Narangerel Altangerel

In vivo diagnostics of early abiotic plant stress response via Raman spectroscopy

Significance Feeding a population of 9 billion in 2050 coupled with the changing climate and environmental stresses motivate us to develop advances in plant science and technology. We present a high-throughput plant phenotyping platform for detection of abiotic stress. The proposed Raman spectroscopic technique for high-throughput stress phenotyping and early stress detection in vivo improves sensitivity with the ability to interrogate individual molecules simultaneously in plants. This technology holds promise for mobile automated systems and precision agriculture. Development of a phenotyping platform capable of noninvasive biochemical sensing could offer researchers, breeders, and producers a tool for precise response detection. In particular, the ability to measure plant stress in vivo responses is becoming increasingly important. In this work, a Raman spectroscopic technique is developed for high-throughput stress phenotyping of plants. We show the early (within 48 h) in vivo detection of plant stress responses. Coleus (Plectranthus scutellarioides) plants were subjected to four common abiotic stress conditions individually: high soil salinity, drought, chilling exposure, and light saturation. Plants were examined poststress induction in vivo, and changes in the concentration levels of the reactive oxygen-scavenging pigments were observed by Raman microscopic and remote spectroscopic systems. The molecular concentration changes were further validated by commonly accepted chemical extraction (destructive) methods. Raman spectroscopy also allows simultaneous interrogation of various pigments in plants. For example, we found a unique negative correlation in concentration levels of anthocyanins and carotenoids, which clearly indicates that plant stress response is fine-tuned to protect against stress-induced damages. This precision spectroscopic technique holds promise for the future development of high-throughput screening for plant phenotyping and the quantification of biologically or commercially relevant molecules, such as antioxidants and pigments.

All-fiber ultralow-energy soliton management at 1.55 µm

A highly nonlinear photonic-crystal fiber (PCF) is shown to enable an efficient coupling of a low-energy picosecond output of an erbium fiber laser into optical solitons. With this fiber, stretched 2.2 ps, 1.2 nJ, 1.55 µm pulses of an erbium fiber laser can be coupled into sub-100 fs optical solitons with an energy slightly below 1 nJ. The peak power and the pulse width of these solitons can be finely tuned by pulse chirp management in a variable-length single-mode fiber, connected to the erbium fiber laser output and cascaded with the PCF.

Quantitative interpretation of time‐resolved coherent anti‐Stokes Raman spectroscopy with all Gaussian pulses

Coherent anti-Stokes Raman scattering is a powerful nonlinear optical spectroscopic technique primarily used in chemistry and biology for detection and diagnostics by excitation and probing of coherent molecular vibrations. Despite many advantages, there are certain limitations to the application of this technique due to the existence of the non-resonant four-wave mixing contamination. This issue is addressed here by offering the time-resolved exact solutions with all Gaussian input pulses. The paper explains signal enhancement with a suppression of the background at the threshold delay time of the probe and presents a one-to-one comparison between the solutions and experimental observations that provides a reconstruction of the pure coherent Raman resonant contribution. These findings add to the deep understanding of coherent Raman spectroscopic experimental data as a hands-on interpreting tool. Copyright

Stimulated fluorescence quenching in nitrogen–vacancy centers of diamond: temperature effects

Laser-induced fluorescence quenching in nitrogen-vacancy (NV) centers in diamond is studied simultaneously with in situ measurements of the heating-induced shift of the electron spin resonance of NV centers in the presence of a microwave field. These experiments reveal a strong correlation between fluorescence suppression in NV centers and the rise of the local temperature inside the diamond crystal. This finding sheds light on quantum pathways behind stimulated fluorescence quenching in NV centers of diamond and may imply significant limitations on the applications of this effect as a method of superresolving imaging in biological systems.

The Dawn of Quantum Biophotonics

Quantum optics and photonics are being used in a variety of bio-technologies for both plants and animals, primarily in the form of quantum optical technology. A new paradigm shift has been emerging in which the biologists define the parameters that are needed for effective use, and the quantum physicists/engineers design and develop the technology to meet those needs. For example, recent exciting developments of new radiation sources improved the detection of trace impurities via quantum coherence, and related effects improve microscopic resolution (Nobel Prize 2014). Furthermore, the use of noise-induced quantum coherence promises to open new vistas in photosynthesis and quantum effects in biology. This requires developing new techniques and pushing the envelope in quantum physics, on the one hand, and bioscience, on the other. In this review we describe recent progress in quantum biophotonics and open questions.

Comparison of Near Infrared Reflectance Spectroscopy and Raman Spectroscopy for Predicting Botanical Composition of Cattle Diets

ABSTRACT Diet selection is an important driver of ecosystem structure and function that is difficult to measure. New spectroscopic instruments are available for evaluating their applicability to ecological field studies. The objective of this study was to compare near-infrared reflectance spectroscopy (NIRS) to Raman spectroscopy of fecal samples for predicting the percentage of honey mesquite (Prosopis glandulosa) in the diet of ruminally fistulated cattle fed three different hay diets and compare them for their ability to discriminate among the three base diets. Spectra were collected from feces from a feeding trial with mesquite fed at 0%, 1%, 3%, and 5% of the diet and base hay diets of timothy hay (Phleum pratense), Sudan hay (Sorghum sudanense), or a 50:50 combination of Bermudagrass hay (Cynodon dactylon) and beardless wheat hay (Triticum aestivum). NIRS and Raman spectra were used for partial least squares regression calibrations with the timothy and Sudan hays and validated with the Bermudagrass/ beardless wheat hay diets. NIRS spectra provided useful calibrations (r2 = 0.88, slope = 1.03, intercept = 1.88, root mean square error = 2.09, bias = 1.95, ratio of performance to deviation = 2.6), but Raman spectra did not. Stepwise discriminant analysis was used to select wavenumbers for discriminating among the hays. Fifteen of 350 possible wavenumbers for NIRS spectra and 29 of 300 possible wavenumbers for Raman spectra met the P ≤ 0.05 entry and staying criteria. Canonical discriminant analysis using these wavenumbers resulted in 100% correct classification for all three base diets, and the Raman spectra provided greater separation than NIRS spectra. Discrimination using Raman spectra was primarily associated with wavenumbers associated with undigestible constituents of the diet (lignin). In contrast, discrimination using fecal NIRS (f.NIRS) spectra was primarily associated with wavenumbers associated with digestible constituents in the diet (protein, starch, and lipid). We believe that Raman spectroscopy deserves further investigation as a quantitative technique in ecological field studies.

Early, in vivo, detection of abiotic plant stress responses via Raman spectroscopy

We demonstrate, for the first time, in vivo early detection of plant stress responses via Raman spectroscopy. In particular, we observed anti-correlation between the two pigment molecules, anthocyanins and carotenoids associated with plant stress responses.

Dual Raman-Brillouin spectroscopic investigation of plant stress response and development

Raman and Brillouin spectroscopy are powerful tools for non-invasive and non-destructive investigations of material chemical and mechanical properties. In this study, we use a newly developed custom-built dual Raman-Brillouin microspectroscopy instrument to build on previous works studying in-vivo stress response of live plants using only a Raman spectroscopy system. This dual Raman-Brillouin spectroscopy system is capable of fast simultaneous spectra acquisition from single-point locations. Shifts and changes in a samples Brillouin spectrum indicate a change in the physical characteristics of the sample, namely mechano-elasticity; in measuring this change, we can establish a relationship between the mechanical properties of a sample and known stress response agents, such as reactive oxygen species and other chemical constituents as indicated by peaks in the Raman spectra of the same acquisition point. Simultaneous application of these spectroscopic techniques offers great promise for future development and applications in agricultural and biological studies and can help to improve our understanding of mechanochemical changes of plants and other biological samples in response to environmental and chemically induced stresses at microscopic or cellular level.

Reply to Dong and Zhao: Plant stress via Raman spectroscopy

Dong and Zhao (1) attempt to provide perspective on our use of Raman spectroscopy in plant stress studies (2). Unfortunately, their experimental criticism is incorrect and their technical suggestions won’t work. The following points support these strong statements.