Entries by Frej Tulin

A close-up view of the thylakoids (eLIFE)

The thylakoid membranes inside the chloroplasts house the major protein complexes required for photosynthesis, including photosystems I and II (PSI/II), the b6f complex and ATP synthase. To optimize photosynthetic efficiency, the distribution and abundance of these complexes are dynamically regulated in response to varying light and growth conditions. However, to study how the spatial organization […]

Nitrate defines shoot size through compensatory roles for endoreplication and cell division (Curr. Biol.)

In this paper, Moreno et al. investigate how nitrate affects the balance between cell proliferation and cell expansion in shoots during early seedling development. They note that the cells in Arabidopsis cotyledons undergo considerable enlargement, and that the increase in cell size is correlated with a switch from the mitotic cell cycle to endoreplication. During […]

Evolution of tetraploid meiosis (PNAS)

Genome duplications are common in plants and thought to be an important contributor to evolutionary innovations, but the increase in ploidy that results from a genome duplication also presents challenges for reproduction. Because there are four sets of homologous chromosomes in the derived tetraploid (instead of two in the diploid ancestor), establishing one-to-one pairing between […]

How to transfer lipids from one membrane to another during thylakoid biogenesis (PNAS)

The thylakoid membranes are located in the stroma of chloroplasts and house the machinery for the photosynthetic light reactions. They emerge largely de novo during the transition from pro-plastids into mature, photosynthesizing chloroplasts. Generating new thylakoid membranes requires a supply of lipids, the biosynthesis of which is thought to occur on the chloroplast inner envelope. […]

Structural basis for WUSCHEL binding (bioRxiv)

The transcription factor WUSCHEL (WUS) plays a central role in organization of the shoot meristem. The three-helix bundle homeodomain in WUS can bind to several distinct DNA sequence motifs in many target genes promoters, but a structural view of these binding events has been lacking. Here Sloan et al. solve the structure of the WUS […]

Sex chromosome evolution in asparagus (Plant Cell)

Separation of male and female flowers on different individuals, called dioecy, has evolved independently many times in flowering plants from hermaphroditic ancestors. A long-standing theory predicts that specialized X and Y sex chromosomes can evolve in dioecious species when mutations occur in two tightly linked genes with antagonistic effects on male and female development. In […]

FERONIA controls pectin- and nitric oxide-mediated male–female interaction (Nature)

In flowering plants, fertilization occurs when a pollen tube, growing down the transmitting tissue, arrives at the ovule, ruptures, and releases its content of sperm cells. The pollen tube is guided towards the ovule by LUREs, small cysteine-rich secreted peptides. Timely rupturing and sperm release depend on the ovule-expressed receptor kinase FERONIA. In this paper, […]

Mars1 kinase signaling in the chloroplast unfolded protein response (eLIFE)

In stressful situations, such as high light and nutrient scarcity, the chloroplast may experience increased proteotoxicity due to a surge in damaging reactive oxygen species. In response, a signal is sent to the nucleus to increase production of many proteins, including proteases and chaperones to help mitigate the damage. This damage control pathway has been […]