A NYN domain protein directly interacts with DCP1 and is required for phyllotactic pattern in Arabidopsis

ABSTRACTIn eukaryotes, general mRNA decay requires the decapping complex. The activity of this complex depends on its catalytic subunit, DCP2 and its interaction with decapping enhancers, including its main partner DCP1. Here, we report that in Arabidopsis, DCP1 also interacts with a NYN domain endoribonuclease, hence named DCP1-ASSOCIATED NYN ENDORIBONUCLEASE 1 (DNE1). Interestingly, we find DNE1 predominantly associated with DCP1 but not with DCP2 and reciprocally, suggesting the existence of two distinct protein complexes. We also show that the catalytic residues of DNE1 are required to repress the expression of mRNAs in planta upon transient expression. The overexpression of DNE1 in transgenic lines leads to growth defects and transcriptomic changes related to the one observed upon inactivation of the decapping complex. Finally, the combination of dne1 and dcp2 mutations, revealed a functional redundancy between DNE1 and DCP2 in controlling phyllotactic pattern formation in Arabidopsis. Our work identifies DNE1, a hitherto unknown DCP1 protein partner highly conserved in the plant kingdom and identifies its importance for developmental robustness.One-sentence summaryDNE1, a NYN domain protein interacts with the decapping activator DCP1 and, together with DCP2, specify phyllotactic patterns in Arabidopsis.

Developmental stochasticity and variation in floral phyllotaxis

Floral phyllotaxis is a relatively robust phenotype; trimerous and pentamerous arrangements are widely observed in monocots and core eudicots. Conversely, it also shows variability in some angiosperm clades such as ‘ANA’ grade (Amborellales, Nymphaeales, and Austrobaileyales), magnoliids, and Ranunculales. Regardless of the phylogenetic relationship, however, phyllotactic pattern formation appears to be a common process. What are the causes of the variability in floral phyllotaxis and how has the variation of floral phyllotaxis contributed to floral diversity? In this review, I summarize recent progress in studies on two related fields to develop answers to these questions. First, it is known that molecular and cellular stochasticity are inevitably found in biological systems, including plant development. Organisms deal with molecular stochasticity in several ways, such as dampening noise through gene networks or maintaining function through cellular redundancy. Recent studies on molecular and cellular stochasticity suggest that stochasticity is not always detrimental to plants and that it is also essential in development. Second, studies on vegetative and inflorescence phyllotaxis have shown that plants often exhibit variability and flexibility in phenotypes. Three types of phyllotaxis variations are observed, namely, fluctuation around the mean, transition between regular patterns, and a transient irregular organ arrangement called permutation. Computer models have demonstrated that stochasticity in the phyllotactic pattern formation plays a role in pattern transitions and irregularities. Variations are also found in the number and positioning of floral organs, although it is not known whether such variations provide any functional advantages. Two ways of diversification may be involved in angiosperm floral evolution: precise regulation of organ position and identity that leads to further specialization of organs and organ redundancy that leads to flexibility in floral phyllotaxis.

Bionic design for the heat sink inspired by phyllotactic pattern

A good heat dissipating condition will help give full play to the performance and reliability of electronic components and devices. To strengthen the heat dissipating performance, a novel bionic heat sink of pin fins has been designed. The configuration of cooling pin fins in this heat sink is based on phyllotaxis theory in biology. The bionic configuration of the cooling pin fins has better homogeneity and complementarity, which can form a reasonable air flow channel to improve its cooling efficiency. For testing and analyzing the performance of the bionic heat sink and the effects of the phyllotactic parameters on the heat dissipating, some contrast experiments have been conducted using thermal infrared imager. The results show that the bionic heat sink has better heat dissipating performance, which can make the surface temperature of the heat block lower by 14.7%. This paper will supply a new and effective solution to heat dissipation problem and has a certain contribution for the development of electrical and electronic industry.

Structural Integrity of Vascular System in Branching Units of Coniferous Shoot

In conifers with spiral phyllotaxis, two numbers: one of the vascular sympodia and the second of cortical resin canals, define the shoot anatomic diameter. This in turn reflects the size and vigor of the apical meristem. Both numbers belong to the mathematical series, associated with the shoot phyllotactic pattern. The number of canals is one step lower in a series than the number of sympodia. The first one, easier to determine, automatically defines the second. Using this protocol and screening the large number of branching shoots of selected conifers, we have discovered strong correlation between orientation of vascular sympodia in the lateral and supporting branches. There was no such correlation with regard to the chiral configurations of phyllotaxis. This finding reveals the presence of special phyllotactic compensation in the case of differences in anatomic diameter of the parental and lateral shoot under the imperative of maintaining the sympodia orientation within one branching unit. Phyllotaxis of the axillary apex is evidently not established at random but adapted to the condition of the subtending axis. The monopodial, regularly branching shoot of conifers is an attractive example of biological system, which is not a sum of independent, iteratively formed units. Rather, it appears to be an entity organized on hierarchically higher level, which emerges from coordination of developmental processes in a population of the units.

Diversity of phyllotaxis in land plants in reference to the shoot apical meristem structure

Regularity and periodicity in the arrangements of organs in all groups of land plants raise questions about the mechanisms underlying phyllotactic pattern formation. The initiation of the lateral organs (leaves, flowers, etc.), and thus, their spatio-temporal positioning, occurs in the shoot apical meristem (SAM) and is related to the structure and organogenic activity of the meristem. In this review, we present some aspects of the diversity and stability of phyllotactic patterns in the major lineages of land plants, from bryophytes to angiosperms, in which SAM structures differ significantly. In addition, we discuss some of the possible mechanisms involved in the formation of the recurring arrangement of the lateral organs.