Mechanism Of The Effect Of Znonps And Senps Priming On Seed Germination And Growth Under Salt Stress During Early Seedling Stage In Rapeseed

Among the oil crops,rapeseed seed is considered as one of the main sources for the production of edible oil,but under different environmental stress conditions,especially salinity stress that results in a significant decrease in plant growth and development,and ultimately reduced the yield.Priming is one of the most important applications,which has a powerful effect on elevating abiotic stress tolerance through improving the seed germination rate,and seedling vigor,thus enhancing germination of weak,damaged,or aged seeds,especially with the use of nanoparticles(nano-priming).Therefore,the current study aimed to increase the understanding of the effect of salinity on rapeseed.The most important results obtained are summarized in the next section:(1)Salinity reduced the seedling growth and changed the metabolism processes during the early seedling growth stageThe present study aimed to understand the influence of NaCl on morpho-physiological parameters and examine the diversity in the ability of rapeseed cultivars to withstand salinity tolerance.Furthermore,it aimed at studying the metabolic variation during seed germination under artificially induced salinity stress.Based on the morphological analysis of the five most common rapeseed cultivars,Yangyou 9,and Zhongshuang 11 displayed the most salt-tolerant and-sensitive cultivars,respectively.Yangyou 9 was significantly correlated with photosynthetic pigments,osmolytes accumulation,antioxidant enzyme activities,and modulated the Na⁺/K⁺ uptake versus Zhongshuang 11,thereby improved the seedling growth.Concerning the metabolites results,the proline content was elevated under salt stress in Yangyou 9 more than in Zhongshuang 11,also we found differences between the rapeseed cultivars regarding oxidative stress balance.Moreover,differences in alkaloids,membrane lipids,and hormone contents in Yangyou 9 and Zhongshuang 11 upon salt treatment.Additionally,other compounds that have nitrogen-containing were involved in response to salinity,including amino acids,serotonin,and polyamine conjugates.The increases of flavonoids and terpenes content in Yangyou 9 was greater than in Zhongshuang11 under the impact of salt stress at 12 and 24 h upon treatment during the seed germination.(2)Nano-priming via ZnONPs improved the seed germination and promoted the seedling growth under salt stress during the early seedling stageAs an essential micronutrient,ZnO can substitute Na⁺ absorption under saline conditions.Therefore,NPs as technological innovation,improve the plant growth efficiency under biotic and abiotic stresses.Thereby,this study was conducted to examine the effect of the ZnONPs phytoremediation properties on seedling biological processes in two rapeseed cultivars under 150 mM of NaCl.Morphological and physiochemical parameters,as well as fatty acid composition and the expression level of BnPER and BnCAM,were estimated to measure the impact of ZnONPs on minimizing the toxicity of salt stress.All concentrations of ZnONPs increased the germination parameters.Meanwhile,the high concentration(ZnO 100%)showed the highest increase in growth traits.Additionally,nano-priming improved osmotic protection,alleviated ROS accumulation,biosynthesis pigments,and enhanced antioxidant adjustment.Nano-priming substituted the Na⁺ by Zn²⁺,K⁺,and Ca²⁺ thus reduced the Na⁺ toxicity in the cell cytosol.To track the effects of priming during seed imbibition,it was noticed that nano-ZnO increased the Linoleic and Linolenic acids among the studied fatty acids composition.Moreover,the gene expression patterns of BnCAM and BnPER reflected the enhancement of germination levels,notably under the influence of ZnO 100%.(3)SeNPs more effective for elevating seed germination and improving the phenotypic characteristics and physiochemical attributes of rapeseed seedlings without the sign of toxicity than Se(?)Sodium selenite(Se(?)),as well as Se nanoparticles(SeNPs),are naturally formed via the reduction of Se oxyanions(Se(?))through biotic pathways.Thereby,we aimed to investigate the phytotoxicity,accumulation,and transformation of SeNPs,and Se(?)under the highest doses at the early seedling stages in B.napus.The seedling morphology showed the damages in leaf and root that disclosed the Se(?)phytotoxicity,while SeNPs improved the phenotypic characteristics of the seedlings without the sign of toxicity.Moreover,SeNPs markedly boosted germination,seedling growth,and biomasses.Higher Se(?)doses decreased the photosynthetic efficiency,and elevated proline accumulation,which led to a weakening of the seedling growth and biomass reduction.Nano-Se minimized the ROS level,and MDA content by activating the antioxidant enzymes,engaged in ROS detoxification.Furthermore,it revealed the role of SeNPs in regulating transcriptional networks,involved in oxidative stress through the expression pattern of these enzyme-related genes.In contrast,Se(?),impair oxidative metabolism by desynchronizing the antioxidants as revealed by decreasing the expression levels of CAT and GR.RT-q PCR results have shown that the vacuole storage functioned as a vital process to cope up with high doses of Se.Our results supported that the selenation was a more functional method of Se detoxification in rapeseed.Also,oxidation and transamination played essential roles in Se tolerance in B.napus.Furthermore,our findings proposed a different degradation pathway that synthesized malformed or deformed selenoproteins and was proved to be an essential way to increase Se tolerance at higher Se(?)doses in rapeseed seedling.(4)Exogenous applications of selenium,especially,SeNPs mitigate salinity influence on rapeseed during the seed germination and the early seedling stageBased on the special physiochemical characteristics of NPs in the biological system,and the positive effect of priming application on plant growth and development,we aimed to explain how the rapeseed seedling responds to exogenous NPs under salinity stress.Our findings clarified the negative influence of salinity on germination and seedling growth.The positive effect of the treatments increased,especially with 150 ?mol L-1.A positive impact was found on FG%,GR,and VI,as well as germination strength,and biomass of seedlings,which improved the seed germinating and seedling growth without any manifestations stressed to the seedling.Furthermore,the positive effect of nano-application and-priming was evident in photosynthesis processes.On the other side,NPs played an important role in an osmotic adjustment under salinity stress,which led to an increase in the efficiency of the plant's defense system by improving the activity of the antioxidant enzymes.The application of Se strikingly SeNPs was modulating the Na⁺ and K⁺ uptake,which improved the seedling growth and showed an association with the restricted accumulation of toxic Na⁺ ions,thus,it prevented the generation of increased oxidative stress due to salt stress.(5)Nanopriming regulate the plant hormones during seed imbibition and early seedling stage under salt stressWe studied the influence of nano-priming on plant hormones and some genes-related seed germination on rapeseed cultivars during seed imbibition and the early seedling stage upon salinity stress to increase the understanding of the improvements of rapeseed seed germination by SeNPs-and ZnONPs-priming.Our results showed that seed priming with SeNPs and ZnONPs elevated FG% and GR of two rapeseed cultivars seed under salt stress.Moreover,ABA genes BnCYP707 A expression decreased during priming time and after sowing,which concluded that the nano-priming application influence the ABA levels then elevated the seed germination with SeNPs and ZnONPs treatments.Our findings suggested the role of nano-priming in regulating GA level,which enhanced the expression levels of BnGA20 ox,BnGA3 ox,and BnCPS,thereby,increasing the germination in primed seeds as compared to unprimed seeds and HP seeds.Our results confirmed that nano-priming via SeNPs and ZnONPs upon salt treatment improved the expression level of BnCAM,BnPER,BnEXP4,and BnRAP28,which promoted seed germination and early seedling growth.