Caracterização genética de arroz (Oryza Sativa L.) através de marcadores moleculares RAPD e eficiência na aquisição de N

Abstract

We have studied the influence of using 6 different coefficients of similarity when grouping 16 varieties of rice analyzed by the RAPD technique. DNA samples of these varieties were amplified using 20 primers, only 15 (75%) of which produced amplified fragments, compresing 90 of these were polimorphic fragments. The analysis of the band, profile produced a “fingerprint”. For the calculation of the similarity index several coefficients were tested: Nei & Li, Jaccard, Ochiai, Russel & Rao, Simple Matching and Rogers & Tanimoto. Comparison among them was carried out through the evaluation of the dendrograms generated by the UPGMA algorithm and by the correlations between the genetic pitches. The coefficients of Nei & Li, Jaccard, and Ochiai discriminated the varieties in three main groups according to their genetic similarities. Our results show that the coefficients of Nei & Li, Jaccard and Ochiai adjusted better the groups with hight genetic similarities. While the coefficients Simple Matching and Rogers & Tanimoto were not as efficient, banding together varieties that are genetically different. In experiments, with the objective to studies the effect of levels (20 or 60 mg N/L) e forms of N (NH4 + and NO3 -) under the kinetics parameters, proton extrusion, the activity of the N-assimilation enzymes and the N-partition in the plant, were conducted in greenhouse, using 5 upland rice varieties (Lageado, IAC 47, Dobradinho, Agulha e Bico Ganga), in nutrient solution. It was observed an ample variation of the kinetics parameters and biochemists, and a distinguishing behavior among varieties in the uptake and use of N. The varieties Agulha and IAC-47 had presented the best combination of KM, Vmáx, GS/GOGAT in conditions of hight avaibility of N- NO3 -, and Bico Ganga, in conditions of low avaibility of N- NO3 - in nutrient solution. In another experiment, with the objective to study the assimilation and remobilização of N in season nitrate conditions, used varieties Sagrimão, Goiano, Zebu, Agulha, IAC 1278, IR08, Comum Branco, IAC 47 e Ligeiro had been cultivated in nutritional solution. The N-assimilation enzymes were estudied in the leaf blades and root of 62 and 69 days old rice plants, under 20 and 200 mg mgN-NO3 -/L. Under higher nitrate supply had increase the activity of the NR, GS and GOGAT in rice plants. The GS activities had been low in roots, in comparison with the activities observed in leaf. The GOGAT activity was bigger in roots, in both the treatments. The GDH-A activity occurred mainly in tessues foliar. The GDH-D activity occurred in leaf as in roots. The GDH-D activity not occurred in tissues foliar. The activity of the enzymes of N-assimilation was higher in tissues foliar. These results seem indicate the leaves as the main site of NH4 +-N assimilation in rice plants under higher NO3 --supply.