The E3 ubiquitin ligase COP1 regulates salt tolerance via GIGANTEA degradation in roots.

Excess soil salinity significantly impairs plant growth and development. Our previous reports demonstrated that the core circadian clock oscillator GIGANTEA (GI) negatively regulates salt stress tolerance by sequestering the SALT OVERLY SENSITIVE (SOS) 2 kinase, an essential component of the SOS pathway. Salt stress induces calcium-dependent cytoplasmic GI degradation, resulting in activation of the SOS pathway; however, the precise molecular mechanism governing GI degradation during salt stress remains enigmatic. Here, we demonstrate that salt-induced calcium signals promote the cytoplasmic partitioning of CONSTITUTIVE PHOTOMORPHOGENIC 1 (COP1), leading to the 26S proteasome-dependent degradation of GI exclusively in the roots. Salt stress-induced calcium signals accelerate the cytoplasmic localization of COP1 in the root cells, which targets GI for 26S proteasomal degradation. Align with this, the interaction between COP1 and GI is only observed in the roots, not the shoots, under salt-stress conditions. Notably, the gi-201 cop1-4 double mutant shows an enhanced tolerance to salt stress similar to gi-201, indicating that GI is epistatic to COP1 under salt-stress conditions. Taken together, our study provides critical insights into the molecular mechanisms governing the COP1-mediated proteasomal degradation of GI for salt stress tolerance, raising new possibilities for developing salt-tolerant crops.

The thiol-reductase activity of YUCCA6 enhances nickel heavy metal stress tolerance in Arabidopsis.

Anthropogenic activities cause the leaching of heavy metals into groundwater and their accumulation in soil. Excess levels of heavy metals cause toxicity in plants, inducing the production of reactive oxygen species (ROS) and possible death caused by the resulting oxidative stress. Heavy metal stresses repress auxin biosynthesis and transport, inhibiting plant growth. Here, we investigated whether nickel (Ni) heavy metal toxicity is reduced by exogenous auxin application and whether Ni stress tolerance in Arabidopsis thaliana is mediated by the bifunctional enzyme YUCCA6 (YUC6), which functions as an auxin biosynthetic enzyme and a thiol-reductase (TR). We found that an application of up to 1 µM exogenous indole-3-acetic acid (IAA) reduces Ni stress toxicity. yuc6-1D, a dominant mutant of YUC6 with high auxin levels, was more tolerant of Ni stress than wild-type (WT) plants, despite absorbing significantly more Ni. Treatments of WT plants with YUCASIN, a specific inhibitor of YUC-mediated auxin biosynthesis, increased Ni toxicity; however yuc6-1D was not affected by YUCASIN and remained tolerant of Ni stress. This suggests that rather than the elevated IAA levels in yuc6-1D, the TR activity of YUC6 might be critical for Ni stress tolerance. The loss of TR activity in YUC6 caused by the point-mutation of Cys85 abolished the YUC6-mediated Ni stress tolerance. We also found that the Ni stress-induced ROS accumulation was inhibited in yuc6-1D plants, which consequently also showed reduced oxidative damage. An enzymatic assay and transcriptional analysis revealed that the peroxidase activity and transcription of PEROXIREDOXIN Q were enhanced by Ni stress to a greater level in yuc6-1D than in the WT. These findings imply that despite the need to maintain endogenous IAA levels for basal Ni stress tolerance, the TR activity of YUC6, not the elevated IAA levels, plays the predominant role inNi stress tolerance by lowering Ni-induced oxidative stress.

Diversity, distribution, and sustainability of traditional medicinal plants in Kaski district, western Nepal.

Medicinal plants are the primary source of traditional healthcare systems in many rural areas mostly in developing countries. This study aimed to document and analyze the diversity, distribution, and sustainability of the traditional medicinal plants used by the Gurung people of the Sikles region in western Nepal. Ethnobotanical data were collected through focus group discussions and individual interviews, and analyzed using descriptive and inferential statistics. Prior informed consent was obtained before each interview. Quantitative ethnobotanical indices such as informant consensus factor, relative frequency of citation, and use values were also calculated. A possible association among these indices was tested using correlation analysis. A total of 115 wild medicinal plant species belonging to 106 genera and 71 families were documented. Asteraceae and Rosaceae were the dominant families whereas herbs were the most dominant life form. Roots were the most used plant part, paste was the most common method of preparation, and most of the medical formulations were taken orally. The highest number of medicinal plants were used to treat stomach disorders. The average informant consensus value of 0.79 indicates a high consensus among respondents in selecting medicinal plants. Lindera neesiana, Neopicrorhiza scrophulariiflora, Paris polyphylla, and Bergenia ciliata were found to be high-ranking medicinal plants based on the relative frequency of citation and use value. The genders did not affect medicinal plants' knowledge but age had a significant correlation. Most of the informants agreed that medicinal plants are under pressure due to overharvesting and a lack of proper forest management practices. The number of medicinal plants reported from the study area indicates that the Gurung people possess rich traditional knowledge, and the vegetation of the Sikles region constitutes rich diversity of medicinal plants.

Foods from the wild: Local knowledge, use pattern and distribution in Western Nepal.

Locally harvested wild edible plants (WEPs) provide food as well as cash income for indigenous peoples and local communities, and they are of great importance in ensuring local food security. However, their uses and availability are poorly documented. This study aimed to enumerate WEP diversity and status of WEPs in a part of the Annapurna Conservation Area, Sikles region, where the population is dominated by the Gurung community. Ethnobotanical data were collected using guided field walks, semi-structured interviews, and field observation. The informant consensus method was employed and group discussions were conducted for triangulation of the information. Free listing and identification tests were performed to assess the knowledge of the informants. Both descriptive statistics and quantitative ethnobotanical methods were used for data analysis. A total of 72 wild food species belonging to 46 families and 61 genera were reported from the study area. Asparagaceae and Rosaceae were the dominant families, and herbs were the dominant life form. Fruits (34 species) were the most frequently used plant parts, followed by young shoots (16 species). Most edible plants were consumed in summer and during rainy seasons. While the age and type of informants had an influence on the number of enumerated plants, gender did not. Key informants and people aged 30-45 reported more species than other groups of respondents. Most of the knowledge about the use of WEPs was acquired from parents and relatives. The consumption of these plants was attributed to diversifying cuisine, spicing staple food, nutri-medicinal values, and cultural practices. People perceived the availability of WEPs to be gradually decreasing. However, WEPs are still abundant and diverse in the study area, and knowledge on their use is well-preserved. These resources provide food and nutrients to local people and can also be a source of cash income. Therefore, the documented information on WEPs may serve as baseline data for further studies on nutritional values and provide guidelines for safe collection. The results also revealed that many wild species are under growing pressure from various anthropogenic factors, suggesting effective community engagement is required for their conservation.