miR156/SPL10 Modulates Lateral Root Development, Branching and Leaf Morphology in Arabidopsis by Silencing AGAMOUS-LIKE 79

Abstract

The developmental functions of miR156-SPL regulatory network have been extensively studied in Arabidopsis, but the downstream genes regulated by each SPL have not been well characterized. In this study, Next Generation Sequencing-based transcriptome analysis was performed on roots of wild type (WT) and miR156 overexpression (miR156OE) plants. One of the SPL genes, SPL10, which represses lateral root growth in Arabidopsis, was significantly downregulated in miR156OE plants. A transcription factor, AGAMOUS-like MADS box protein 79 (AGL79), was also significantly downregulated in the miR156OE plants, but was upregulated in the SPL10 overexpression (SPL10OE) Arabidopsis plants. In addition, SPL10 was found to bind to the core consensus SPL binding sequences in AGL79 gene. Moreover, analyses of complementation lines revealed a linear relationship between SPL10 and AGL79 in regulating Arabidopsis plant development. In addition, it was observed that plant phenotypes are AGL79 dose-dependent, with higher expression causing narrow leaf shape, less number of leaves and early flowering time, whereas relatively lower AGL79 overexpression produce plants with more rosette leaves and more lateral branches. Our findings revealed direct binding of SPL10 to AGL79 promoter, which further suggests a role for miR156/SPL10 module in plant lateral root growth by directly regulating AGL79.

MADS‐box genes underground becoming mainstream: plant root developmental mechanisms

“…Tansley review New Phytologist initiation sites (Moreno-Risueno et al, 2010). By contrast, knockout lines of AGL79 have more LRs in than wild-type plants do (Gao et al, 2018). Table S1 summarizes the available expression data for several MADS-box genes mentioned in this review in different plant species.…”

Regulation of flowering time by SPL10/MED25 module in Arabidopsis

“…Here, we showed that overexpression of SPL10 promotes expression of FUL , LFY , AP1 , SOC1 and miR172b , and SPL10 binds directly to the promoters of FUL and AP1 . AGL79 , a MADS‐box protein‐encoding gene, was also found to be a direct target gene of SPL10 (Gao et al ., ; Fig. ).…”

“…Recently, HISTONE ACETYLTRANSFERASE 1 (HAC1), an evolutionarily conserved coactivator, has been reported to physically and functionally associate with MED25 to activate the expression of jasmonic acid responsive genes by H3K9 acetylation (An et al ., ). SPL10 also enhances the transcript levels of miR172b , AGL79, FUL , and AP1 during floral transition and shoot maturation (Shikata et al ., ; Wu et al ., ; Gao et al ., ; Fig. ).…”

“…Among the three clades of miR156 ‐targeted SPL genes, SPL3/4/5 and SPL9/15 have been studied more extensively than SPL10/11/2 (Wang et al ., ; Yamaguchi et al ., ; Kim et al ., ; Hyun et al ., ; Jung et al ., ). Although SPL10 has been reported to regulate flowering time, single mutant of spl10 does not have a flowering‐time phenotype (Xu et al ., ; Gao et al ., ). Consistent with previous studies, our results show that overexpression of SPL10 , SPL11 or SPL2 promoted flowering, whereas spl10/11/2 triple mutant showed late‐flowering phenotype (Fig.…”

“…Using ectopic expression of SPL10 , Gao et al . () have recently characterized the function of SPL10 in flowering time and even identified AGL79 as a direct target gene. Furthermore, the creation of spl10/11 double mutant by the CRISPR/Cas9 technique has shed light on the function of spl10/11/2 clade in flowering‐time regulation (Xu et al ., ).…”