A Preliminary Study On The Hyper-gravity Response Mechanism Of Malus Hupehensis

Hyper-gravity technology is currently used in biochemical engineering and other aspects.The use of hyper-gravity in plant breeding is mostly concentrated on the physiological and biochemical level,and there are few reports on the relevant research on the molecular level.Therefore,this study used hyper-gravity stress on 2-month-old seedlings of Malus hupehensis to determine the physiological and biochemical changes,paraffin sections were used to observe the anatomical structure of their leaves,and transcriptomics were used to analyze the enrichment of differentially expressed genes and the utilization of microregions.Spectral scanners conducted preliminary explorations on the mechanism of calcium in the process of hyper-gravity stress on the seedlings of Malus hupehensis,in order to explain the effects of hyper-gravity stress on plants and reveal the mechanism of action between calcium and hyper-gravity.The results of the study are as follows:1.Hyper-gravity stress changed the chlorophyll content,proline content,soluble protein content,,cell membrane permeability,malondialdehyde content,and antioxidant enzyme activity in the leaves of Malus hupehensis seedlings,at T2（5000 g×6 h）and T4（10000 g×6 h）treatment,the content increased significantly and was significantly different from the control.2.According to the transcriptological analysis of CK,T2 and T4,the differentially expressed genes are mainly enriched in metal ion binding and chlorophyll binding in GO function analysis;in KEGG function analysis is mainly enriched in fructose and mannose metabolism,glycine,serine and threonine acid metabolism pathway;heat map analysis of differentially expressed genes showed that the expression levels of differentially expressed genes increased firstly and then declined with the increase of the intensity of hyper-gravity stress;after BLAST of NCBI,differentially expressed genes were found that the differentially expressed genes were mainly auxin response protein,qT-PCR results of ethylene-responsive transcription factors,NAC domain transcription factors and WRKY transcription factors are basically consistent with the transcriptome results.3.The effect of exogenous spraying of calcium reagent on hyper-gravity stress is as follows: spraying different concentrations of CaCl₂ to T2 and T4 treatments can alleviate the damage caused by hyper-gravity stress to the seedlings of Malus hupehensis to varying degrees.Spray 15 mmol· L^-1 CaCl₂ has the best effect;spraying different concentrations of EGTA will aggravate the damage caused by hyper-gravity stress to the seedlings of Malus hupehensis,and 25 mmol·L^-1 EGTA has the most obvious inhibitory effect.Exogenous spraying of calcium reagent has a positive regulatory effect on differentially expressed genes,and the expression pattern of differential genes is closely related to the spraying concentration and the intensity of hyper-gravity stress.4.Hyper-gravity stress increased the calcium content in the leaves of Malus hupehensis seedlings,and at the same time,the hyper-gravity stress caused calcium in the leaves to be mainly distributed near the veins;exogenous spraying of calcium reagents changed the calcium content of Malus hupehensis seedlings.At the same time,calcium is concentrated from the distribution near the veins to the edge of the leaf.