A systems biology approach identifies a regulator,BplERF1,of cold tolerance in Betula platyphylla

Cold is an abiotic stress that can greatly affect the growth and survival of plants.Here,we reported that an AP2/ERF family gene,BplERF1,isolated from Betula platyphylla played a contributing role in cold stress tolerance.Overexpression of BplERF1 in B.platyphylla transgenic lines enhanced cold stress tolerance by increasing the scavenging capability and reducing H_(2)O_(2) and malondialdehyde(MDA)content in transgenic plants.Construction of BplERF-mediated multilayered hierarchical gene regulatory network(ML-hGRN),using Top-down GGM algorithm and the transcriptomic data of BplERF1 overexpression lines,led to the identification of five candidate target genes of BplERF1 which include MPK20,ERF9,WRKY53,WRKY70,and GIA1.All of them were then verified to be the true target genes of BplERF1 by chromatin-immunoprecipitation PCR(ChIP-PCR)assay.Our results indicate that BplERF1 is a positive regulator of cold tolerance and is capable of exerting regulation on the expression of cold signaling and regulatory genes,causing mitigation of reactive oxygen species.

Phytochrome B interacts with LIGULELESS1 to control plant architecture and density tolerance in maize

Over the past few decades,significant improvements in maize yield have been largely attributed to increased plant density of upright hybrid varieties rather than increased yield per plant.However,dense planting triggers shade avoidance responses(SARs)that optimize light absorption but impair plant vigor and performance,limiting yield improvement through increasing plant density.In this study,we demonstrated that high-density-induced leaf angle narrowing and stem/stalk elongation are largely dependent on phytochrome B(phyB1/B2),the primaryphotoreceptor responsible for perceiving red(R)and far-red(FR)light in maize.We found that maize phyB physically interacts with the LIGULELESS1(LG1),a classical key regulator of leaf angle,to coordinately regulate plant architecture and density tolerance.The abundance of LG1 is significantly increased by phyB under high R:FR light(low density)but rapidly decreases under low R:FR light(high density),correlating with variations in leaf angle and plant height under various densities.In addition,we identified the homeobox transcription factor HB53 as a target co-repressed by both phyB and LG1 but rapidly induced by canopy shade.Genetic and cellular analyses showed that HB53 regulates plant architecture by controlling the elongation and division of ligular adaxial and abaxial cells.Taken together,these findings uncover the phyB-LG1-HB53 regulatory module as a key molecular mechanism governing plant architecture and density tolerance,providing potential genetic targets for breeding maize hybrid varieties suitable for high-density planting.