Effectiveness Evaluation And Molecular Mechanism Of The Strigolactones Analogue In Rice Tillering Inhibition

Rice tillering is an agronomic trait closely related to the plant architecture of rice,and is a key factor in determining rice yield.Strigolactones(SLs)are a new type of phytohormones commonly found in plants,and play an important role in regulating rice tillering.However,due to the extremely low SL content in plants,scientists have achieved substitution by artificially synthesizing their analogs.Among them,GR24 has the highest biological activity and the widest range of applications,but its synthetic route is generally too long,which is not conducive to commercialization.In this study,the structure of GR24 was analyzed to design and synthesize a compound with a novel molecular structure.By studying the plant morphology difference of rice strigolactones synthase gene(d10)mutant and receptor gene(d14)mutant after compound treatment and related molecular biology experiments,we evaluate the effectiveness of these compounds and explore the molecular mechanisms by which these compounds regulate rice tillering.The main findings are as follows:1.Summarize the previous research experience and divide the structure of GR24 into"conservative structural regions" and "non-conservative structural regions".According to the ideas of simplifying the molecular structure of the "non-conservative structure",introducing heteroatoms,and removing the methyl group in the "conservative structure",a total of 31 compounds of the novel monopod analogs were synthesized.According to the molecular structure type of " non-conserved structure regions",31 compounds are divided into phenols,carboxylic acids,esters and amino acids.2.Using rice strigolactones synthase gene(d10)mutant as material,hydroponic test,control treatment and compound treatment were designed to study the effect of foreign aid applied compound on rice plant morphology.The results showed that some compounds significantly inhibited tiller growth of rice d10 mutants,adventitious roots became shorter,and plant height became shorter.The results of treatment with different compound concentrations showed that the effective concentration of the compounds to significantly inhibit tillering was about 50 μM,and the effective concentration of some compounds to significantly inhibit tillering can be as low as 30 μM.If the compound concentration is less than 8 μM,the tillering inhibitory effect is not significant.In addition,the application method of the compound was also discussed.The root application compound treatment and the leaf spray compound treatment were designed.The results showed that the root application compound significantly inhibited tillering,while the leaf application compound did not significantly inhibit tillering.3.In order to explore the role of compounds in regulating rice tillering,hydroponic experiments were conducted using rice strigolactones synthase gene(d10)mutant and strigolactones insensitive receptor gene(d14)mutant as materials.Compared with control treatment,No.5 or No.6 compound(50μM)treatment can significantly inhibit tiller growth of rice d10 mutant,but not inhibit tiller growth of rice d14 mutant.This indicates that such compounds may regulate tiller growth of plants through the strigolactones pathway.4.Through yeast double hybrid experiment,it was found that under the treatment of No.5,No.6 and No.18 compound,D14 interacts with d53 protein,which is consistent with the result of GR24 treatment.The expression levels of strigolactones downstream genes in compound treatment and control treatment at 0h,4h and 8h were measured.The results showed that No.18 compound treatment significantly promoted the expression of D53,CKX9 and OsTB1,which was consistent with the expression change trend after GR24 treatment.At the same time,the results showed that the expression of RR5 at the stem base increased significantly after compound treatment,which was different from the expression change after GR24 treatment.It shows that such compounds can regulate the growth of plant tillers through the strigolactones pathway,and may also regulate plant growth through other hormone signaling pathways.This study mainly proves that after the methyl group in the "conservative structure region" is removed,the compound can still inhibit rice tillering.The compound regulates plant tillering through the strigolactones pathway and also regulates plant growth through other pathways.Different compounds with "non-conservative structural regions" have different performances in the tillering of the plant with the strigolactones pathway,which also shows that it still affects the activity of the strigolactones,and the mechanism remains to be further studied.