Análise proteômica em Lippia alba (Verbenaceae)(Mill.) N.E.Brown

Abstract

Lippia alba is a plant vastly utilized in popular medicine due to its antimicrobial, antispasmodic, anti-inflammatory, analgesic and pro-digestive features. It is commonly known in Brazilian Portuguese as “cidreira”, “erva cidreira” along with other popular names and “bushy matgrass” in English. It is widely used in Brazil and South America. The species display large genetic variation, five cytotypes have been described with 2n=30, 38, 45, 60 and 90. The study of these chromosomal variations has led to proposing the formation of an autopolyploid complex derived from unilateral and bilateral crossings of cytotypes by reduced and/or non-reduced gametes. There have been advances concerning the knowledge on L. alba and on the formation of the polyploid complex. Various approaches have been employed, such as analysis of data generated from karyotyping, cytogenetics, cytometry and molecular genetics. The present work aims at contributing to elucidate the possibility of biological variations by assessing, comparatively, the proteomic profile of the ploidy levels described for the species (diploid, aneuploid, triploid, tetraploid and hexaploid). Protein extraction from leaves has been carried out with posterior dimensional electrophoretic separation. Later, we performed spot analysis and protein identification by mass spectrometry. When comparing the proteomic profile from the diploid sample to the remaining ploidy levels, expression differences were observed between the spots analyzed. The differences showed to be either qualitative, due to the variation in presence of spots, and quantitative, as observed in the volume percentage of each spot. In addition, we identified 44 proteins, being 27 related to photosynthesis, 12 to metabolism and energy, 3 chaperones, and 2 tubulins with structural function. For each of the identified proteins, it was possible to observe similarities and divergences concerning expression amidst the ploidy levels studied. The proteins identified possess relevant roles in primary metabolism of L. alba. Our data suggest that alterations in genome size do not provoke representative alterations on the proteomic profile, with the exception of the triploid sample, which displayed a particular profile.