Full text
| |
| Author(s): |
Livia Camilla Trevisan Scorza
Total Authors: 1
|
| Document type: | Doctoral Thesis |
| Press: | Campinas, SP. |
| Institution: | Universidade Estadual de Campinas (UNICAMP). Instituto de Biologia |
| Defense date: | 2015-08-26 |
| Examining board members: |
Marcelo Carnier Dornelas;
Adriana Pinheiro Martinelli;
Maria Helena de Souza Goldman;
Rogerio Margis;
Juliana Lischka Sampaio Mayer
|
| Advisor: | Marcelo Carnier Dornelas |
| Abstract | |
An important issue in plant biology is how morphological novelties are produced during evolution. The genus Passiflora represents an example of plants that display complex structures whose origins have not been clarified yet, such as the corona filaments in the flowers and the tendrils that grow in the axils of the leaves, next to a flower bud. Adult plants of Passiflora edulis constantly produce flower buds. The axillary meristem (AM) is subdivided into two domes, one that forms the tendril and another one that forms the flower meristem (FM). A second AM is formed in between the tendril flower complex and the stem, which corresponds to the vegetative bud. The ontogeny and the arrangement of these structures have led some authors to consider the tendril in Passiflora as part of the primary axis of a reduced inflorescence, but the molecular mechanisms that define these structures of common origin, but with completely different final shapes are not clear. In order to understand these mechanisms, the tendril growth was analyzed using morphological and anatomical data, which concluded that the tendril grows from the bottom, similarly to the growth pattern of leaves. MADS-box genes of the AP1 / FUL lineage were identified and their expression patterns evaluated in P. edulis. PeAP1 is expressed throughout the AM, including the FM and the tendril. PeAP1 expression levels in the tendrils remain high even after maturity. PeAP1 was also detected in other meristematic regions, such as stem apical meristem and the axillary bud. In the flower, PeAP1 was detected mainly in sepals and petals, but in situ hybridization showed transcripts in regions that will form the corona, in tapetum cells and microspores, as well as in ovules. The presence of PeAP1 in these regions suggest a role in regulating the expression of other transcription factors required for organ specification, in addition to maintaining the floral meristem and perianth organ identity. The expression of PeAP1 in the tendrils could also be related to this role and not only to the floral identity. PeFUL showed widespread expression in all tissues, but at higher levels in leaves, stem, carpels and fruits. The expression in the fruit may be related to the ripening process. Genes that typically confer polarity in plant organs were also identified such as the YABBY, ARP and HD-ZIPIII, as well as meristem marker genes, such as the KNOX genes. PeSTM and PeKNAT1 are expressed in FMs and in tendril and bract primordia, but the expression is suppressed as these organs develop, being restricted to the FM, which brings evidence that the tendril initially grows as a lateral stem branch. PePHAN is expressed in leaf primordia and in the beginning of the development of tendrils and bracts, and apparently the expression is decreased as the tendril grows, possibly leading to abaxialization of the tendril. Finally, reference genes for normalization in expression analysis by qRT-PCR were identified and from the genes tested, PeCAC and PeSAND had the higher expression stability among the different P. edulis tissues (AU) | |