Treatment Effects on Intra- and Interspecific Pollination in Chile Pepper (Capsicum spp.)

Heat tolerance is important for the sustainable production of many crops, including chile pepper. Tolerance to high temperature is complex and involves various component traits, with pollen viability being among the most important. in vitro pollen assays for heat tolerance have been widely used in chile pepper; however, associations between the pollen treatment and pollination have not been widely explored. The objectives of this study were to validate the utility of in vitro heat stress pollen characterization through in vivo pollination during summer and winter seasons and to evaluate the cross-compatibility among wild and domesticated species to initiate introgression population development. Seven entries of wild and domestic Capsicum species grown during the summer and winter seasons were used to evaluate pollination success rate. Pollen was either used directly or treated at 38 °C for four hours before making reciprocal self- and cross-pollination among all the entries. Significant associations between in vitro pollen treatment and pollination success rate during summer and winter seasons were identified. Heat treatment was a greater contributor to variability than the growing environment, which validates previous reports on the usefulness of studying pollen in vitro in selection for heat tolerance. Accessions of the wild progenitor C. annuum var glabriusculum, PBC 1969 and PBC 1970, were identified as a potential heat-tolerant source for use in breeding and future research. This work provides a basis for future research in exploring additional heat tolerance components as well as for the development of phenotyping assays for pollen or other floral traits.