Visiting Scientists

Juliana Marcolino Gomes

Associated of Labex Scientist Alexandre Lima Nepomuceno

Quantitative gene expression evaluation of Soybean/A.thaliana clock gene orthologs in response to drought.

Research Team: Juliana Marcolino Gomes (PhD student), Frank Harmon (PhD), Alexandre Nepomuceno (PhD).

Objectives: a) Evaluate the expression pattern of all known Soybean circadian clock genes (Arabidopsis thaliana orthologs) under drought stress and how these genes interact and modulate tolerance mechanisms; b) Analyze the expression pattern of drought responsive genes along 24h time course, under optimal and water deficit situations.

Approach: A drought sensitive genotype (BR-16) was submitted to water deficit situations and qPCR was used to measure expression levels of clock genes (GmTOC1, GmZTL, GmPRR3, GmPRR7, GmPRR9, GmGI, GmCCA1, GmLUX, GmELF4, GmJMJD5, GmCHE). In the same data points isoforms of Drought responsive genes (GmABAR, GmREMORIN, GmGOLS, GmERF, GmDREB1, GmDREB2, GmDREB3, GmLEA, GmAREB, GmSnRK2, GmPP2C) present at Abscisic Acid (ABA) dependent and Independent pathways are also being analyzed. The expression level of these 30 genes is being examined every 4h in a time course of 24h at a 14/10h day/night photoperiod in two water deficit treatments, at 30% (mild) and 15% (Severe) Soil Gravimetric Humidity (GH).

Results: Preliminary results show a clear impact of dehydration on clock genes expression when compared to control plants at optimal watering conditions (70% GH). Also, it is possible to observe how drought responsive genes have their expression oscillating along the day, in stressing conditions, but also at optimal watering conditions. These preliminary findings confirm the importance of the time of day on defense mechanisms. Ever since key genes involved in protecting cell structures during dehydration might have specific times of the day when their expression is more relevant. Considering that plants try to recover from drought at night when transpiration halts, a tight equilibrium at transcription/proteomic level is in place, thus plants can get the best use of day/night environments to survive and produce decedents. Identification of key genes involved on the circadian clock interactions with plant defenses mechanisms to drought, may be used for genetic modifications to drought tolerance, or used on genome-wide selection approaches.