Gene Cloning Of MdHMGR1 From Apple And Its Functional Analysis In Tomato

Terpenoids, is widely distributed in nature and have the most species natural plant products, it also has important physiological and social functions. In recent years, more and more attention has been paid to investigate the terpenoids metabolic pathways, the key enzyme of terpenoids metabolic pathway is imperative to research.HMGR is the first ratelimiting enzyme of MVA way in the terpenoids metabolic pathways, converts HMG-Co A transform into MVA, and is an important regulatory site in the cytoplasm terpenoids metabolism ways. HMGR usually exist with small gene families in plants, HMGR plays an important role in plants growth and development. In this study,HMGR1 from the White Pearmain apple was cloned first, then construct expression vector of MdHMGR1 with CaMV35 S promoter and with MdHMGR1 promoter, respectively, ang overexpress them into tomatoes.We got two kinds of transgenic tomatoes: 35S+HMGR1 and MdHMGR1-1+HMGR1 transgenic tomatoes which were used to study the expression regulation function of two different promoters and the time-space and tissue specificity of MdHMGR1 expression in transgenic tomato, and the gene function in plant growth and development. The main results as follows:(1) MdHMGR1 expressed in root, stem, leaf and fruit of the transgenic plants, but they have different expression patterns. In 35S+HMGR1 transgenic tomato, MdHMGR1 have highly expression in root, stem, leaf and fruit, but in MdHMGR1-1+HMGR1 transgenic tomato, MdHMGR1 only expression high in root and fruit, and the expression quantity is much higher than it in 35S+HMGR1 transgenic tomato, so the expression of MdHMGR1 in MdHMGR1-1+HMGR1 transgenic tomato has tissue specificity.(2) The induced expression pattern of MdHMGR1 is very difference under the treatment of ABA, ETH, GA, IAA, MeJA and SA. The expression of MdHMGR1 increased under these hormone treated with 2h or 4h. Most obvious among them is MeJA and SA treatments.(3) Overexpressing MdHMGR1 can induced root elongation of transgenic tomato. The root length of MdHMGR1-1+HMGR1 transgenic tomato is longer than 35S+HMGR1 genetic tomato and wild type tomato. And 35S+HMGR1 transgenic tomato root length slightly longer than the wild type of tomato root length. Treatment of the tomato seeds in medium which with HMGR inhibitor lovastatin result in the root length is shorter than before treatment, and root length of MdHMGR1-1+HMGR1 transgenic tomato still longer than 35S+HMGR1 genetic tomatoes and wild type tomato.(4) In the process of fruit development, the change of longitudinal diameter and transverse diameter show an S-shaped curve.Fruit volume rapid expansion period of MdHMGR1-1+HMGR1 transgenic tomato is earlier than 35S+HMGR1 tomato and wild type,and 35S+HMGR1 transgenic tomato earlier than wild type.Fruit shape index is irregular of35S+HMGR1 transgenic tomato, but it is regular of MdHMGR1-1+HMGR1 genetic tomatoes and wild type.(5) Overexpression MdHMGR1 promote fruit early cell division. Volume of transgenic tomato fruit is larger, and MdHMGR1-1+HMGR1 transgenic tomato fruit is the largest.HMGR inhibitor lovastatin injected into the tomato fruit at middle development period can induce normal mature but can't at early growth periods, which suggest that MdHMGR1 can improve early fruit cell division activity.(6) CTK, IAA in MdHMGR1-1+HMGR1 tomato plants in young fruit content is higher than 35S+HMGR1 and wild type tomato.(7) 35S+HMGR1 and MdHMGR1-1+HMGR1 genetically transgenic tomato can resist salt to some extent.After salt treatment, the content of chlorophyll and carotenoid is in MdHMGR1-1+HMGR1 transgenic tomato is higher than it in 35S+HMGR1 tomato transgenic tomatoes and wild type tomato. And chlorophyll and carotenoid content in 35S+HMGR1transgenic tomato is slightly higher than the wild type of tomatoes, but no significant difference.(8) After salt treatment, MdHMGR1-1+HMGR1 transgenic tomato antioxidant enzymes activity APX, SOD, POD and CAT is significantly higher than 35S+HMGR1 tomatotransgenic tomatoes and wild type tomato. And the antioxidant enzyme activity of APX, SOD,POD and CAT is not significant difference in 35S+HMGR1 transgenic tomatoes and wild type tomato.