Drought is considered the major abiotic stress limiting crop productivity. This study seeks to identify proteins involved in the drought response in sugarcane stems submitted to drought stress. The integration of nuclei enrichment sample preparation with the shotgun proteomic approach results in great coverage of the sugarcane stem proteome with 5381 protein groups identified. A total of 1204 differentially accumulated proteins are detected in response to drought, among which 586 and 618 are increased and reduced in abundance, respectively. A total of 115 exclusive proteins are detected, being 41 exclusives of drought-stressed plants and 74 exclusives of control plants. In the control plants, most of these proteins are related to cell wall metabolism, indicating that drought affects negatively the cell wall metabolism. Also, 37 transcription factors (TFs) are identified, which are low abundant nuclear proteins and are differentially accumulated in response to drought stress. These TFs are associated to protein domains such as leucine-rich (bZIP), C2H2, NAC, C3H, LIM, Myb-related, heat shock factor (HSF) and auxin response factor (ARF). Increased abundance of chromatin remodeling and RNA processing proteins are also observed. It is suggested that these variations result from an imbalance of protein synthesis and degradation processes induced by drought.

Kielmeyera coriacea Mart. (Clusiaceae), popularly known as "pau-santo", is a typical Brazilian cerrado tree known due to its varied secondary metabolites. This study aimed to determine the allelopathic potential of the hydroalcoholic extract of leaves of K. coriacea through bioassays of seed germination, seedling growth and mitotic index of Lactuca sativa L. (lettuce). In addition it was done the tetrazolium assay and a phytochemical screening. The extract concentrations caused alterations in germination parameters, in root growth and in the mitotic index. The phytochemical screening showed the presence of triterpenes, coumarins, steroids, flavonoids and condensed tannins, compounds known to confer allelopathic characteristics upon other species. These data indicate that K. coriacea presents an allelopathic potential because its leaf extracts interfere with germination and growth without any interference of pH and osmotic potential in the results.

Highlights Following the step by step described in this protocol is it is possible to measure long-distance electrical signaling induced by several stimuli, including wounding, current application, irrigation, and others. Extracellular electrical signal measurements were associated to gas exchange measurements using an infra-red gas analyzer (IRGA, model Li-6400, Li-Cor) and turgor pressure measurements using a patch clamp pressure probe (ZIM-probe, YARA ZIM-plant Technology). The technique is interesting to study electrical signaling in association with other physiological parameters in plants. We present results that validate the protocol and discuss the troubleshooting that may compromise measurements and data collection.

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