Identification Of Drought Resistance And Resistance Characteristics Analysis Of Gossypium Anomalum Introgression Lines In Gossypium Hirsutum Background

Nowadays,there is a serious shortage of water resources in the word,including China.The drought caused by the shortage of water resources has a great impact on the sustainability of the development of cotton production in China.Xinjiang is the main cotton production area in China.The continental climate has led to a dry climate,intense evaporation,the decrease of annual precipitation and the uneven distribution of precipitation in Xinjiang.Drought has become one of the biggest factors affecting cotton production in Xinjiang.In the process of cotton production,reducing the utilization of water resources while maintaining cotton yield is one of the goals of Xinjiang cotton breeding.Gossypium anomalum(2n = 2x = 26),a diploid wild cotton species of the cotton genus that grows in southwestern Africa and the edge of the Sahara Desert,has many excellent traits,including strong drought tolerance.In our previous study,we developed a set of G.anomalum introgression lines covering 70% of G.anomalum genome,and the average response rate of G.hirsutum reincarnation parent genome is 97.09%.By setting up drought resistance tests in Xinjiang,contrast with normal irrigation and drought stress treatment for water control treatment,various index methods were used to identify the drought resistance of G.anomalum introgression lines.The relevant physiological and biochemical indicators were determined to evaluate the drought resistance of G.anomalum introgression lines under dry shed conditions.The main findings are as follows:1.Under the field conditions in Xinjiang,the drip irrigation technique under mulch was used to treat 64 G.anomalum introgression lines populations and the recurrent parent Su8289 under drought stress at flowering and boll setting stage.Through the inspection of agronomic traits,yield traits and fiber quality traits were found to be affected by the drought stress except fiber strength.2.A variety of comprehensive evaluation indicators combined with principal component analysis,gray correlation analysis,correlation analysis,cluster analysis and stepwise regression to establish the drought resistance prediction model regression equation were conducted to identify the drought resistance and screen the drought resistance index of G.anomalum introgression lines.Finally,42 of 64 G.anomalum introgression lines were identified as drought-resistant materials.CSIL2、CSIL3、CSIL14、CSIL31、CSIL53 showed high drought resistance.Four characters including micronaire value、lint percentage、boll weight and boll number of per plant could be as evaluation index for drought resistance of G.anomalum introgression lines at flowering and boll setting stage.3.According to the comprehensive drought resistance results obtained at flowering and boll setting stage in Xinjiang and the seedling stage in laboratory,3 drought resistant materials(CSIL14,CSIL49,CSIL65)and 3 sensitive materials(CSIL13,CSIL23,CSIL29)were selected.The agronomic characters,physiological and biochemical indexes of the 6experimental materials and the recurrent parent Su 8289 were further determined under the conditions of drought shed in Nanjing.The results showed that with the increase of drought stress,the leaf thickness of the recurrent parent and 6 test materials showed a gradually increasing trend.The leaf thickness of CSIL49 was significantly higher than recurrent parent.The stomata density of 6 materials decreased with the intensification of drought stress.Compared with the recurrent parent,except for the CSIL65,the stomatal density of the remaining 5 materials were significantly higher than recurrent parent.However,the stomatal densities of the 3 drought-resistant materials were all lower than those of the sensitive materials.The chlorophyll content of the 7 test materials increased with the severity of water stress.Among them,the chlorophyll content of 2 sensitive materials CSIL23 and CSIL29 increased more than recurrent parent.The photosynthetic rate and transpiration rate of 7 test materials showed a gradual decline with the strengthening of the drought stress.However,the photosynthetic rate and transpiration rate of the drought-resistant material CSIL14 were higher than recurrent parent.The proline content of7 test materials showed an increasing trend.The free proline of the drought-resistant materials CSIL49 and CSIL65 were significantly higher than recurrent parent;The soluble sugar content of leaves of drought resistance material CSIL49 was significantly higher than recurrent parent.The antioxidant activities(CAT,POD and SOD)of different introgression lines and recurrent parents showed a significant increasing trends.Compared with recurrent parents,the CAT activity and SOD activity of drought resistant materials CSIL14 and CSIL49 were significantly higher.In summary,it was speculated that the drought resistance of CSIL14,CSIL49 and CSIL65 may be related to better photosynthesis and antioxidant capacity,high antioxidant capacity and permeability,and low stomatal density and reduced water loss,respectively.