The Response Mechanism Of Drought Stress In Pugionium Gaertn Plants

Pugionium cornutum?L.?Gaertn.and Pugionium dolabratum Maxim.belong to Pugionium Gaertn plants,they were known as a wild vegetables that had the homology of medicine and food,and high quality and drought-resistant germplasm resources.In this study,four soil water treatments of P.cornutum and P.dolabratum were set up by pot-culture methods in greenhouse.By measuring the effects on the morphological and growth indicators,water physiological,osmotic regulation material,antioxidant system,ascorbic acid metabolism related enzymes under different drought stress intensity,and to evaluate drought resistance between P.cornutum and P.dolabratum by comprehensive drought resistance coefficients and average subordinate function.Analyzing the transcriptome sequencing and differentially expressed gene of P.dolabratum leaves under drought stress were to exposit the response to mechanism of P.Gaertn.In order to protect,develop and utilize the wild unique germplasm resources and provide the guidance for drought resistant cultivation and breeding of P.cornutum and P.dolabratum.The specific results showed that:1,With the increase of drought stress,the growth indicators of P.Gaertn decreased;The effect of drought stress on the growth inhibition of P.cornutum was stronger than P.dolabratum.Leaf water content,free water content,the ratio of free water and bound water,root water content,leaf relative water content of P.cornutum and P.dolabratum decreased,leaf bound water content and water saturation deficit increased;The reduced range of root water content,leaf relative water content,water potential,and the increase of leaf water saturation deficit of P.cornutum were greater than P.dolabratum.The PMP and the contents of Pro,FAA,SS,RS in roots and leaves increased;The SP contents and root activity of P.dolabratum were greater than P.cornutum.The PMP content and PMP increase range of P.cornutum under severe drought were greater than P.dolabratum.The comprehensive drought resistance coefficients and average subordinate function of these indicators of P.cornutum were less than P.dolabratum.2,With the increase of drought stress,the contents of reactive oxygen species and MDA increased in roots and leaves of P.cornutum and P.dolabratum;The activities of POD,APX,GST increased firstly and then decreased,the CAT activity increased in roots and leaves;The activity of antioxidant enzymes SOD,GR,LOX and GPX were different from those in the leaves and roots;The content of ASA increased firstly and then decreased,the content of GSH increased,and the content of CAR decreased in roots and leaves;The content of VE in leaves increased and in roots decreased;The T-AOC increased in roots and leaves.The antioxidant ability of P.dolabratum was higher than P.cornutum.3,With the increase of drought stress,in roots and leaves of P.cornutum and P.dolabratum,the content of ASA,T-ASA increased firstly and then decreased,the content of DHA,GSH,GSSG and T-GSH increased,the ratio ASA and DHA,GSH and GSSG decreased,The activities of GalLDH,GalDH,DHAR,MDHAR,AAO,APX,GR increased firstly and then decreased.The enzyme activities reached their maximum during moderate drought stress.The activities of ascorbic acid metabolism related enzymes and the ratio ASA and DHA,GSH and GSSG,the content of ASA,GSH in roots and leaves of P.dolabratum were higher or close to them of P.cornutum.All mentioned above showed that P.dolabratum exhibited higher drought resistance than P.cornutum.4,The transcriptome sequencing of P.dolabratum leaves under drought stress was performed.53.20Gb clean data was obtained,every clean data was over 5.58Gb,197,320transcript and 91,361 unigene were obtained.COG function was classified into 24 classes;KOG function was classified into 25 classes;GO analysis was classified into 54 classes,and there were 22 biological processes,18 cellular component and 14 molecular function.5,Unigene with a false discovery rate?FDR?<0.01 and an absolute value of log₂FC?1 were defined as statistically significant DEG.There were 404 DEG between moderate drought and control?64 up-regulated gene,340 down-regulated gene?,there were 176DEG between extreme drought and control?139 up-regulated gene,37 down-regulated gene?.There were 35 KEGG pathways types in moderate drought and control differential expression genes,there were 24 KEGG pathways types in extreme drought and control,and there were 15 common KEGG pathways types between moderate,extreme drought and control.