The enzyme zeaxanthin epoxidase (ZEP) catalyzes the conversion of zeaxanthin to violaxanthin, a key reaction for ABA biosynthesis and the xanthophyll cycle. Both processes are important for acclimation to environmental stress conditions, in particular drought (ABA biosynthesis) and light (xanthophyll cycle) stress. Hence, both ZEP functions may require differential regulation to optimize plant fitness. The key to understanding the function of ZEP in both stress responses might lie in its spatial and temporal distribution in plant tissues. Therefore, we analyzed the distribution of ZEP in plant tissues and plastids under drought and light stress by use of a ZEP-specific antibody. In addition, we determined the pigment composition of the plant tissues and chloroplast membrane subcompartments in response to these stresses. The ZEP protein was detected in all plant tissues (except flowers) concomitant with xanthophylls. The highest levels of ZEP were present in leaf chloroplasts and root plastids. Within chloroplasts, ZEP was localized predominantly in the thylakoid membrane and stroma, while only a small fraction was bound by the envelope membrane. Light stress affected neither the accumulation nor the relative distribution of ZEP in chloroplasts, while drought stress led to an increase of ZEP in roots and to a degradation of ZEP in leaves. However, drought stress-induced increases in ABA were similar in both tissues. These data support a tissue- and stress-specific accumulation of the ZEP protein in accordance with its different functions in ABA biosynthesis and the xanthophyll cycle.

The ability of stem cells to divide and differentiate is necessary for tissue repair and homeostasis. Appropriate spatial and temporal mechanisms are needed. Local intercellular signaling increases expression of specific genes that mediate and maintain differentiation. Diffusible signaling molecules provide concentration-dependent induction of specific patterns of cell types or regions. Differentiation of adjacent cells, on the other hand, requires cell–cell contact and subsequent signaling. These two types of signals work together to allow stem cells to provide what organisms require. The ability to grow organoids has increased our understanding of the cellular and molecular features of small “niches” that modulate stem cell function in various organs, including the small intestine.

(+)-Sesamin, (+)-sesamolin, and (+)-sesaminol glucosides are phenylpropanoid-derived specialized metabolites called lignans, and are rich in sesame (Sesamum indicum) seed. Despite their renowned anti-oxidative and health-promoting properties, the biosynthesis of (+)-sesamolin and (+)-sesaminol remained largely elusive. Here we show that (+)-sesamolin deficiency in sesame is genetically associated with the deletion of four C-terminal amino acids (Del4C) in a P450 enzyme CYP92B14 that constitutes a novel clade separate from sesamin synthase CYP81Q1. Recombinant CYP92B14 converts (+)-sesamin to (+)-sesamolin and, unexpectedly, (+)-sesaminol through an oxygenation scheme designated as oxidative rearrangement of α-oxy-substituted aryl groups (ORA). Intriguingly, CYP92B14 also generates (+)-sesaminol through direct oxygenation of the aromatic ring. The activity of CYP92B14 is enhanced when co-expressed with CYP81Q1, implying functional coordination of CYP81Q1 with CYP92B14. The discovery of CYP92B14 not only uncovers the last steps in sesame lignan biosynthesis but highlights the remarkable catalytic plasticity of P450s that contributes to metabolic diversity in nature.

The evolutionary origins of neurons remain unknown. Although recent genome data of extant early-branching animals have shown that neural genes existed in the common ancestor of animals, the physiological and genetic properties of neurons in the early evolutionary phase are still unclear. Here, we performed a mass spectrometry-based comprehensive survey of short peptides from early-branching lineages Cnidaria, Porifera and Ctenophora. We identified a number of mature ctenophore neuropeptides that are expressed in neurons associated with sensory, muscular and digestive systems. The ctenophore peptides are stored in vesicles in cell bodies and neurites, suggesting volume transmission similar to that of cnidarian and bilaterian peptidergic systems. A comparison of genetic characteristics revealed that the peptide-expressing cells of Cnidaria and Ctenophora express the vast majority of genes that have pivotal roles in maturation, secretion and degradation of neuropeptides in Bilateria. Functional analysis of neuropeptides and prediction of receptors with machine learning demonstrated peptide regulation of a wide range of target effector cells, including cells of muscular systems. The striking parallels between the peptidergic neuronal properties of Cnidaria and Bilateria and those of Ctenophora, the most basal neuron-bearing animals, suggest a common evolutionary origin of metazoan peptidergic nervous systems.