The miRNA–mRNA Networks Involving Abnormal Energy and Hormone Metabolisms Restrict Tillering in a Wheat Mutant dmc

Abstract

Tillers not only determine plant architecture but also influence crop yield. To explore the miRNA regulatory network restraining tiller development in a dwarf-monoculm wheat mutant (dmc) derived from Guomai 301 (wild type, WT), we employed miRNome and transcriptome integrative analysis, real-time qRT-PCR, histochemistry, and determinations of the key metabolites and photosynthesis parameters. A total of 91 differentially expressed miRNAs (DEMs) were identified between dmc and WT. Among them, 40 key DEMs targeted 45 differentially expressed genes (DEGs) including the key DEGs encode growth-regulating factors (GRF), auxin response factors (ARF), and other proteins involved in the metabolisms of hormones and carbohydrates, etc. Compared with WT, both the chlorophyll contents and the photosynthesis rate were lower in dmc. The contents of glucose, sucrose, fructose, and maltose were lower in dmc. The contents of auxin (IAA) and zeatin (ZA) were significantly lower, but gibberellin (GA) was significantly higher in the tiller tissues of dmc. This research demonstrated that the DEMs regulating hormone and carbohydrate metabolisms were important causes for dmc to not tiller. A primary miRNA–mRNA regulatory model for dmc tillering was established. The lower photosynthesis rate, insufficient energy, and abnormal hormone metabolisms restrict tillering in dmc.

Regulation of Aegilops tauschii Coss Tiller Bud Growth by Plant Density: Transcriptomic, Physiological and Phytohormonal Responses

“…tauschii at HPD cannot provide sufficient energy for the normal elongation of tiller buds, revealing that the outgrowth of tiller bud requires sufficient energy. A consistent phenomenon has been found in the wheat mutant duc with fewer tillers, and the restriction of its tillering was due to the lower photosynthesis rate of leaves and insufficient energy for the outgrowth of its tiller buds (An et al, 2019). Koumoto et al (2013) proposed that the supply of sucrose might be a vital factor for the development of tiller bud of the rice monoculm mutation moc2, largely supporting the findings in this research.…”

Key wheat GRF genes constraining wheat tillering of mutant dmc

“…The tiller ability of the transgenic wheat overexpression miR396 is significantly decreased ( Song, 2016 ). Our miRNome and transcriptome integrative analysis about the mutant dmc and WT found that the highly expressed tae-miR396b ( T. aestivum microRNA396b) down-regulated the expressions of many TaGRFs ( TaGRF1 , TaGRF2 , TaGRF5 , TaGRF9 , TaGRF10 and TaGRF12 ) in dmc during tillering ( He et al, 2018 ; An et al, 2019 ). It demonstrated that the miR396/ GRF regulatory module played a key role in wheat tiller development.…”

“…The mutant dmc was obtained according to the method described in the previous article ( An et al, 2019 ). All the plant materials were planted in our experimental field (34°25′ N, 115°39′ E, 49 m a.s.l .).…”

“…qRT-PCR was performed as described previously by An et al (2019) . The primers of TaGRFs were designed using Primer-Blast of NCBI website ( ).…”

“…Common wheat is one of the most important food crops worldwide. Previously, we have reported a dwarf-monoculm wheat mutant ( dmc ) derived from Guomai 301 ( He et al, 2018 ), and found that wheat miR396b (tae-miR396b) and several of its target TaGRFs are involved in regulating wheat tillering in dmc ( An et al, 2019 ). This provides a good opportunity to design experiments exploring the molecular mechanisms of wheat tiller development.…”