Las Dras. María Belén Picó Sirvent y María Jesús Rodrigo Esteve actuaron como secretario y vocal del tribunal, respectivamente, presidiendo el tribunal el Dr. Pablo Salvador Fernández Escámez. La tesis recibió la máxima calificación de sobresaliente cum laude. En la fotografía algunas imágenes del acto al que no pudo asistir el codirector de la tesis al encontrarse fuera de España.
La tesis se ha realizado por compendio de artículos pero con su resumen, introducción, material y métodos y capítulos correspondientes a varias publicaciones (principalmente dos de ellas en revistas internacionales), así como una discusión general y sus conclusiones. El resumen de la tesis en castellano y en inglés aparece más abajo.
|Momento de lectura previa por parte del tribunal|
|Inicio de la exposición|
|La Dra. Noelia dos Santos y Juan Pablo Fernández Trujillo tras la lectura de la tesis doctoral.|
Melon fruit (Cucumis melo L.) is highly appreciated by consumers for its sweet taste and pleasant aroma, being a crop of great importance in Spain and particularly in the Region of Murcia C. melo L. is characterized by its great genetic diversity and physiological behavior which makes it a ideal model for the study of metabolism and ripening in fleshy fruits. The aim of this thesis was identify Quantitative Trait Loci (QTLs) associated with melon quality parameters and characterize some of its effects, especially associated with the production of aromatic volatile compounds and texture of melon fruit. The relationship between the physiological behavior of the fruit and some of its characteristics is also established. Near-isogenic lines or NILs of melon with different physiological behavior and obtained by crossing of two non-climacteric parents, the Spanish cultivar inodorus type ‘Piel de Sapo’ (PS) and the Korean exotic accession PI 161375 conomon type ‘Shongwan Charmi’ (SC) were used. The NILs contained a homozygous introgression almost unique of parental SC in the genetic background of parental PS. The analyses realized in melon fruits has allowed comparing the NILs with the parental PS and so detect differences by means of several univariate and multivariate statistical techniques in order to identify QTLs of interest in the melon genetic map and locate discriminant aromas. The climacteric behavior of NIL 6M1 and cultivar ‘Védrantais’ (slight and moderate, respectively) was associated with increased production of esters (acetate and no acetate) and sulfur-derived compounds, showing at least a partial ethylene-dependence for their synthesis. Aldehydes, alcohols and ketones were associated with non-climacteric behavior of the control PS, cultivar ‘Nicolas’ and NILs SC10-2 and SC7-1, shown its ethylene-independentcharacter.QTLs associated with flesh firmness and aroma volatile production in melon NILs with introgressions in the linkage groups (LGs) III/VI (climacteric behavior) or VII and X (non-climacteric behavior) had been identified. A QTL (ff7.2) located in the LG VII associated with higher flesh firmness in NIL SC7-1 was mapped and related to the higher content of cell wall structural components, as galactose and α-cellulose residue. Another QTL associated with increased pectin degradation was associated to climacteric QTLs of the NIL SC3-5-1, whereas another QTL related to introgresión which produce
climacteric (located in LG III) was associated to esters production. Other thirty-two QTLs, twelve identified in the LG VII and twenty in the LG X were associated with the production of certain volatile aromas serving as potential biomarkers of higher flesh firmness (especially aldehydes produced via aminoacid) and other textural differences (especially related to synthesis of sulfur-derived compounds and compounds obtained via methionine) between non climacteric melon NILs. Melon NILs with different physiological behavior have been results of great interest to elucidate the ethylene-dependent, ethylene-independent or only partially ethylene-dependent character of aroma volatiles and texture, as well as the interrelation among two of the most important parameters that define the characteristics of this fruit, and therefore to increase the knowledge about the ethylene and its effects on global and partial fruit quality in general and melon in particular.
Keywords: α-cellulose, acetate esters, alcohols, aldehydes, aminoacids, aroma precursors, aromatic volatile compounds, cell wall, climacteric, Cucumis melo L., ethylene, flesh firmness, fruit quality, fruit ripening, genotype, hemicellulose, introgression lines, ketones, linkage group, metabolic pathways, molecular markers, multivariate analysis, near-isogenic lines, neutral sugars, non acetate esters, non-climacteric, partial least squares analysis, physiological behavior, ‘Piel de Sapo’, principal component analysis, Quantitative Trait Loci, random forest analysis,‘Shongwan Charmi’, sulfur-derived compounds, texture, univariate analysis, uronic acids, xyloglucans.