The commitment of barley microspores into embryogenesis correlates with miRNA‐directed regulation of members of the SPL, GRF and HD‐ZIPIII transcription factor families

Abstract

Microspore embryogenesis is a model for developmental plasticity and cell fate decisions. To investigate the role of miRNAs in this development, we sequenced sRNAs and the degradome of barley microspores collected prior to (day 0) and after (days 2 and 5) the application of a stress treatment known to induce embryogenesis. Microspores isolated at these timepoints were uniform in both appearance and in their complements of sRNAs. We detected 68 miRNAs in microspores. The abundance of 51 of these miRNAs differed significantly during microspore development. One group of miRNAs was induced when the stress treatment was applied, prior to being repressed when microspores transitioned to embryogenesis. Another group of miRNAs were up‐regulated in day‐2 microspores and their abundance remained stable or increased in day‐5 microspores, a timepoint at which the first clear indications of the transition toward embryogenesis were visible. Collectively, these miRNAs might play a role in the modulation of the stress response, the repression of gametic development, and/or the gain of embryogenic potential. A degradome analysis allowed us to validate the role of miRNAs in regulating 41 specific transcripts. We showed that the transition of microspores toward the embryogenesis pathway involves miRNA‐directed regulation of members of the ARF, SPL, GRF, and HD‐ZIPIII transcription factor families. We noted that 41.5% of these targets were shared between day‐2 and day‐5 microspores while 26.8% were unique to day‐5 microspores. The former set may act to disrupt transcripts involved in pollen development while the latter set may drive the commitment to embryogenesis.

Comparative proteomic analysis provides new insights into regulation of microspore embryogenesis induction in winter triticale (× Triticosecale Wittm.) after 5-azacytidine treatment

“…Up-regulation of GSTF2 during the first stages of ME in different species has been described 9 , 12 , 26 . Its role is probably related to cell protection against the harmful effects of ROS generation, enhancement of microspores viability and reprogramming efficiency 31 , 52 .…”

“…Reprogramming of the microspore and initiation of embryogenesis involve genome-wide changes of gene expression that allow the cell fate program to be halted and switched to a new developmental pathway 8 . Recently harnessed advanced methods of wide transcriptome analysis allowed the selection of differentially expressed genes during ME initiation and ELS development 9 – 12 . Majority of them has been identified as being involved in cell protection against stress, sugar metabolism, signaling and proteolysis.…”

Androgenesis-Based Doubled Haploidy: Past, Present, and Future Perspectives

“…Recently, Bélanger et al (2020) investigated the role of miRNA for developmental plasticity and cell fate reprogramming within the barley microspore. Their findings indicated that the switch toward embryo differentiation involved miRNA-directed regulation of members of the ARF, SPL, GRF, and HD-ZIPIII transcription factor families.…”

Understanding In Vitro Tissue Culture-Induced Variation Phenomenon in Microspore System

“…Some of them appear due to stress responses. Furthermore, miRNA-directed regulation of several transcription factor families (ARF, SPL, GRF, and HD-ZIPIII) was needed for the transition of microspores toward the embryogenesis pathway [ 207 ]. Differential expression of small RNAs was also denoted in the early development of broccoli ( Brassica oleracea var.…”