02965naa a2200241 a 450000100080000000500110000800800410001910000220006024500780008226000090016030000110016952021990018065000110237965000230239065000090241365300110242265300120243365300220244570000170246770000210248470000190250577301990252414616552004-10-15       1999    bl uuuu     u00u1 u    #d1 aNEPOMUCENO, A. L.  aGene expression in brazilian soybean genotypes tolerant to water deficit.  c1999  ap.439.  aAbiotic stresses such as drought can significantly reduce crop yields and restrict the areas on which crops can be cultivated. The implications of this are tremendous since not only are producers affected but the entire society also. The development of new cultivars more tolerant to water deficits is one of the options to attenuate this problem. However, tolerance to drought in plants clearly is not a simple trait, but a complex of mechanisms working in combination to avoid or to tolerate water deficits. All mechanisms that plants use to tolerate drought do have a molecular/genetic basis. Comparison of gene expression in different genotypes and treatments should provide underlying information needed to analyze the biological processes that control how organisms respond to stress situations. This work has been conducted with the main objective of identifying, cloning and sequencing genes differentially expressed during water deficit in Brazilian soybean genotypes tolerant to drought. Physiological characterization results showed that cultivars BR-4 and OCEPAR 4 have a higher tolerance for periods of drought when compared with cultivars BR-16 and BRAGG. These four soybean genotypes are now been analyzed with the use of Differential Display (DD) a technique that uses mRNA as template to obtain representative cDNAs by reverse transcription and polymerase chain reaction. Differentially expressed cDNAs are extracted from the gel, cloned and sequenced. Earlier work conducted with cotton identified 52 mRNA transcripts differentially expressed during drought. Some of these transcript sequences were transformed in probes to survey Embrapa soybean germplasm bank to see if transcripts of these same gene families are expressed in soybean during water deficit. The differentially expressed mRNA transcripts identified in soybean can also be used as probes to screen germplasm. Plant physiological studies on responses to water deficit, molecular mapping of traits related to drought tolerance and the development of drought tolerant genotypes might be helped by these results. Furthermore, some of the identified genes may show a high potential for plant transformation studies.  aBrazil  asoil water deficit  aSoja  aBrasil  aSoybean  aTolerancia a seca1 aNEUMAIER, N.1 aFARIAS, J. R. B.1 aCASAGRANDE, E.  tIn: WORLD SOYBEAN RESEARCH CONFERENCE, 6., 1999, Chicago. Proceedings: invited and contributed papers and posters. Chicago: University of Illinois / Soybean Research & Development Council, 1999.