The outbreak of the COVID-19 pandemic is partially due to the challenge of identifying asymptomatic and pre-symptomatic carriers of the virus, and thus highlights a strong motivation for diagnostics that can be rapidly deployed with high sensitivity. On the other hand, several concerned SARS-CoV-2 variants, including the Omicron, are required to be identified as soon as the samples are identified as ‘positive’. Unfortunately, a traditional PCR test does not allow their specific identification. Herein, for the first time, we have developed MOPCS (Methodologies of Photonic CRISPR Sensing), which combines an optical sensing technology-surface plasmon resonance (SPR), and the ‘gene scissors’ CRISPR technique to achieve both high sensitivity and specificity of viral variants’ measurement. MOPCS is a low-cost, CRISPR/Cas12a system-empowered SPR gene detecting platform that can analyze viral RNA, without the need for amplification, within 38 min from sample input to results output, and achieve a limit of detection of 15 fM. MOPCS achieves a highly sensitive analysis of SARS-CoV-2 and mutations appear in variants B.1.617.2 (Delta), B.1.1.529 (Omicron), and BA.1 (a subtype of Omicron). This platform was also used to analyze some recently collected patient samples from a local outbreak in China and identified by the Centers for Disease Control and Prevention. This innovative CRISPR-empowered SPR platform will further contribute to various fast, sensitive, and accurate detection of target nucleic acid sequences with single-base mutations.

In this paper, the influence of drought hardening on the growth, development, resistance physiology, leaf microstructure and stomatal behavior of potato seedlings under drought stress was studied, and the mechanism of drought hardening improvement of potato seedling drought resistance was elucidated. We found that drought stress had several adverse effects on potato seedlings, yet drought hardening alleviated the decrease in relative water content (RWC), net photosynthetic rate (P n) and chlorophyll content and inhibited the increase in relative electric conductivity and malondialdehyde (MDA) content. Compared with contrast seedlings, drought-hardened seedlings also had enhanced root vigor, increased antioxidant enzyme activity and higher levels of abscisic acid (ABA), proline (Pro), soluble sugars and polyamines (PAs) under drought stress. In addition, the stomatal density of potato seedling leaves increased significantly, while the leaf area, stomatal size and stomatal aperture decreased with drought hardening treatment. These changes led to reduced leaf transpiration rate (T r) and improved water utilization efficiency (WUE). The changes in leaf microstructure also had a positive effect on the drought resistance of the drought-hardened potato seedlings. So it can be concluded that through increasing the content of some endogenous hormones, osmotic regulatory substances and the activities of antioxidant enzymes, the resistance physiology of drought-hardened potato seedlings was enhanced.

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