Hyperoside promotes pollen tube growth by regulating the depolymerization effect of actin-depolymerizing factor 1 on microfilaments in okra

Abstract

Mature pollen germinates rapidly on the stigma, extending its pollen tube to deliver sperm cells to the ovule for fertilization. The success of this process is an important factor that limits output. The flavonoid content increased significantly during pollen germination and pollen tube growth, which suggests it may play an important role in these processes. However, the specific mechanism of this involvement has been little researched. Our previous research found that hyperoside can prolong the flowering period of Abelmoschus esculentus (okra), but its specific mechanism is still unclear. Therefore, in this study, we focused on the effect of hyperoside in regulating the actin-depolymerizing factor (ADF), which further affects the germination and growth of pollen. We found that hyperoside can prolong the effective pollination period of okra by 2–3-fold and promote the growth of pollen tubes in the style. Then, we used Nicotiana benthamiana cells as a research system and found that hyperoside accelerates the depolymerization of intercellular microfilaments. Hyperoside can promote pollen germination and pollen tube elongation in vitro. Moreover, AeADF1 was identified out of all AeADF genes as being highly expressed in pollen tubes in response to hyperoside. In addition, hyperoside promoted AeADF1-mediated microfilament dissipation according to microfilament severing experiments in vitro. In the pollen tube, the gene expression of AeADF1 was reduced to 1/5 by oligonucleotide transfection. The decrease in the expression level of AeADF1 partially reduced the promoting effect of hyperoside on pollen germination and pollen tube growth. This research provides new research directions for flavonoids in reproductive development.

Maize stigmas react differently to self-/cross-pollination and fungal invasion

“…Phenylpropanoids are a structurally diverse group of phenylalanine-derived metabolites involved in the synthesis of flavonoids and lignins used by plants to build cell walls. Flavonoids have been well studied in pollen grains as they are plant-specific compounds required for pollen germination and tube growth, and are constituents of the pollen cell wall and work as positive effectors for pollen tube elongation (Muhlemann et al 2018; Dong et al 2021; Wu et al 2023; Xue et al 2023). Thus, downregulation of phenylpropanoids and consequently flavonoids likely arrests pollen tube growth as observed in incompatible pollinations of maize (Lausser et al 2010).…”

Integrated transcriptomic and proteomic analysis of a cytoplasmic male sterility line and associated maintainer line in soybean

“…The PMEs and BGAL 15 may be involved in the cell wall loosening associated with pollen expansion during microspore development. In okra ( Abelmoschus esculentus ), AeADF1 has been shown to promote pollen germination and pollen tube growth ( Dong et al., 2021 ). Here, actin depolymerizing factor 7 (GmADF7) and its interacting proteins were significantly down-regulated in W931A, indicating that they may inhibit pollen germination and thus cause soybean sterility.…”

Melatonin‐mediated CcARP1 alters F‐actin dynamics by phosphorylation of CcADF9 to balance root growth and salt tolerance in pigeon pea

“…Based on this phenomenon, we focused on the ADF gene family. In previous studies of other species, we found that the regulation of ADF family proteins on F‐actin dynamics plays a key role in reproductive development, including promoting pollen tube growth (Dong et al ., 2021; Meng et al ., 2018) and improving seed setting rate (Yang et al ., 2021). Earlier studies showed that ADF family genes regulate microfilament dynamics in plant leaf guard cells and affect stomatal opening and closing (Zhao et al ., 2016).…”