Gene Expression and Functional Analysis of Soybean Genes with Diurnal Oscillation during Drought Stress

Date: Monday, January 12, 2015
Juliana Marcolino Gomes , State University of Londrina/ Embrapa Soybean, Londrina, Brazil
Thiago J. Nakayama , Federal University of Viçosa/ Embrapa Soybean, Londrina, Brazil
Rafaela Ribeiro Reis , State University of Londrina/ Embrapa Soybean, Londrina, Brazil
Fabiana Aparecida Rodrigues , Embrapa Soybean, Londrina, Brazil
Liliane M. Mertz Henning , Embrapa Soybean, Londrina, Brazil
Renata Fuganti-Pagliarini , Embrapa Soybean, Londrina, Brazil
Hugo B. Correa Molinari , Embrapa Agroenergy, Brasília, Brazil
Frank Harmon , ARS/USDA Plant Gene Expression Center, Albany, CA
Alexandre Nepomuceno , Embrapa Soybean, Londrina, Brazil
Drought is the major limiting factor influencing productivity of commercially important crops. In the past several years, drought has severely affected soybean areas worldwide, and climate change sceneries suggest increase of drought stress episodes. The circadian clock drives diurnal and seasonal oscillations in organisms, enhancing fitness and could play an important role in drought responses. Because little is known about the relations between the circadian clock and drought stress, we used RT-qPCR and RNA-seq to assess the gene expression profiles in response to drought along the day. Soybean plants were analyzed under moderate and severe drought stress conditions, sampling with 4-hour intervals during 24h. The resultant gene expression database allowed us to select candidate genes for functional analysis by overexpression in Arabidopsis. Plants were transformed by the floral dip method and transformants were selected in MS medium containing the selection marker hygromycin. The transgene presence was checked by PCR with specific primers. Drought and osmotic stress experiments were performed with one-copy homozygous lines. Our results show that the overexpression of a soybean gene encoding a stress-responsive A/B Barrel Domain protein decreased germination velocity in response to different PEG concentrations, suggesting an increase of osmotic stress sensitivity. On the contrary, the overexpression of a gene coding a yet uncharacterized-protein increased transgenic plants survival in response to drought. Together our results suggest that we identified key genes in drought tolerance. Further studies of the transgenic plants will help to unveil the drought tolerance mechanisms, contributing to the development of drought tolerant soybeans.