| At different growth periods,the demand for water is different,the effects of water stress on the growth and yield are not the same,there are some differences in the rehydration compensation after the water stress,therefore,revealing the impact of drought stress and rehydration on crop physiology and yield is an international frontier issue in the field of biological water saving.Clarification of the water demand of the key growth period,in order to carry out reasonable water management,to improve the efficiency of crop water use,becomes an inevitable choice of breakthrough in restricts grain production bottleneck because of shortage of water resources.In this paper,the potato cultivar "Kexin No.1" was selected as the research object,the water control experiment was carried out under the conditions of indoor potted and outdoor shelter,the effects of different soil water content on the growth,physiology,yield and its component factors,gene expression differences of potato were studied separately at the bud growth period,seedling stage,tuber formation period and tuber expansion period,to clarify the effects of drought stress and rehydration on the yield formation process at different growth period,The main results were as followed:1.At the bud growth period,bud number was more and bud was strong at soil moisture content of 70%.When the soil moisture content was 100%,potato began to rot after about one week,and the potato failed to germinate into seedlings.When the soil moisture content was 85%,the potato germinated at 6d after sowing,but in the stress of about 21 days,the potato began to rot,resulting in buds unusual growth;When the soil moisture content were 55%and 40%,germination time of potato was late about 7 days compared to 70%treatment.2.The content of ABA increased with the prolongation of stress time at the bud growth period,and first decreased and then increased with the increase of soil relative water content,the contents of IAA,ZR and GA decreased with the prolongation of stress time,and first increased and then decreased with the increase of soil relative water content,at the 70%-85%soil relative water content,the contents of IAA,ZR and GA were the highest while ABA was the lowest.3 At the seedling stage,with the increase of soil water content,all Morphological indexes were gradually increased except height and stolon number,during the stress and rehydration time,leaf relative water content,SPAD,root activity and Photosynthetic parameters were increased and then decreased,at the 70%-85%soil water content these indices were highest,with the prolongation of stress time the differences between treatments were increased,after rehydration,leaf relative water content,leaf SPAD value and root activity increased rapidly at the 40%-55%soil water content,after 14 days rehydration,there was no significant differences between 40%-55%and 70%-85%,while 100%treatment was significant lower than other treatments,however increased;The proline,malondialdehyde,soluble sugar content,SOD,CAT,POD activity and leaf relatively conductivity first decreased and then increased with the increase of soil water content,at the 70%-85%soil water content these indices were the lowest,at the 40%-55%soil water content,these indices rapidly decreased after rehydration.After 7 days rehydration,these indices had been reduced to near 70%-85%level of treatment,while 100%treatment was higher than other treatments,however increased.4.There was no significant differences among the number of potato per plant,the weight per tuber,yield per plant and commodity potato rate in the range of 40%-85%soil relative water content at seedling stage,but weight per tuber and yield per plant of 100%soil relative water content were significantly lower than other treatments,commodity potato rate was significantly lower than other three treatments except 40%soil relative water content too.5.The results showed that the optimum water content of the tuber formation period was 85%,the plant height,the number of main stem were increased.stem diameter,branch,stolon,leaf area index,dry matter accumulation,leaf relative water content,SPAD,root activity and Photosynthetic parameters of potato first increased and then decreased with the increase of soil water content,at the 85%soil water content these indices were the highest,the leaf relative conductivity,soluble sugar content,proline,malondialdehyde,SOD,CAT,POD activity and stomatal resistance first decreased and then increased with the increase of soil water content,at the 85%soil water content these indices were the lowest.After rehydration,the change of leaf relative conductivity was smaller,SPAD and root activity still decreased,but the degree of declining was reduced.40%and 55%restored more slowly,that of 100%restored more quickly,the change of 70%and 85%was smaller.At the tuber expansion period,the change trend of indices under different soil water content was the same as the tuber formation period,but the change rate was gentler and the recovery degree after rehydration was also slower.6.At the tuber formation period,the yield of 85%treatment was the highest,it was significantly higher than other treatment.There was no significant difference among large potato rate of different soil water contents,and the number of potato per plant of 85%was higher than other treatments,the number of potato per plant of 40%was lower than other treatments except 55%.The yield of 40%、55%、70%、100%treatments accounted for 41.9%,54.3%,71.3%,68.4%of yield at 85%treatment separately,the degree of declining production was lager.At the tuber expansion period,the yield of 85%treatment was the highest,the next is the yield of 100%treatment,there was no significant differences among the yield of 55%、70%、85%、100%,except 40%relative soil water content.7.From the production results,water stress at seedling stage,tuber formation period,tuber expansion period will result in reducing the potato yield,the effect of different growth period on the yield was:tuber formation period>seedling stage>tuber expansion period,which meant that the water stress in the tuber formation period had a greater effect on the yield,and the later replenishment compensation effect was also poor.In addition,the effect of excess water on the bud growth period and the seedling stage was more significant,and the effect of water deficit on tuber formation and tuber expansion period was more significant.8.The high-throughput sequencing was used to study the gene expression of potato after water stress and rehydration.The results showed that there were 655 differentially expressed genes in the drought treatment versus drought control,and there were 644 DEGs in the rehydration treatment versus rehydration control,there were 113 shared genes between DT vs DCK and RT vs RCK,there are 8 genes had different changes in the two groups,it meant there were some differences in the expression and function mechanism of the same gene in different processes,and the same gene had multiple functions at the same time,and played different roles in different habitats.9.The differentially expressed genes were categorized by GO enrichment,the top three enrichment of GO function in DT vs DCK were 0071554,0016209,0005975,which were related to cell wall tissue synthesis,antioxidant activity,carbohydrate metabolism process,the top three enrichment of GO function in RT vs RCK were 0016310,0016773,0006468,respectively,which associated with phosphorylation,including phosphotransferase activity,protein phosphorylation.10.The top three significant differences in DT vs DCK of KEGG pathways were sot00941:flavonoid metabolism,sot00945:stilbenoid,diarylheptanoid and gingerol biosynthesis,sot00561:glycerolipid metabolism,10 DEGs,6 DEGs,9 DEGs were involved in the pathways respectively.The top three significant differences in RT vs RCK of KEGG pathways were sot00480:glutathione metabolism,sot04626:plant-pathogen interaction,sot00430:taurine and hypotaurine metabolism,12 DEGs,17 DEGs,3 DEGs were involved in the pathways respectively.11.The accuracy of the transcriptome sequencing data was verified by qRT-PCR.The results showed that the expression of 10 verified genes in real time fluorescent quantitative PCR was consistent with that of high-throughput sequencing,and the accuracy of sequencing data was verified. |
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