microRNAs (miRNAs) and small interfering RNAs (siRNAs) are small non-coding RNAs (ncRNAs) that trigger RNA interference (RNAi) in eukaryotic organisms.  The biogenesis pathways for these ncRNAs are well established in Drosophila melanogaster, Aedes aegypti, Bombyx mori and other insects, but lacking in hymenopteran species, particularly in parasitoid wasps.  Pteromalus puparum is a parasitoid of pupal butterflies.  This study identified and analyzed two pathways by interrogating the P. puparum genome.  All core genes of the two pathways are present in the genome as a single copy, except for two genes in the siRNA pathway, R2D2 (two copies) and Argonaute-2 (three).  Conserved domain analyses showed the protein structures in P. puparum were similar to cognate proteins in other insect species.  Phylogenetic analyses of hymenopteran Dicer and Argonaute genes suggested that the siRNA pathway-related genes evolved faster than those in the miRNA pathway.  The study found a decelerated evolution rate of P. puparum Dicer-2 with respect to Dicer-1, which was contrary to other hymenopterans.  Expression analyses revealed high mRNA levels for all miRNA pathway genes in P. puparum adults and the siRNA related genes were expressed in different patterns.  The findings add valuable new knowledge of the miRNA and siRNA pathways and their regulatory actions in parasitoid wasps.

Plant photosynthesis assimilates CO₂ from the atmosphere, and CO₂ diffusion efficiency is mainly constrained by stomatal and mesophyll resistance.  The stomatal and mesophyll conductance of plants are sensitive to abiotic stress factors, which affect the CO₂ concentrations at carboxylation sites to control photosynthetic rates.  Early studies conducted relevant reviews on the responses of stomatal conductance to the environment and the limitations of mesophyll conductance by internal structure and biochemical factors.  However, reviews on the abiotic stress factors that systematically regulate plant CO₂ diffusion are rare.  Therefore, in this review, the rapid and long-term responses of stomatal and mesophyll conductance to abiotic stress factors (such as light intensity, drought, CO₂ concentration and temperature) and their physiological mechanisms are summarized.  Finally, future research trends are also investigated.