IC4R009-miRNA-2010-20729483

Project Title

Genome-wide identification and analysis of drought-responsive microRNAs in Oryza sativa

In addition to regulating growth and development, the most important function of microRNAs (miRNAs) in plants is the regulation of a variety of cellular processes underlying plant adaptation to environmental stresses. In this project, to gain a deep understanding of the mechanism of drought tolerance in rice, the researchers carried out genome-wide profiling and analysis of miRNAs in drought-challenged rice across a wide range of developmental stages, from tillering to inflorescence formation, using a microarray platform.

Twenty pre-germinated seeds of rice cv. IRAT109 were planted in soil in a 1/5000a Wagner’s pot. Four pots of rice plants were grown in parallel; one was subject to stress treatment at the tillering stage, one was stress challenged at the inflorescenceforming stage, and the other two pots were grown under normal condition; that is, without suffering drought stress caused by withholding of water as in the treatments. At growth stage 6.1 which is characterized by the number of leaves on the main stem of a plant, that is equivalent to the tillering stage in paddy field production, water was withheld to develop drought stress, while control pots received normal watering. Typical stress symptoms, such as leaf rolling, appeared on the eighth day after water withholding (8 DAW) when the absolute water content of the soil decreased to <4.5%. Total RNA was then extracted on 10, 12, and 14 DAW using TRNzol Total RNA Reagent (Tiangen, China) according to the manufacturer’s instructions. The growth status of the stressed rice is shown in Fig. 1A. The second drought stress was then imposed when the flag leaf appeared. Stress symptoms started to emerge on 4 DAW and total RNA was extracted on 5 and 6 DAW (Fig. 1B). RNA was extracted from the plants grown in the control pots in the above two phases. These RNA samples were profiled by a miRNA array platform.

Figure 1. Growing status of rice plants under drought stress.

National Key Laboratory of Crop Genetic Improvement, College of Plant Science, Huazhong Agricultural University, Wuhan 430070,

China