Using HPLC, it was demonstrated that the major free phenolic compound in the pericarp and seed coat of red rice was cyanidin, which belong to anthocyanidin glucoside, exist only in the episperm of red rice as content of 1.64±0.10 mg/g. Anthocyanidin glucoside play a significant role in eliminating free radicals and reacting oxygen species (ROS) to prevent cellular oxidative stress. However, the chemical stability of anthocyanidin glucoside has been one of the major drawbacks for health applications. For longer storage, our results showed that red rice anthocyanidin glucoside could be stored with 0.3 % Vitamin C or 0.5 % NaHSO 3 , and be protected from light, high temperature, high pH and metal ions in environment. Antioxidant activity verified that anthocyanidin glucoside performed better than Vitamin C in ferrous ions chelating activity, scavenging activities for hydroxyl and DPPH radicals. Overall, the red rice might be used as a natural antioxidant supplement applying medical treatments in future days.
Cadmium (Cd) is a well-known metal imposing threats to human health, and it can be accumulated in polished rice over the permitted range of 0.2 mg kg−1 (GB 2762-2017). It has been reported that selenium (Se) application decreases Cd uptake. Se-rich diets have gained attention recently, but the potential of Se-rich rice in mitigating Cd stress needs further investigation. In this study, a pot experiment in the field was conducted to assess the influence of environmental factors and exogenous split application of Se on the nutritional status of rice under Cd stress. The results indicated that the increased fertilizer treatment in soil bulk linearly increased the metal content in rice grains. Approximately 50–70% of metal was recovered in rice tissues, while 5–20% of the metal that was applied leached down into the soil. A Se concentration of 0.4 mg kg−1 could significantly improve the total Se content in grain and mitigate Cd toxicity (1 mg kg−1) below the permitted range. Panicles and roots were more active for total Se accumulation in Se-rich and non-Se-rich rice, respectively. Polishing and milling operations can significantly reduce the Cd content, as rice bran in rice tissues accumulated most of the metal’s residues. The late matured rice cultivars consumed more heat units, and more metal contents were found in them. Collectively, it was found that Se can mitigate Cd toxicity, but the rice cultivation at T2 (high Cd; 2 mg kg−1 and Se; 1 mg kg−1) increased the metal uptake capability and health-risk index in polished rice, with its Se content heightened over permitted range of 0.04 to 0.30 mg kg−1 (GB/T 22499-2008). However, further molecular studies are required, in order to completely access the inverted Se accumulation behavior in rice tissues at high Cd soil stress.
The regenerative potential in response to wounding varies widely among species. Within the plant lineage, the liverwort
Marchantia polymorpha
displays an extraordinary regeneration capacity. However, its molecular pathways controlling the initial regeneration response are unknown. Here, we demonstrate that the Mp
ERF15
transcription factor gene is instantly activated after wounding and is essential for gemmaling regeneration following tissue incision. MpERF15 operates both upstream and downstream of the MpCOI1 oxylipin receptor by controlling the expression of oxylipin biosynthesis genes. The resulting rise in the oxylipin dinor-12-oxo-phytodienoic acid (dn-OPDA) levels results in an increase in gemma cell number and apical notch organogenesis, generating highly disorganized and compact thalli. Our data pinpoint Mp
ERF15
as a key factor activating an oxylipin biosynthesis amplification loop after wounding, which eventually results in reactivation of cell division and regeneration. We suggest that the genetic networks controlling oxylipin biosynthesis in response to wounding might have been reshuffled over evolution.
BackgroundThe element selenium (Se) deficiency is thought to be a global human health problem, which could disperse by daily-supplement from Se-rich food. Increasing the accumulation of Se in rice grain is an approach matched to these nutrient demands. Nonetheless, Se is shown to be essential but also toxic to plants, with a narrow margin between deficiency and toxicity. Notably, the regulatory mechanism balancing the accumulation and tolerance of Se in Se-rich rice plants remains unknown.ResultsIn this study, we investigated the phenotypical, physiological, and biochemical alterations of Se-rich rice in the exposure to a variety of Se applications. Results showed that the Se-rich rice was able to accumulate more abundance of Se from the root under a low Se environment comparing to the Se-free rice. Besides, excessive Se led to phytotoxic effects on Se-rich rice plants by inducing chlorosis and dwarfness, decreasing the contents of antioxidant, and exacerbating oxidative stresses. Furthermore, both phosphate transporter OsPT2 and sulfate transporters OsSultr1;2 may contribute to the uptake of selenate in rice.ConclusionsSe-rich red rice is more sensitive to exogenous application of Se, while and the most effective application of Se in roots of Se-rich rice was reached in 20 μM. Our findings present a direct way to evaluate the toxic effects of Se-rich rice in the Se contaminated field. Conclusively, some long-term field trial strategies are suggested to be included in the evaluation of risks and benefits within various field managements.
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