Expressão diferencial de genes na germinação do mutante de arroz M3-202 sob baixas temperaturas

Abstract

The most rice cultivated in Brazil are from the Indica subspecies, which is sensitive at low temperatures that occurs on the South Brazil, the main producer. The close genetic basis of the national cultivars had difficulted to obtain of cold tolerant cultivars. A way to increase the genetic variability is induced mutations and genetic selections from mutant populations. After to improvement the genetic variability, genetical and molecular studies may allow identification and selection desired genotypes. The objective of the study was to produce and isolate express cDNA fragments in the M3-202 rice mutant family in cold response during the germination. The mutant was compared with the following genotypes: BRS Firmeza (cold tolerant), SCS BRS-113 Tio Taka (cold susceptible), and the cultivar BRS-7 Taim (cold susceptible) wild type. The seeds of these genotypes were submitted to the germination at 25 °C and 13 °C to access differential expression. After germination, the embryos were isolated from each genotype at 1, 2, 3 days after sowing to 25 ºC and at 4, 8, 11, 14 days to 13 ºC, and extracted the total RNA using the Pure Link Plant RNA Isolation Kit. For the synthesis of double-strand cDNAs we used the SuperScriptTM Double-Stranded cDNA Synthesis Kit followed selective amplifications using the AFLP Starter Primer Kit. Polymorphic fragments in the two evaluated temperatures; 42 expressed fragments were identified in the mutant in contrast with the wild type. In relation to BRS Firmeza, the M3-202 presented 7 fragments with the same molecular weight, at 13 °C, those absent in the wild type. The differentially expressed more intense fragments were recovered for subsequent sequencing and expressed genes identification in the mutant family and, possibly, to relate with the cold tolerance in the germination stage in the future studies.