REFLEXOS DA AUSÊNCIA DE CLOROFILA NA COMPOSIÇÃO DE PAREDE CELULAR E NA FISIOLOGIA DE PLÂNTULAS ALBINAS DE FLAMBOYANT [Delonix regia (Bojer ex Hook) Raf.]

Abstract

The partial or complete loss of chlorophyll pigments characterizes a rare phenomenon in plants, the plant albinism. Albino seedlings of [Delonix regia (Bojer ex Hook) Raf.]. were recently reported and a previous study showed changes in stomatal micromorphology and in the leaf tissues dimensions, in relation to wild-type homologs. Thus, the present study aimed to determine the possible effects of chlorophyll loss on the physiology, metabolism and cell wall structure of leaves and epicotyls of albino seedlings of D. regia, as observed in recent works published with studies of Sequioa sempervirens (D. Don.) Endl.). D. regia seeds were germinated and the frequency of wild type (WT) and albino seedlings was determined. Chlorophyll content, as well as metabolites associated with carbon and nitrogen metabolism were quantified. Leaflet and epicotyl samples of both phenotypes were processed following common procedures for analysis with light and immunofluorescence microscopy. The albino seedlings represented 16% of the seeds present in the pods. However, only 15% of the pods rise to albino seedlings. These seedlings had chlorophyll and carbohydrate content with lower concentrations of glucose, fructose, sucrose and starch. In contrast, the protein and amino acid content was, respectively, 31.8% and 65.3% higher compared to wild-type counterparts. The albino seedlings presented leaflets and epicotyls with less histological differentiation. Gas exchange analyzes also showed that albinism alters the photosynthetic apparatus efficiency, since the rate of carbon assimilation, transpiration, water use efficiency and stomatal conductance were lower in albino seedlings. The results also indicated the occurrence of oxidative and lipid stress in them, although the content of most macro and micronutrients was higher in albino seedlings. It is observed lower deposition of pectins and xyloglucan in the cell walls of albino organs. These results show the broad reflection of the chlorophyll loss in the metabolism and physiology of D. regia and the essential role of photosynthetic pigments in the development of plant tissues, thus, differences between wild and albino seedlings can be highlighted in several aspects of studies related to the subject.