Evaluation Of Salt Tolerance At Seedling Stage And Analysis Of Salt Tolerance-related Genes Expression In Three Quinoa Cultivars

Soil salinization is the main factor that reduces the quality of crops,reduces the yield,and even fails to grow and develop normally.The cultivation of halophytes in saline-alkali land is conducive to the improvement and utilization of saline-alkali soil.Quinoa is a salt-tolerant crop with strong stress resistance and rich nutrition.In this paper,’Yanli 1’,’Yanli 2’and’Yanli 3’were used as the test varieties,and 5 gradients of NaCl solution were set,respectively 0（CK）,100（S1）,200（S2）,300（S3）,400（S4）,500（S5）mmol·L^-1were subjected to salt stress on quinoa seedlings.In the experiment,the physiological and biochemical indicators were measured and then comprehensively evaluated according to the membership function value method.Then,the gene family analysis of the related salt tolerance gene CAT was carried out,and the quantitative RT-q PCR method was used to determine the gene expression under stress.The experimental results and conclusions are as follows:（1）Under short-term low-concentration NaCl stress（S1,S2 groups）,the change was not obvious,and the plant height of’Yanli 1’and’Yanli 3’increased,which has a certain growth promoting effect.Long-term high concentration Under NaCl treatment（S4,S5groups）,leaf curling,chlorosis,and dehydration occurred.Among them,’Yanli 2’had some lodging,the most serious damage and the worst salt tolerance.（2）Under the salt stress treatment,the Fv/Fo（potential photochemical efficiency）,q P（photochemical reaction quenching coefficient）,ΦPSII（actual photochemical efficiency）and ETR（electron transfer efficiency）of three kinds of quinoa all increased with salt stress.The intensification of salt stress showed a decreasing trend;the content of photosynthetic pigments showed a trend of increasing first and then decreasing;the relative conductivity,MAD（malondialdehyde）,soluble sugar content,soluble protein content and H₂O₂content gradually increased with the deepening of salt stress;SOD（superoxide dismutase）,POD（peroxidase）,CAT（catalase）and APX（ascorbic acid peroxidase）all increased first and then decreased with the increase of salt concentration.（3）According to the morphological characteristics of the three quinoa varieties and the determination of various physiological indicators,the correlation analysis of 19indicators was carried out,and 4 main components with certain representativeness were obtained.The membership function method was used to analyze and calculate the ranking.The order of saltiness from strong to weak is:’Yanzi 3’>’Yanli 1’>’Yanli 2’.（4）Four CAT family members were identified from the quinoa genome,with high sequence similarity,clustered in two subgroups,and 11 related cis-acting elements were predicted to respond to abscisic acid,defense and stress,and drought.It is speculated to be involved in the regulation of abiotic stress and biotic stress in quinoa.Among them,CqCAT1 and CqCAT2 are highly expressed in petioles,leaves and seedlings,and CqCAT3and CqCAT4 are more expressed in flowers and immature seeds.RT-q PCR showed that under NaCl stress,the expression of CqCAT1 and CqCAT2 was significantly induced in the aerial part,and the expression of CqCAT3 in the aerial part showed a short-term induction,which was similar in the roots.