Differential gene expression among three sex types reveals a MALE STERILITY 1 (CpMS1) for sex differentiation in papaya

Background Carica papaya is a trioecious plant species with a genetic sex-determination system defined by sex chromosomes. Under unfavorable environmental conditions male and hermaphrodite exhibit sex-reversal. Previous genomic research revealed few candidate genes for sex differentiation in this species. Nevertheless, more analysis is still needed to identify the mechanism responsible for sex flower organ development in papaya. Results The aim of this study was to identify differentially expressed genes among male, female and hermaphrodite flowers in papaya during early (pre-meiosis) and later (post-meiosis) stages of flower development. RNA-seq was used to evaluate the expression of differentially expressed genes and RT-qPCR was used to verify the results. Putative functions of these genes were analyzed based on their homology with orthologs in other plant species and their expression patterns. We identified a Male Sterility 1 gene (CpMS1) highly up-regulated in male and hermaphrodite flower buds compared to female flower buds, which expresses in small male flower buds (3–8 mm), and that might be playing an important role in male flower organ development due to its homology to MS1 genes previously identified in other plants. This is the first study in which the sex-biased expression of genes related to tapetum development in the anther developmental pathway is being reported in papaya. Besides important transcription factors related to flower organ development and flowering time regulation, we identified differential expression of genes that are known to participate in ABA, ROS and auxin signaling pathways (ABA-8-hydroxylases, AIL5, UPBEAT 1, VAN3-binding protein). Conclusions CpMS1 was expressed in papaya male and hermaphrodite flowers at early stages, suggesting that this gene might participate in male flower organ development processes, nevertheless, this gene cannot be considered a sex-determination gene. Due to its homology with other plant MS1 proteins and its expression pattern, we hypothesize that this gene participates in anther development processes, like tapetum and pollen development, downstream gender specification. Further gene functional characterization studies in papaya are required to confirm this hypothesis. The role of ABA and ROS signaling pathways in papaya flower development needs to be further explored as well.Ope

Taro raphide‐associated proteins: Allergens and crystal growth

Abstract Calcium oxalate raphide crystals are found in bundles in intravacuolar membrane chambers of specialized idioblasts cells of most plant families. Aroid raphides are proposed to cause acridity in crops such as taro (Colocasia esculenta (L.) Schott). Acridity is irritation that causes itchiness and pain when raw/insufficiently cooked tissues are eaten. Since raphides do not always cause acridity and since acridity can be inactivated by cooking and/or protease treatment, it is possible that a toxin or allergen‐like compound is associated with the crystals. Using two‐dimensional (2D) gel electrophoresis and mass spectrometry (MS) peptide sequencing of selected peptides from purified raphides and taro apex transcriptome sequencing, we showed the presence on the raphides of peptides normally associated with mitochrondria (ATP synthase), chloroplasts (chaperonin ~60 kDa), cytoplasm (actin, profilin), and vacuole (V‐type ATPase) that indicates a multistage biocrystallation process ending with possible invagination of the tonoplast and addition of mucilage that may be derived from the Golgi. Actin might play a crucial role in the generation of the needle‐like raphides. One of the five raphide profilins genes was highly expressed in the apex and had a 17‐amino acid insert that significantly increased that profilin's antigenic epitope peak. A second profilin had a 2‐amino acid insert and also had a greater B‐cell epitope prediction. Taro profilins showed 83% to 92% similarity to known characterized profilins. Further, commercial allergen test strips for hazelnuts, where profilin is a secondary allergen, have potential for screening in a taro germplasm to reduce acridity and during food processing to avoid overcooking

Mejoramiento genético en tacaco

Informe final de proyecto de investigaciónSe visitaron varias zonas del país, con el fin de buscar genotipos de tacaco (Sechium tacaco) con características superiores, tales como ausencia de fibra en la pulpa, buen sabor, tamaño grande, y textura de pulpa agradable. Para esto se realizaron visitas a mercados, supermercados y verdulerías, con el fin de obtener información acerca de zonas de producción de tacaco y productores de esta hortaliza, en Cartago, Zona Sur, Alajuela y Guanacaste. Se colectaron frutos de los genotipos, que se consideran los de mejor calidad, y Todas las plantas existentes en las diversas localidades pertenecientes a la Universidad de Costa Rica, están disponibles para su utilización por parte de investigadores costarricenses, o para su propagación para beneficio de los agricultores costarricenses. La forma de reproducción tradicional del tacaco es por semilla; pero esta práctica es poco eficiente dada la baja viabilidad de las mismas y el prolongado tiempo de germinación (2-6 meses), además de que esta forma de propagación genera variación de características de interés en tacaco: ausencia de espinas o menor cantidad de fibras en el mesocarpo. Lo anterior, aunado al poco conocimiento en cuanto a técnicas de propagación vegetativa de tacaco, obliga a desarrollar protocolos de propagación asexual mediante la técnica de micropropagación in vitro que permitan clonar “variedades” con características agronómicas promisorias en esta especie. No existe en la literatura ningún protocolo descrito para la propagación asexual de tacaco mediante micropropagación in vitro, por lo que establecer el protocolo con aporte de literatura generada en especies relacionadas (como el chayote) ha tomado más tiempo del esperado. El establecimiento del material ha presentado problemas de contaminación y oscurecimiento, que se han intentado resolver haciendo modificaciones al protocolo de desinfección (tipo de desinfectante, concentración del desinfectante, tiempo en desinfectante, incubación en una solución antioxidante) e incluyendo en el medio de cultivo de establecimiento (MS + 3% sacarosa + 0,2% Phytagel) compuestos antioxidantes (carbón activado). Sin embargo, los porcentajes de contaminación y oxidación siguen siendo altos. También se realizaron pruebas con diferentes reguladores de crecimiento para la multiplicación del material previamente introducido y establecido. El porcentaje de éxito en la propagación in vitro ha sido muy bajo. El porcentaje de germinación de las semillas es un poco mayor al 50%. se sembraron en tres sitios: 1. Estación Experimental Fabio Baudrit (La Garita, Alajuela), Universidad de Costa Rica. 2. Finca Experimental Fraijanes (Fraijanes, Alajuela), Universidad de Costa Rica. 3. Finca Experimental Interdisciplinaria de Modelos Agroecológicos-FEIMA (Turrialba), Sede del Atlántico, Universidad de Costa Rica. Existen también las plantas ubicadas en el invernadero del CIGRAS.Universidad de Costa Rica/[736-B2-A07]/UCR/Costa RicaUCR::Vicerrectoría de Investigación::Unidades de Investigación::Ciencias Agroalimentarias::Estación Experimental Agrícola Fabio Baudrit Moreno (EEAFBM

Mejoramiento genético en tacaco (Sechium tacaco)

Resumen de conferenciaEl objetivo fue identificar y reproducir material genético promisorio de alta calidad en el cultivo de tacaco, que es la única especie de planta comestible endémica exclusivamente de Costa Rica. Se realizó una colecta de materiales genéticos de alta calidad en diversas regiones de Costa Rica, y se reprodujeron dichos materiales en condiciones in vitro y en invernadero; además, se establecieron bancos de germoplasma en cuatro sitios del país. Se realizó una caracterización morfológica de los frutos. Se identificaron cuatro genotipos de tacaco con características de alta calidad, tales como ausencia de fibra en la pulpa, y buen sabor y textura, procedentes de Tilarán, Paraíso, Escazú y Alajuela. Se establecieron microestacas in vitro, y plantas en invernadero en el CIGRAS y en bancos de germoplasma a campo abierto en Fraijanes, Alajuela, Turrialba y Heredia. El peso del fruto varía entre 25,7 – 48,9 g, y el número de espinas por fruto varía entre 0 – 32. Se avanzó en el desarrollo de protocolos de propagación asexual mediante la técnica de micropropagación in vitro, aunque el porcentaje de éxito ha sido muy bajo. El establecimiento in vitro del material ha presentado problemas de contaminación y oxidación; para tratar de solventar este problema se han realizado modificaciones al protocolo de desinfección (tipo de desinfectante, concentración del mismo, tiempo en desinfección, incubación en solución antioxidante, e inclusión de antioxidantes en el medio de cultivo). También se probaron reguladores de crecimiento añadidos al medio de cultivo para mejorar la brotación de los explantes.Universidad de Costa Rica/[]/UCR/Costa RicaInstituto Nacional de Innovación y Transferencia en Tecnología Agropecuaria/[]/INTA/Costa RicaUCR::Vicerrectoría de Investigación::Unidades de Investigación::Ciencias Agroalimentarias::Estación Experimental Agrícola Fabio Baudrit Moreno (EEAFBM

Transcription analysis of softening-related genes during postharvest of papaya fruit (Carica papaya L. ‘Pococí’ hybrid)

Fruit of Carica papaya L. (papaya) has several post-harvest problems mainly caused by quick softening that reduces its shelf life. This softening is directly related to degradation and modification of cell wall oligosaccharides. Therefore, it is important to study, understand and, eventually, regulate the softening process of this fruit to increase its shelf life. This work aims at looking for correlations between transcription patterns of four genes potentially involved in papaya fruit softening with postharvest treatments and the softening process. Papaya fruit (‘Pococí’ hybrid) were treated with ethylene (275–300 mL L−1), 1-methylcyclopropene (1-MCP, 300 nL L−1), or not treated, as control. Fruit were subsequently stored for eleven days at 18–20 °C and 95% relative humidity. During the evaluation period, firmness (N) and color (CIE L*, a* and b*) of pulp and peel were determined; pH, titratable acidity (TA) and total soluble solids (TSS) of pulp were also measured; in addition, transcription patterns of polygalacturonase, endoxylanase, pectinesterase and expansin genes were determined by real time PCR. Treatments showed differences in terms of firmness, color, pH, TA, ripening index and accumulation of transcripts of some genes. Transcription of polygalacturonase and endoxylanase genes correlated negatively with firmness of pulp and peel; whereas pectinesterase gene was positively correlated with peel firmness. No correlation with transcription of the expansin gene analyzed was found. Our results also suggest that polygalacturonase and endoxylanase correlated negatively with papaya fruit firmness and that 1-MCP treatment repressed and reduced the expression of these two genes, respectively. According to these results, silencing genes that encode polygalacturonases or endoxylanases might be a potential strategy to confirm their crucial role on papaya ripening.Food Security Center of the University of Hohenheim/[]/FSC/AlemaniaUniversidad de Costa Rica/[734-B3-106]/UCR/Costa RicaUCR::Vicerrectoría de Investigación::Unidades de Investigación::Ciencias Agroalimentarias::Centro para Investigaciones en Granos y Semillas (CIGRAS)UCR::Vicerrectoría de Docencia::Ciencias Agroalimentarias::Facultad de Ciencias Agroalimentarias::Escuela de Tecnología de AlimentosUCR::Vicerrectoría de Investigación::Unidades de Investigación::Ciencias Agroalimentarias::Estación Experimental Agrícola Fabio Baudrit Moreno (EEAFBM)UCR::Vicerrectoría de Investigación::Unidades de Investigación::Ciencias Agroalimentarias::Centro de Investigaciones Agronómicas (CIA)UCR::Vicerrectoría de Investigación::Unidades de Investigación::Ciencias Agroalimentarias::Centro Nacional de Ciencia y Tecnología de Alimentos (CITA

Seed germination of pitaya (Hylocereus spp.) as affected by seed extraction method, storage, germination conditions, germination assessment approach and water potential

To breed and preserve pitaya (Hylocereus spp.) genetic resources, reliable information on seed storage and germination conditions is needed. Therefore, this study was undertaken to evaluate the effects of the following factors on germination of pitaya seeds: seed extraction method (manual vs. enzymatic seed extraction), storage time and conditions (up to 12 months at room temperature and in a cold storage chamber), germination conditions [temperature (15, 20, 25 and 30ºC) and light (blue, red and darkness)], germination assessment method (conventional vs. automated with digital image analysis), harvesting season (2014 and 2015), and water potential (−0.5, −1.0 and −2.0 MPa induced by polyethylene glycol 6000 or NaCl). Results showed that freshly extracted seeds germinated close to 100% within one week. Enzymatic seed extraction increased germination speed. Room temperature-stored seeds lost viability compared to cold-stored seeds, whose germination did not change across 12 months of storage. When seeds were germinated at 15°C and in darkness, germination rate and speed decreased. Conventional and image analysis approaches showed a high coefficient of determination when measuring seed germination and allowed to calculate additional parameters, such as maximum germination (gMAX) and time to achieve 50% germination (T50). Water potential of −0.5 MPa negatively affected seed vigor but not gMAX; germination was inhibited below −1.0 MPa. Hylocereus seeds were more affected by polyethylene glycol 6000 than by NaCl at the same water potential.UCR::Vicerrectoría de Investigación::Unidades de Investigación::Ciencias Agroalimentarias::Centro para Investigaciones en Granos y Semillas (CIGRAS)UCR::Vicerrectoría de Investigación::Unidades de Investigación::Ciencias Agroalimentarias::Instituto de Investigaciones Agrícolas (IIA

Differential gene expression during floral transition in pineapple

Abstract Pineapple (Ananas comosus var. comosus) and ornamental bromeliads are commercially induced to flower by treatment with ethylene or its analogs. The apex is transformed from a vegetative to a floral meristem and shows morphological changes in 8 to 10 days, with flowers developing 8 to 10 weeks later. During eight sampling stages ranging from 6 h to 8 days after treatment, 7961 genes were found to exhibit differential expression (DE) after the application of ethylene. In the first 3 days after treatment, there was little change in ethylene synthesis or in the early stages of the ethylene response. Subsequently, three ethylene response transcription factors (ERTF) were up‐regulated and the potential gene targets were predicted to be the positive flowering regulator CONSTANS‐like 3 (CO), a WUSCHEL gene, two APETALA1/FRUITFULL (AP1/FUL) genes, an epidermal patterning gene, and a jasmonic acid synthesis gene. We confirm that pineapple has lost the flowering repressor FLOWERING LOCUS C. At the initial stages, the SUPPRESSOR OF OVEREXPRESSION OF CONSTANS 1 (SOC1) was not significantly involved in this transition. Another WUSCHEL gene and a PHD homeobox transcription factor, though not apparent direct targets of ERTF, were up‐regulated within a day of treatment, their predicted targets being the up‐regulated CO, auxin response factors, SQUAMOSA, and histone H3 genes with suppression of abscisic acid response genes. The FLOWERING LOCUS T (FT), TERMINAL FLOWER (TFL), AGAMOUS‐like APETELAR (AP2), and SEPETALA (SEP) increased rapidly within 2 to 3 days after ethylene treatment. Two FT genes were up‐regulated at the apex and not at the leaf bases after treatment, suggesting that transport did not occur. These results indicated that the ethylene response in pineapple and possibly most bromeliads act directly to promote the vegetative to flower transition via APETALA1/FRUITFULL (AP1/FUL) and its interaction with SPL, FT, TFL, SEP, and AP2. A model based on AP2/ERTF DE and predicted DE target genes was developed to give focus to future research. The identified candidate genes are potential targets for genetic manipulation to determine their molecular role in flower transition

Salt tolerance evaluation and mini-core collection development in Miscanthus sacchariflorus and M. lutarioriparius

Marginal lands, such as those with saline soils, have potential as alternative resources for cultivating dedicated biomass crops used in the production of renewable energy and chemicals. Optimum utilization of marginal lands can not only alleviate the competition for arable land use with primary food crops, but also contribute to bioenergy products and soil improvement. Miscanthus sacchariflorus and M. lutarioriparius are prominent perennial plants suitable for sustainable bioenergy production in saline soils. However, their responses to salt stress remain largely unexplored. In this study, we utilized 318 genotypes of M. sacchariflorus and M. lutarioriparius to assess their salt tolerance levels under 150 mM NaCl using 14 traits, and subsequently established a mini-core elite collection for salt tolerance. Our results revealed substantial variation in salt tolerance among the evaluated genotypes. Salt-tolerant genotypes exhibited significantly lower Na+ content, and K+ content was positively correlated with Na+ content. Interestingly, a few genotypes with higher Na+ levels in shoots showed improved shoot growth characteristics. This observation suggests that M. sacchariflorus and M. lutarioriparius adapt to salt stress by regulating ion homeostasis, primarily through enhanced K+ uptake, shoot Na+ exclusion, and Na+ sequestration in shoot vacuoles. To evaluate salt tolerance comprehensively, we developed an assessment value (D value) based on the membership function values of the 14 traits. We identified three highly salt-tolerant, 50 salt-tolerant, 127 moderately salt-tolerant, 117 salt-sensitive, and 21 highly salt-sensitive genotypes at the seedling stage by employing the D value. A mathematical evaluation model for salt tolerance was established for M. sacchariflorus and M. lutarioriparius at the seedling stage. Notably, the mini-core collection containing 64 genotypes developed using the Core Hunter algorithm effectively represented the overall variability of the entire collection. This mini-core collection serves as a valuable gene pool for future in-depth investigations of salt tolerance mechanisms in Miscanthus

DataSheet_2_Salt tolerance evaluation and mini-core collection development in Miscanthus sacchariflorus and M. lutarioriparius.pdf

Marginal lands, such as those with saline soils, have potential as alternative resources for cultivating dedicated biomass crops used in the production of renewable energy and chemicals. Optimum utilization of marginal lands can not only alleviate the competition for arable land use with primary food crops, but also contribute to bioenergy products and soil improvement. Miscanthus sacchariflorus and M. lutarioriparius are prominent perennial plants suitable for sustainable bioenergy production in saline soils. However, their responses to salt stress remain largely unexplored. In this study, we utilized 318 genotypes of M. sacchariflorus and M. lutarioriparius to assess their salt tolerance levels under 150 mM NaCl using 14 traits, and subsequently established a mini-core elite collection for salt tolerance. Our results revealed substantial variation in salt tolerance among the evaluated genotypes. Salt-tolerant genotypes exhibited significantly lower Na+ content, and K+ content was positively correlated with Na+ content. Interestingly, a few genotypes with higher Na+ levels in shoots showed improved shoot growth characteristics. This observation suggests that M. sacchariflorus and M. lutarioriparius adapt to salt stress by regulating ion homeostasis, primarily through enhanced K+ uptake, shoot Na+ exclusion, and Na+ sequestration in shoot vacuoles. To evaluate salt tolerance comprehensively, we developed an assessment value (D value) based on the membership function values of the 14 traits. We identified three highly salt-tolerant, 50 salt-tolerant, 127 moderately salt-tolerant, 117 salt-sensitive, and 21 highly salt-sensitive genotypes at the seedling stage by employing the D value. A mathematical evaluation model for salt tolerance was established for M. sacchariflorus and M. lutarioriparius at the seedling stage. Notably, the mini-core collection containing 64 genotypes developed using the Core Hunter algorithm effectively represented the overall variability of the entire collection. This mini-core collection serves as a valuable gene pool for future in-depth investigations of salt tolerance mechanisms in Miscanthus.</p

DataSheet_1_Salt tolerance evaluation and mini-core collection development in Miscanthus sacchariflorus and M. lutarioriparius.pdf

Marginal lands, such as those with saline soils, have potential as alternative resources for cultivating dedicated biomass crops used in the production of renewable energy and chemicals. Optimum utilization of marginal lands can not only alleviate the competition for arable land use with primary food crops, but also contribute to bioenergy products and soil improvement. Miscanthus sacchariflorus and M. lutarioriparius are prominent perennial plants suitable for sustainable bioenergy production in saline soils. However, their responses to salt stress remain largely unexplored. In this study, we utilized 318 genotypes of M. sacchariflorus and M. lutarioriparius to assess their salt tolerance levels under 150 mM NaCl using 14 traits, and subsequently established a mini-core elite collection for salt tolerance. Our results revealed substantial variation in salt tolerance among the evaluated genotypes. Salt-tolerant genotypes exhibited significantly lower Na+ content, and K+ content was positively correlated with Na+ content. Interestingly, a few genotypes with higher Na+ levels in shoots showed improved shoot growth characteristics. This observation suggests that M. sacchariflorus and M. lutarioriparius adapt to salt stress by regulating ion homeostasis, primarily through enhanced K+ uptake, shoot Na+ exclusion, and Na+ sequestration in shoot vacuoles. To evaluate salt tolerance comprehensively, we developed an assessment value (D value) based on the membership function values of the 14 traits. We identified three highly salt-tolerant, 50 salt-tolerant, 127 moderately salt-tolerant, 117 salt-sensitive, and 21 highly salt-sensitive genotypes at the seedling stage by employing the D value. A mathematical evaluation model for salt tolerance was established for M. sacchariflorus and M. lutarioriparius at the seedling stage. Notably, the mini-core collection containing 64 genotypes developed using the Core Hunter algorithm effectively represented the overall variability of the entire collection. This mini-core collection serves as a valuable gene pool for future in-depth investigations of salt tolerance mechanisms in Miscanthus.</p