The plant F-box protein more axillary growth 2 (MAX2) is a key factor in the signal transduction of strigolactones (SLs) and karrinkins (KARs). As the main component of the SKP1-CUL1-FBX (SCF) complex ubiquitin ligase E3, MAX2 is responsible for specifically recognizing the target proteins, suppressor of MAX2 1/SMAX1-like proteins (SMAX1/SMXLs), which would be degraded after ubiquitination. It can thereby regulate plant morphogenesis and stress responses. There exist homologous genes of MAX2 in the important grain and oil crop soybean (Glycine max). However, its role in plant defense responses has not been investigated yet. Here, GmMAX2b, a homologous gene of MAX2, was successfully cloned from stressed soybean. Bioinformatics analysis revealed that there were two MAX2 homologous genes, GmMAX2a and GmMAX2b, with a similarity of 96.2% in soybean. Their F-box regions were highly conserved. The sequence alignment and cluster analysis of plant MAX2 homologous proteins basically reflected the evolutionary relationship of plants and also suggested that soybean MAX2 might be a multifunctional protein. Expression analysis showed that plant pathogen infection and salicylic acid treatment induced the expression of GmMAX2b in soybean, which is consistent with that of MAX2 in Arabidopsis. Ectopic expression of GmMAX2b compensated for the susceptibility of Arabidopsis max2-2 mutant to pathogen, indicating that GmMAX2b positively regulated plant disease resistance. In addition, yeast two hybrid technology was used to explore the potential target proteins of GmMAX2b. The results showed that GmMAX2b interacted with SMXL6 and weakly interacted with SMXL2. In summary, GmMAX2b is a positive regulator in plant defense responses, and its expression is induced by pathogen infection and salicylic acid treatment. GmMAX2b might exert its effect through interaction with SMXL6 and SMXL2. This study expands the theoretical exploration of soybean disease resistant F-box and provides a scientific basis for future soybean disease resistant breeding.
Glycine max/metabolism* ; Disease Resistance/genetics* ; Plant Diseases/immunology* ; Plant Proteins/genetics* ; Cloning, Molecular ; Gene Expression Regulation, Plant ; F-Box Proteins/genetics* ; Arabidopsis/genetics* ; Phylogeny

Objective:To evaluate the quality of root filling with Resilon/Epiphany Self-Etch(RESE).Methods:30 recently extrac-ted mandibular premolars were randomly divided into 2 groups.After root canal preparation,the roots in experimental group(n =1 4) were filled with RESE,those in control group(n =1 6)were filled with Gutta-percha/AH plus.The quality of the optical obturation was evaluated by X-ray photography.Results:The buccolingual X-ray scores of the two filling materials were higher than the mesiodistal sores(P <0.05),there was no statistical significance between the two kinds of filling materials(P >0.05).The mesiodistal X-ray score of RESE group was higher than that of Gutta-percha/AH plus group(P <0.05).Conclusion:The X-ray resistance of the RESE filling system is more favorable than Gutta-percha/AH plus for the evaluation of root filling quality by X-ray examination.