The Analysis On The Function Of OsMADS18 In Rice Development

Rice is the staple food of more than half of the world's population.Therefore,scientific researches on rice growth and development will make a great difference.Until now,the biggest challenge for rice cultivation is freshwater resources.Insufficient water resources will seriously disturb the normal growth of rice and even cause serious loss of rice yield.ABA(abscisic acid)is one of the classic phytohormones and plays essential role in the development of plants.How the members in APETALA1(AP1)/FRUITFULL(FUL)-like family respond to ABA is elusive.In this study,we studied the role of OsMADS18.Focusing on analyzing its function in rice vegetative development and in responsiveness of ABA,we concluded that,OsMADS18,one of the memer of AP1/ FUL-like family,is of vital role in the development of rice.The main results are summaried in below:1.The results from analyzing the transgenic lines of OsMADS18pro-GUS,indicated that,in maturated seed and seed germination process,the expression of OsMADS18 is barely detectable,its expression level could be gradually accumulated and the highest level of OsMADS18 expression could be measured in the stage of flowering;after flowering,the expression of OsMADS18 declined.This expression profile was confirmed by using the analysis of q RT-PCR.2.OE5 and OE8,two of transgenic lines with modulated overexpression(OE)of OsMADS18,and two of RNA interference(RNAi)transgenic lines,RNAi5 and RNAi6,were chosen for subsequent analyses in this study.3.Highly accumulated chalky was observed in the seeds of RNAi5 and RNAi6,thus the delayed seed germination was resulted.In OE5 and OE8,the growth of young seedlings was severely altered,shorter roots and less tillering were produced,the reduced plant architecture was significant.4.Two homozygous lines of Clustered Regularly Interspaced Short Palindromic Repeats(CRISPR)/Cas9 were identified,and they were named as osmads18-cas9-1(cas9-1)and osmads18-cas9-7(cas9-7).With comparing to those of the wild-type,the tillering and lateral growth of cas9-1 and cas9-7 were obviousely altered.In addition,delayed flowering time and severely disturbed seed-setting showed in the cas9 mutants,suggesting the vital role of OsMADS18 in the development of rice.5.Several ABREs(ABA-responsive elements)were predicted in the promoter of OsMADS18,suggesting its correlation with ABA-regulation.As the results,OE5 and OE8 were of decreased sensitivity to the treatment of ABA.Phenotype such as accelerated water loss was measured in detached-leaves from OE5 and OE8.In contrast,the plants of RNAi5,RNAi6 and the cas9 mutants showed enhanced drought tolerance.6.Inhibited expressions of a set of ABA responsive genes,members of Osb ZIP(basic leucine zipper)family,were detected in OE5 and OE8,whereas increased expressions of them were quantified in RNAi5,RNAi6 and cas9 mutants,suggesting the negative function of OsMADS18 in responding to ABA.7.The memerane-and the nucleus-localization traits were obtained in analysing the fusion protein of YFP-OsMADS18.The localization of YFP-OsMADS18 was mainly shown at the plasma membrane(PM)of the sheath cells in young seedlings,but,it was detected in the nucleus when the plants were at the later developmental stages.The translocation,from the PM to the nucleus could be induced by ABA-treatment.Considering OsMADS18 is a MADS-box transcription factor,OsMADS18 may belong to membrane-bound transcription factors(MTFs)family.8.OsMADS18 consists of four domains.Expressing the three domains of the N-terminus,it resulted phenotypes resembling what showed in cas9 mutants.However,when the C-terminal domain was expressed solely,no significant phenotype was produced.9.OsMADS18 could not only interact with OsMADS14 and OsMADS15 but also could interact with OsMADS57,suggesting the functional correlation of OsMADS18 and OsMADS57 in the shoot development of rice.