Influences of the Populus deltoids seedlings treated with exogenous methyl jasmonate on the growth and development of Lymantria dispar larvae

Lyantria dispar larvae were fed with the leaves of Populus deltoids seedlings exposed to methyl jasmonate （MeJA） for 24 h. The growth and development of the larvae were investigated, and phenolics contents in treated leaves including pyrocatechol, caffeic acid, coumarin, fernlic acid and benzoic acid were also surveyed by high-pressure liquid chromatography （HPLC）. Results indicated that approximate digestibility, efficiency of conversion of ingested food, efficiency of conversion of digested food, and weight of the larvae were inhibited obviously, especially from the sixth day, which may result from the increase of total phenolics contents in treated leaves. This result provides strong supports for MeJA acting as the airborne signal molecule between woody plants.

Cell specialization and coordination in Arabidopsis leaves upon pathogenic attack revealed by scRNA-seq

Plant defense responses involve several biological processes that allow plants to fight against pathogenic attacks.How these different processes are orchestrated within organs and depend on specific cell types is poorly known.Here,using single-cell RNA sequencing(scRNA-seq)technology on three independent biological replicates,we identified several cell populations representing the core transcriptional responses of wild-type Arabidopsis leaves inoculated with the bacterial pathogen Pseudomonas syringae DC3000.Among these populations,we retrieved major cell types of the leaves(mesophyll,guard,epidermal,companion,and vascular S cells)with which we could associate characteristic transcriptional reprogramming and regulators,thereby specifying different cell-type responses to the pathogen.Further analyses of transcriptional dynamics,on the basis of inference of cell trajectories,indicated that the different cell types,in addition to their characteristic defense responses,can also share similar modules of gene reprogramming,uncovering a ubiquitous antagonism between immune and susceptible processes.Moreover,it appears that the defense responses of vascular S cells,epidermal cells,and mesophyll cells can evolve along two separate paths,one converging toward an identical cell fate,characterized mostly by lignification and detoxification functions.As this divergence does not correspond to the differentiation between immune and susceptible cells,we speculate that this might reflect the discrimination between cellautonomous and non-cell-autonomous responses.Altogether our data provide an upgraded framework to describe,explore,and explain the specialization and the coordination of plant cell responses upon pathogenic challenge.