Caffeine (CAF), a primary flavor component in tea, is one of the main reasons for the popularity of tea beverages.  As an important secondary metabolite in tea plants, the CAF content varied greatly among different tea accessions.  However, the genetic mechanisms underlying the CAF biosynthesis were still unclear.  In this study, we performed a genome-wide association study (GWAS) on 359 tea accessions in the Guizhou Plateau to identify genetic variation associated with CAF content.  A total of 19 significant single nucleotide polymorphisms (SNPs) and key gene (CsAK) involved in CAF biosynthesis were identified.  Subcellular localization revealed that the CsAK-GFP fusion protein was located on the cell membrane.  Antisense oligodeoxynucleotide (AsODN) targeting the CsAK gene to the buds and leaves revealed that the expression levels of the CsAK gene were significantly reduced, and the corresponding CAF content was also decreased in AsODN-treated tea plants.  Overexpression of the CsAK gene in eukaryotic cells resulted in the accumulation of key intermediate product (L-methionine) during CAF biosynthesis process.  These findings offered a theoretical foundation for future tea breeding programs aimed at cultivating excellent germplasm with high or low levels of CAF.

Straw return is a promising strategy for managing soil organic carbon (SOC) and improving yield stability.  However, the optimal straw return strategy for sustainable crop production in the wheat (Triticum aestivum L.)–cotton (Gossypium hirsutum L.) cropping system remains uncertain.  The objective of this study was to quantify the long-term (10 years) impact of carbon (C) input on SOC sequestration, soil aggregation and crop yields in a wheat–cotton cropping system in the Yangtze River Valley, China.  Five treatments were arranged with a single-factor randomized design as follows: no straw return (Control), return of wheat straw only (Wt), return of cotton straw only (Ct), return of 50% wheat and 50% cotton straw (Wh-Ch) and return of 100% wheat and 100% cotton straw (Wt-Ct).  In comparison to the Control, the SOC content increased by 8.4 to 20.2% under straw return.  A significant linear positive correlation between SOC sequestration and C input (1.42–7.19 Mg ha⁻¹ yr⁻¹) (P<0.05) was detected.  The percentages of aggregates of sizes >2 and 1–2 mm at the 0–20 cm soil depth were also significantly elevated under straw return, with the greatest increase of the aggregate stability in the Wt-Ct treatment (28.1%).  The average wheat yields increased by 12.4–36.0% and cotton yields increased by 29.4–73.7%, and significantly linear positive correlations were also detected between C input and the yields of wheat and cotton.  The average sustainable yield index (SYI) reached a maximum value of 0.69 when the C input was 7.08 Mg ha⁻¹ yr⁻¹, which was close to the maximum value (SYI of 0.69, C input of 7.19 Mg ha⁻¹ yr^–1) in the Wt-Ct treatment.  Overall, the return of both wheat and cotton straw was the best strategy for improving SOC sequestration, soil aggregation, yields and their sustainability in the wheat–cotton rotation system.

Saliva plays a crucial role in mediating plant-insect interactions, yet the functional diversity of salivary proteins remains poorly understood. Here, we identify NlSP6935, a salivary gland-specific protein conserved among rice planthoppers but absent in bamboo-feeding relatives. Silencing NlSP6935 causes severe lethality, feeding impairment, and infertility in Nilaparvata lugens, independent of host plant resistance. Transient expression assays reveal that NlSP6935 suppresses H₂O₂ accumulation in plants, while overexpression in rice downregulates terpenoid biosynthesis and enhances host attractiveness. However, transgenic NlSP6935 plants only weakly rescue RNAi-induced lethality, demonstrating its dual role in insect physiology and plant defense suppression. Our findings reveal a novel effector essential for both planthopper survival and host adaptation, providing new insights into pest control strategies.