KATANIN-dependent mechanical properties of the stigmatic cell wall mediate the pollen tube path in Arabidopsis

Abstract

Successful fertilization in angiosperms depends on the proper trajectory of pollen tubes through the pistil tissues to reach the ovules. Pollen tubes first grow within the cell wall of the papilla cells, applying pressure to the cell. Mechanical forces are known to play a major role in plant cell shape by controlling the orientation of cortical microtubules (CMTs), which in turn mediate deposition of cellulose microfibrils (CMFs). Here, by combining imaging, genetic and chemical approaches, we show that isotropic reorientation of CMTs and CMFs in aged Col-0 and katanin1-5 (ktn1-5) papilla cells is accompanied by a tendency of pollen tubes to coil around the papillae. We show that this coiled phenotype is associated with specific mechanical properties of the cell walls that provide less resistance to pollen tube growth. Our results reveal an unexpected role for KTN1 in pollen tube guidance on the stigma by ensuring mechanical anisotropy of the papilla cell wall.

The neglected other half ‐ role of the pistil in plant heat stress responses

“…Consistent with this, total and water-soluble calcium contents were found to be significantly higher in the heat-tolerant cotton cultivar than in the sensitive cultivar under heat stress (38/20 C; Snider et al, 2009). Additionally, cytoskeleton and mechanical properties of the cell wall of stigma/style also play a key role in pollen germination and directing pollen tube growth (Riglet et al, 2020). Recently, Katanin 1 (KAT 1), a microtubule-severing enzyme, has been identified to properly guide the early pollen tube growth in the stigma papillae in Arabidopsis (Riglet et al, 2020).…”

“…Additionally, cytoskeleton and mechanical properties of the cell wall of stigma/style also play a key role in pollen germination and directing pollen tube growth (Riglet et al, 2020). Recently, Katanin 1 (KAT 1), a microtubule‐severing enzyme, has been identified to properly guide the early pollen tube growth in the stigma papillae in Arabidopsis (Riglet et al, 2020).…”

“…Additionally, cytoskeleton and mechanical properties of the cell wall of stigma/style also play a key role in pollen germination and directing pollen tube growth (Riglet et al, 2020). Recently, Katanin 1 (KAT 1), a microtubule-severing enzyme, has been identified to properly guide the early pollen tube growth in the stigma papillae in Arabidopsis (Riglet et al, 2020). Interestingly, KAT1 has been shown to be important for salt tolerance in Arabidopsis (Yang, An, Luo, He, & Wang, 2020), but whether the KAT1 also plays a role during heat stress in guiding the pollen tube growth is unknown.…”

A Complex Journey: Cell Wall Remodeling, Interactions, and Integrity During Pollen Tube Growth

“…Interestingly, a recent report showed a role for KATANIN (KTN1), a microtubule-severing enzyme that regulates cortical microtubule dynamics, guiding early PT growth in stigma papillae (Riglet et al, 2020). By studying KTN1 mutants, the authors concluded that the KTN1-dependent cytoskeleton dynamics and the mechanical properties of the cell wall have a major role in guiding early pollen tube growth in stigma papillae (Riglet et al, 2020).…”

Cell identity specification in plants: lessons from flower development

“…Solid lines represent direct regulation of target genes, and dashed lines represent movement. SEM images in (A) are reprinted with permission from Riglet et al (2020) (‘papillate cells’), Meyer et al (2017) (‘giant cells and small cells’), Yang et al (2019) (‘conical cells’), Emmanuel Boutet (Plant biocurator for UniProtKB/Swiss-Prot) (‘stomata and pavement cells’), and Stefan Eberhard (University of Georgia, USA; provided by Wellcome collection under a CC BY-NC 4.0 licence) (‘trichomes’).…”