Biology subjects

Barja, M. V.

Publications and source records attributed to Barja, M. V..

2 recordsLinked to original sources

bioRxiv2022

Tomato geranylgeranyl diphosphate synthase isoform 1 specifically interacts with phytoene synthase isoform 3 to produce strigolactones in tomato roots.

O_LICarotenoids are photoprotectant pigments and precursors of the hormones abscisic acid (ABA) and strigolactones (SL). Carotenoids are produced in plastids from geranylgeranyl diphosphate (GGPP), which is diverted to the carotenoid pathway by phytoene synthase (PSY). In tomato (Solanum lycopersicum), 3 genes encode plastid-targeted GGPP synthases (SlG1 to 3) and 3 genes encode PSY isoforms (PSY1 to 3). C_LIO_LIHere we investigated the function of SlG1 by generating loss-of-function lines and combining their metabolic and physiological phenotypes with gene co-expression and co-immunoprecipitation analyses. C_LIO_LILeaves and fruits of slg1 lines showed a wild-type phenotype in terms of isoprenoid accumulation, photosynthesis and development. Consistently, SlG1 is co-expressed with PSY3 and other genes involved in the production of carotenoids and SL (but not ABA) only in roots. SlG1 was also found to physically interact with the root-specific PSY3 isoform (and not with PSY1 and PSY2). Root SL (but not ABA) levels were reduced in slg1 lines. C_LIO_LIOur results confirm a specific role of SlG1 in SL production in combination with PSY3. This role appears to be restricted to roots as slg1 plants do not exhibit the shoot phenotype displayed by other SL-deficient mutants. C_LI

plant biology↗

bioRxiv2021

The intrinsic chaperone network of Arabidopsis stem cells confers protection against proteotoxic stress

The biological purpose of plant stem cells is to maintain themselves while providing new pools of differentiated cells that form organs and rejuvenate or replace damaged tissues1-3. Protein homeostasis, or proteostasis, is required for cell function and viability4-7. However, the link between proteostasis and plant stem cell identity remains unknown. In contrast to their differentiated counterparts, we find that root stem cells can prevent the accumulation of aggregated proteins even under proteotoxic stress conditions such as heat stress or proteasome inhibition. Notably, root stem cells exhibit enhanced expression of distinct chaperones that maintain proteome integrity. Particularly, intrinsic high levels of the TRiC/CCT chaperonin determine stem cell maintenance and their remarkable ability to suppress protein aggregation. Overexpression of CCT8, a key activator of TRiC/CCT assembly8, is sufficient to ameliorate protein aggregation in differentiated cells and confer resistance to proteotoxic stress in plants. Taken together, our results indicate that enhanced proteostasis mechanisms in stem cells could be an important requirement for plants to persist under extreme environmental conditions and reach extreme long ages. Thus, proteostasis of stem cells could provide insights to design and breed plants tolerant to environmental challenges caused by the climate change.

plant biology↗