Photosynthetic traits and antioxidative defense responses of Pinus yunnanensis after joint attack by bark beetles Tomicus yunnanensis and T.minor

Bark beetles Tomicus yunnanensis and T.minor are two important pests of Pinus yunnanensis and can cause massive death of pine trees.In this study,we examined several traits related to photosynthesis in P.yunnanensis and their relationship with antibiotic defense responses after joint attack by the two bark beetles at the shoot and the trunk stages.When shoots were attacked by the beetles,the abundance of chlorophylls,carotenoids,and the rates of net photosynthesis(Pn)and transpiration(E)decreased in needles,while the levels of superoxide dismutase and malondialdehyde remained unchanged in both needles and phloem.The activity of peroxidases also remained unchanged in needles,but increased in phloem.The activity of catalases increased in both needles and phloem.When trunks were attacked by the bark beetles,chlorophyll abundance,Pn,E,and antioxidative enzyme activities all declined,and the declines were more pronounced than in the attacked shoots.A decrease in protein concentrations was also observed in needles and phloem from the attacked pines.Attack on shoots by the bark beetles suppressed host defense and provided a favorable environment for larval growth and development,resulting in long-term decline of pine growth potential.The results suggest that attacks on trunks by beetles caused more severe damage to host trees than attacks on shoots.

Controllable transitions among phase-matching conditions in a single nonlinear crystal

Entangled photon pairs are crucial resources for quantum information processing protocols.Via the process of spontaneous parametric downconversion(SPDC),we can generate these photon pairs using bulk nonlinear crystals.Traditionally,the crystal is designed to satisfy a specific type of phase-matching condition.Here,we report controllable transitions among different types of phase matching in a single periodically poled potassium titanyl phosphate crystal.By carefully selecting pump conditions,we can satisfy different phase-matching conditions.This allows us to observe first-order Type-II,fifth-order Type-I,third-order Type-0,and fifth-order Type-II SPDCs.The temperature-dependent spectra of our source were also analyzed in detail.Finally,we discussed the possibility of observing more than nine SPDCs in this crystal.Our work not only deepens the understanding of the physics behind phase-matching conditions,but also offers the potential for a highly versatile entangled biphoton source for quantum information research.

Identification of atypical T4SS effector proteins mediating bacterial defense

To remain competitive,proteobacteria use various contact-dependent weapon systems to defend against microbial com-petitors.The bacterial-killing type IV secretion system(T4SS)is one such powerful weapon.It commonly controls the killing/competition between species by secreting the lethal T4SS effector(T4E)proteins carrying conserved XVIPCD domains into competing cells.In this study,we sought knowledge to understand whether the bacterial-killing T4SS-producing bacteria encode T4E-like proteins and further explore their biological functions.To achieve this,we designed a T4E-guided approach to discover T4E-like proteins that are designated as atypical T4Es.Initially,this approach required scientists to perform simple BlastP search to identify T4E homologs that lack the XVIPCD domain in the genomes of T4SS-producing bacteria.These homologous genes were then screened in Escherichia coli to identify antibacterial candidates(atypical T4Es)and their neighboring detoxification proteins,followed by testing their gene cotranscription and validating their physical interactions.Using this approach,we did discover two atypical T4E proteins from the plant-beneficial Lysobacter enzymogenes and the phytopathogen Xanthomonas citri.We also provided substantial evidence to show that the atypical T4E protein Le1637-mediated bacterial defense in interspecies interactions between L.enzymogenes and its competitors.Therefore,the newly designed T4E-guided approach holds promise for detecting functional atypical T4E proteins in bacterial cells.