PhasiRNAs in Plants: Their Biogenesis, Genic Sources, and Roles in Stress Responses, Development, and Reproduction

Plant Cell. 2020 Oct;32(10):3059-3080. doi: 10.1105/tpc.20.00335. Epub 2020 Aug 18.


Phased secondary small interfering RNAs (phasiRNAs) constitute a major category of small RNAs in plants, but most of their functions are still poorly defined. Some phasiRNAs, known as trans-acting siRNAs, are known to target complementary mRNAs for degradation and to function in development. However, the targets or biological roles of other phasiRNAs remain speculative. New insights into phasiRNA biogenesis, their conservation, and their variation across the flowering plants continue to emerge due to the increased availability of plant genomic sequences, deeper and more sophisticated sequencing approaches, and improvements in computational biology and biochemical/molecular/genetic analyses. In this review, we survey recent progress in phasiRNA biology, with a particular focus on two classes associated with male reproduction: 21-nucleotide (accumulate early in anther ontogeny) and 24-nucloetide (produced in somatic cells during meiosis) phasiRNAs. We describe phasiRNA biogenesis, function, and evolution and define the unanswered questions that represent topics for future research.

Publication types

  • Research Support, Non-U.S. Gov't
  • Research Support, U.S. Gov't, Non-P.H.S.
  • Review

MeSH terms

  • Evolution, Molecular
  • Gene Expression Regulation, Plant
  • MicroRNAs / genetics
  • Plant Development / genetics
  • Plant Physiological Phenomena / genetics*
  • RNA, Long Noncoding / genetics
  • RNA, Plant / physiology*
  • RNA, Small Interfering / genetics*
  • Stress, Physiological / genetics*


  • MicroRNAs
  • RNA, Long Noncoding
  • RNA, Plant
  • RNA, Small Interfering