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Summary: Calcium ion (Ca2+) serves as a versatile and conserved second messenger in orchestrating immune responses. In plants, plasma membrane‐localized Ca2+‐permeable channels can be activated to induce Ca2+ influx from extracellular space to cytosol upon pathogen infection. Notably, different immune elicitors can induce dynamic Ca2+ signatures in the cytosol. During pattern‐triggered immunity, there is a rapid and transient increase in cytosolic Ca2+, whereas in effector‐triggered immunity, the elevation of cytosolic Ca2+ is strong and sustained. Numerous Ca2+ sensors are localized in the cytosol or different intracellular organelles, which are responsible for detecting and converting Ca2+ signals. In fact, Ca2+ signaling coordinated by cytosol and subcellular compartments plays a crucial role in activating plant immune responses. However, the complete Ca2+ signaling network in plant cells is still largely ambiguous. This review offers a comprehensive insight into the collaborative role of intracellular Ca2+ stores in shaping the Ca2+ signaling network during plant immunity, and several intriguing questions for future research are highlighted. [ABSTRACT FROM AUTHOR]

Aims: The study aims to identify a novel plant growth‐promoting bacteria (PGPB), which contributes to promoting growth and reducing cadmium (Cd) concentration in rice under Cd‐contaminated conditions. Methods and Results: Nine bacterial strains were isolated from plants grown in Cd‐contaminated soil. These bacteria were tolerant to 1000 μmol/L CdCl2, capable of producing indole‐3‐acetic acid, fixing nitrogen and solubilizing phosphate. The result of hydroponic experiment showed that under the control and Cd stress conditions, the dry weight of the Tm02‐inoculated rice seedlings increased significantly. Furthermore, under Cd stress, the concentration of Cd in the shoot of the Tm02‐inoculated seedlings decreased significantly, while there was no significant difference in Cd concentration between treatment with other eight strains and noninoculated seedlings. The same results were observed in the pot experiment as well, where there was a significantly reduced Cd concentration in rice grains of the Tm02‐inoculated rice plants. Tm02 was classified as Pantoea agglomerans through 16S rDNA sequencing. Conclusions: A novel PGPB strain Tm02 was identified and confirmed that it has the function of promoting rice growth and reducing Cd concentration in rice grain under Cd‐contaminated conditions. This strain has the potential to improve rice yield in Cd‐contaminated paddy fields. Significance and Impact of the Study: This study provides a new example of using PGPB to improve the tolerance of rice to Cd pollution. [ABSTRACT FROM AUTHOR]

The cadmium (Cd) tolerance of 21 Italian ryegrass ( Lolium multiflorum Lam.) were investigated in this study by evaluating the process of seed germination on exposure to excess Cd. Excess Cd resulted in the significant growth inhibition, particularly of root growth. The relation between Cd concentrations and inhibition rate of root or shoot elongation can be well described by a logarithmic equation. The maximum values of IC50 (Cd concentration when the root or shoot elongation decreased to 50% compared with control) were observed in root and shoot of 'Idy II', whereas the minimums showed in 'Nioudachi' and 'Harukaze'. Cadmium dramatically inhibited the seed germination of 21 cultivars. By comparison of physiological parameters including the absolute and relative value of root and shoot length, germination rate, germination energy, germination index and vigor index, all the tested cultivars exhibited variation when exposed to the same strength of Cd stress. In addition, the values of evaluation index, subordinate function were used to evaluate the Cd tolerance among cultivars treated with excess Cd. As a result, cultivar 'Idy II' was identified to be most tolerant to Cd stress, cultivar 'Tachiwase' was the most sensitive one. Cluster analysis indicated that 21 cultivars of Italian ryegrass can be classified into four groups, Cd-tolerant, moderate Cd-tolerant, low Cd-tolerant and Cd-sensitive groups. The results will be basic information for cultivating forage crops used as bioenergy crops in Cd polluted environments. [ABSTRACT FROM AUTHOR]

Two cultivars of switchgrass, 'Alamo' (lowland type) and 'Cave-in-Rock' (upland type), were used to examine the morph-physiological responses of plants to different cadmium (Cd) levels under hydroponic condition treated with 0, 10, 20 and 40 μmol L−1 CdCl2 for 2 weeks. The main results showed that both seedlings of 'Alamo' and 'Cave-in-Rock' can survive even in 40 μmol L−1 CdCl2 treatment. However, the growth of the two cultivars was significantly (at least P < 0.05) inhibited by Cd stress. The plant biomass, water content, photosynthetic pigments content, total root length (RL), root surface area (RA), root volume (RV) and number of root tips of two tested cultivars were significantly decreased after treatment with Cd. 'Alamo' showed higher capability of Cd translocation from root to shoot than 'Cave-in-Rock', but 'Cave-in-Rock' had higher capability of Cd uptake and accumulation than 'Alamo'. 'Cave-in-Rock' accumulated higher Cd in root than 'Alamo', the root average diameter, RL, RA and RV at the root segment in 0.3-0.9 mm diameter in 'Cave-in-Rock' were dramatically higher than those of 'Alamo', which indicates that a well-developed root system may contribute to higher Cd accumulation in 'Cave-in-Rock'. Above all, both 'Alamo' and 'Cave-in-Rock' could be cultivated in Cd polluted area. At the same time, they have bioremediation function, especially, this function of seedling in 'Cave-in-Rock' should be greater than 'Alamo', since the amount of Cd absorption and accumulation in 'Cave-in-Rock' was significant higher than 'Alamo'. [ABSTRACT FROM AUTHOR]

Pot experiments were carried out to examine the responses of growth, physiological properties, copper (Cu) absorption and translocation in two bamboo species, Phyllostachys auresulcata ‘Spectabilis’ and Pleioblastus chino ‘Hisauchii’ Two-year old plants with similar size were exposed to excess Cu treatments, in order to demonstrate their Cu tolerance and potential ability of phytoremediation under Cu-polluted soil as biofuel feedstock. Pots were irrigated with aqueous solutions of Cu in concentrations of 500, 1000 and 2000 mg CuSO 4·5H 2O kg −1, against the control (tap water). Plant growth, chlorophyll contents, photosynthesis rate, malondialdehyde (MDA) content, Cu concentrations in leave, stem and root, and Cu contents in shoot per pot were measured after transplanted plants were grown under excess Cu treatments for 60 days. Two bamboo species had different responses to tolerance and allocation of supplied Cu. As Cu treatments rose, the percentage of senescent shoot and MDA content increased, and the chlorophyll content and photosynthetic capacity decreased. Such changes in Hisauchii were more obvious than in Spectabilis. However, number of emerged shoots did not differ between the two species across four Cu treatments. In the efficiency of decontamination, Hisauchii was more effective than Spectabilis, since either the Cu concentrations in leaves, stems and roots or Cu contents in shoot per pot in Cu treatments from 500 to 2000 mg kg −1 were higher in Hisauchii than in Spectabilis It is suggested that the potential capability of absorbing Cu might cause the different response to cu stress between the two bamboo species. Both bamboo species can be considered to exhibit enough potential to develop in Cu-polluted areas of China as bioenergy resources and phytoremediation plants. [ABSTRACT FROM AUTHOR]

This study aimed to evaluate the gene expression of HSP70 and HMA3 in the switchgrass inoculated with plant-growth-promoting-bacteria (PGPB) under cadmium (Cd) stress and to observe the benefit of PGPB in plant growth and development. Plants were grown in hydroponic culture and treated with PGPB inoculants: Pseudomonas grimontii, Pantoea vagans, Pseudomonas veronii, and Pseudomonas fluorescens with the strains Bc09, So23, E02, and Oj24, respectively. The experimental results revealed that HSP70 and HMA3 genes expressed highly in the PGPB-inoculated plants under Cd stress. In addition, the expression of HSP70 and HMA3 genes was considerably higher in the first two days after successive four-day exposure of Cd in plants compared to the last two days of exposure. Increased biomass and indole-3-acetic-acid production with reduced Cd accumulation were observed in the PGPB-inoculated plants under Cd stress compared to the Cd-control plants. These PGPB, with their beneficial mechanisms, protect plants by modifying the gene expression profile that arises during Cd-toxic conditions and increased the healthy biomass of switchgrass. This demonstrates there is a correlation among the growth parameters under Cd stress. The PGPB in this study may help to intensify agriculture by triggering mechanisms to encourage plant growth and development under heavy metal stress. [ABSTRACT FROM AUTHOR]

Calcium ion (Ca 2+ ) serves as a versatile and conserved second messenger in orchestrating immune responses. In plants, plasma membrane-localized Ca 2+ -permeable channels can be activated to induce Ca 2+ influx from extracellular space to cytosol upon pathogen infection. Notably, different immune elicitors can induce dynamic Ca 2+ signatures in the cytosol. During pattern-triggered immunity, there is a rapid and transient increase in cytosolic Ca 2+ , whereas in effector-triggered immunity, the elevation of cytosolic Ca 2+ is strong and sustained. Numerous Ca 2+ sensors are localized in the cytosol or different intracellular organelles, which are responsible for detecting and converting Ca 2+ signals. In fact, Ca 2+ signaling coordinated by cytosol and subcellular compartments plays a crucial role in activating plant immune responses. However, the complete Ca 2+ signaling network in plant cells is still largely ambiguous. This review offers a comprehensive insight into the collaborative role of intracellular Ca 2+ stores in shaping the Ca 2+ signaling network during plant immunity, and several intriguing questions for future research are highlighted., (© 2024 The Authors New Phytologist © 2024 New Phytologist Foundation.)