| Lilium is a perennial herbaceous plant of Liliaceae,which has high ornamental value and economic value.DELLA protein,as an important regulatory protein in gibberellin signaling pathway,plays an important role in plant growth and development.Based on the transcriptome sequencing results,we obtained LiDELLA gene from ‘Tiger Babies' and ‘Whistler',and carried out bioinformatics analysis,subcellular localization,protein stability analysis under gibberellin treatment and tissue-specific expression analysis.Differences in gibberellin responses between two lily cultivars were analyzed by exogenous gibberellin and paclobutrazol treatment.By overexpressing LiDELLA1 gene in Arabidopsis thaliana,its function was preliminarily verified.The study aimed to clarify the function of LiDELLA gene and provide theoretical basis for further study on the biological function of DELLA protein in lily and its action mechanism in gibberellin signal transduction,and opened up new development ideas and directions for lily germplasm innovation.The research results were as follows:1.Transcriptome sequencing analysis was carried out on leaves of ‘Tiger Babies' treated with paclobutrazol at different times,and the paclobutrazol treatment had a certain effect on GA signaling.CPS,KS,KO gene expression levels decreased;KAO expression increased and T3 h expression was highest;GA20OX,GA3 OX,GA2OX expression significantly increased;DELLA gene and receptor GID1 C gene expression was consistent,and the expression level was the highest at T3 h and the expression of GID2 gene was decreased.In addition,genes related to signal transduction of other plant hormones were found in the data.For example,XERICO,ABI5 and MYC2 were positively regulated by DELLA,while BZR1,PIF3 and PIF4 were negatively regulated by DELLA.2.Three sequences were obtained from ‘Tiger Babies',named LiDELLA1,LiDELLA2,LiDELLA3,and a sequence was obtained from ‘Whistler' named LiDELLA4.The open reading frame length of these four genes were 1,743 bp,1,686 bp,1,401 bp and 1,401 bp,encoding 580,561,466 and 466 amino acids,respectively.LiDELLA1 and LiDELLA2 proteins had DELLA and GRAS subfamily domains,but LiDELLA2 proteins lacked LRII conservative domain,while LiDELLA3 and LiDELLA4 proteins only had GRAS subfamily domains,lacking DELLA and VHYNP conservative domains for sensing gibberellin effects.3.LiDELLA1 protein was mainly located in the nucleus,and gibberellin treatment had no significant effect on LiDELLA1 protein.4.LiDELLA1 gene was differentially expressed in different organs of ‘Tiger Babies',and the expression in stem and leaf.5.The plant height of ‘Tiger Babies' increased by 28.36%,16.15%,12.91% and 15.81% compared with CK at germination,seedling,budding and flowering stages after gibberellin treatment;and its of ‘Whistler' only increased by 0.76%,3.65%,3.31% and 3.04%.The diameter of seed ball decreased by 6.55% and 4.21%,fresh weight decreased by 13.03% and 7.34%,respectively.The expression levels of GA2 OX,GA3OX,GA20 OX,GID1,GID2 and DELLA genes in ‘Tiger Babies' were significantly different from those in CK,while the expression levels of these six genes in ‘Whistler' did not change significantly.The results showed that the two lily cultivars responded differently to gibberellin,‘Tiger Babies' were more sensitive to gibberellin,and ‘Whistler' was an insensitive variety.After paclobutrazol treatment,the plant height of ‘Tiger Babies' decreased by 34.05%,73.86%,72.33% and 70.22% compared with CK in lily germination,seedling,budding and flowering,and the plant height of ‘Whistler' decreased by 32.77%,58.89%,59.93% and 52.22%.The diameter of the bulbs of the two lily cultivars decreased by 20.10% and 19.48%,and the fresh weight decreased by 48.92% and 32.95%,respectively.The expressions of these six genes were increased compared with CK.The results showed that paclobutrazol treatment inhibited the growth of these two lily cultivars.6.The pYBA1132-LiDELLA1 vector was constructed and transformed into Arabidopsis Thaliana.The results showed that the rosette radius of the four transgenic arabidopsis strains decreased by 32.22%,38.40%,43.69% and 30.03%,respectively,and the plant height was reduced by 28.03%,35.54%,42.47% and 25.48%,respectively,compared with the wild type.The overexpression of LiDELLA1 gene could inhibit the stem elongation and leaf growth of Arabidopsis Thaliana. |
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