Philippe JEAN-PIERRE

Monitoring aboveground biomass carbon (AGC) stocks and their changes is crucial for understanding the global carbon cycle and the impact of climate change. Among remotely sensed methods, the use of the L-band (1.4 GHz) vegetation optical depth (L-VOD) derived from passive microwave satellite observations, offers rapid updates for timely monitoring of interannual AGC changes. L-VOD is sensitive to changes in the total water content of vegetation, which is determined by both AGC (the biomass of vegetation) and vegetation moisture content. While several methods have been used to understand and correct for the influence of the latter parameter when inferring AGC from L-VOD, there is still a lack of quantified corrections for its impact. Moreover, varying benchmark biomass datasets and fitting functions are currently used for converting L-VOD to AGC, making it difficult to harmonize or compare AGC estimates at regional and global scales. To address these issues, we first corrected the L-VOD time series for changes in the vegetation moisture content and then implemented a systematic global-scale calibration, resulting in annual AGC data set (called INRAE-BORDEAUX AGC, hereafter IB AGC) from 2010 to 2020 at a 25 km resolution. The accuracy assessments showed that IB AGC had a reasonably good spatial agreement with LiDAR referenced AGC data (R 2 = 0.60). Moreover, when aggregated at the national level, IB AGC exhibited stronger consistency with long-term net changes from country-level forest inventory data (R 2 = 0.62) than other mainstream satellite products. It is expected that IB AGC will provide an independent means for better monitoring the global vegetation carbon stocks and their variability in response to climate change.

Above-ground biomass carbon (AGC) in live vegetation is a main land carbon stock and can increase or decrease from environmental changes and direct human activities such as deforestation or forest management 1,2 . The carrier of AGC, above-ground biomass (AGB), has been recognized as an Essential Climate Variable (ECV) by the Global Climate Observing System (GCOS) 3 , serving as a critical input for constraining Earth system models 4,5 and a requisite for countries in their mandated carbon accounting 6-8 . Most of the Earth biomass is in forests, with large regional differences of carbon stocks and stocks density per unit area. Accurately monitoring changes

This preliminary study shows that Brassica napus WSCP1 delays chlorophyll degradation and inhibits serine proteases during dark-induced leaf senescence in Arabidopsis.

Autophagy is essential for homeostasis and nutrient recycling. Its activity increases with aging and in response to deficiencies. The effects of defective autophagy on root metabolism have not yet been described. Addressing this question through root proteome analyses, we found that most V-ATPases were less abundant in the roots of autophagy mutants than in wild type. V-ATPases deficit, associated with lower root water contents and lower nitrate, magnesium, and potassium concentrations, indicated that the disturbance of cellular ion and water management in autophagy mutants was likely related to vacuole function. Isotopic δ 13 C analyses and leaf temperature measurements using thermography showed that water deficit in autophagy mutants was not due to excess transpiration, as the conductance of stomata was reduced in mutants compared to wild type. Many proteins related to the catabolism of amino acids and lipids and the tricarboxylic acid (TCA) cycle were over-abundant in atg mutants. The increase in several proteases that paralleled amino acid catabolism suggested that in the absence of autophagic flux, compensatory processes could be established to degrade proteins, recycle amino acids, and fuel TCA. Whether the V-ATPases defect affects energy metabolism and promotes lipid and amino acid catabolism to compensate and fuel TCA remains to be explored. In conclusion, this report establishes for the first time a correlation between autophagy and vacuole function through V-ATPases, particularly with regard to water and ion management. Additionally, this report shows the exacerbation of amino acid catabolism in relation to the stimulation of the TCA cycle in autophagy mutants.