Genetic Dissection Of ZmACS7 Regulating Stem Lodging Resistance-Related Traits In Maize

Maize(Zea mays L.)is one of the broad cultivation cereal crops in the world.Increasing the maize yield per unit area is not due to increased yield potential per plant;instead,it has mainly relied on increased plant density.However,high planting density conditions;increased the risk of plant susceptibility to lodging.The number and size of the stalk vascular bundle and stalk fiber content are closely related to maize stem resistance lodging.However,little has been reported about the molecular mechanism of related lodging-related resistance traits and regulate genes of the stem lodging resistance in maize at home and abroad.Here,this study uses the mutant Sdw3 and functional loss mutant zmacs7-2 for organizational anatomy observation and the number of vascular bundles and the content of cellulose(CEL),hemicellulose(HCEL),and lignin(LIG)measurement.Verified stem lodging resistance function of ZmACS7 gene using genetic transformation Arabidopsis thaliana.We have analyzed 172 maize inbred lines of the differences between the number of small vascular bundles(NSVB)and the number of large vascular bundles(NLVB)in the bottom of the tassel spindle(TBTS).We performed two maize inbred lines with different fiber content(high-fiber HCB/low-fiber JI63)third internode stem at V10(the tenth-leaf stage),DTS(days to silking),AS 10(10 days after silking),AS20(20 days after silking)transcriptome and metabolome analysis.Further,explore the impact of ZmACS7 on the development of maize stalk fibers in different developmental periodsThe main results were as follows:1.Stem cytology observation and composition analysis found that the mutant Sdw3 in TBTS,the peduncle stem,and the bottom-third internode stem of cell wall content(CEL,HCEL,LIG)were decreased.In the mutant Sdw3,the HCEL content in the third section was significantly reduced(2.46%),and the CEL and LIG content was reduced(no significance).These results indicated that the ZmACS7 gene affects bottom-third internode fiber development and negatively regulates secondary cell wall biosynthesis.Compared to the wild type,the mutant Sdw3 per unit area NSVB and NLVB increased.The mutant zmacs7-2 compared with the B73 line.It can elongate the internode and enhance the plant height and ear height at the DTS stage.2.We were using cytological observation,mutant acs7-d.It reduced fiber wall development,inhibited stem elongation,and enhanced cambium activity.Using genetic analysis,ethylene impedes fiber cell wall biosynthesis through a conserved hierarchical transcriptional regulation.Further,ethylene overproducing mutant acs7-d also affected plant growth.Compared with the wild type(WT),the acs7-d mutant showed short leaf pedicels and small leaf blades during vegetative growth.At the mature stage,the acs7-d mutant plants were dwarf,small siliques,and reduced seedsets.ACS7 positively regulates the cambium development.The cambial cell proliferation phenotype of acs7-d depends on functional WOX4,indicating that the two parallel pathways,ethylene and TDIF signaling,converge at WOX4 positively in regulating cambium activity.3.Using organizational anatomical research,found that 172 maize inbred belonged to five hybrid dominant groups;analyze the differences between NSVB and NLVB in TBTS.The results showed that coefficients of variation of NSVB and NLVB in TBTS in different inbred lines were 16.67%～21.69%and 25.83%～32.19%,respectively.The highly significant differences between either NSVB or NLVB were revealed in different inbred lines.The broad-sense heritability on NSVB and NLVB were 78.87%and 82.58%,respectively.At the same time,a significantly positive correlation between NSVB relative to NLVB was observed.Both NSVB and NLVB represented a similarity in the tendency in different heterotic groups(Lancaster<Reid Yellow Dent<P group<Lvda Red Cob<Tangsipingtou).4.Based on the analysis of RNA-seq transcriptome,high fiber content inbred line HCB,102 common DEGS were identified at four growth development,and low fiber content was identified as 106 common DEGs in JI 63.Based on the analysis of non-targeted metabolism,HCB identified 40 DAMs,and JI 63 identified 12 DAMs.Further,clarify that the critical period for the ZmACS7 gene regulating stem fiber development was AS20.In summary,ZmACS7 is a gene closely related to maize lodging resistance.It mainly plays a role in regulating the SVB and SF of the stem stalk internodes.There are vast differences in SVB in existing maize germplasm resources.The least was the Lancaster group,and the most was the Tangsipingtou group.The critical period of the effect of the ZmACS7 gene on the development of stem fibers was initially identified.