| Soybean cyst nematode(SCN)is the most damaging soybean pest worldwide.The Bacillus megaterium Sneb207 was previously shown to inhibit the activity of SCN,but little is known about the underlying mechanism.This study was aimed to evaluate thecontrol mechanism of Sneb207 as a seed-coat treatment of soybean against SCN.The results were as follows:1.Vertify the Sneb207 inhibited soybean cyst nematode on the soybean and induced systemic resistance of soybean.We showed that coated the seeds of susceptible soybean cultivars with Sneb207 significantly reduced the number of juveniles and cysts in the root,and prolonged the developmental stage of SCN.We used the split-root system to further demonstrate that treatment of soybean root with Sneb207 induced systemic resistance.Evaluated Bacillus inhibits soybean cyst nematode under field condition in two stations of Northeast China.Our results showed that Sneb207 and SN100 treatment greatly reduced SCN reproduction and significantly promoted plant growth and yield production,suggesting that Sneb207 can be used individually or in combination.Sneb207 is a promising seed-coating agent that may be used as an alternative bio-nematicide for controlling SCN in soybean fields.2.RNAseq technology was used to test the differential transcriptional group in soybean roots when inoculated with Sneb207 or SCN.These results indicate that plant hormone signal transduction pathway,plant pathogen interaction pathway,starch and sucrose pathway,and phenylpropanoid biosynthesis pathway differ greatly in genes,and play a major role in nematode resistance.3.Identification of internal reference genes for accurate gene expression analysis in soybean roots interacted with Heterodera glycines and Bacillus.Ten candidate reference genes(ELF1A,ELF1 B,CYP2,UBC4,UBQ10,TUB4,G6 PD,ACT2/7,ACT11,and CONS4)were evaluated and their expression stability was analyzed in Sneb207 strain coated soybean roots and SCN infected soybean roots.All the data were statistically analyzed using ge Norm,Norm Finder,Best Keeper and Ref Finder.The results showed that ACT2/7 and CONS4 were the most stable genes among soybean-Sneb207-nematode interactions.Furthermore,CYP2 and ELF1 B were the most stable reference genes among soybean-nematode interactions.Moreover,G6 PD,and ELF1 A could also be used as stable reference genes among soybean-Bacillus interactions.Consider all the conditions,ACT11,ACT2/7 and G6 PD also be used as reference genes correction of q RT-PCR data.In addition,q RT-PCR showed that 38 disease resistance related genes were consistent with the results of RNA-Seq.4.Vertified the physiological control mechanism of Sneb207 against soybean cyst nematode.Under Sneb207 coated or uncoated soybean,the J2 inoculation compared to the uninoculated,the content of auxin(IAA),gibberellin(GA)and abscisic acid(ABA)chang a lot and play an important role in Sneb207 induced soybean resistance to SCN.Further,the content of soluble sugar in soybean root was detected by high performance liquid chromatography.That fructose,glucose and sucrose in soybean were changed at 3,7 and 14 days after nematode inoculation,means that the content of fructose,glucose and sucrose related to the development of the nematode,in particular,in sucrose.5.To make clear the effect of amino acids on Sneb207 resistance to SCN.Under Sneb207 coated or uncoated soybean,the J2 inoculation compared to the uninoculated,the content of aspartic acid and glutamic acid changed a lot and play an important role in Sneb207 induced soybean resistance to SCN.Further,different amino acid coating soybean seed were used to investigate the effects of plant growth index and soybean cyst nematode.The results showed that arginine had the most significant effect on plant growth,Proline,lysine,alanine,glutamic acid and arginine significantly decreased the number of cysts.Thus,Asp play an important role in the resistance to nematodes. |
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