Comparative genetic analysis of flowering time adaptation in legumes

Weller, J. L. et al.- Resumen de la comunicación oral presentada en la "8th International Conference on Legume Genetics and Genomics (ICLGG)", que tuvo lugar en Siófok, Hungría, entre el 18 y el 22 de septiembre de 2017.A better understanding of flowering genes in legume crops will be valuable in understanding their prehistoric expansion from regions of initial domestication, in breeding for new environments and in accessing wider genetic diversity present in wild crop relatives. We are using a comparative approach to explore the genetic network controlling flowering time adaptation in a number of legume species. In addition to the use of induced mutants in pea (Pisum sativum) and barrel medic (Medicago truncatula), recent work has focused on characterization of natural variation in crop species including pea, lentil (Lens culinaris) and chickpea (Cicer arietinum). We have performed comparative phylogenetic analyses of many of the major flowering gene families in legumes, and examined the expression patterns of key genes, including members of the FT family of florigen genes. A positional candidate gene approach has enabled the identification of putative causal genes for major flowering loci and shown a striking conservation in certain genomic regions conferring flowering time adaptation across several species. Evidence on the molecular and physiological basis for adaptive changes at these loci will be presented and possible reasons for their prominence will be discussed.Peer reviewe

Genetic Diversity among Wild Common Beans from Northwestern Argentina Based on Morpho-agronomic and RAPD Data

The genetic diversity among 10 wild populations of common bean Phaseolus; vulgaris var. aborigineus was analyzed by means of RAPD markers and morpho-agronomic data. The study was performed on populations collected from different sites located in the provinces of Jujuy, Salta and Tucuman in northwestern Argentina. Ten quantitative traits and 33 random primers were scored. Clustering based on morpho-agronomic traits and RAPD markers generated similar phenograms that grouped bean populations based on their site of collection. The levels of diversity observed among populations were low suggesting they have a common ancestor. The levels of diversity shown by morpho-agronomic traits were higher compared to those of molecular markers, most probably due to the effect of the environment. Furthermore, a 480-bp DNA band identified a group of wild populations collected from similar sites. Breeding strategies need to exploit this diversity to broaden the genetic base of commercial beans to develop high yield cultivars.Instituto de Fisiología Vegeta

Preliminar screening of runner bean for tolerance to low temperature at early stage

The runner bean requires moderate temperatures for optimum germination. The low temperatures at sowing delay both germination and plant emergence and reduce establishment of beans when planted early in the growing season. The objectives of this work were to identify potential runner bean germplasm from Spain with tolerance to low temperature. Seeds of 18 accessions of runner bean were germinated in climatic chambers at 14 ºC (day)/8 ºC (night) temperature. The accessions PHA-0311, PHA-0409 and PHA-1018 had the best performance under experimental the cold conditions.Research was supported by the projects AGF2000-1613 and RF03-024-C6-2 from the Spanish Government.Peer reviewe

Patrones electroforéticos en geles bidimensionales de la proteina faseolina en distintas variedades de Phaseolus vulgaris L.

Comunicaciones a congreso

Genetics of intra-gene pool and inter-gene pool hybridization for seed traits in common bean (Phaseolus vulgaris L.) germplasm from Europe

11 páginas, 6 tablas.Due to adaptation to new ecological and manmade conditions, the large diversity evolved in the European common bean germplasm is of particular interest for plant breeding. The knowledge of the genetic relationships within and among races and gene pools and their performance per se will provide bean breeders with a starting point in designing crosses using contrasting and complementary parents to broaden the genetic base within the different commercial classes. A genetic study of seed size variation and protein markers in progeny derived from 16 intraracial, interracial and inter-gene pools European common bean populations was conducted. General and specific combining ability (GCA and SCA) values were significant for seed weight, indicating that both additive and nonadditive genetic effects were involved in conditioning seed weight. Interracial populations showed transgressive values due to the accumulation of large-seeded alleles. Genetic variation inside Andean germplasm, and Chile and Peru races in particular, exhibited useful genetic progress in these populations, providing lines with a large seed size, and so, an excellent market potential. The distribution of incompatibility between both gene pools (Mesoamerican and Andean) of the common bean was explored. Inter-gene pool populations provided lower means of inbred segregants than the mid-parent value. Therefore, a good option it would be select for large seed size according to a recurrent or congruity inbred-backcrossing selection programs. Analysis of allele markers frequencies in inter-gene populations showed segregation distortion with a higher than expected frequency of alleles from the Mesoamerican gene pool, many of which were fixed in the F7 lines. The presence of a great percentage of markers that showed segregation distortion in these populations (87%) indicated that this phenomenon can be amplified by using distance related common bean genotypes. In addition, a high percentage of heterozygotes for the Phs locus (for the seed storage protein phaseolin) was found, which suggest that the Andean homozygous TT could not be expressed in Mesoamerican genetic background due to the action of some form of female specific mechanisms that affected gene exchange between parental germplasm in inter-gene pool populations. The present work provides useful information in the establishment of large seed size germplasm that could have a great deal of interest among breeders and may offer some possibilities to exploit existing variation within and between common bean races.Research was supported by the projects AGF97-0324 and AGL2005-01268/AGR from the Spanish Government, PGIDIT02RAG40301PR from the Galician Government (Spain), and EUFEDER Funds. A.M. González thanks her fellowship to Ministry of Education, Culture and Sports of Spain.Peer reviewe

Transcriptional Dynamics and Candidate Genes Involved in Pod Maturation of Common Bean (Phaseolus vulgaris L.)

The authors want to thank the research facilities provided by the Campus de Excelencia Internacional Agroalimentario (CeiA3).Pod maturation of common bean relies upon complex gene expression changes, which in turn are crucial for seed formation and dispersal. Hence, dissecting the transcriptional regulation of pod maturation would be of great significance for breeding programs. In this study, a comprehensive characterization of expression changes has been performed in two common bean cultivars (ancient and modern) by analyzing the transcriptomes of five developmental pod stages, from fruit setting to maturation. RNA-seq analysis allowed for the identification of key genes shared by both accessions, which in turn were homologous to known Arabidopsis maturation genes and furthermore showed a similar expression pattern along the maturation process. Gene- expression changes suggested a role in promoting an accelerated breakdown of photosynthetic and ribosomal machinery associated with chlorophyll degradation and early activation of alpha-linolenic acid metabolism. A further study of transcription factors and their DNA binding sites revealed three candidate genes whose functions may play a dominant role in regulating pod maturation. Altogether, this research identifies the first maturation gene set reported in common bean so far and contributes to a better understanding of the dynamic mechanisms of pod maturation, providing potentially useful information for genomic-assisted breeding of common bean yield and pod quality attributes.Ministerio de Ciencia, Innovacion y Universidades (MCIU/AEI/FEDER, UE) AGL2017-88174-R RTC2017-6198-2 AGL2017-88702-C2-2-RJunta de Andalucia 612

Marker-based linkage map of Andean common bean (Phaseolus vulgaris L.) and mapping of QTLs underlying popping ability traits

Abstract Background Nuña bean is a type of ancient common bean (Phaseolus vulgaris L.) native to the Andean region of South America, whose seeds possess the unusual property of popping. The nutritional features of popped seeds make them a healthy low fat and high protein snack. However, flowering of nuña bean only takes place under short-day photoperiod conditions, which means a difficulty to extend production to areas where such conditions do not prevail. Therefore, breeding programs of adaptation traits will facilitate the diversification of the bean crops and the development of new varieties with enhanced healthy properties. Although the popping trait has been profusely studied in maize (popcorn), little is known about the biology and genetic basis of the popping ability in common bean. To obtain insights into the genetics of popping ability related traits of nuña bean, a comprehensive quantitative trait loci (QTL) analysis was performed to detect single-locus and epistatic QTLs responsible for the phenotypic variance observed in these traits. Results A mapping population of 185 recombinant inbred lines (RILs) derived from a cross between two Andean common bean genotypes was evaluated for three popping related traits, popping dimension index (PDI), expansion coefficient (EC), and percentage of unpopped seeds (PUS), in five different environmental conditions. The genetic map constructed included 193 loci across 12 linkage groups (LGs), covering a genetic distance of 822.1 cM, with an average of 4.3 cM per marker. Individual and multi-environment QTL analyses detected a total of nineteen single-locus QTLs, highlighting among them the co-localized QTLs for the three popping ability traits placed on LGs 3, 5, 6, and 7, which together explained 24.9, 14.5, and 25.3% of the phenotypic variance for PDI, EC, and PUS, respectively. Interestingly, epistatic interactions among QTLs have been detected, which could have a key role in the genetic control of popping. Conclusions The QTLs here reported constitute useful tools for marker assisted selection breeding programs aimed at improving nuña bean cultivars, as well as for extending our knowledge of the genetic determinants and genotype x environment interaction involved in the popping ability traits of this bean crop.The authors thank Quival-Frutos Secos El Nogal (Pontevedra, Spain) for technical support and Diputación de Pontevedra for farm facilities. We also thank Rosana Pereira Vianello Brondani from Embrapa Arroz e Feijão, CNPq (Brasil) for supplying some microsatellite primers. MDLF was supported by a research contract of the Xunta de Galicia. This work has been funded by grants PET2008_0167, EUI2009-04052 and AGL2011-25562 of the Ministerio de Ciencia e Innovación and PGIDI03RAG16E of the Xunta de Galicia.Peer Reviewe

Historia del cultivo de la judía: su evolución más allá de las áreas de origen y domesticación

The common bean (Phaseolus vulgaris L.) is the most important grain legume for direct human consumption on a global scale. Current bean germplasm collections show a wide variation of phenotypes, although genetic erosion is gradually affecting this species as in many countries local traditional varieties are being replaced by elite cultivars. This crop has spread to every continent over the past few centuries, which has resulted in a complex genetic structure of bean germplasm outside its areas of origin and domestication (South and Central America). Some evidence indicates that this germplasm is more complex than previously thought and contains additional, as yet unexplored, diversity. This is especially the case in southern Europe, particularly in the Iberian Peninsula, where it was introduced in the early sixteenth century and has been documented as a secondary focus of domestication of the species. The integration of omic data into bean germplasm documentation databases and its combination with genotypic, phenotypic and agro-ecological data is opening a new era for the enhancement and efficient use of common bean genetic resources as the main grain legume in Europe and worldwide.La judía común (Phaseolus vulgaris L.) es la leguminosa de grano más relevante para el consumo humano directo en escala global. Las colecciones de germoplasma de judía actuales muestran una amplia variación de fenotipos, aunque en muchos países las variedades locales están siendo reemplazados por cultivares de élite, concentrando la producción agraria en un número cada vez más reducido de cultivares con la consecuente erosión genética o pérdida de biodiversidad. Este cultivo se ha extendido por todos los continentes durante los últimos siglos, lo que ha dado lugar a una compleja estructura genética fuera de sus áreas de origen y domesticación (Mesoamérica y Sudamérica). Diversas evidencias indican que el germoplasma europeo contiene una diversidad adicional mayor de la esperada especialmente en el Sur de Europa, y particularmente en la Península Ibérica, dónde fue introducida a comienzos del siglo XVI, y que ha sido documentada como un centro de domesticación secundaria de la especie. La integración de datos ómicos en las bases de datos de documentación del germoplasma de judía y su combinación con datos genéticos, fenotípicos y agro-ecológicos está abriendo una nueva era para la valorización y el uso eficiente de los recursos genéticos de la judía común como la principal leguminosa de grano para consumo humano en Europa y globalmente

Decoding gene expression signatures underlying vegetative to inflorescence meristem transition in the common bean

The tropical common bean (Phaseolus vulgaris L.) is an obligatory short-day plant that requires relaxation of the photoperiod to induce flowering. Similar to other crops, photoperiod-induced floral initiation depends on the differentiation and maintenance of meristems. In this study, the global changes in transcript expression profiles were analyzed in two meristematic tissues corresponding to the vegetative and inflorescence meristems of two genotypes with different sensitivities to photoperiods. A total of 3396 differentially expressed genes (DEGs) were identified, and 1271 and 1533 were found to be up-regulated and down-regulated, respectively, whereas 592 genes showed discordant expression patterns between both genotypes. Arabidopsis homologues of DEGs were identified, and most of them were not previously involved in Arabidopsis floral transition, suggesting an evolutionary divergence of the transcriptional regulatory networks of the flowering process of both species. However, some genes belonging to the photoperiod and flower development pathways with evolutionarily conserved transcriptional profiles have been found. In addition, the flower meristem identity genes APETALA1 and LEAFY, as well as CONSTANS-LIKE 5, were identified as markers to distinguish between the vegetative and reproductive stages. Our data also indicated that the down-regulation of the photoperiodic genes seems to be directly associated with promoting floral transition under inductive short-day lengths. These findings provide valuable insight into the molecular factors that underlie meristematic development and contribute to understanding the photoperiod adaptation in the common bean