Exogenous application of molybdenum affects the expression of CBF14 and the development of frost tolerance in wheat

Molybdenum inhibited the growth of Phytophthora nicotiana and improved the resistance of Nicotiana tabacum L. against tobacco black shank

Tobacco black shank (TBS) is a soil-borne fungal disease caused by Phytophthora nicotiana (P. nicotianae), significantly impeding the production of high-quality tobacco. Molybdenum (Mo), a crucial trace element for both plants and animals, plays a vital role in promoting plant growth, enhancing photosynthesis, bolstering antioxidant capacity, and maintaining ultrastructural integrity. However, the positive effect of Mo on plant biotic stress is little understood. This study delves into the inhibitory effects of Mo on P. nicotianae and seeks to unravel the underlying mechanisms. The results showed that 16.32 mg/L of Mo significantly inhibited mycelial growth, altered mycelial morphological structure, damaged mycelial cell membrane, and ultimately led to the leakage of cell inclusions. In addition, 0.6 mg/kg Mo applied in soil significantly reduced the severity of TBS. Mo increased photosynthetic parameters and photosynthetic pigment contents of tobacco leaves, upregulated expression of NtPAL and NtPPO resistance genes, as well as improved activities of SOD, POD, CAT, PPO, and PAL in tobacco plants. Furthermore, Mo could regulate nitrogen metabolism and amino acids metabolism to protect tobacco plants against P. nicotianae infection. These findings not only present an ecologically sound approach to control TBS but also contribute valuable insights to the broader exploration of the role of microelements in plant disease management.

QTL mapping and identification of candidate genes for cold tolerance at the germination stage in wild rice

BACKGROUND

Cold damage stress significantly affects rice growth (germination and seedling) and causes serious losses in yield in temperate and high-altitude areas around the globe.

OBJECTIVE

This study aimed to explore the cold tolerance (CT) locus of rice and create new cold-tolerant germplasm. We constructed a chromosome segment substitution line (CSSL) with strong CT and fine mapped quantitative trait loci (QTLs) associated with CT by performing the whole-genome resequencing of CSSL with phenotypes under cold treatment.

METHODS

A chromosome CSSL, including 271 lines from a cross between the cold-tolerant wild rice Y11 (Oryza rufipogon Griff.) and the cold-sensitive rice variety GH998, was developed to map QTLs conferring CT at the germination stage. The whole-genome resequencing was performed on CSSL for mapping QTLs of associated with CT at the germination stage.

RESULTS

A high-density linkage map of the CSSLs was developed using the whole-genome resequencing of 1484 bins. The QTL analysis using 615,466 single-nucleotide polymorphisms (SNPs) led to the identification of 2 QTLs related to germination rate at low-temperature on chromosome 8 (qCTG-8) and chromosome 11 (qCTG-11). The qCTG-8 and qCTG-11 explained 14.55% and 14.31% of the total phenotypic variation, respectively. We narrowed down qCTG-8 and qCTG-11 to 195.5 and 78.83-kb regions, respectively. The expression patterns of important candidate genes in different tissues, and of RNA-sequencing (RNA-seq) in CSSLs, were identified based on gene sequences in qCTG-8 and qCTG-11 cold-induced expression analysis. LOC_Os08g01120 and LOC_Os08g01390 were identified as candidate genes in qCTG-8, and LOC_Os11g32880 was identified as a candidate gene in qCTG-11.

CONCLUSIONS

This study demonstrated a general method that could be used to identify useful loci and genes in wild rice and aid in the future cloning of candidate genes of qCTG-8 and qCTG-11. The CSSLs with strong CT were supported for breeding cold-tolerant rice varieties.

Growth stage and molybdenum treatment affect cadmium accumulation, antioxidant defence and chlorophyll contents in Cannabis sativa plant

Cadmium (Cd) uptake and accumulation in plant tissues is affected by physiological stage of a plant and presence of mineral nutrients in soil. We investigate the effect of micronutrient Mo (0.5, 1.0 and 2.0 ppm) on biomass, Cd accumulation, photosynthetic pigments and endogenous phenolics and soluble proline in Cannabis sativa plant grown in 25 and 50 ppm Cd polluted soil. Molybdenum was applied as seed soaking and soil addition treatments. The plants were harvested in two stages i.e. vegetative (6 weeks) and reproductive stages (12 weeks). It was found that seed soaking treatment of 1.0 ppm Mo most significantly increased biomass, Cd accumulation (1.76 ± 0.19 mg Cd/DBM) and phenolics (104.5 ± 4.46 ppm) concentration in the plant tissues. Molybdenum treatments highly increased Cd bio-concentration at reproductive stage as compared to vegetative stage in plants grown in 50 ppm Cd polluted soil. Translocation of Cd from roots into leaves was significantly increased by Mo treatments at reproductive stage as compared to vegetative stage. Strong inter-correlations existed between total phenolics, Cd accumulation, dry biomass and chlorophyll contents of the plant.

Effects of molybdenum on water utilization, antioxidative defense system and osmotic-adjustment ability in winter wheat (Triticum aestivum) under drought stress

Molybdenum (Mo), as an essential trace element in plants, plays an essential role in abiotic stress tolerance of plants. To obtain a better understanding of drought tolerance enhanced by Mo, a hydroponic trial was conducted to investigate the effects of Mo on water utilization, antioxidant enzymes, non-enzymatic antioxidants, and osmotic-adjustment products in the Mo-efficient '97003' and Mo-inefficient '97014' under PEG simulated drought stress. Our results indicate that Mo application significantly enhanced Pn, chlorophyll, dry matter, grain yield, biomass, RWC and WUE and decreased Tr, Gs and water loss of wheat under drought stress, suggesting that Mo application improved the water utilization capacity in wheat. The activities of antioxidant enzymes such as superoxide dismutase, peroxidase, catalase, ascorbate peroxidase and the contents of non-enzymatic antioxidants content such as ascorbic acid, reduced glutathione, carotenoid were significantly increased and malonaldehyde contents were decreased by Mo application under PEG simulated drought stress, suggesting that Mo application enhanced the ability of scavenging active oxygen species. The osmotic-adjustment products such as soluble protein, proline and soluble sugar were also increased by Mo application under PEG simulated drought stress, indicating that Mo improved the osmotic adjustment ability in wheat. It is hypothesized that Mo application might improve the drought tolerance of wheat by enhancing water utilization capability and the abilities of antioxidative defense and osmotic adjustment. Similarities and differences between the Mo-efficient and Mo-inefficient cultivars wheat in response to Mo under drought stress are discussed.