In flowering plants, successful pollination is important for sexual reproduction. It involves a series of intercellular communication pathways between male and female tissues. This cell-cell communication includes the attraction and reception of the male gametophyte, or pollen tube (PT), by the synergid cells of the female gametophyte, also known as the embryo sac (ES). To achieve reproductive success, it is important to manipulate reproduction at both quality and quantity levels. In other words, flowering plants can only produce as many seeds as they produce ovules and these ovules must be able to be fertilized to make seeds. In <i>Arabidopsis thaliana</i>, <i>NORTIA (NTA)</i>, a member of the MILDEW RESISTANCE LOCUS O (MLO) family of proteins, plays a critical role in the communication process that regulates PT reception. Upon PT arrival at the filiform apparatus, <i>NTA</i>becomes polarly redistributed from the Golgi-associated compartment to the filiform apparatus of the synergid cell, indicating that PT-triggered regulation of the synergid secretory system is important for synergid function during pollination. In the first part of this dissertation, I will describe my research of the female controlled reproductive success at molecular and cell biology level with a focus on <i>NTA</i>. Moreover, the ovules contain the female gametophytes which are fertilized during pollination to initiate seed development. Thus, ovule development is an essential and crucial process during plant growth. More importantly, the number of ovules will limit the quantity of reproductive success. However, the major regulators are still poorly understood. The remaining chapters of my dissertation describethe identification of key components that affect the number of ovules during plant development by using natural variation in <i>Arabidopsis thaliana </i>and the correlations of ovule number with flowering time. Discovering new ovule number regulators could provide new tools for improving the agricultural productivity.<br>

Apomixis holds vast potential for improving agriculture worldwide. It would make plant breeding faster, allow for fixation of hybrid genotypes, and help genetically isolate transgenic crops. However, efforts to introduce apomixis into agriculturally important crops, through either plant breeding or molecular genetics, have failed to produce any new apomictic varieties. This could possibly be remedied if researchers better understood the genetics of apomixis, including the underlying genes, their regulation, and the cellular pathways they control. My work increased our knowledge of these processes by using a mixture of novel methods and underutilized resources. In this study I pursued a two-pronged approach that involved both traditional and reverse molecular genetic techniques. I analyzed the Semigamy mutation from Pima Cotton (Gossypium barbadense), which produces large numbers of haploid and chimeric offspring. Although interesting and potentially useful, little is known about this gene, its expression, regulation, and localization, or the cellular processes in which it is involved. This knowledge advanced our understanding of both this part of apomixis and plant reproduction in general. I was able to determine that the Semigamy mutation is recessive to the wild-type and is incompletely expressed even in the homozygous state. Second, I attempted to recreate the various steps of apomixis in the model species Arabidopsis thaliana using the host of tools made available by its fully sequenced genome. Mutants in various organisms, including microbes, plants, and animals, have phenotypes resembling various components of apomixis, and the sequences of most of the genes involved are available in public databases. I identified homologous Arabidopsis genes by comparing these sequences against the entire Arabidopsis genome. Mutants carrying altered versions of these genes were then studied and characterized using various techniques to see if they had any effect on plant reproduction. This method had not been used to study apomixis before this study and revealed several new reproductive Arabidopsis mutations, specifically those in genes homologous to the S. cerevisiae ste12 and rec8 genes. These results will advance the study of apomixis and potentially enable researchers to one day apply it to agriculturally important crop species.

Apomixis holds vast potential for improving agriculture worldwide. It would make plant breeding faster, allow for fixation of hybrid genotypes, and help genetically isolate transgenic crops. However, efforts to introduce apomixis into agriculturally important crops, through either plant breeding or molecular genetics, have failed to produce any new apomictic varieties. This could possibly be remedied if researchers better understood the genetics of apomixis, including the underlying genes, their regulation, and the cellular pathways they control. My work increased our knowledge of these processes by using a mixture of novel methods and underutilized resources. In this study I pursued a two-pronged approach that involved both traditional and reverse molecular genetic techniques. I analyzed the Semigamy mutation from Pima Cotton (Gossypium barbadense), which produces large numbers of haploid and chimeric offspring. Although interesting and potentially useful, little is known about this gene, its expression, regulation, and localization, or the cellular processes in which it is involved. This knowledge advanced our understanding of both this part of apomixis and plant reproduction in general. I was able to determine that the Semigamy mutation is recessive to the wild-type and is incompletely expressed even in the homozygous state. Second, I attempted to recreate the various steps of apomixis in the model species Arabidopsis thaliana using the host of tools made available by its fully sequenced genome. Mutants in various organisms, including microbes, plants, and animals, have phenotypes resembling various components of apomixis, and the sequences of most of the genes involved are available in public databases. I identified homologous Arabidopsis genes by comparing these sequences against the entire Arabidopsis genome. Mutants carrying altered versions of these genes were then studied and characterized using various techniques to see if they had any effect on plant reproduction. This method had not been used to study apomixis before this study and revealed several new reproductive Arabidopsis mutations, specifically those in genes homologous to the S. cerevisiae ste12 and rec8 genes. These results will advance the study of apomixis and potentially enable researchers to one day apply it to agriculturally important crop species.

A series of field trials were performed in order to compare the yield stability of plants of the independent vascular supply (IVS) type peduncle vascular architecture with those of the more usual branched type. The IVS plants gave a low stable, source-limited yield; the plants attained maturity four weeks earlier than those of Maris Bead. The source-sink relationships of the genotypes investigated were established. The potential values of IVS type plants as commercial varieties are discussed. Studies of the growth and development revealed a difference in pod wall structure and the distribution of stomata and pod hairs: this could be related to pod drying. The growth of all parts of the raceme was studied by plotting fresh and dry weight changes, a sequence of development of tissues was established, the peduncle growing first, then the pedicel, then the pod and finally the seed. Genotypic differences in growth rate were observed. These findings were related to the accompanying vascular development within the raceme. The source of the assimilates rapidly translocated into the seeds during early, rapid growth was established. The results obtained are discussed and an ideotype constructed on the basis of the information obtained.

No description available.

AN ABSTRACT OF THE DISSERTATION OF RENEE A LOPEZ SWALLS, for the Doctor of Philosophy degree in PLANT BIOLOGY, presented on June 27, 2016, at Southern Illinois University Carbondale. TITLE: THE SPECIAL WALLS AROUND GAMETES IN CERATOPTERIS RICHARDII AND AULACOMNIUM PALUSTRE: USING IMMUNOCYTOCHEMISTRY TO EXPOSE STRUCTURE, FUNCTION, AND DEVELOPMENT MAJOR PROFESSOR: Dr. Karen S. Renzaglia Gametes are arguably the most important cells formed during the sexual life cycle of plants. The ancestral condition of gametes in land plants is the production of small motile sperm cells and larger non-motile eggs. Unique walls or cell matrices are formed during the development of these highly specialized cells, and are integral to their proper development and maturation. Yet, the polysaccharide composition, structural function, and metabolic processes of these special gamete cell walls remain unexplored beyond examination in the light microscope. Utilizing histochemical techniques coupled with immunocytochemical localizations with monoclonal antibodies (MAbs), I give a detailed survey of AGP and cell wall polymer distribution during male and female gametogenesis in the model fern, Ceratopteris richardi, and for comparison with both Ceratopteris and seed plants, I examined the same cell wall polymers during spermatogenesis in Aulacomnium palustre, a moss species. AGPs are abundant in the extraprotoplasmic matrix that surrounds differentiating sperm and egg cells in the fern, Ceratopteris richardii. During spermatogenesis, AGPs are speculated to regulate growth of flagella and cell morphogenesis through cell signaling via Ca+2 oscillations. Immunogold localizations revealed that AGPs are differentially expressed in the egg envelope in C. richardii. These glycoproteins are extremely abundant prior to fertilization but decrease substantially after fusion of the male gamete with the egg cytoplasm. Contrary to the AGP-filled matrix surrounding developing spermatids, developing eggs are bathed in (1,5)-α-L-arabinan pectins and not AGPs. Lastly, I examined the unique cell walls that are integral to sperm cell differentiation and release in both Ceratopteris and Aulacomnium. The preponderance of callose and hemicelluloses in the walls of the male gametes of Ceratopteris and Aulacomnium, respectively, and the importance of these polysaccharides in development are discussed. Taken together, the studies that comprise this dissertation advance significantly our understanding of cell wall dynamics during gametogenesis in early land plants.

A highly specific steroid regulated transcription system system in Saccharomyces cerevisae was used to screen for phytoestrogens indioecious plants. Yeast cells were co-transformed with a human estrogen receptor expression plasmid and a reporter plasmid containing the E. coli β-galactosidase gene.

No description available.

As espécies florestais arbóreas nativas apresentam interações com coleópteros que se desenvolvem no interior das estruturas reprodutivas. Foram estudadas as seguintes espécies florestais arbóreas nativas e identificados os coleópteros a elas associados: Pterogyne nitens Tul. (amendoim-bravo) - Tricorynus sp. (Anobiidae) e Ormiscus sp. (Anthribidae); Stryphnodendron adstringens (Mart.) Cov. (barbatimão) - Acanthoscelides sp. (Bruchidae); Cassia grandis L. f. (cássia-grande) - Pygiopachymerus lineola (Bruchidae); Tabebuia alba (Cham.) Sandwith (ipê-amarelo) - Sitophilus linearis (Curculionidae); Hymenaea courbaril var. stilbocarpa (Hayne) Lee & Lang (jatobá) - Tricorynus sp. (Anobiidae); Chorisia speciosa (A. St. - Hil.) Dawson (paineira) - Lonchophorus obliquus (Curculionidae); Caesalpinia ferrea var. leiostachya Benth. (pau-ferro) - Pityophthorus sp. (Scolytidae); Aspidosperma polyneuron Müll. Arg (peroba) - Tricorynus sp. (Anobiidae) e Rhinochoenus stigma (Curculionidae); Enterolobium contortisiliquum (Vell.) Morong (timbó) - Stator pacarae(Bruchidae). / This paper deals with the identification of Coleoptera (species and family) associated to the reproductive structures of the following native forest tree species: Pterogyne nitens Tul. ("amendoim-bravo") - Tricorynus sp. (Anobiidae) and Ormiscus sp. (Anthribidae); Stryphnodendron adstringens (Mart.) Cov.("barbatimão") - Acanthoscelides sp. (Bruchidae); Cassia grandis L. f. ("cássiagrande") - Pygiopachymerus lineola (Bruchidae); Tabebuia alba (Cham.) Sandwith ("ipê-amarelo") - Sitophilus linearis (Curculionidae); Hymenaea courbaril var. stilbocarpa (Hayne) Lee & Lang ("jatobá") - Tricorynus sp. (Anobiidae); Chorisia speciosa (A. St. - Hil.) Dawson ("paineira") - Lonchophorus obliquus (Curculionidae); Caesalpinia ferrea var. leiostachya Benth. ("pau-ferro") - Pityophthorus sp. (Scolytidae); Aspidosperma polyneuron Müll. Arg ("peroba") - Tricorynus sp. (Anobiidae) and Rhinochoenus stigma(Curculionidae); Enterolobium contortisiliquum (Vell.) Morong ("timbó") - Stator pacarae (Bruchidae).

As espécies florestais arbóreas nativas apresentam interações com coleópteros que se desenvolvem no interior das estruturas reprodutivas. Foram estudadas as seguintes espécies florestais arbóreas nativas e identificados os coleópteros a elas associados: Pterogyne nitens Tul. (amendoim-bravo) - Tricorynus sp. (Anobiidae) e Ormiscus sp. (Anthribidae); Stryphnodendron adstringens (Mart.) Cov. (barbatimão) - Acanthoscelides sp. (Bruchidae); Cassia grandis L. f. (cássia-grande) - Pygiopachymerus lineola (Bruchidae); Tabebuia alba (Cham.) Sandwith (ipê-amarelo) - Sitophilus linearis (Curculionidae); Hymenaea courbaril var. stilbocarpa (Hayne) Lee & Lang (jatobá) - Tricorynus sp. (Anobiidae); Chorisia speciosa (A. St. - Hil.) Dawson (paineira) - Lonchophorus obliquus (Curculionidae); Caesalpinia ferrea var. leiostachya Benth. (pau-ferro) - Pityophthorus sp. (Scolytidae); Aspidosperma polyneuron Müll. Arg (peroba) - Tricorynus sp. (Anobiidae) e Rhinochoenus stigma (Curculionidae); Enterolobium contortisiliquum (Vell.) Morong (timbó) - Stator pacarae(Bruchidae). / This paper deals with the identification of Coleoptera (species and family) associated to the reproductive structures of the following native forest tree species: Pterogyne nitens Tul. ("amendoim-bravo") - Tricorynus sp. (Anobiidae) and Ormiscus sp. (Anthribidae); Stryphnodendron adstringens (Mart.) Cov.("barbatimão") - Acanthoscelides sp. (Bruchidae); Cassia grandis L. f. ("cássiagrande") - Pygiopachymerus lineola (Bruchidae); Tabebuia alba (Cham.) Sandwith ("ipê-amarelo") - Sitophilus linearis (Curculionidae); Hymenaea courbaril var. stilbocarpa (Hayne) Lee & Lang ("jatobá") - Tricorynus sp. (Anobiidae); Chorisia speciosa (A. St. - Hil.) Dawson ("paineira") - Lonchophorus obliquus (Curculionidae); Caesalpinia ferrea var. leiostachya Benth. ("pau-ferro") - Pityophthorus sp. (Scolytidae); Aspidosperma polyneuron Müll. Arg ("peroba") - Tricorynus sp. (Anobiidae) and Rhinochoenus stigma(Curculionidae); Enterolobium contortisiliquum (Vell.) Morong ("timbó") - Stator pacarae (Bruchidae).