In insects, the number and specificity of antennal lobe glomeruli often reflect the number and diversity of expressed chemosensory genes, which are linked to its ecological niche and specific olfactory needs.  The oriental armyworm, Mythimna separata, is an important and common lepidopteran pest of cereal crops.  Given its reliance on the olfactory system for crucial behaviors, understanding the evolutionary potential of this system requires a thorough characterization of the anatomical structure of the primary olfactory center.  Here, we systematically identified all antennal lobe glomeruli of M. separata based on synaptic antibody immunostaining and mass staining of the olfactory sensory neurons.  A total of 69 glomeruli were identified in females and 65 in males, and an intuitive nomenclature based on glomerular positions was applied.  Our findings uncovered some sex-specific glomeruli in this species.  There were ten female-specific glomeruli and three male-specific glomeruli, except for the macroglomerular complex (MGC) units, with a notable observation that the female labial pit organ glomerulus was larger than its male counterpart.  Additionally, we identified four antennal-lobe tracts (ALTs) and retrograde labeling from the calyx revealed that all glomeruli were innervated by the medial ALT projection neurons.  The comparison of the olfactory system structures between M. separata and sympatric moths supports their evolutionary convergence in noctuid moths.  These results collectively lay the foundation for future studies on olfactory processing in M. separata.

Soil microorganisms play critical roles in ecosystem function.  However, the relative impact of the potassium (K) fertilizer gradient on the microbial community in wheat‒maize double-cropping systems remains unclear.  In this long-term field experiment (2008–2019), we researched bacterial and fungal diversity, composition, and community assemblage in the soil along a K fertilizer gradient in the wheat season (K0, no K fertilizer; K1, 45 kg ha⁻¹ K₂O; K2, 90 kg ha⁻¹ K₂O; K3, 135 kg ha⁻¹ K₂O) and in the maize season (K0, no K fertilizer; K1, 150 kg ha⁻¹ K₂O; K2, 300 kg ha⁻¹ K₂O; K3, 450 kg ha⁻¹ K₂O) using bacterial 16S rRNA and fungal internally transcribed spacer (ITS) data.  We observed that environmental variables, such as mean annual soil temperature (MAT) and precipitation, available K, ammonium, nitrate, and organic matter, impacted the soil bacterial and fungal communities, and their impacts varied with fertilizer treatments and crop species.  Furthermore, the relative abundance of bacteria involved in soil nutrient transformation (phylum Actinobacteria and class Alphaproteobacteria) in the wheat season was significantly increased compared to the maize season, and the optimal K fertilizer dosage (K2 treatment) boosted the relative bacterial abundance of soil nutrient transformation (genus Lactobacillus) and soil denitrification (phylum Proteobacteria) bacteria in the wheat season.  The abundance of the soil bacterial community promoting root growth and nutrient absorption (genus Herbaspirillum) in the maize season was improved compared to the wheat season, and the K2 treatment enhanced the bacterial abundance of soil nutrient transformation (genus MND1) and soil nitrogen cycling (genus Nitrospira) genera in the maize season.  The results indicated that the bacterial and fungal communities in the double-cropping system exhibited variable sensitivities and assembly mechanisms along a K fertilizer gradient, and microhabitats explained the largest amount of the variation in crop yields, and improved wheat‒maize yields by 11.2–22.6 and 9.2–23.8% with K addition, respectively.  These modes are shaped contemporaneously by the different meteorological factors and soil nutrient changes in the K fertilizer gradients.

The leucine-rich repeat receptor kinase flagellin-sensing 2 gene (MdFLS2; Gene ID: MDP0000254112) was cloned from Royal Gala apple (Malus×domestica Borkh.).  This gene contained a complete open reading frame of 3 474 bp that encoded 1 158 amino acids.  The phylogenetic tree indicated that Prunus persica FLS2 exhibited the highest sequence similarity to MdFLS2.  The PlantCare database suggests that the promoter sequence of MdFLS2 contains several typical cis-acting elements, including ethylene-, gibberellin-, salicylic acid-, and drought-responsive elements.  Quantitative real-time PCR analysis showed that MdFLS2 was widely expressed in the different tissues of the apple and most highly expressed in the leaves.  Furthermore, MdFLS2 was significantly induced by the flagellin elicitor peptide flg22.  Treatment of the apple seedling leaves with flg22 resulted in an increase in leaf callose levels with increased treatment duration.  An increase in the production of O₂^– along with the expression of disease-related genes was also observed.  An oxidative burst was detected in the treated seedlings, but not in the control seedlings, indicating that flg22 had stimulated the expression of the MdFLS2 gene and its downstream target genes.  Furthermore, the ectopic expression of MdFLS2 complemented the function of the Arabidopsis fls2 mutant and conferred enhanced flg22 tolerance to the transgenic Arabidopsis, suggesting that MdFLS2 acts as a positive regulator in the response to pathogens in apple.