LATERAL BRANCHING OXIDOREDUCTASE, one novel target gene of Squamosa Promoter Binding Protein‐like 2, regulates tillering in switchgrass

Abstract

Summary Strigolactones (SLs) play a critical role in regulating plant tiller number. LATERAL BRANCHING OXIDOREDUCTASE (LBO) encodes an important late‐acting enzyme for SL biosynthesis and regulates shoot branching in Arabidopsis. However, little is known about the function of LBO in monocots including switchgrass (Panicum virgatum L.), a dual‐purpose fodder and biofuel crop. We studied the function of PvLBO via the genetic manipulation of its expression levels in both the wild‐type and miR156 overexpressing (miR156OE) switchgrass. Co‐expression analysis, quantitative real‐time polymerase chain reaction (qRT‐PCR), transient dual luciferase assay, and chromatin immunoprecipitation‐qPCR were all used to determine the activation of PvLBO by miR156‐targeted Squamosa Promoter Binding Protein‐like 2 (PvSPL2) in regulating tillering of switchgrass. PvLBOtranscripts dramatically declined in miR156OE transgenic switchgrass, and the overexpression of PvLBO in the miR156OE transgenic line produce fewer tillers than the control. Furthermore, we found that PvSPL2 can directly bind to the promoter of PvLBO and activate its transcription, suggesting that PvLBO is a novel downstream gene of PvSPL2. We propose that PvLBO functions as an SL biosynthetic gene to mediate tillering and acts as an important downstream factor in the crosstalk between the SL biosynthetic pathway and the miR156‐SPL module in switchgrass.

MicroRNA156ab regulates apple plant growth and drought tolerance by targeting transcription factor MsSPL13

“…SPL transcription factors bind to GTAC cis -elements to regulate the expression of downstream genes ( Yang et al 2022 ). Hence, based on our RT-qPCR results ( Fig.…”

Lessons from a century of apical dominance research

“…Based on knowledge of physiology and hormone interactions in the branching network ( Hayward et al , 2009 ; Beveridge and Kyozuka, 2010 ), co-expression analysis across three treatments and available Arabidopsis SL mutants yielded identification of LATERAL BRANCHING OXIDOREDUCTASE (LBO) ( Brewer et al , 2016 ) and D27 ( Lin et al , 2009 ; Alder et al , 2012 ; Waters et al , 2012a ; Abuauf et al , 2018 ) by reverse genetics (taking advantage of publicly available Arabidopsis stock mutants). The mutant for LBO has a weaker branching phenotype than other SL biosynthesis mutants, but the mutation is found to affect particular SL levels and branching phenotypes in diverse species ( Walker et al , 2019 ; Yoneyama and Brewer, 2021 ; Yang et al , 2022 ). Based on biochemical and grafting studies, LBO acts downstream of MAX1 in Arabidopsis to produce a non-canonical SL (defined below).…”

Strigolactones and Shoot Branching: What Is the Real Hormone and How Does It Work?

“…Regardless, LBO function is important for the regulation of shoot branching/tillering, as the lbo mutant in arabidopsis has an increased branching phenotype, albeit one which is weaker than other mutants in the core SL biosynthesis pathway ( Brewer et al. 2016 ), and altered expression of LBO impacts tillering in Panicum virgatum L. (switchgrass) ( Yang et al. 2022 ).…”