| Lepidium apetalum is an early spring short-lived plant belonging to Cruciferae,it can germinate under low temperature treatment.It was found that the seeds of Lepidium apetalum could enhance the tolerance to low temperature,which might be due to the expression of some genes to enhance the cold tolerance of plants.Therefore,based on the data of Lepidium apetalum seed transcriptome before and after low-temperature germination arrest,ABC1 transcription factors and encoding LEA protein genes with significant difference were screened.In order to reveal the regulatory mechanism of two types of genes in relieving low temperature germination stagnation and seedlings tolerance to abiotic stress,a large number of experiments were carried out with two types of genes.The results are as follows:1.The results of the study on ABC1 transcription factors were as follows:（1）21 members of the ABC1 genes were screened based on the data of Lepidium apetalum seed transcriptome before and after relieving the stagnation of cold germination.The results of fluorescence quantitative analysis showed that there were 6 up-regulated genes,7 down-regulated genes and 8 non-significantly different genes in seven-day-old Lepidium apetalum seedlings under low temperature stress.（2）The results of fluorescence quantitative analysis showed that La ABC1-3 was up-regulated under cold stress,but down-regulated under drought and salt stress.La ABC1-21 was up-regulated in abiotic stress,especially in response to salt and drought stress.（3）The ful-length c DNA sequence was obtained by cloning the target gene,and the recombinant p MDC32-La ABC1-3 and p MDC32-La ABC1-21,were constructed successfully by using p MDC32 plant expression vector.Arabidopsis thaliana was transformed by dip flowering method,and plants resistant to hygromycin in T0 generation were screened.2.The results of the study of LEA protein family genes:（1）There were 27 encoding LEA protein family genes in the seeds of Lepidium apetalum,including 20 down-regulated genes,3 up-regulated genes and 4 non-significantly different genes.The gene named La LEA,with high expression and significant difference was selected from the up-regulated gene.（2）The q RT-PCR analysis showed that the expression of La LEA had a sensitive expression response to low temperature,salt stress and drought stress.It was speculated that La LEA played an important role in the response of Lepidium apetalum seedlings to cold stress,salt stress,drought stress and so on abiotic stress.（3）Bioinformatics analysis showed that La LEA have a open reading frame of624 bp,which could encode a protein of 208 amino acids,and rich in threonine, alanine,glutamine and lysine.The secondary structure was mainly composed of alpha-helix and irregular curl,which had characteristics of good stability and strong hydrophilicity.It plays an important role in the tolerance of Lepidium apetalum to abiotic stress.In conclusion,up-regulation of La ABC1-21 and La LEA genes enhances tolerance to abiotic stress in Lepidium apetalum,up-regulation of La ABC1-3 gene under low temperature stress enhances cold tolerance of seedlings and down-regulates expression under drought and salt stress,may be related to the growth and metabolism of Lepidium apetalum,which provided a basis for elucidating the stress resistance function of ABC1 transcription factors and LEA protein family and the mechanism of Lepidium apetalum adaptable to adversity. |
