The bps signal: embryonic arrest from an auxin-independent mechanism in bypass triple mutants

Genome-wide identification and functional prediction of BYPASS1-related (BPS1) homologs in soybean

The BYPASS1-related gene (BPS1) encodes a protein with an unknown functional domain that regulates plant organ growth and development by inhibiting the continuous production of a root-derived long-distance signaling molecule called bypass (bps). We conducted a comprehensive study to investigate the BPS gene family in soybean and identified twenty-three BPS genes in Glycine max and twenty BPS genes in Glycine soja (wild soybean). Collinearity analysis revealied the existence of multiple orthologs of soybean BPS genes in wild soybean, indicating incomplete conservation between the BPS genes of soybean and wild soybean. Phylogenetic analysis successfully categorized all BPS genes into five distinct groups. We further scrutinized their chromosomal locations, gene structures, conserved motifs, cis-acting elements, and expression patterns. Leveraging publicly available data on genetic variation, phenotypic variation, and single-cell transcriptome sequencing of root nodules, we discovered a potential association between BPS genes and multiple soybean traits, particularly those related to the root nodule phenotype. This pioneering study provides a systematic and comprehensive examination of the BPS gene family in soybean. The findings establish a robust foundation for future investigations into the functional roles of BPS genes in plant growth and development.

Supplementary Information

The online version contains supplementary material available at 10.1007/s11032-023-01403-2.

A cryptic natural variant allele of BYPASS2 suppresses the bypass1 mutant phenotype

The Arabidopsis (Arabidopsis thaliana) BYPASS1 (BPS1) gene encodes a protein with no functionally characterized domains, and loss-of-function mutants (e.g. bps1-2 in Col-0) present a severe growth arrest phenotype that is evoked by a root-derived graft-transmissible small molecule that we call dalekin. The root-to-shoot nature of dalekin signaling suggests it could be an endogenous signaling molecule. Here, we report a natural variant screen that allowed us to identify enhancers and suppressors of the bps1-2 mutant phenotype (in Col-0). We identified a strong semi-dominant suppressor in the Apost-1 accession that largely restored shoot development in bps1 and yet continued to overproduce dalekin. Using bulked segregant analysis and allele-specific transgenic complementation, we showed that the suppressor is the Apost-1 allele of a BPS1 paralog, BYPASS2 (BPS2). BPS2 is one of four members of the BPS gene family in Arabidopsis, and phylogenetic analysis demonstrated that the BPS family is conserved in land plants and the four Arabidopsis paralogs are retained duplicates from whole genome duplications. The strong conservation of BPS1 and paralogous proteins throughout land plants, and the similar functions of paralogs in Arabidopsis, suggests that dalekin signaling might be retained across land plants.

Recent advances in understanding carotenoid-derived signaling molecules in regulating plant growth and development

Carotenoids (C40) are synthesized in plastids and perform numerous important functions in these organelles. In addition, carotenoids can be processed into smaller signaling molecules that regulate various phases of the plant's life cycle. Besides the relatively well-studied phytohormones abscisic acid (ABA) and strigolactones (SLs), additional carotenoid-derived signaling molecules have been discovered and shown to regulate plant growth and development. As a few excellent reviews summarized recent research on ABA and SLs, this mini review will focus on progress made on identification and characterization of the emerging carotenoid-derived signals. Overall, a better understanding of carotenoid-derived signaling molecules has immediate applications in improving plant biomass production which in turn will have far reaching impacts on providing food, feed, and fuel for the growing world population.

The plant vascular system: evolution, development and functions

The emergence of the tracheophyte-based vascular system of land plants had major impacts on the evolution of terrestrial biology, in general, through its role in facilitating the development of plants with increased stature, photosynthetic output, and ability to colonize a greatly expanded range of environmental habitats. Recently, considerable progress has been made in terms of our understanding of the developmental and physiological programs involved in the formation and function of the plant vascular system. In this review, we first examine the evolutionary events that gave rise to the tracheophytes, followed by analysis of the genetic and hormonal networks that cooperate to orchestrate vascular development in the gymnosperms and angiosperms. The two essential functions performed by the vascular system, namely the delivery of resources (water, essential mineral nutrients, sugars and amino acids) to the various plant organs and provision of mechanical support are next discussed. Here, we focus on critical questions relating to structural and physiological properties controlling the delivery of material through the xylem and phloem. Recent discoveries into the role of the vascular system as an effective long-distance communication system are next assessed in terms of the coordination of developmental, physiological and defense-related processes, at the whole-plant level. A concerted effort has been made to integrate all these new findings into a comprehensive picture of the state-of-the-art in the area of plant vascular biology. Finally, areas important for future research are highlighted in terms of their likely contribution both to basic knowledge and applications to primary industry.