Citric acid (CA), as an organic chelator, plays a vital role in alleviating copper (Cu) stress-mediated oxidative damage, wherein a number of molecular mechanisms alter in plants. However, it remains largely unknown how CA regulates differentially abundant proteins (DAPs) in response to Cu stress in Brassica napus L. In the present study, we aimed to investigate the proteome changes in the leaves of B. L. seedlings in response to CA-mediated alleviation of Cu stress. Exposure of 21-day-old seedlings to Cu (25 and 50 μM) and CA (1.0 mM) for 7 days exhibited a dramatic inhibition of overall growth and considerable increase in the enzymatic activities (POD, SOD, CAT). Using a label-free proteome approach, a total of 6345 proteins were identified in differentially treated leaves, from which 426 proteins were differentially expressed among the treatment groups. Gene ontology (GO) and KEGG pathways analysis revealed that most of the differential abundance proteins were found to be involved in energy and carbohydrate metabolism, photosynthesis, protein metabolism, stress and defense, metal detoxification, and cell wall reorganization. Our results suggest that the downregulation of chlorophyll biosynthetic proteins involved in photosynthesis were consistent with reduced chlorophyll content. The increased abundance of proteins involved in stress and defense indicates that these DAPs might provide significant insights into the adaptation of Brassica seedlings to Cu stress. The abundances of key proteins were further verified by monitoring the mRNA expression level of the respective transcripts. Taken together, these findings provide a potential molecular mechanism towards Cu stress tolerance and open a new route in accelerating the phytoextraction of Cu through exogenous application of CA in B. napus.

Hydropriming rice seeds effectively improve the germination percentage, shortens the germination period, and promotes seedling growth. The impact of seed hydropriming is to speed up growth under dry soil conditions, thereby avoiding drought damage. This study analyzes the effect of hydropriming on morpho-physiological changes in the water uptake of rice seeds using “Kasalath” and “Nipponbare” under water-deficit conditions. Upon exposure to osmotic stress, both varieties showed delays in the time to reach germination. In addition, all germination phases exhibited reductions in the activity of alpha-amylase and total soluble sugar by osmotic stress; however, in all germination phases of the hydroprimed seeds, the activity and contents of those were significantly increased, resulting in increased size of the coleoptile, plumule, and radicle. In hydroprimed seeds, “Kasalath” was superior to “Nipponbare” in the ratio of the water-deficit-to-well-watered conditions for all traits related to germination, which may have been attributable to hydropriming having a greater effect on “Kasalath”. Interestingly, Primed “Kasalath” had a lower level of α-amylase, despite the having a higher content of total soluble sugars than primed “Nipponbare”.

Rice (Oryza sativa L.) is a staple crop that provides essential nutrients and energy; however, it is sensitive to heat stress, posing a threat to sustainable productivity. Heat stress can cause delayed germination in progeny, increased oxidative stress, reduced biomass accumulation, and excessive water loss. Notably, heat stress memory induced through heat priming can be inherited, potentially strengthening heat tolerance in subsequent generations. This study examined the effects of heat priming and heat stress on delayed germination, shoot length, and shoot fresh and dry weight under elevated-temperature conditions. The results showed that while heat stress delayed germination in progeny, heat priming significantly accelerated germination rates. Furthermore, heat stress elevated oxidative stress levels, thereby hindering biomass synthesis. In contrast, heat priming helped maintain low levels of reactive oxygen species (ROS) and malondialdehyde (MDA), contributing to greater biomass accumulation. These findings suggest that heat priming enhances transgenerational heat tolerance in rice, leading to faster germination, higher biomass accumulation, and improved ROS homeostasis in progeny.

This study investigates the effects of heat-priming during the tillering and booting stages of rice and associated changes in proteome expression. Heat stress, particularly during reproductive stages, significantly impacts rice yields, with temperature rises predicted to reduce crop production globally. Plants use priming to mitigate abiotic stress, whereby pre-exposure to moderate stress enhances their responses to subsequent stress. This process, known as 'stress memory' or heat-priming, enables plants to acquire thermotolerance, allowing them to mount a more effective defense against future extreme heat. However, studies on stress memory have not been sufficiently conducted. We identified several physiological and proteomic alterations in heat-primed N22 at the tillering or booting stages under heat stress applied at the flowering stage. The heat priming increased shoot length, tiller number, dry weight, and leaf area regardless of the growth period. Moreover, the fertility rate, reduced by heat stress, was increased by heat priming. Through LC/MS-MS analysis, 334 common proteins were identified. Through Gene Ontology and KEGG pathway analysis, it was found that translation, structural constitution of ribosome, cytoplasm, and metabolic pathway were most involved in heat stress in heat-primed rice. The up-expression of these proteins may suggest alleviation of heat priming through more energy generation, restoration of misfolded proteins, and effective ROS regulation. Through mRNA validation, it was discovered that proteins are regulated by not only their transcript level but also post-transcriptional modification. Our study provided a molecular perspective on the complex mechanism of heat priming that can alleviate heat stress.