SUNFLOWER: BREEDING AND GENETIC RESOURCES AT INTA, ARGENTINA

HEINZ, N.; FILIPPI, CV; MONTECCHIA, J; RIVAROLA, M; HEINZ, R; MAZZALAY, A.; DOMINGUEZ, M; TROGLIA, C; GONZALEZ, S; CORRO-MOLAS, A; PANIEGO, N; ALVAREZ, D.; GONZÁLEZ, J; QUIROZ, F; FASS, M; FERNANDEZ, P; LIA, VV

CORDOBA

Simposio; 1º Simposio internacional de mejoramiento genético vegetal; 2021

Introduction: the cultivation of sunflower in Argentina began in the late 19th century with the introduction by German immigrants from Volga, Russia, in the province of Entre Ríos. Successive cultivation and empirical selection led to the adaptation of sunflower to local conditions (Castaño, 2018). Unlike other crops, in Argentina sunflower has been bred earlier than in other countries. At the beginning of the 20th century, Pergamino (1939) and Manfredi (1947) Experimental Stations started a research and development program to produce seeds of identified and homogeneous varieties in sufficient quality and quantity for the domestic market of sunflower, the main oilseed in Argentina. The creation of INTA (1956) emphasized the activity of sunflower genetic improvement in the Experimental Stations with focus on yield increase. Objectives: the aim of this presentation is to address the origin and evolution of the sunflower breeding program in Argentina, especially in INTA. The initial focus was on the empirical selection of introduced landraces, including more recently the conservation and use of genetic resources, refinement of conventional improvement, and the genomic and bioinformatic tools in selection. Materials and methods: the earliest records of cultivated sunflower populations were those adapted to local conditions by immigrant peasants from southern Russia Landraces. Until the 1950s, the introduction of modern cultivars with their subsequent adaptation remained the main activity. Later on, crosses between adapted local cultivars and germplasm introduced mainly from Russia, Canada, and the United States resulted in cultivars superior for yield and resistance to diseases, mainly Black Rust (caused by Puccinia helianthi) which had severely affected sunflower production in 1952. Oil content was initially improved by increasing grain weight and kernel percentage. In the 1960s, INTA researchers began interspecific crosses with wild species close to sunflower (H. annuus, H. argophyllus, and H. debilis ssp. Cucumerifolius) in order to achieve resistance to rust and other diseases, as well as to obtain greater adaptability. Yield selection was carried out in comparative yield trials and through statistical analyzes, whereas disease resistance selection was strengthened by evaluations in the field and under controlled conditions. Oil content was improved by selection using solvent extraction and laboratory analysis (Soxlet and Twisselman methods). The methods used to improve grain yield were mainly based on mass and recurrent selection and, to a lesser extent, on individual selection for disease resistance. With the commercial exploitation of cytoplasmic male sterility introduced from France in 1970, private companies worldwide, including Argentina, started activities to obtain hybrids. Breeding programs focused on the development of lines to produce improved hybrids. In the late 1970s and throughout the 1980s, hybrids replaced open-pollinated varieties by incorporating local germplasm developed by INTA. To exploit heterosis, breeders made use of individual selection and biometric statistics. Genetic composites were developed from multiple crosses. The use of nuclear magnetic resonance equipment allowed rapid and effective selection for oil content. The National Sunflower Genetic Resources Plan was established in 1990 and its activities include documentation, conservation, characterization, evaluation and utilization of germplasm. Genetic variability has been intensively exploited using population and individual selection methods to isolate, identify and introgress genes involved in disease resistance and quality. Mutation induction has also been used to increase genetic variability. Statistical packages have been applied for selection of lines and hybrids based on performance and stability parameters, genotype x environment interaction, heritability, gene action, etc. Thus, germplasm exchange has increased and so available genetic variability for breeding programs. Research and Development Joint Ventures contracts and Transfer Agreements were also signed to promote and market the resulting commercial products. Since 2006, INTA has implemented the Project Portfolio system to integrate research, development and extension activities throughout the institution. In this context, the Sunflower Improvement Project renewed its objectives to obtain sunflower lines and hybrids with higher productivity, stability and plasticity and tolerance to biotic and abiotic stresses related to climate change, with the adequate industrial and commercial quality demanded by the agroindustry. Strong links have been established with organizations such as CONICET and universities. Breeding sunflower for the confectionery industry started by introducing cultivars and crossing them with local germplasm. A core population named Association Mapping Population (AMP) was generated using lines from Germplasm Collection and Improvement Program. Genome-wide distributed SNP markers and SSR panels have been generated, and studies of genetic diversity, identity and purity, as well as quantitative traits have been performed. Genomic regions associated with resistance to head rot (SHR) caused by Sclerotinia sclerotiorum (Filippi et al. 2017), Verticillium wilt (VW) caused by Verticillium dahliae, (Montecchia et al. 2021) and head and stem canker (SHC) caused by Diaporthe sp.) have been characterized. AMP is also being evaluated to identify new sources of tolerance to water stress. Results: in the late 19th century, the initial locally adapted introductions gave rise to Russian Giant, American Giant, Mammoth and other populations (Kugler, et al, 1958). All of these populations are tall, long-cycle and with variable colored grains, which are predominantly striated. These populations, together with new introductions, mainly from Russia, the United States, Canada and Eastern Europe, formed the basis for the production of the first working collections for sunflower improvement in Argentina. Later, these compiled the INTA collection of sunflower genetic resources. First formal introductions of foreign varieties and subsequent crosses between themselves and with wild Helianthus sp. led to obtaining the first disease-resistant varieties. These crosses were made in Manfredi: MANFREDI INTA (1960) (Bauer, 1988), IMPIRA INTA (1962), CORDOBES INTA (1965), TEGUA INTA (1976), IBERA INTA (1978) and CALCHÍN INTA (1984); in Pergamino: GUAYACÁN INTA (1963), ÑANDUBAY INTA, PEHUEN INTA (1969), GUAYACÁN 2 (1979) and AGUARIBAY INTA (1982); and in Sáenz Peña: CHARATA INTA (1980) and CABURÉ INTA (1985). The germplasm composites PGRK, P2, P3 and P4 were released in the 1970s to reinforce and complement the efforts of seed companies. INTA initiated a cooperative stage with commercial firms in 1990 to develop and spread sunflower lines and hybrids. Some of these hybrids are registered in the National Registry of Cultivars and were obtained in Pergamino: INPRA 03 (1991), INPRA 06 (1993); in Balcarce: FLORAL 100 (2009) and FLORAL 600 (2011) (both ornamental types); and in Manfredi: PRO INTA AGD 239 (1996), PROTÓN ER 301 (2000) and PROTÓN R 302 (2000), ALBISOL 21 DMR (2006), AYMARA INTA (2012), PROTON 290 (2013) and CALCHAQUÍ INTA (2018). The High Oleic acid type hybrids are registered as BS 90 INTA (2007) and BS 92 INTA (2008), whereas the Confectionery type as BS 57 INTA (2007), BS 58 INTA (2009), BS 59 INTA (2012) and K 5101 CF INTA (2019). On the other hand, the hybrids resistant to IMI herbicides are under the nominations FEBO 817 CL INTA (2017), CHANÉ CL INTA (2018) and K 3153 CL INTA (2019). The wild populations of naturalized sunflower in Argentina were integrated into the INTA Germplasm Bank at Manfredi in 2006, in collaboration with CONICET and the South National University (UNS) (Cantamutto et al. 2009). Selection for disease resistance, such as the SuCMoV virus, was also carried out (Alvarez, D. et al., 2014) and molecular markers linked to mildew resistance have been identified (Marcellán, O. et al. 2005). Hormonal profile in sunflower genotypes under water stress has been studied in collaboration with Río Cuarto University (Alemano, S et al. 2005 and Andrade, A. et al. 2009), with the selection of the drought tolerant lines B71 and R432. The analysis of physical and nutritional quality of confectionary sunflower has been carried out in collaboration with the University of Villa María (Sandrinelli T R et al, 2018). A group of advanced INTA experimental hybrids is being evaluated annually before being registered and commercially released. In Pergamino and Manfredi Exp. Stations, researchers have released 39 maintainer lines with their male sterility and 18 restorer lines. Germplasm developed by INTA has made important contributions to breeding programs not only in Argentina but also worldwide (González et al, 2015). In the USA, using INTA genotypes, researchers developed five rust resistance differential lines (HAR1, HAR2, HAR3, HAR4 and HAR5) (Gulya, T., 1985), two of them (HAR4 and HAR5) with resistance to mildew as well. In addition, using INTA?s SELECTCION 8018 (from cv TEGUA INTA), US researchers registered three synthetic maintainer lines (BRS1, BRS2 and BRS3), two lines resistant to birds (NDBR1 and NDBR2) and the maintainer line HA 369 (Miller and Gulya, 1990). In France, INRA researchers have developed two differential lines for mildew by combining USDA and INTA germoplasm (QHP1 and QHP2) (Agriobtention, 2002). Complementarily, other genotypes with resistance to the main diseases and improved industrial oil quality were developed. In Canada, USDA genotypes derived from INTA germplasm were used to create a bird-resistant restorer and maintenance lines (CM614 and CM617). The Estanzuela 75 variety was obtained in Uruguay through the selection of INTA germplasm. Working with the AMP QTL for SHR, researchers have identified four lines harboring up to eight favorable genetic variants (HA1848, HaCOI_1, G33, G34, SNP117, SNP136, SNP44, SNP128) (Filippi et al, 2020). Four of those variants have been validated by independent studies (Zubrzycki et al. 2017, Fass et al. 2020). On this AMP, five Verticillium wilt resistant genotypes (PMA159, PMA41, PMA26, PMA89, and PMA24) have been identified, along with 23 related genomic areas (Montecchia et al 2021). Resistance to the program´s elite lines has been built using these genotypes and traits. In Argentina, there is an increasing interest for resistance to stem (SSC) and head (SHC) cankers caused by the Diaporthe sp. (Corro-Molas et al 2019). Resistant lines involving at least 6 loci on chromosomes 2 and 10 have been identified. Responses to SHR and SSC / SHC were found to have a positive correlation. These findings are guiding the introgression of resistance traits into elite lines. This AMP is also under evaluation to identify new sources of tolerance to drought stress, as well as the genomic regions responsible for this resistance. Leaf senescence contrasting lines are also studied to identify candidate genes associated with the regulation of the character (Moschen et al. 2019). The development of germplasm includes the development of two multiparental populations of maintainer lines from the crosses of eight genetically diverse parental genotypes (Dominguez et al. 2019). Also, maintainer and restorer genotypes were used to construct mutagenized populations (Fass, M et al. 2019). Conclusions: different breeding strategies used at INTA were successful in producing valuable genotypes.The so-called ?Argentine germplasm? has a distinctive genetic constitution and is still used as genetic resource in sunflower breeding projects, highlighting its contribution at both national and international level.