DIVERSIDADE CULTURAL, MORFOLóGICA E GENéTICA DE DIAZOTRóFICOS ISOLADOS DE NóDULOS DE BRACATINGA1

摘要

Nitrogen is one of the essential macronutrients for living beings, which makes it one of the limiting factors for plant growth. Only a portion of the prokaryotes, the diazotrophics, has the ability to reduce atmospheric nitrogen to otherforms available to plants. Bracatinga is an economically important arboreal species capable of establishing mutualistic symbiosis with diazotrophic organisms. Its main uses are: energy production, wood, forage, chemical industry of natural products, beekeeping, landscaping and shadowing and recovery of degraded areas and riparian zones. The present study aimed to establish relationship between cultural and morphological diversity and genetic variabilityfrom nodules of bracatinga isolated in different edaphoclimatic conditions. Root nodules randomly collectedfrom seven areas between the Vale do Itajaí, Plateau South and Midwest of the State of Santa Catarina. Broad cultural diversity was observed among the present diazotrophics, and there was a predominance of fast-growing isolates of colony with milky white coloration, round shape, flat edge and mucoid surface. Among the evaluated parameters, transparency of the colony, mucus production and pH modification were considered relevant to the differentiation of isolates. Taxonomic characterization of the isolates was performed by comparison of the sequenced fragments, being the isolated species of this sample setfrom the genera Burkholderia, Pseudomonas, Pantoea and Rhizobium.