Regulating programmed cell death in plant cells: Intracellular acidification plays a pivotal role together with calcium signaling.

Programmed cell death (PCD) occurs in different tissues in response to a number of different signals in plant cells. Drawing from work in several different contexts, including root-cap cell differentiation, plant response to biotic and abiotic stress, and some self-incompatibility (SI) systems, the data suggest that, despite differences, there are underlying commonalities in the early decision-making stages of PCD. Here, we focus on how 2 cellular events, increased [Ca2+]cyt levels and cytosolic acidification, appear to act as early signals involved in regulating both developmental and stimulus-induced PCD in plant cells.

Transposable elements cause the loss of self-incompatibility in citrus.

Self-incompatibility (SI) is a widespread prezygotic mechanism for flowering plants to avoid inbreeding depression and promote genetic diversity. Citrus has an S-RNase-based SI system, which was frequently lost during evolution. We previously identified a single nucleotide mutation in S-RNase, which is responsible for the loss of SI in mandarin and its hybrids.

Contrasting self-recognition rejection systems for self-incompatibility in Brassica and Papaver.

Self-incompatibility (SI) plays a pivotal role in whether self-pollen is accepted or rejected. Most SI systems employ two tightly linked loci encoding highly polymorphic pollen (male) and pistil (female) S-determinants that control whether self-pollination is successful or not. In recent years our knowledge of the signalling networks and cellular mechanisms involved has improved considerably, providing an important contribution to our understanding of the diverse mechanisms used by plant cells to recognise each other and elicit responses.

Depletion plays a pivotal role in self-incompatibility, revealing a link between cellular energy status, cytosolic acidification and actin remodelling in pollen tubes.

Self-incompatibility (SI) involves specific interactions during pollination to reject incompatible ('self') pollen, preventing inbreeding in angiosperms. A key event observed in pollen undergoing the Papaver rhoeas SI response is the formation of punctate F-actin foci. Pollen tube growth is heavily energy-dependent, yet ATP levels in pollen tubes have not been directly measured during SI.

Self-incompatibility requires GPI anchor remodeling by the poppy PGAP1 ortholog HLD1.

Glycosylphosphatidylinositol-anchored proteins (GPI-APs) are tethered to the outer leaflet of the plasma membrane where they function as key regulators of a plethora of biological processes in eukaryotes. Self-incompatibility (SI) plays a pivotal role regulating fertilization in higher plants through recognition and rejection of "self" pollen. Here, we used Arabidopsis thaliana lines that were engineered to be self-incompatible by expression of Papaver rhoeas SI determinants for an SI suppressor screen.