Pribil, M. | Search bioRxiv

bioRxiv2020

Efficient cooperation of chloroplasts and mitochondria enhances ATP and sucrose production

Efficient photosynthesis requires a balance of ATP and NADPH production/consumption in chloroplasts and the exportation of reducing equivalents from chloroplasts is important for balancing stromal ATP/NADPH ratio. Here we showed that the overexpression of purple acid phosphatase 2 on the outer membranes of chloroplasts and mitochondria can streamline the production and consumption of reducing equivalents in these two organelles, respectively. A higher capacity of consumption of reducing equivalents in mitochondria can indirectly help chloroplasts to balance the ATP/NADPH ratio in stroma and recycle NADP+, the electron acceptors of the linear electron flow. A higher rate of ATP and NADPH production from the linear electron flow, a higher capacity of carbon fixation by the Calvin-Benson-Bassham cycle and a greater consumption of NADH in mitochondria, enhance photosynthesis in the chloroplasts, ATP production in the mitochondria, sucrose synthesis in the cytosol, and eventually boosting plant growth and seed yields in the overexpression lines.

plant biology↗

bioRxiv2019

Antimicrobial solid media for screening non-sterile Arabidopsis thaliana seeds

BackgroundStable genetic transformation of plants is a low-efficiency process, and identification of positive transformants usually relies on screening for expression of a co-transformed marker gene. Often this involves germinating seeds on solid media containing a selection reagent. Germination on solid media requires surface sterilization of seeds and careful aseptic technique to prevent microbial contamination, but surface sterilization techniques are time consuming and can cause seed mortality if not performed carefully. We developed an antimicrobial cocktail that can be added to solid media to inhibit bacterial and fungal growth without impairing germination, allowing us to bypass the surface sterilization step. ResultsAdding a combination of terbinafine (1 {micro}M) and timentin (200 mg/L) to solid media delayed the onset of observable microbial growth and did not affect germination of non-sterile seeds from ten different wild-type and mutant Arabidopsis thaliana accessions. The method was also compatible with Nicotiana tabacum germination. Seedlings sown in non-sterile conditions could be maintained on antimicrobial media for up to a week without observable contamination. The antimicrobial cocktail was compatible with rapid screening methods for hygromycin B, phosphinothricin (BASTA) and nourseothricin resistance genes, meaning that positive transformants can be identified from non-sterile seeds in as little as four days after stratification and transferred to soil before the onset of visible microbial contamination. ConclusionThe antimicrobial cocktail presented here delays microbial growth for long enough to permit germination of non-sterile Arabidopsis thaliana seedlings on solid media and it is compatible with rapid screening methods. We were able to select genetic transformants on solid media without seed surface sterilization, eliminating a tedious and time-consuming step.

plant biology↗