The Role Of MiR171b In The Regulation Of Growth And Development In Tomato

Tomato is one of the most widely cultivated economic vegetable crops in the world,thus become an important model plant for vegetable science researchers.Seemingly,the study of tomato growth and development mechanism provides some theoretical guidance for the development of horticultural breeding and even facility cultivation.Tomato growth and development is regulated by many factors during including plant micro-RNAs.As an important negative regulatory factor in plants growth,miRNA participates in various stages of growth and development including the regulation of various stress resistance by regulating multiple endogenous biochemical processes.In this paper,miR171 b transgenic tomato plants like mutant and overexpression were raised to study the precise function of miR171 b in tomato growth and development;and the specific influence of miR171 b on tomato yield quality and other production application indicators was studied.The main research results are as follows:1.Cultivation of tomato miR171 b mutant and overexpression material.We used gene cloning technology and CRISPR-Cas9 technology to construct a tomato miR171 b overexpression and mutant vector.Using Agrobacterium infection and tissue culture methods,combined with next-generation sequencing and qRT-PCR technology,we finally obtained 3 Two independent tomato mir171 b mutant lines and two independent tomato miR171 b overexpression materials.The successful construction of the mir171 b mutant and miR171 b overexpression material is sufficient for the subsequent experiments.2.miR171 b participates in the process of tomato growth and pollen development.miR171 b deletion promoted seed germination and tomato biomass accumulation.By measuring the height and fresh weight of tomato plants and combining the determination of photosynthetic parameters,we found that the plant height and fresh weight of the two mutant lines of the mutant mir171 b were significantly increased compared to the wild type(WT),and their net photosynthesis The rate and transpiration rate were significantly enhanced.However,the biomass accumulation of the overexpressed material miR171b-was significantly reduced compared to WT.And the study also found that miR171 b also altered the plant hormone balance and the secondary metabolite anthocyanin accumulation in tomato leaves.After miR171 b loss of function,the salicylic acid(SA)and abscisic acid(ABA)content in the leaves of plants decreased compared to WT,and the jasmonic acid(JA)content increased to a certain extent.Compared with WT,the content of auxin(IAA)in miR171 b overexpressed leaves was significantly decreased.At the same time,the loss of miR171 b function promoted the accumulation of anthocyanins in tomato leaves.In the determination of tomato pollen viability and in vitro germination rate,it was found that the pollen viability and pollen germination rate in miR171 b mutant plants were significantly increased,while the results of overexpressed plants were reversed.Through these experiments,we believe that miR171 b had a negative regulatory effect on plant growth.Overexpression of miR171 b inhibited seed germination,inhibited early plant growth and development,and affected plant photosynthesis,thus affecting plant biomass.And the miR171 b affects the growth potential of the plant due to its hormone balance,as miR171 b negatively regulates the accumulation of anthocyanin in leaves.The deletion of miR171 b increases the accumulation of anthocyanin,thus improving plant resistance and promoting plant growth.And miR171 b plays a negative regulatory role in tomato pollen germination and the deletion of miR171 b promotes good pollen development.3.The effects of miR171 b on fruit yield and nutrient quality of tomato were studied.The results from this experiment revealed that the deletion of miR171 b increased fruit quantity and yield per plant,while the decrease of fruit quantity and yield per plant was observed in overexpressed lines.We further studied the ethylene release in fruits after green ripening,and found that the deletion of miR171 b promoted the time point of respiratory jump in fruits,while the overexpression of miR171 b led to the delay in time point of respiratory jump in fruits.We further analyzed the nutrient content in mature fruits,and noticed that the deletion of miR171 b increased glucose,fructose and lycopene content,while lowers acid content.Our results shows that the deletion of miR171 b increases fruit yield and also has a significant effect on nutrient accumulation in them.From the results discussed above,the biological function of miR171 b during tomato growth and development and its internal regulation mechanism were systematically revealed.Among them,mutation of miR171 b gene through gene editing technology to improve tomato fruit yield and quality provides new ideas and new technologies for improving tomato germplasm resources.