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. 2021 May 2;33(7):2320–2339. doi: 10.1093/plcell/koab120

Figure 8.

Figure 8

Proposed model of the role of SlPIF4 in regulating tapetal and pollen development under normal and moderately low temperatures. Under an optimal temperature regime, SlDYT1 enhances the DYT1-TDF1-AMS-MYB80 transcriptional cascade by directly activating SlTDF1 during tapetum development. Programmed tapetum degradation triggered by the DYT1-TDF1-AMS-MYB80 transcriptional module allows the tapetum to provide the developing microspores with enzymes, carbohydrates, and nutrients. Under moderately low-temperature conditions, SlPIF4 enhances SlDYT1-mediated activation of SlTDF1 by forming a SlDYT1–SlPIF4 heterodimer complex with SlDYT1. Overaccumulation of SlTDF1 and its downstream genes postpones tapetal PCD and further results in pollen abortion. Knocking out SlPIF4 blocks the overactivation of SlTDF1 in tomato anthers at low temperature. While the overaccumulation of SlPIF4 might alter programmed tapetum development by competitively binding to SlDYT1 or by interacting with SlDYT1 under optimal temperature regime. PM, plasma membrane; Sp, sporopollenin precursors.