Oxygen, secreted proteins and small RNAs: mobile elements that govern anther development

Abstract

Correct anther development is essential for male fertility and subsequently agricultural yield. Defects in anther development range from the early stage of stamen formation until the late stage of tapetum degeneration. In particular, the specification of the four distinct somatic layers and the inner sporogenous cells need perfect orchestration relying on precise cell–cell communication. Up to now, several signals, which coordinate the anther´s developmental program, have been identified. Among the known signals are phytohormones, environmental conditions sensed via glutaredoxins, several receptor-like kinases triggered by ligands like MAC1, and small RNAs such as miRNAs and the monocot-prevalent reproductive phasiRNAs. Rather than giving a full review on anther development, here we discuss anther development with an emphasis on mobile elements like ROS/oxygen, secreted proteins and small RNAs (only briefly touching on phytohormones), how they might act and interact, and what the future of this research area might reveal.

The Rab Geranylgeranyl Transferase Beta Subunit Is Essential for Embryo and Seed Development in Arabidopsis thaliana

“…Another possibility is that a regulatory molecule that acts on auxin levels in the embryo indirectly is produced in the maternal tissues and exported to the embryo sac. Very few genes have been shown to affect the embryo development in a sporophytic maternal mode, but among them are genes encoding for miRNAs [ 82 , 83 , 84 , 85 , 86 ]. For example, the miRNA167A gene affects embryo development in a maternal sporophyte-dependent manner [ 86 ] and regulates the level of mRNAs for auxin-dependent transcription factors ARF6 and ARF8 [ 86 , 87 , 88 ].…”

“…ARF6 and ARF8 are negative regulators of auxin levels in the cell, and the arf6 arf8 double mutant shows increased free auxin activity in the cytoplasm [ 88 ]. A similar mechanism involving miRNAs may then play a role in the differentiation and development of other structures in rgtb1 mutants, such as the young ovules [ 15 , 82 , 95 ] or pollen ([ 54 ] and this work). Coincidently, other phenotypic traits in the rgtb1 are reminiscent of arf6 arf8 double mutant phenotypes, such as dichotomous branching at the apical meristem [ 53 ], pollen tube deformations [ 54 ], integument asymmetry [ 15 ] and anther indehiscence.…”

SlTDP1 Is Required To Specify Tapetum Identity And For The Regulation Of Redox Homeostasis In Tomato Anthers

“…Overlapping with the genetic network controlling anther development, additional factors and signalling molecules participate in the communication between the somatic and sporogenous tissues. These factors include hormones, secreted proteins, miRNAs and cellular redox state (Dukowic-Schulze and van der Linde, 2021). For instance, the analysis of gibberellin (GA) deficient mutants suggest that the primary site of hormone action are tapetal cells and low GA levels have an indirect effect on the formation of functional pollen grains (Aya et al ., 2009).…”

Try or Die: Dynamics of Plant Respiration and How to Survive Low Oxygen Conditions

“…For example, high local rates of O 2 consumption have been shown to occur in the phloem of castor bean (Ricinus communis L.), which reaches O 2 levels of about 7% [9], and in the shoot apical meristem of Arabidopsis and Solanum lycopersicum, which shows O 2 levels below 5% [15]. Furthermore, an O 2 gradient is formed within developing monocot anthers as a result of rapid cell proliferation, which has been shown using Zea mays mutants (Zmmsca1, male sterile converted anther1), characterized by an early developmental defect after anther primordial formation [7,16].…”