Cadmium Accumulation Characteristics And Response Mechanism Of Cadmium Stress In Oriental Melon

Soil pollution of heavy metal has been considered as one of the main problems in the agricultural production.In order to ensure the safety of productivity in over criteria of heavy metal cadmium,this paper based on the investigation of heavy metal accumulation in farm soil and Oriental Melon,screening the suitable Oriental Melon varieties for cadmium region,research the difference of cadmium accumulation and distribution among varieties of Oriental Melon,and the analysis of antioxidant system and transcription group of Oriental Melon under cadmium stress was carried out,which could provide theoretical basis for the adjustment of planting structure in areas with excessive cadmium.The findings are as follows:1.Most of the soils were slightly acidic which were used to grow Oriental Melon of survey sample in industrialized regions.Cadmium was the main pollutants in the soils.The accumulation of heavy metals in melon fruit was low and the accumulation have large varied amplitude.The accumulated amounts of Cd,Cr,Pb,Hg and As in thick-skinned melon fruits were 0.016~0.024?ND?ND~0.08?ND~0.001? 0.003~0.006 mg·kg-1,The accumulated amounts of Cd,Cr,Pb,Hg and As in Oriental Melon fruits were 0.011~0.032?ND~0.084?ND~0.019?ND~0.004?ND~0.013 mg·kg-1.Cadmium content in the fruit of Oriental Melon varies have large varied amplitude,so more attention should be paid to the production of t Oriental Melon in heavy metal contaminated areas.2.The content of cadmium and fruit quality of the Oriental Melon were analyzed through field cadmium contaminated soil cultivation.The results showed that the distribution of Cadmium in Oriental Melon plants is the base stem leaves > root > upper stem leaves > fruit.There were differences in cadmium absorption and accumulation among different Oriental Melon varieties.The content of cadmium in 12 Oriental Melon fruits was lower than the limit index of cadmium in melon fruit(0.05 mg·kg-1)specified in GB2762-2012.Among them,the content of cadmium in the fruit of IVF-28 was the lowest,0.0153 mg·kg-1.3.The flux rate of ions Ca2+,K+ and Cd2 + and the subcellular distribution of Cd2+ in roots and leaves of two genotypes of Oriental Melon were determined by NMT.The results showed that the Cd2+ in the root hair region of two melons was incurrent,the Cd2+ flow rate of IVF-28 was higher than that of the XT-G,and the Cd2+ at the base of the stem was the X-T-G higher than the IVF-28;The K+ of vascular bundles at the root hair region and stem base showed an outward tendency,and the stem base was larger than the root hair region,and the K+ flow rate at the stem base of IVF-28 was greater than that of the X-TG;Ca2+ in the root hair region of two melon varieties was incurrent,IVF-28 was higher than the X-T-G,and Ca2+ in vascular tissue at the base of the stem was outwards,and the X-T-G was higher than IVF-28.The distribution of cadmium absorbed by Oriental Melon in the root system and leaves is cell wall > cell soluble substance > organelle.Therefore,vacuolation and cell wall fixation may be important patience mechanisms for Oriental Melon stress on Cd.The Cd2 + flow rate in vascular tissue at stem base can accurately reflect the potential of different Oriental Melon varieties to transfer and accumulate Cd2+.4.The growth of Oriental Melon seedlings under cadmium stress is limited,cadmium concentration is increased,the growth of Oriental Melon seedlings is affected,and plant height and stem thickness are gradually decreasing.Cadmium stress enhanced the protective enzyme activity of Oriental Melon CAT,SOD,POD,and increased the content of H2O2,MDA,GSH,and PRO.5.The X-T-G and the X-T-G CK,a total of 1,302 DEG were detected,650 gene expression was significantly increased,and 652 gene expression was significantly reduced.In the IVF-28 and IVF-28 CK,a total of 3,980 DEGs were detected,and 1,831 gene expressions were significantly increased and 2,149 gene expressions were significantly reduced.The different genes of different groups showed that there were 661 different genes between the X-T-G and the IVF-28 group.Differential expression gene enrichment of Oriental Melon leaves under cadmium stress is the most common in biological and metabolic processes.In molecular function,catalytic activity is the species with the highest concentration and annotation of differential expression genes;Among the cell components,cystic and stromal cysts are the most abundant species with different genes.In addition,in the cell components of cadmium sensitive type IVF-28,the photosynthetic system,photo film,optical system II,optical system II oxygen emission process,Redox enzymes,and cystic membrane were significantly enriched.