Cultivation Of Pecan Rootstocks Induced By Gibberellin Dwarf Gene

Carya illinoensis,also known as long pecan and American pecan,is a world-famous high-grade dried fruit,oil tree and fruit and fruit.Its fruit is rich in nutrients and has high health value.The study found that long-term consumption of American pecans has obvious effects of anti-aging,stomach,heart disease and cardiovascular disease.However,the thin shell pecan tree is tall,which is not conducive to artificial picking of fruit and daily maintenance management.The cultivation of dwarf rootstock can facilitate the breeding of thin shell pecans and the promotion of fruit.Gibberellins(GAs)is an important hormone regulating plant height.The cloning and molecular mechanism of related strains are extremely important for the rational regulation of plant growth and development and agricultural production.In this paper,100 mg L-1 gibberellin was sprayed on the pecans,the relative expression of CiGA20ox,CiGA3ox and CiGA2ox in different periods(0d,7d,14d,21d,28d)and different parts(0d,28d)were detected by real-time fluorescence quantitative detection to understand the feedback regulation mechanism of CiGA20ox,CiGA3ox and CiGA2ox in gibberellin;construct positive and negative sense vectors and homologous transformation,then transfer to pecan embryos by Agrobacterium-mediated method to obtain pecan dwarf plants.The main findings are as follows1?The results showed that after four weeks of gibberellin,the internode length and the elongation of the main root length of pecan seedlings were significantly different compared with the control but the number of internodes did not change.The average growth of the plants was as high as 2.9 cm which was nearly 2 times of the control,the difference of which was extremely significant.2?The results of real-time PCR showed that GA20ox,GA3ox and GA2ox had different spatial and temporal expression differences in the growth period of pecan.Exogenous gibberellin can continuously reduce the expression of CiGA20ox.After 28 days,the expression of CiGA20ox content decreased 38.6%compared with the control;The expression level of CiGA3ox fell to alow of 75.4%after 7 days and rose back after 28 days,finally the expression level increased 350%compared with the control;On the whole the expression level of CiGA2ox showed a wavy change,first showed a rapid increase after 7 days,then returning to the initial level after 21 days,finally increased 220%compared with the control after 28 days.CiGA3ox accumulates in the stem of pecan seedlings,which has a significant change in transcriptional level compared to CiGA20ox and CiGA2ox.3?CiGA2ox,CiGA20ox and CiGA3ox of pecan are closely related to hickory and walnuts,hickory have the closest relationship with pecans.It can be seen that the homology of GA20ox,GA2ox and GA3ox proteins in the same family is relatively close,indicating that the GA20ox,GA2ox and GA3ox proteins of the pecans are relatively conservative in evolution.4?The GA20ox RNA interference vector was transferred into the somatic embryos of pecan by Agrobacterium-mediated transformation and the positive somatic embryos and positive regenerated plants of pecans were obtained.The results showed that RNA interference decreased the expression of GA20ox gene in the regenerated plants of the pecans,which was 27.5%of the wild type and the difference was extremely significant.The plant height of the pecan regenerated plants after RNA interference was significantly reduced,which was 45%of the wild type.Moreover,the regenerated plants after the disturbance are shortened and the leaves become lighter and smaller.In order to further verify the reliability of RNA interference results,this study further transferred the GA20ox overexpression vector into the body of the pecan.The results showed that the gene expression of the overexpressed plants decreased,the plant height increased significantly and the internode length increased,the leaves become bigger and lighter.5?The CiGA2ox overexpression vector was transferred into the pecan embryo by Agrobacterium-mediated transformation.The positive somatic embryo and positive regenerated plant of pecan were obtained.The results of qRT-PCR showed that the expression of CiGA2ox gene in positive regenerative plants increased significantly,which was 2.64 times of wild type.The plant height of regenerated plants overexpressing CiGA2ox gene was significantly lower than control,which was 52%of wild type;the internode length decreased by 42.4%,the leaves became darker and smaller.