Natural resistances to viruses in cucurbits

Cucurbit viruses cause considerable economic losses worldwide. The most common viral diseases affecting this crop family are Potyviruses, Cucumoviruses, Criniviruses, Ipomoviruses, Tobamoviruses, and the emerging Begomoviruses. Four main cucurbit crops are grown worldwide,namely melon, cucumber (Cucumis), watermelon (Citrullus), and squash (Cucurbita). Huge natural variation is also available within each genus, providing valuable sources of genetic resistance to these diseases. Intraspecific and intrageneric diversity and crossability are key factors to select the optimum breeding strategies. Melon and cucumber are diverse species for which intraspecific resistance is available. Conversely, in Citrullus and Cucurbita, wild relatives provide the resistance diversity absent in watermelon and in C. pepo. Some of the classical sources used by breeders, many of which are multi-resistant, come from corresponding origin centers in Asia, Africa, and America, as well as from secondary centers of diversity. Genetic studies have identified dominant and recessive and often complex resistance. Many of the genes identified have been mapped and markers for MAS are available, but higher mapping resolutions are required to identify the corresponding genes. Only a few genes could be cloned and functionally characterized. Efforts are underway to use genome mapping and functional genomics to advance toward a genomic-assisted breeding against viral diseases in cucurbits.info:eu-repo/semantics/publishedVersio

Tackling intraspecific genetic structure in distribution models better reflects species geographical range

Genetic diversity provides insight into heterogeneous demographic and adaptive history across organisms' distribution ranges. For this reason, decomposing single species into genetic units may represent a powerful tool to better understand biogeographical patterns as well as improve predictions of the effects of GCC (global climate change) on biodiversity loss. Using 279 georeferenced Iberian accessions, we used classes of three intraspecific genetic units of the annual plant Arabidopsis thaliana obtained from the genetic analyses of nuclear SNPs (single nucleotide polymorphisms), chloroplast SNPs, and the vernalization requirement for flowering. We used SDM (species distribution models), including climate, vegetation, and soil data, at the whole-species and genetic-unit levels. We compared model outputs for present environmental conditions and with a particularly severe GCC scenario. SDM accuracy was high for genetic units with smaller distribution ranges. Kernel density plots identified the environmental variables underpinning potential distribution ranges of genetic units. Combinations of environmental variables accounted for potential distribution ranges of genetic units, which shrank dramatically with GCC at almost all levels. Only two genetic clusters increased their potential distribution ranges with GCC. The application of SDM to intraspecific genetic units provides a detailed picture on the biogeographical patterns of distinct genetic groups based on different genetic criteria. Our approach also allowed us to pinpoint the genetic changes, in terms of genetic background and physiological requirements for flowering, that Iberian A. thaliana may experience with a GCC scenario applying SDM to intraspecific genetic units

Mechanical transmission of Tomato leaf curl New Delhi virus to cucurbit germplasm: selection of tolerance sources in Cucumis melo

[EN] Cucurbits are major crop species, including fruits and vegetables cultivated worldwide that supply essential vitamins and minerals to current diets in developed and developing countries. Viral diseases are main factors affecting cucurbits cultivation. The most widespread and damaging have been aphidborne viruses belonging to the Potyviridae family. Whitefly-transmitted begomoviruses (Geminiviridae) have been identified more recently in different cucurbit species. A severe outbreak of Tomato leaf curl New Delhi virus (ToLCNDV) occurred in pumpkins and melons in the main production area of Southern Spain in 2012 2014. We developed a mechanical inoculation method to facilitate the screening of germplasm against this virus. Mechanical transmission with this method was confirmed in 4 genera and 13 species of the family, including the main crops, cucumber, melon, watermelon and pumpkins, and also crop related exotic germplasm (landraces and wild species) used for cucurbits breeding. Diversity in the response was observed within and among species. Tolerance to mechanical transmission of ToLCNDV was identified in melon, within Cucumis melo subsp. agrestis var. momordica and in wild agrestis accessions. All the tolerant accessions came from India, the country in which this virus was firstly reported. Some of these accessions have been previously reported to be tolerant or resistant to other viruses and as they are fully crossable to commercial melons, they are good sources to develop new melon varieties with tolerance to ToLCNDV.This work was supported by Project E_RTAE2013-00020-C04-03 from the Spanish Instituto Nacional de Investigaciones Agrarias (INIA). Authors thank M. Arnedo (Ramiro Arnedo S.A.) for providing zucchini infected plants from affected greenhouses in Almeria.López Del Rincón, C.; Ferriol Molina, M.; Picó Sirvent, MB. (2015). Mechanical transmission of Tomato leaf curl New Delhi virus to cucurbit germplasm: selection of tolerance sources in Cucumis melo. Euphytica. 204:679-691. https://doi.org/10.1007/s10681-015-1371-xS679691204Álvarez JM, González-Torres R, Mallor C (2005) Potential sources of resistance to Fusarium wilt and powdery mildew in melons. HortScience 40:1657–1660Bandaranayake WMEK, Wickramarachchi WART, Wickramasinghe HAM, Rajapakshe RGAS, Dissanayake DMKK (2014) Molecular detection and characterization of begomoviruses associated with cucurbitaceae vegetables in Skingri Lanka. J Natl Sci Found Sri Lanka 42:239–245Chang HH, Ku HM, Tsai WS, Chien RC, Jan FJ (2010) Identification and characterization of a mechanical transmissible begomovirus causing leaf curl on oriental melon. Eur J Plant Pathol 127:219–228Dhillon NPS, Monforte AJ, Pitrat M, Pandey S, Singh PK, Reitsma KR, Garcia-Mas J, Sharma A, McCreight JD (2012) Melon landraces of India: contributions and importance. In: Janick J (ed) Plant Breeding Rev. Wiley, Hoboken, pp 85–150Doyle JJ, Doyle JL (1990) Isolation of plant DNA from fresh tissue. Focus 12:13–15Fauquet CM, Briddon RW, Brown JK, Moriones E, Stanley J, Zerbini M, Zhou X (2008) Geminivirus strain demarcation and nomenclature. Arch Virol 153:783–821Fernández-Trujillo JP, Picó B, García-Mas J, Álvarez JM, Monforte AJ (2011) Breeding for fruit quality in melon. In: Jenks MA, Bebeli PJ (eds) Breeding for fruit quality. Wiley, HobokenFerriol M, Picó B (2008) Pumpkin and winter squash. In: Prohens J, Nuez F (eds) Handbook of plant breeding, vol 1., Vegetables ISpringer, Heidelberg, pp 317–349Islam S, Munshi AD, Verma M, Arya L, Mandal B, Behera TK, Kumar R, Lal SK (2010) Genetics of resistance in Luffa cylindrica Roem. against tomato leaf curl New Delhi virus. Euphytica 174:83–89Islam S, Munshi AD, Verma M, Arya L, Mandal B, Behera TK, Kumar R, Lal SK (2011) Screening of Luffa cylindrica Roem. for resistance against Tomato leaf curl New Delhi Virus, inheritance of resistance, and identification of SRAP markers linked to the single dominant resistance gene. J Hortic Sci Biotechnol 86:661–667Ito T, Sharma P, Kittipakorn K, Ikegami M (2008) Complete nucleotide sequence of a new isolate of Tomato leaf curl New Delhi virus infecting cucumber, bottle gourd and muskmelon in Thailand. Arch Virol 153:611–613Juárez M, Legua P, Mengual CM, Kassem MA, Sempere RN, Gómez P, Truniger V, Aranda MA (2013) Relative incidence, spatial distribution and genetic diversity of cucurbit viruses in eastern Spain. Ann Appl Biol 162:362–370Juárez M, Tovar R, Fiallo-Olivé E, Aranda MA, Gosálvez B, Castillo P, Moriones E, Navas-Castillo J (2014) First detection of Tomato leaf curl New Delhi virus infecting Zucchini in Spain. Plant Dis 98:857–858Jyothsna P, Haq QMI, Singh P, Sumiya KV, Praveen S, Rawat R, Briddon RW, Malathi VG (2013) Infection of tomato leaf curl New Delhi virus (ToLCNDV), a bipartite begomovirus with betasatellites, results in enhanced level of helper virus components and antagonistic interaction between DNA B and betasatellites. Appl Microbiol Biotechnol 97:5457–5471Khan MS, Ji SH, Chun SC (2012) Begomoviruses and their emerging threats in South Korea: a review. Plant Pathol J 28:123–136King SR, Davis AR, Zhang XP, Crosby K (2010) Genetics, breeding and selection of rootstocks for Solanaceae and Cucurbitaceae. Sci Hortic 127:106–111Munera M, Giné A, Pocurull M, Picó B, Gisbert C, Sorribas FJ (2014) Comportamiento de líneas de Cucumis metuliferus, Citrullus lanatus var. citroides y C. colocynthis frente a Meloidogyne spp. Como potenciales portainjertos de melón, pepino y sandía. XVII Congreso de la Sociedad Española de Fitopatología 7–10 de octubre de 2014Navas-Castillo J, López-Moya JJ, Aranda MA (2014) Whitefly-transmitted RNA viruses that affect intensive vegetable production. Ann Appl Biol 165:155–171Papidam M, Beachy RN, Fauquet CM (1995) Tomato leaf curl geminivirus from India has a bipartite genome and coat protein is not essential for infectivity. J Gen Virol 76:25–35Paris HS (2008) Summer Squash. In: Prohens J, Nuez F (eds) Handbook of plant breeding, vol 1., Vegetables ISpringer, Heidelberg, pp 351–379Paris HS, Brown RN (2005) The genes of pumpkin and squash. HortScience 40:1620–1630Paris HS, Kabelka E (2009) Gene list for Cucurbita species, 2009. Cucurbit Genet Coop Rep 31–32:44–69Picó B, Sifres A, Nuez F (2005) Quantitative detection of cucumber vein yellowing virus in susceptible and partially resistant plants using real-time PCR. J Virol Methods 128:14–20Pitrat M (2008) Melon. In: Prohens J, Nuez F (eds) Handbook of plant breeding, vol 1., Vegetables ISpringer, Heidelberg, pp 283–315Roy A, Bal SS, Fergany M, Kaur S, Singh H, Malik AA, Singh J, Monforte AJ, Dhillon NPS (2012) Wild melon diversity in India (Punjab State). Genet Resour Crop Evol 59:755–767Samretwanich K, Chiemsombat P, Kittipakorn K, Ikegami M (2000) Tomato leaf curl geminivirus associated with cucumber yellow leaf disease in Thailand. J Phytopathol 148:615–617Sohrab SS, Karim S, Varma A, Abuzenadah AM, Chaudhary AG, Damanhouri GA, Mandal B (2013) Characterization of Tomato Leaf Curl New Delhi Virus infecting cucurbits: evidence for sap transmission in a host specific manner. Afr J Biotechnol 12:5000–5009Sohrab SS, Karim S, Varma A, Azhar EI, Abuzenadah AM, Mandal B (2014) Sap transmission of Tomato Leaf Curl New Delhi Virus infecting sponge gourd in northern India. J Plant Interact 9:241–248Srivastava KM, Hallan V, Raizada RK, Chandra G, Singh BP, Sane PV (1995) Molecular cloning of Indian tomato leaf curl virus genome following a simple method of concentrating the supercoiled replicative form of viral DNA. J Virol Methods 51:297–304Usharani KS, Surendranath B, Paul-Khurana SM, Garg ID, Malathi VG (2004) Potato leaf curl—a new disease of potato in northern India caused by a strain of Tomato leaf curl New Delhi virus. Plant Pathol 53:23

"Mini PS": A new mini melon breeding line exploiting the "Dudaim" variability

[EN] 'Piel de Sapo' is one of the most consumed market class of melons in the Mediterranean area and it represents an important economic crop in Spain. The 'Mini PS' melon breeding line, which bears two main introgressions from the dudaim 'Queen's pocket' melon in the Piel de Sapo genetic background, was evaluated for its fruit quality traits in three environments. Some interesting commercial characteristics were detected, such as a notable decrease in the fruit weight and a rounder shape, compared with Piel de Sapo, while the other quality traits were not altered. Thus, this mini melon line, ideal as a personal melon, may be useful in the development of new melon cultivars.This work was supported by the Spanish Ministerio de Educacion through an ERA-NET Plant Genomics project (MELRIP: GEN2006-27773-C2-2-E), by the Spanish Ministerio de Economia de Empresa through a Plant KBBE project (SAFQIM: PIM2010PKB-00691). It was also partially supported by the projects AGL2014-53398-C2-2-R and AGL2017-85563-C2-1-R from Ministerio de Economia y Competitividad and Ministerio de Ciencia, Innovacion y Universidades (cofunded with FEDER funds).Castro, G.; Perpiña Martin, G.; Picó Sirvent, MB.; Esteras Gómez, C. (2020). "Mini PS": A new mini melon breeding line exploiting the "Dudaim" variability. Horticultural Science. 47(4):217-220. https://doi.org/10.17221/86/2019-HORTSCIS21722047

Quantifying temporal change in plant population attributes : insights from a resurrection approach

Rapid evolution in annual plants can be quantified by comparing phenotypic and genetic changes between past and contemporary individuals from the same populations over several generations. Such knowledge will help understand the response of plants to rapid environmental shifts, such as the ones imposed by global climate change. To that end, we undertook a resurrection approach in Spanish populations of the annual plant Arabidopsis thaliana that were sampled twice over a decade. Annual weather records were compared to their historical records to extract patterns of climatic shifts over time. We evaluated the differences between samplings in flowering time, a key life-history trait with adaptive significance, with a field experiment. We also estimated genetic diversity and differentiation based on neutral nuclear markers and nucleotide diversity in candidate flowering time (FRI and FLC) and seed dormancy (DOG1) genes. The role of genetic drift was estimated by computing effective population sizes with the temporal method. Overall, two climatic scenarios were detected: intense warming with increased precipitation and moderate warming with decreased precipitation. The average flowering time varied little between samplings. Instead, within-population variation in flowering time exhibited a decreasing trend over time. Substantial temporal changes in genetic diversity and differentiation were observed with both nuclear microsatellites and candidate genes in all populations, which were interpreted as the result of natural demographic fluctuations. We conclude that drought stress caused by moderate warming with decreased precipitation may have the potential to reduce within-population variation in key life-cycle traits, perhaps as a result of stabilizing selection on them, and to constrain the genetic differentiation over time. Besides, the demographic behaviour of populations probably accounts for the substantial temporal patterns of genetic variation, while keeping rather constant those of phenotypic variation

Nuevas Estrategias de Análisis de la Diversidad Genética Natural: Identificación de Variantes Alélicas en Genes de Interés Mediante Ecotilling

Los recientes avances en Genética y Genómica están proporcionando una gran cantidad de información sobre la secuencia y la función de los genes, lo que supone la base para el desarrollo de nuevas estrategias de estudio de la diversidad. En este artículo se describe una nueva metodología de uso creciente, utilizada para la detección de polimorfismos genéticos en poblaciones naturales: EcoTILLING. Esta herramienta se ha empleado con éxito en diversas especies, no sólo para estudiar la variabilidad existente, sino con fines de mejora vegetal o animal. En este artículo se incluye una breve revisión teórica y una explicación práctica detallada. Con la explicación planteada se pretende facilitar el aprendizaje de esta nueva estrategia de análisis de la diversidad al alumno de Ciencias de la vida (Agronomía, Biología, Veterinaria, Medio ambiente, Biotecnología..), tanto a nivel teórico como práctico.Esteras Gómez, C.; Picó Sirvent, MB. (2011). Nuevas Estrategias de Análisis de la Diversidad Genética Natural: Identificación de Variantes Alélicas en Genes de Interés Mediante Ecotilling. http://hdl.handle.net/10251/1021

Marcadores moleculares basados en PCR: Marcadores SSR o STR (Simple Sequence Repeats o Short Tandem Repeats). Microsatélites

Una vez que el alumno haya estudiado con detenimiento este documento y los recursos de apoyo asociados, será capaz de: 1. Definir y explicar cómo surge y en qué consiste el polimorfismo en las secuencias microsatélite. 2. Distinguir y aplicar las diferentes metodologías empleadas para la el uso de estas secuencias como marcadores genéticos. 3. Analizar e interpretar los resultados obtenidos.Picó Sirvent, MB.; Esteras Gómez, C. (2012). Marcadores moleculares basados en PCR: Marcadores SSR o STR (Simple Sequence Repeats o Short Tandem Repeats). Microsatélites. http://hdl.handle.net/10251/1674

TILLING: una herramienta para el estudio de la función de los genes y la generación de nueva variación

Las nuevas técnicas de secuenciación de alto rendimiento están incrementando de manera muy rápida el número de secuencias disponibles en un amplio rango de organismos. En muchos casos, no se dispone de información acerca de la función de las secuencias génicas. Por ello, existe una necesidad creciente de asociar la variación nucleotídica en una secuencia a cambios fenotípicos, determinando así la función del gen. En este artículo docente se describe una metodología de uso creciente, empleada para el estudio de la función génica, además de para la generación de nueva variación: TILLING. Esta herramienta se ha empleado con éxito en diversas especies. A continuación se describen los fundamentos de la técnica y sus aplicaciones prácticas. La explicación planteada facilitará el aprendizaje de esta nueva estrategia de análisis de la función génica al alumno de Ciencias de la vida (Agronomía, Forestales, Medio ambiente, Biología, Biotecnología..), tanto a nivel teórico como práctico.Esteras Gómez, C.; Picó Sirvent, MB. (2011). TILLING: una herramienta para el estudio de la función de los genes y la generación de nueva variación. http://hdl.handle.net/10251/1034

Involvement of ethylene biosynthesis and signalling in fruit set and early fruit development in zucchini squash (Cucurbita pepo L.)

Background We have identified a kind of parthenocarpy in zucchini squash which is associated with an incomplete andromonoecy, i.e. a partial conversion of female into bisexual flowers. Given that andromonoecy in this and other cucurbit species is caused by a reduction of ethylene production in the female flower, the associated parthenocarpic development of the fruit suggested the involvement of ethylene in fruit set and early fruit development.Results We have compared the production of ethylene as well as the expression of 13 ethylene biosynthesis and signalling genes in pollinated and unpollinated ovaries/fruits of two cultivars, one of which is parthenocarpic (Cavili), while the other is non-parthenocarpic (Tosca). In the latter, unpollinated ovaries show an induction of ethylene biosynthesis and ethylene signal transduction pathway genes three days after anthesis, which is concomitant with the initiation of fruit abortion and senescence. Fruit set and early fruit development in pollinated flowers of both cultivars and unpollinated flowers of Cavili is coupled with low ethylene biosynthesis and signalling, which would also explain the partial andromonoecy in the parthenocarpic genotype. The reduction of ethylene production in the ovary cosegregates with parthenocarpy and partial andromonoecy in the selfing progeny of Cavili. Moreover, the induction of ethylene in anthesis (by ethephon treatments) reduced the percentage of bisexual parthenocarpic flowers in Cavili, while the inhibition of ethylene biosynthesis or response (by AVG and STS treatments) induces not only andromonoecy but also the parthenocarpic development of the fruit in both cultivars.Conclusions Results demonstrate that a reduction of ethylene production or signalling in the zucchini flower is able to induce fruit set and early fruit development, and therefore that ethylene is actively involved in fruit set and early fruit development. Auxin and TIBA treatments, inducing fruit set and early fruit development in this species, also inhibit ethylene production and the expression of ethylene biosynthesis and response genes. A model is presented that discusses the crosstalk between ethylene and auxin in the control of fruit set and early fruit development in zucchini squash.This work was supported by grants AGL2008-05619-C02-02/ALI and AGL2011-30568-C02-02/ALI, partly funded by ERDF (European Regional Development Fund) and by the Spanish Ministry of Science and Innovation, and grant CVI-02617, funded by ERDF and by the Consejería de Innovación, Ciencia y Empresa, Junta de Andalucía, Spain. C.M. and Z.M. acknowledge FPU program scholarships from MEC, Spain. S.M. is funded by grant PTA2011-479-I from the Spanish Ministry of Science and Innovation

Drought tolerance assessment of melon germplasm searching for adaptation to climate change

[EN] Shortage of irrigation water at critical melon growth stages can be the most important limiting factor in the future due to climate change, especially in the Mediterranean region. Apart from the improvement of irrigation systems and crop management, the development of drought tolerant cultivars by genetic breeding is the best solution to achieve stable yields. Screening germplasm collections is a prerequisite for that. A melon core collection was evaluated in the current work in two assays. Seven morphological traits were assessed at plantlet stage and compared under drought and standard conditions imposed. Significant differences for all traits were recorded among the sixty accessions evaluated. Clustering analysis also grouped the accessions according to their response to drought, detecting some landraces and wild types of interest, mainly of Indian and African origin, although the best behavior under drought was found in a flexuosus melon from Irak. Some Spanish inodorus landraces also showed better response than the average behavior of commercial types. The employment of this set of traits has allowed screening a large germplasm collection in an easy and non-expensive way, in one of the most sensitive developmental stages.The authors thank the Erasmus mundus team, WELCOME project, Third Cohort, for offering funds for the research and scholarship activities. Also, they thank the Conselleria d'Educació, Investigació, Cultura i Esport (Generalitat Valenciana) for funding the project Prometeo (2017/078).Elsayed, H.; Peiró Barber, RM.; Picó Sirvent, MB.; Esteras Gómez, C. (2019). Drought tolerance assessment of melon germplasm searching for adaptation to climate change. African Journal of Agricultural Research. 14(27):1180-1196. https://doi.org/10.5897/AJAR2018.13807S11801196142