Omics analyses in citrus reveal a possible role of RNA translation pathways and Unfolded Protein Response regulators in the tolerance to combined drought, high irradiance, and heat stress

Environmental changes derived from global warming and human activities increase the intensity and frequency of stressful conditions for plants.Multiple abiotic factors acting simultaneously enhance stress pressure and drastically reduce plant growth,yield,and survival.Stress combination causes a specific stress situation that induces a particular plant response different to the sum of responses to the individual stresses.Here,by comparing transcriptomic and proteomic profiles to different abiotic stress combinations in two citrus genotypes,Carrizo citrange(Citrus sinensis×Poncirus trifoliata)and Cleopatra mandarin(Citrus reshni),with contrasting tolerance to different abiotic stresses,we revealed key responses to the triple combination of heat stress,high irradiance and drought.The specific transcriptomic response to this stress combination in Carrizo was directed to regulate RNA metabolic pathways and translation processes,potentially conferring an advantage with respect to Cleopatra.In addition,we found endoplasmic reticulum stress response as common to all individual and combined stress conditions in both genotypes and identified the accumulation of specific groups of heat shock proteins(HSPs),such as small HSPs and HSP70s,and regulators of the unfolded protein response,BiP2 and PDIL2-2,as possible factors involved in citrus tolerance to triple stress combination.Taken together,our findings provide new insights into the acclimation process of citrus plants to multiple stress combination,necessary for increasing crop tolerance to the changing climatic conditions.

Autophagy, apoptosis and organelle features during cell exposure to cadmiumč

Cadmium(Cd)induces several effects in different tissues,but our knowledge of the toxic effects on organelles is insuffi cient.To observe the progression of Cd effects on organelle structure and function,HuH-7 cells(human hepatic carcinoma cell line)were exposed to CdCl2 in increasing concentrations(1μM–20μM)and exposure times(2 h–24 h).During Cd treatment,the cells exhibited a progressive decrease in viability that was both time-and dose-dependent.Cd treated cells displayed progressive morphological changes that included cytoplasm retraction and nuclear condensation preceding a total loss of cell adhesion.Treatment with 10μM for 12 h led to irreversible damages.Before these drastic and irreparable damages,treated cells(5μM for 12 h)presented a progressive loss of mitochondrial function and cytoplasm acidifi cation as well as dysfunction and disorganization of microfi laments and endoplasmic reticulum.These damages led to the induction of apoptotic events and an increase in autophagic bodies in the cytoplasm.These results revealed that Cd affects multiple intra-cellular targets that induce alterations in the mitochondria,cytoskeleton,endoplasmic reticulum and acidic compartments,ultimately culminating in cell death via apoptotic and autophagic pathways.

Monoclonal Antibody Production and Immunolocalization of a Salinity Stress-Related Protein in Rice (Oryza sativa)

Among various physiological responses to salt stress, the synthesis of a lectin-related protein of 14.5 kDa was observed in rice plants （Oryza sativa L.） under the treatment of 170 mmol/L NaCl. In order to better understand the role of the SALT protein in the physiological processes involving salinity, it was irnmunolocalized in mesophilic cells of leaf sheath and blade of a rice variety IAC-4440 following monoclonal antibodies produced by hybridome culture technique. This variety turned out to be an excellent model for that purpose, since it accumulates SALT protein even in absence of salt treatment and it has been classified as moderately sensitive to salinity and a superior grain producer. This feature was relevant for this work since it allowed the use of plants without the deleterious effects caused by salinity. Immunocytochemistry assays revealed that the SALT protein is located in the stroma of chloroplasts under non-stressing condition. Since the chloroplast is the main target affected by salinity and considering that the SALT protein does not present any apparent signal peptide for organelle localization, its lectin-like activity seems to play an important role in the establishment of stable complexes, either to other proteins or to oligosaccharides that are translocated to the chloroplast.

Flight performance and wing morphology in the bat Carollia perspicillata:biophysical models and energetics

Studies on functional performance are important to understand the processes responsible for the evolution of diversity.Morphological trait variation within species influences the energetic cost of locomotion and impacts life history traits,with ecological and evolutionary consequences.This study examined wing morphology correlates of flight performance measured by energetic expenditure in the Seba’s short-tailed bat,Carollia perspicillata.In the flight experiments,nature caught bats(59 females,57 males)were allowed to fly for 3 min in a room.After each flight,thermographic images were taken to measure body temperature,and biophysical models were used to calculate sensible heat loss as a measure of energetic expenditure.Wing morphological traits were measured for each individual and associated with heat loss and power required to fly on performance surfaces.Wing morphological traits explained 7-10%of flight energetic cost,and morphologies with the best performance would save the energy equivalent to 9-30%of total daily requirements.The optimal performance areas within the C.perspicillata morphospace were consistent with predicted selection trends from the literature.A trade-off between demands for flight speed and maneuverability was observed.Wing loading and camber presented sexual dimorphism.These morphological differences are likely associated with more economical but less maneuverable flight in females,leading them to fly more often in open areas along the forest edge.Our findings demonstrate how small scale changes in wing morphology can affect life history strategies and fitness.