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Rice is one of the greatest calorie supply for the world population, especially since its production is almost entirely destined to direct human consumption and its demand will increase along with the world population. There are efforts worldwide to increase rice yields by obtaining new improved and stabilized rice lines. The rice anther culture, a fast and cheap technique, allows to obtain double haploid lines in less than one year. We report its application with an improved protocol in four Mediterranean japonica rice genotypes at F2 generation. We performed a screening test for cold-pretreatment at 5.0±0.1°C and concluded that the optimum duration was 9 days as it produced the higher rate of anther-derived callus induction. This revised protocol was successfully applied to the four genotypes, obtaining good results in all the procedure's steps. At the end, more than 100 of double haploid green plants were generated. Moreover, 9 lines obtained from the anther culture procedure showed good qualities for the Spanish market at the growing, farming and grain production level during the field assays. Therefore, we report an improved anther culture procedure for obtaining double haploid lines from temperate japonica rice genotypes showing high commercialization expectance.

[spa] El objetivo principal de esta Tesis es producir estrategias para la productividad, perdurabilidad y calidad mediante el desarrollo de nuevas variedades comerciales de arroz mediterráneo (O. sativa) e introducir alelos de tolerancia a la salinidad y resistencia a herbicidas mediante speed breeding, para proteger el sector del arroz contra el cambio climático, la invasión de malas hierbas y penetración del caracol manzana (P. maculata). En cuanto a los objetivos específicos, son los siguientes: 1. Cruzar líneas de arroz tolerantes a salinidad y resistente a herbicida por hibridación forzada siguiendo un esquema de retro-cruzamiento. 2. Poner a punto una técnica de rescate de embriones (embryo rescue) para optimizar el speed breeding (mejora acelerada de variedades) en el programa de retrocruces. 3. Establecer una selección in vitro de los embriones que presenten tolerancia al herbicida Cicloxidim. 4. Selección por PCR de los descendientes que presenten marcador SSR Saltol. 5. Selección por CAPS de los descendientes que presenten el alelo mutante de resistencia a Cicloxidim. 6. Aplicación de selección de mayor retorno al parental recurrente mediante marcadores KASPar. 7. Evaluación de las líneas Saltol en ensayos de campo en el Delta del Ebro., [eng] Rice (Oryza sativa) is a crop with a major economic interest and the projection of global world growth make the increase of the food production an imminent need. Framed in the gramineous family (Poaceae), this crop is a diploid species with 24 chromosomes, and it is the most important basic harvesting plant in the world, as it satisfies the caloric needs of half of the world’s population. The Oryza genus includes 24 species, but just two of them are cultivated: Oryza sativa and Oryza glaberrima. Firstly, O. sativa is characterized by its length, approximately about 0.4 to 2 meters and its semiaquatic nature. O. sativa cultivars are classified in five subspecies, corresponding to indica, aus, aromatic, temperate japonica and tropical japonica. The aus are minor groups commonly considered subspecies or ecotypes indica (from the Himalayan region), the temperate japonica (from China, Korea, Japan and Europe), tropical japonica (from Malaysia, Indonesia and Philippines) and aromatic (from Pakistan, India and some other countries). Secondly, O. Glaberrima is cultivated in a minority way in west Africa. The japonica subspecies is the most cultivate in Europe due to its adaptation to temperate climates and its use as an ingredient of local typical dishes worldwide known as the Italian risotto or the Spanish paella. The global rice production in 2019 reached the 500.6 millions of tons, a value 0.8% lower than the historical maximum of 2018, with 506.3 millions of tons, due to climatic factors. In Europe, the production of rice only reaches the 0.6% of the global production, with Italy and Spain as the main producers. This Thesis is part of the NEURICE project (New commercial European RICE), a HORIZON 2020 project funded by the European Union. We used two varieties japonicas sensitive temperate salinity provided by Càmara Arrossera of the Montsià a long grain PL12 and one medium grain PM37, were crossed with two Indica donors carrying Saltol: FL478, a salinity-tolerant RIL obtained from the Pokkali x IR29 cross and IR64- Saltol, a salt-tolerant NIL obtained from the cross FL478 x IR64 . The crosses between PL12 and FL478 were called LP, and the crosses between PM37 and IR64- Saltol were called MS. This thesis has managed to evaluate, for the first time, tolerance to salinity in the new Saltol LP and MS lines from the crosses between the parents and to obtain the new Saltol lines. Therefore, the thesis is divided into three research areas or experiments: 1) The introgression of a QTL Saltol to obtain new lines of rice tolerant to salinity verified through two years of field trials where interesting morphological analogies were found with respect to the number of shoots / plants, number of panicles / plants, length of the plant and panicle fertility percentage to mitigate the adverse impact of salinity and avoid the loss of apple snail production in the Ebro delta. 2) in vitro optimization for six different varieties of Mediterranean template japonica and a tropical indica by the addition of an adjustable concentration design such as 2.50 µM, 3.00 µM, 3.25 µM and 3.50 µM (concentration at the limit of lethality) of the herbicide Cycloxidim to select resistant individuals, 3) the crossing of a herbicide- resistant tropical indica line with six commercial Mediterranean elite lines by forced hybridization following a backcrossing scheme, using an optimized embryo rescue technique to accelerate the process and CAPS selection of the descendants presenting the mutant OsACC2 allele of resistance to the herbicide Cicloxidim.

[eng] Rice belongs to the Poaceae family and Oryza genus. The genus Oryza comprehends 24 species, being 22 wild and 2 cultivated. These two cultivated species correspond to Oryza sativa, originated in Asia, nowadays cultivated and consumed worldwide, and Oryza glaberrima, originated in Africa, but cultivated and consumed limitedly in West Africa, both are diploid (2n=24) (Bernis & Pamies, 2006; Wei & Huang, 2019). Traditionally, Oryza sativa has been classified into two subspecies, indica and japonica. Molecular analyses, as well as biochemical and hybrid sterility analyses, point out at the separate domestication of Oryza rufipogon populations as the origin for these two subspecies (Garris et al., 2005; Rakshit et al., 2007; Wei et al., 2012), with a gene flow present from japonica to indica (Yang et al., 2012). Indica rice is usually long grained, less sticky and with a lower level of amylopectin than japonica rice, which is short grained and sticky. There are also phenotypical differences between these subspecies, for example, japonica plants are generally shorter, the leaves have a lighter color and shaper shape. Also, the tiller number is lower in japonica than in the indica plants (Wei & Huang, 2019). The O. sativa plant is a semiaquatic annual monocot grass although rice can live as perineal in the tropics (McLean et al., 2013). The plant has a height that varies from 80 to 150 centimeters depending on the variety and growing conditions (Bernis & Pamies, 2006), or even less in modern varieties. Its morphology varies according to the development stage, this being the vegetative phase or the reproductive phase. The vegetative phase includes the germination, the seedling and the tillering stage. The reproductive phase comprehends panicle initiation, also called heading, and flowering stages. As a food, rice contributes to the 20% of calories ingested worldwide (Kubo & Purevdorj, 2004), reaching half of the calories ingested daily in some areas (Counce et al., 2000). In terms of consumption, as well as production, Asia is the main continent (McLean et al., 2013). The rice production and consumption in Europe is minor compared to Asia. Despite that, rice holds an important sociocultural role since it is one of the basic foods of the Mediterranean diet. Some regions have developed famous rice dishes, like risotto in Italy or paella in Spain. The annual rice consumption per capita in Europe is 6-18 kilograms in the southern regions, and 3.5-5.5 kilograms in the northern regions (McLean et al., 2013). The main European producer is Italy, followed by Spain. These two countries hold more than 75% of the total rice production in Europe. Rice in Europe is also of ecological importance, due to the great biodiversity that inhabits and benefits from the paddy fields. Around 70-80% of rice cultivated in Europe are japonica varieties, and the rest indica (Bernis & Pamies, 2006; Ferrero, 2007). Agriculture is the most important bioeconomy sector in Spain, with a value of 43.8 million of euros in 2015 and coping the 50.9% employment of all bioeconomy sectors (Lániez & Periago, 2016). Rice mobilized 258.766 millions of euros in Spain in 2019 (MINECO, 2019). Thus, the studies dedicated to improving different aspects of the rice production in Spain are crucial. This thesis has made a multidisciplinary approach, from genetics to the field, in order to study Mediterranean rice varieties considering its actual applicability for the Spanish rice industry through three experimental approaches: (i) an improvement of the anther culture protocol for two Mediterranean temperate japonica varieties and two tropical japonica varieties trough the addition of additives to the media; (ii) testing the salt-tolerance of Saltol-introgressed varieties to select those that will help to fight the apple snails plague in the Ebro Delta; and (iii) a study of genetic and physicochemical aspects of the rice pearl in five Mediterranean varieties, an important feature in gastronomical terms.