Precision agriculture requires new technologies for rapid diagnosis of plant stresses, such as nutrient deficiency and drought, before the onset of visible symptoms and subsequent yield loss. Here, we demonstrate a portable Raman probe that clips around a leaf for rapid, in vivo spectral analysis of plant metabolites including carotenoids and nitrates. We use the leaf-clip Raman sensor for early diagnosis of nitrogen deficiency of the model plant Arabidopsis thaliana as well as two important vegetable crops, Pak Choi (Brassica rapa chinensis) and Choy Sum (Brassica rapa var. parachinensis). In vivo measurements using the portable leaf-clip Raman sensor under full-light growth conditions were consistent with those obtained with a benchtop Raman spectrometer measurements on leaf-sections under laboratory conditions. The portable leaf-clip Raman sensor offers farmers and plant scientists a new precision agriculture tool for early diagnosis and real-time monitoring of plant stresses in field conditions.

Nutrient deficiency alters growth and development of crop plants and compromises yield. Real-time non-invasive monitoring of the nutritional status of crops would allow timely applications of fertilizers to optimize for growth and yield at different times of the plant's life cycle. Here, we used Raman spectroscopy to characterize Arabidopsis and two varieties of leafy vegetable crops under nitrogen sufficient and deficient conditions. We showed that the 1046 cm −1 Raman peak serves as a specific signature of nitrogen status in planta, which can be used for early diagnosis of nitrogen deficiency in plants before onset of any visible symptoms. Our research can be applied toward crop management for sustainable and precision agriculture.

Osteoclasts are bone tissue macrophages critical to maintain bone homeostasis. However, whether osteoclasts are susceptible to flaviviral infections and involved in dengue virus (DV)-induced disease pathogenesis is still unknown. In this study, we found that osteoclasts were preferentially susceptible to DV infection and produced similar amounts of cytokines and infectious virions as macrophages. Interestingly, DV-induced cytokine secretion and nuclear translocation of the transcription factor NFATc1 in osteoclast via the Syk-coupled myeloid C-type lectin member 5A (CLEC5A). Moreover, DV caused transient inflammatory reaction in bone tissue and upregulated osteolytic activity to release C-telopeptide of type I collagen (CTX-1) from bone tissue. Furthermore, DV-induced osteolytic activity was attenuated in CLEC5A-deficient mice, and administration of antagonistic anti-CLEC5A mAb inhibited DV-activated osteolytic activity and reduced CTX-1 serum level in vivo. This observation suggests that osteoclasts serve as a novel target for DV, and transient upregulation of osteolytic activity may contribute to the clinical symptoms in dengue patients.Key messagesCultured osteoclasts were susceptible to DV infection.Osteoclasts produced similar amounts of cytokines and infectious virions as macrophages.DV induced nuclear translocation of NFATc1 in osteoclast via CLEC5A.DV caused transient inflammatory reaction in bone tissue and upregulated osteolytic activity.Antagonistic anti-CLEC5A mAb inhibited DV-activated osteolytic activity in vivo.Electronic supplementary materialThe online version of this article (doi:10.1007/s00109-016-1409-0) contains supplementary material, which is available to authorized users.