The COBRA-like (COBL) gene family has been associated with the regulation of cell wall expansion and cellulose deposition. COBL mutants result in reduced levels and disorganized deposition of cellulose causing defects in the cell wall and inhibiting plant development. In this study, we report the identification of 24 COBL genes (GmCOBL) in the soybean genome. Phylogenetic analysis revealed that the COBL proteins are divided into two groups, which differ by about 170 amino acids in the N-terminal region. The GmCOBL genes were heterogeneously distributed in 14 of the 20 soybean chromosomes. This study showed that segmental duplication has contributed significantly to the expansion of the COBL family in soybean during all Glycine-specific whole-genome duplication events. The expression profile revealed that the expression of the paralogous genes is highly variable between organs and tissues of the plant. Only 20% of the paralogous gene pairs showed similar expression patterns. The high expression levels of some GmCOBLs suggest they are likely essential for regulating cell expansion during the whole soybean life cycle. Our comprehensive overview of the COBL gene family in soybean provides useful information for further understanding the evolution and diversification of COBL genes in soybean.

Intensive agriculture maintains high crop yields through chemical inputs, which are well known for their adverse effects on environmental quality and human health. Innovative technologies are required to reduce the risk generated by the extensive and harmful use of pesticides. The plant biostimulants made from humic substances isolated from recyclable biomass offer an alternative approach to address the need for replacing conventional agrochemicals without compromising the crop yield. The stimulatory effects of humic substances are commonly associated with plant hormones, particularly auxins. However, jasmonic acid (JA) is crucial metabolite in mediating the defence responses and governing plant growth and development. This work aimed to evaluate the changes in the biosynthesis and signalling pathway of JA in tomato seedlings treated with humic acids (HA) isolated from vermicompost. We use the tomato model system cultivar Micro-Tom (MT) harbouring a reporter gene fused to a synthetic promoter that responds to jasmonic acid (JERE::GUS). The transcript levels of genes involved in JA generation and activity were also determined using qRT-PCR. The application of HA promoted plant growth and altered the JA status, as revealed by both GUS and qRT-PCR assays. Both JA enzymatic synthesis (LOX, OPR3) and JA signalling genes (JAZ and JAR) were found in higher transcription levels in plants treated with HA. In addition, ethylene (ETR4) and auxin (ARF6) signalling components were positively modulated by HA, revealing a hormonal cross-talk. Our results prove that the plant defence system linked to JA can be emulated by HA application without growth inhibition.

RNA-directed DNA methylation (RdDM) is an epigenetic mechanism involved in several biological processes in plants, requiring complex machinery including the chromatin remodeling protein CLASSY (CLSY). The CLSY family regulates global and locus-specific DNA methylation and was initially identified in Arabidopsis thaliana. Despite reports in other plants, detailed knowledge about CLSY proteins in soybean is scarce. In this work, we used profile hidden Markov models (profile HMMs) specifically constructed for CLSY detection to identify new members in soybean and to analyze their phylogenetic relationships across bryophyte, basal angiosperm, basal eudicot, monocots, and eudicots. We identified two new candidates for CLSY1-2 and one for DRD1 in soybean and, for the first time, detected CLSY and DRD1 genes in Aquilegia coerulea. Phylogenetic analysis indicated two main CLSY groups: one similar to Arabidopsis CLSY1-2 and another to CLSY3-4. Gene duplication analysis demonstrated that whole-genome duplication/segmental duplication events contributed to CLSY family expansion in soybean. RT-qPCR analysis showed that CLSY and five other epigenetic regulator genes had stress-modulated expression during soybean germination under salt and osmotic stress, with variation among cultivars. Our findings enhance comprehension of the evolutionary dynamics of the CLSY family and furnish insights into their response to abiotic stress in soybean.