Aquaphotomics Research of Cold Stress in Soybean Cultivars with Different Stress Tolerance Ability: Early Detection of Cold Stress Response.

Jelena Muncan,Roumiana Tsenkova,Shinichiro Kuroki,Balasooriya Mudiyanselage Siriwijaya Jinendra

doi:10.3390/molecules27030744

Abstract

The development of non-destructive methods for early detection of cold stress of plants and the identification of cold-tolerant cultivars is highly needed in crop breeding programs. Current methods are either destructive, time-consuming or imprecise. In this study, soybean leaves’ spectra were acquired in the near infrared (NIR) range (588–1025 nm) from five cultivars genetically engineered to have different levels of cold stress tolerance. The spectra were acquired at the optimal growing temperature 27 °C and when the temperature was decreased to 22 °C. In this paper, we report the results of the aquaphotomics analysis performed with the objective of understanding the role of the water molecular system in the early cold stress response of all cultivars. The raw spectra and the results of Principal Component Analysis, Soft Independent Modeling of Class Analogies and aquagrams showed consistent evidence of huge differences in the NIR spectral profiles of all cultivars under normal and mild cold stress conditions. The SIMCA discrimination between the plants before and after stress was achieved with 100% accuracy. The interpretation of spectral patterns before and after cold stress revealed major changes in the water molecular structure of the soybean leaves, altered carbohydrate and oxidative metabolism. Specific water molecular structures in the leaves of soybean cultivars were found to be highly sensitive to the temperature, showing their crucial role in the cold stress response. The results also indicated the existence of differences in the cold stress response of different cultivars, which will be a topic of further research.

Highlights

Soybean (Glycine max (L.) Merr.) is one of the most important crops in the legume family with significant economic importance
The research was directed toward two goals: (1) early temperature stress detection in soybean based on the near infrared (NIR) spectral signature of cultivars’ leaves, and (2) better understanding the molecular structure of water in leaves and how it is related to the overall stress response
This study was conducted using near infrared spectroscopy and aquaphotomics as a novel method for non-destructive detection of the cold stress response

Summary

Introduction

Soybean (Glycine max (L.) Merr.) is one of the most important crops in the legume family with significant economic importance. Soybean plants are susceptible to cold stress: cold halts the growth or results in injuries during all stages of development [4,5,6,7,8,9] Despite these constraints, soybean has continued its expansion into cool climatic areas of the world [10,11]. Soybean has continued its expansion into cool climatic areas of the world [10,11] In such areas, plants often undergo several degrees of low-temperature stress, and occasional cold stress injuries lead to decreased crop productivity and significant economic losses [12]. Cold stress, defined as the temperature in a range low enough to suppress growth without ceasing cellular functions, is known to induce several abnormalities at various levels of cellular organization [15]: (1) altered fluidity and damage of the membranes [16]; (2) the decrease in the uptake of nutrients and water, leading to cell desiccation and starvation [17]; (3) the conformational changes of proteins and nucleic acids [9];

Methods

Results

Discussion

Conclusion