Comparative Genome-Wide Analysis of MicroRNAs and Their Target Genes in Roots of Contrasting Indica Rice Cultivars...

Area of Science:

• Plant Biology
• Genetics
• Agronomy

Background:

• Global climate change intensifies drought stress, threatening rice production and food security.
• Plant roots are crucial for sensing drought and water acquisition.
• MicroRNAs (miRNAs) are known to play roles in plant abiotic stress responses, but their specific functions in rice drought tolerance are not fully understood.

Purpose of the Study:

• To investigate the differential expression of microRNAs (miRNAs) in the roots of contrasting rice cultivars under terminal drought stress.
• To identify novel miRNAs and their target genes involved in drought response mechanisms in rice.

Main Methods:

• Comparative analysis of known and novel miRNA expression in drought-sensitive (IR-64) and drought-tolerant (N-22) rice cultivars under reproductive-stage drought stress.
• Identification of differentially expressed miRNAs and their exclusively expressed counterparts in root tissues.

Main Results:

• 270 known and 91 novel miRNAs showed differential expression in rice roots under drought stress.
• Specific miRNAs (e.g., osamiR812, osamiR166, osamiR156, osamiR167, osamiR396) were highly differentially expressed.
• Drought-tolerant N-22 roots exhibited exclusive expression of 18 known and 12 novel miRNAs, compared to only 2 known miRNAs in sensitive IR-64 roots.
• Target genes of these miRNAs included drought-responsive transcription factors involved in development and hormone signaling.

Conclusions:

• Novel miRNAs identified in this study are promising candidates for genetic improvement of rice for terminal drought tolerance.
• Understanding miRNA-mediated drought response pathways can contribute to developing climate-smart rice varieties for sustainable agriculture.