Small RNA transcriptomes of mangroves evolve adaptively in extreme environments

Area of Science:

• Plant molecular biology
• Genomics
• Environmental adaptation

Background:

• MicroRNAs (miRNAs) and endogenous small interfering RNAs (siRNAs) are crucial for plant responses to environmental stress.
• Mangroves thrive in challenging saline and arid conditions, suggesting unique regulatory mechanisms.
• Understanding mangrove small RNA (sRNA) biology is key to deciphering their adaptive strategies.

Purpose of the Study:

• To characterize the sRNA transcriptomes of two mangrove species, Bruguiera gymnorrhiza and Kandelia candel.
• To compare mangrove sRNA regulatory networks with those of glycophytes (non-salt-tolerant plants).
• To identify specific sRNAs and their targets involved in mangrove stress tolerance and nutrient homeostasis.

Main Methods:

• Small RNA (sRNA) sequencing of Bruguiera gymnorrhiza and Kandelia candel.
• Comparative computational analyses of sRNA transcriptomes.
• Target prediction for identified miRNAs and siRNAs.

Main Results:

• Distinct sRNA regulatory networks were identified in mangroves, differing from glycophytes.
• 32 known and 3 novel miRNA families were discovered, with targets involved in stress responses.
• Mangroves exhibit differential expression of known miRNAs and unique small interfering RNAs (siRNAs), including TAS3 trans-acting siRNAs (tasiRNAs), contributing to stress adaptation.

Conclusions:

• Evolutionary changes in sRNA expression and network rewiring are vital for plant stress adaptation.
• Specific sRNAs identified in mangroves are likely key contributors to salt and drought tolerance and nutrient homeostasis.
• These findings provide insights into the molecular mechanisms underlying mangrove survival in extreme environments.