Reproductive and weight traits were analyzed for Angus (A), Brahman (B), Hereford (H), and Nellore (N) straightbred cows; F1 NA cows; 3/8N 5/8A cows and quarter blood composite cows (BANH) of the four straightbreds in Central Texas. Heterosis was estimated for calf crop born (CCB), calf crop weaned (CCW), and calf survival (CS) by linear contrasts within cow breed groups. F1 NA cows expressed heterosis (P < 0.0001) for CCB (0.22) and CCW (0.20). Except for the 3/8N 5/8Ac cows, which resulted from the mating of NA bulls to 3/4A 1/4N cows, all of the crossbred cow breed types expressed significant heterosis (P < 0.05) when compared to the weighted average of the parental purebreds for CCB. BANHc cows that were the result of mating NA bulls to HB cows expressed heterosis for CCB (0.35) (P < 0.001) and CCW (0.29) (P < 0.05). The 3/8N 5/8Aa females produced by mating 3/4N 1/4A bulls to NA cows expressed heterosis (P < 0.0001) for CCW (0.20). Heterosis for calf survival was near zero for all breed types, but only two breed types of 3/8N 5/8A cows were significantly greater than the weighted average of the parental purebreds. Heterosis for birth weight (BWT) and weaning weight (WWT) was also analyzed by linear contrasts within cow breed groups. The BANHb and BANHc cows produced from mating NA bulls to BH and HB F1 cows, respectively, expressed heterosis for BWT (2.89 + 0.79 (P < 0.001) and 3.38 + 1.51 (P < 0.05)). All cow breed types expressed significant heterosis (P < 0.05) for WWT. The BANH2 cows resulting from the mating of NA bulls to F2 HB or BH cows expressed heterosis (P < 0.0001) for WWT (52.01 kg + 9.88).

No description available.

159 leaves : tables, graphs, photos ; 30 cm. / Title page, contents and abstract only. The complete thesis in print form is available from the University Library. / Thesis (Ph.D.1977) from the Dept. of Agronomy, University of Adelaide

München, Techn. University, Diss., 2007.

Malgré son potentiel, l’hétérosis a rarement été étudié, et encore moins exploité, chez les levures, espèces d’intérêt biotechnologique majeur. Ce travail avait pour objectif d’explorer ce phénomène chez deux espèces de levure, Saccharomyces cerevisiae et S. uvarum, dans des conditions proches de celles de l’œnologie. Pour la première fois des hybrides interspécifiques ont été inclus dans un dispositif diallèle complet. Un autre aspect original de ce travail résidait dans l’approche intégrative choisie, qui combinait l’étude de phénotypes aux niveaux métabolique, cellulaire et populationnel. Un panel de 66 souches (55 hybrides et leurs 11 parents) a été analysé pour 35 caractères à deux températures et avec trois réplicats, soit au total 396 fermentations alcooliques. Ces données nombreuses et complexes nous ont conduits non seulement à utiliser, mais aussi à développer divers outils statistiques et de modélisation originaux pour l’interprétation des données. Après avoir vérifié que les interactions nucléo-cytoplasmiques n’influençaient pas la variation des caractères étudiés, nous avons tout d’abord montré que les sources de variation (effet souche, effet température et interactions souche*température) différaient selon les types de caractères. Nous avons ensuite comparé globalement les trois groupes d’hybrides : intraspécifiques S. cerevisiae*S. cerevisiae, intraspécifiques S. uvarum*S. uvarum et interspécifiques S. cerevisiae*S. uvarum, et avons observé que l’hybridation interspécifique pouvait engendrer des phénotypes présentant de meilleures aptitudes œnologiques et une homéostasie supérieure à celle des hybrides intraspécifiques. Ce dernier résultat pourrait expliquer que l’hybridation interspécifique soit si fréquente chez les levures naturelles et domestiquées. / Despite its biotechnological interest, heterosis has not commonly been studied or exploited in the yeast genus. This work aimed to explore this phenomenon within two yeast species well adapted to oenological conditions, Saccharomyces cerevisiae and S. uvarum. Eleven parental strains and their 55 intra- and inter-specific hybrids were phenotyped under enological conditions, at two temperatures in three replicates. A total of 396 alcoholic fermentations were characterized in depth through 35 phenotypic traits with original statistical and modeling tools. We first showed that, depending on the types of trait - kinetics parameters, life-history traits, enological parameters and aromas -, the sources of variation (strain, temperature and strain*temperature effects) differed in a large extent. Then we compared globally three groups of hybrids and their parents at two growth temperatures: intraspecific hybrids S. cerevisiae*S. cerevisiae, intraspecific hybrids S. uvarum*S. uvarum and interspecific hybrids S. cerevisiae*S. uvarum. We found that hybridization could generate multi-trait phenotypes with improved oenological performances and better homeostasis with respect to temperature. These results could explain why interspecific hybridization is so common in natural and domesticated yeast, and open the way to applications for wine-making.

Orientador: João Antonio da Costa Andrade / Banca: Mario Luiz Teixeira de Moraes / Banca: Maria Elisa Ayres Guidetti Zagatto Paterniani / Resumo: A utilização de híbridos de gerações F 2 de híbridos simples, com exploração eficiente da heterose, pode contribuir significativamente para o aumento do rendimento da cultura do milho, seja pelo uso direto ou para extração de novas linhagens e obtenção de novos híbridos. Este trabalho teve por objetivo identificar gerações F 2 de híbridos simples para essas finalidades, para a segunda safra da cultura. As 12 gerações F 2, os 66 híbridos resultantes do dialelo completo entre elas e quatro testemunhas, foram avaliados em um látice 9x9 quádruplo em Selvíria-MS na segunda safra em 2015. Os caracteres avaliados foram florescimento feminino (FF), altura de plantas (AP), altura de espigas (AE), nota geral para doença (ND), plantas acamadas mais quebradas (AQ), prolificidade (PR) e rendimento de grãos (RG). De acordo com os resultados da análise dialélica de Gardner e Eberhart, os híbridos com potencial para uso direto como híbrido duplo e/ou extração de linhagens para obtenção de novos híbridos foram: F 2 DKB 390 x F 2 60XB14, F 2 JM2M90 x F 2 60XB14, F 2 IVF5-IVD8 x F 2 60XB14, F 2 DKB 350 x F 2 60XB14, F 2 DKB 390 x F 2 AG 8088 e F 2 8F/9D x F 2 AG 8088 / Abstract: Using F 2 generations of single-cross hybrids, with efficient exploitation of heterosis, can contribute significantly to increase corn grain yield, either through direct use or extraction of new lines and obtaining new hybrids. This study aimed toidentifyF 2 generations of single-cross hybrids for these purposes, for the second season crop. The 66 hybrids from 12 F 2 parentals resulted of a complete diallel and four checks were evaluated in a quadruple lattice 9x9 experimental design and analyzed according to Gardner and Eberhart diallel analysis. The following traits were evaluated: female flowering (FF), plant height (AP), ear height (AE), general disease note (ND), lodged plants plus broken (AQ), prolificacy (PR) and grain yield (RG), Selvíria-MS, second crop in 2015. According to the results, the hybrids with potential for using directly as double hybrid and/or for lines extractions to obtain new hybrids were: F 2 DKB 390 x F 2 60XB14, F 2 JM2M90 x F 2 60XB14, F 2 IVF5-IVD8x F 2 60XB14, F 2 DKB 350 x F 2 60XB14, F 2 DKB 390 x F 2 AG 8088 and F 2 8F/9D x F 2 AG 8088 / Mestre

Orientador: Marcelo Agenor Pavan / Coorientador: Norberto da Slva / Banca: Arlete Marchi Tavares de Melo / Banca: Paulo Tarcísio Della Vecchia / Banca: Rumy Goto / Banca: Antonio Ismael Inácio Cardoso / Resumo: O objetivo deste trabalho foi estimar a magnitude da heterose e das capacidades de combinação em um cruzamento dialélico parcial em cebola (Allium cepa L.) visando à resistência a raiz rosada e inferir possíveis correlações entre a resistência e algumas características agronômicas. O cruzamento dialélico parcial foi realizado utilizando dois grupos de linhagens parcialmente endogâmicas. O grupo I foi constituído de linhagens parentais femininas, macho estéreis, originárias de uma População Tropical Brasileira, selecionada para plantio no verão. O grupo II foi constituído de linhagens parentais masculinas, que em sua maioria são originárias de populações de cebola Crioula, obtidas por meio de autofecundações sucessivas e mantidas através de seleção massal dentro das linhagens. A resistência a raiz rosada foi avaliada por escalas de notas de 1 a 5. Avaliaramse as seguintes características agronômicas: vigor foliar, arquitetura foliar, número de folhas, altura de folha (cm), número total de bulbos e peso total de bulbos (Kg). Utilizou-se o delineamento experimental de blocos ao acaso com três repetições. Houve ação dos efeitos aditivos para resistência a raiz rosada, verificando-se a magnitude de efeitos não aditivos em algumas combinações. Não houve correlação entre resistência a raiz rosada e peso total de bulbos, porém é possível realizar seleção intrapopulacional com as linhagens utilizadas no presente trabalho e obter híbridos com bom nível resistência a raiz rosada e boas características agronômicas / Abstract: The objective of this work was estimate the heterosis and combining ability in a partial diallel crossing in onion (Allium cepa L.) aiming resistance to pink root and infer possible correlations of it with agronomic traits. The partial diallel was carried out between two groups of partly endogamic inbred lines. The group I consisted of parental male-sterile female inbred lines, originated from a Brazilian Tropical Onion Population selected for sowing during the summer. The group II consisted of parental male inbred lines, most of them originated from a Crioula population, obtained by successive self-pollinations and mass. The resistance to pink root was evaluated by a scale from 1 to 5. The following traits were evaluated: foliar vigor, foliar architecture, number of leaves, plant height (cm), total number of bulbs and total weight of bulbs (Kg). The experimental randomized block design with three replications was utilized. The additive effects for pink root resistance were found and non-additive effects were observed in some combinations. There were no correlation between pink root resistance and bulb total weight, but is possible to make intrapopulation selection with the inbred lines used in the current work and get hybrids with good level of pink root resistance and good agronomic traits / Doutor

Reproductive, maternal and weight traits were analyzed for Angus (A), Brahman (B), Hereford (H), and Nellore (N) straightbred cows; F1 NA; 3/8N 5/8A cows; and four breed composite cows (BANH) at the McGregor Research Station in Central Texas. Heterosis was estimated for calf crop born (CCB) (n = 1,698), calf crop weaned (CCW) (n = 1,698), calf survival (CS) (n = 1,388), birth weight (BW) (n = 1380), weaning weight (WW) (n = 1,198), and cow weight at palpation (PWT) (n = 1,929) by linear contrasts for cow breed and cow breed group. F1 NA and the quarter breed composite BANH dam group expressed significant (P < 0.0001) heterosis for calf crop born and calf crop weaned. The 3/8 N 5/8 Aa produced by matings of 3/4 A 1/4 N bulls to NA dams expressed significantly more heterosis for CCB (P < 0.0001) and CCW (P < 0.01), while the 3/8 N 5/8 Ac dams expressed less heterosis than predicted from the dominance model for both traits. For CS the 3/8 N 5/8 Aa expressed the same amount of heterosis as predicted from the dominance model of 0.05, while the 3/8 N 5/8 Ab and 3/8 N 5/8 Ac dams expressed less heterosis than predictions based on the dominance model. Heterosis estimates were only significantly higher (P < 0.10) for BANHb dams than expectations from the dominance model. For BW all the BANH cows expressed significant heterosis except for the BANH2 cows which expressed significant (P < 0.05) negative heterosis of -0.96 kg. Calves out of F1 NA cows were heaviest at weaning with 239 kg. All BANH cows expressed significant (P < 0.0001) heterosis for weaning weight except for the BANHc cows. These heterosis estimates were higher than those expected from the dominance model for BANHb and BANH2 cows, while the heterosis estimate was slightly lower in BANHa cows and similar for BANHc cows. All 3/8 N 5/8 A cows expressed less heterosis for WW than prediction from the dominance model. Nellore cows were the heaviest at four years of age with 542 kg. Only the BANHb and BANHc cows expressed significant (P < 0.05) heterosis for PWT. None of the 3/8 N 5/8 A cows expressed heterosis for cow weight at palpation. Results from this study showed that heterosis levels expressed by the different crossbred cow types were generally equal or higher to those predicted by the dominance model.

Ετέρωση, γνωστή επίσης ως υβριδική ευφορία, αναφέρεται στην φαινοτυπική ανωτερότητα ενός ετερόζυγου υβριδίου σε σύγκριση με τους ομόζυγους γονείς του. Πρόσφατες πρόοδοι στην χαρτογράφηση γενετικών τόπων ποσοτικών χαρακτήρων σε Saccharomyces cerevisiae έχουν αποκαλύψει αρκετούς στόχους που συνδέονται με την ετέρωση, όπως το γονίδιο που κωδικοποιεί την ριβοσωματική πρωτεΐνη L39. Για να διερευνήσουμε περαιτέρω τη δυνητική επίδραση της ετέρωσης στην ευκαρυωτική πρωτεϊνική σύνθεση, χρησιμοποιήσαμε τα ομοζυγωτικά γονικά στελέχη 6x6 και BYxBY, σε σύγκριση με τα υβρίδια 6xBY και 6xBY6, και το ημιζυγωτικό στέλεχος Δ6xBY στο οποίο λείπει ένα από τα δύο αλληλόμορφα του γονιδίου. Μετά από πειράματα in vitro, ελέγξαμε την poly(U) εξαρτώμενη δραστηριότητα πολυμερισμού φαινυλαλανίνης, τη μεταφραστική πιστότητα, τη δραστικότητα της πεπτιδυλοτρανσφεράσης και επιπλέον την ευαισθησία έναντι του αντιβιοτικού κυκλοεξιμίδιο. Σύμφωνα με τα στοιχεία μας, τόσο τα υβριδικά στελέχη όσο και το ημιζυγωτικό στέλεχος έδειξαν αυξημένη συχνότητα λάθους, ενώ η δράση της ΡΤάσης παρουσίασε σημαντική αύξηση μόνο στην περίπτωση του υβριδικού στελέχους 6xBY. Επιπλέον, η ανθεκτικότητα έναντι του κυκλοεξιμιδίου ήταν αυξημένη για όλα σε σύγκριση με τα γονικά στελέχη, υποδεικνύοντας ότι η ετέρωση μπορεί να συνδέεται απ 'ευθείας με τον μηχανισμό της πρωτεϊνοσύνθεσης, ανοίγοντας έτσι ένα άλλο νέο παράθυρο για να διερευνηθεί περαιτέρω αυτό το σημαντικό φαινόμενο. / Heterosis, known also as hybrid vigor, refers to the phenotypic superiority of an heterozygous hybrid compared to its homozygous parents. Recent advances in quantitative trait loci (QTL) mapping in Saccharomyces cerevisiae have uncovered several targets associated with heterosis, such as the gene encoding ribosomal protein L39 (RPL39 or spb2)(?). To further explore the potential effect of heterosis on eukaryotic protein synthesis, we used the homogygous parental strains 6x6 and BYxBY, in comparison to hybrids 6xBY and 6xBY6, and the hemizygous strain Δ6xBY lacking one of the two alleles of RPL39 (spb2). Following in vitro experiments, we tested the poly(U) dependent phenylalanine polymerization activity, the translational fidelity, the peptidyl-transferase activity and additionally the susceptibility versus the antibiotic cycloeximide. According to our data, both hybrid and hemizygous strains showed increased error frequency while the PTase activity exhibited significant increase only in the case of the hybrid strain 6xBY. Moreover, the immunity versus the antibiotic cycloeximide was increased for all compared to the parental strains, indicating that heterosis may be directly associated with protein synthesis machinery, thus opening another new window to explore further this important phenomenon.

Heterosis, the phenotypic superiority of first generation progeny over that of its inbred parents, has been extensively investigated. However, differences in the phenology and dynamic growth patterns between parents and offspring provide challenges in understanding causal factors behind superior trait values. For maize, manipulation of heterosis to increase grain yield has been of primary importance, and the number of spikelets that develop on the female inflorescence is the primary determinant of grain yield. The initial experiment examined heterosis in genetic backgrounds that led to minimal differences in phenology and plant architecture. Growth curves were used to characterize the dynamic expression of heterosis between the hybrid and the inbred parents for a series of vegetative and reproductive traits across stages of development. The second experiment was conducted to determine the effects that stress due to planting density might have on the number of properly developed spikelets, as the first experiment, along with results from the literature, provided evidence to suggest that a proportion of the later forming spikelets found on the distal portion of the female inflorescence were not capable of producing kernels. Results from the initial experiment suggested that expression of heterosis for individual characteristics – such as fresh weight, whose percent mid-parent heterosis was 82% at V4 and declined steadily to 17% at V11 – begins at a high level and decreased during development. On a whole plant level – as determined by a combined analysis of the values and growth rates of the individual characteristics – heterosis increases throughout development until it reaches a steady-state level. Results from the second experiment indicated that increasing plant density did not affect the total number of spikelets per ear but decreased the number of kernels per ear, and it was found that the number of properly developed spikelets per ear was equal to the number of kernels per ear in eight of the nine genotypes tested. Optimal growth stages for more in-depth investigation of transcriptomic changes that may identify causal genetic factors of heterosis for yield were not found, and stress increases the proportion of improperly developed spikelets causing a loss in kernel number. / Natural Sciences and Engineering Research Council of Canada, Ontario Ministry of Agriculture, Food and Rural Affairs, Canadian Foundation for Innovation, and Ontario Innovative Trust