Promotion Of Wheat Seed Germination By Bacillus Subtilis QM3 And Its Effect On β-amylase In Early Germination

Seed germination is the basis and initial stage in the process of plant growth and development.In the modern agricultural production,timely and uniform germination is the key determinant for many crops,and closely related to the subsequent plant growth process,which ultimately affect the yield and quality of grain.Microbial accelerants are widely used to improve soil environment,promote seed germination and plant growth,and enhance plant resistance on account of their environmental friendliness and green sustainability.Bacillus subtilis QM3 is a plant growth promoting rhizobacteria(PGPR)with function of growth promoting,disease and pests prevention and colonization,and can improve the resistance of plants.In this study,the B.subtilis QM3 was added into the growth of wheat seeds.The author tests morphological index of seed germination and analysis the activity of earlyβ-amylase with the qualitative and quantitative method.The early isoenzyme ofβ-amylase induced by B.subtilis QM3 also is studied.The result of study provides certain scientific references for how Bacillus subtilis can promote early germination of Wheat seeds.The results are as follows:(1)Wheat seeds were added into different concentrations of B.subtilis QM3,and they were cultivated for seven days.Then the indexes were measured including germination rate,germination potential,bud length,root length,fresh weight,dry weight,root shoot ratio,total amylase and,etc.The results showed that the germination rate of the treatment group was significantly higher than that of the control group(p<0.05),and variation trend of germination potential was similar to the tread of germination rate.10~7CFU/m L B.subtilis QM3 increased the most significantly in the sprout length.Compared with the control group,the sprout length and root length separately increased by 26.74±0.58%and 39.33±0.32%on the 4th day of germination.The fresh weight and dry weight of B.subtilis QM3 respectively increased by16.22±0.36%and 11.25±0.33%compared with treatment group on the 5th day;On the fourth day,the fresh weight of underground part,the fresh weight of above ground part and the ratio of root to shoot respectively increased by 20.53±0.13%,13.98±0.12%and 5.75±0.16%compared with the control group of 10~7CFU/m L B.subtilis QM3.In addition,the content of total amylase increased significantly at six o’clock,and 10~6CFU/m L B.subtilis QM3 at six o’clock increased by 18.8±0.17%compared with control group in the early stage of wheat germination.(2)After measurement with different concentrations of B.subtilis QM3,the apparent activity of amylase,liquefaction of endosperm and the activity ofβ-amylase were measured in the early stage of seed germination.The results showed that compared with the control group,the apparent activity of amylase and the liquefaction of endosperm in the treatment group were much more obvious than those in the control group.The activity ofβ-amylase in seeds tested with 10~6 CFU/ml B.subtilis QM3 significantly increased by 18.5±0.25%after germination for six hours.In addition,the activity ofβ-amylase increased significantly(p<0.05)23.4±0.94%(10~6 CFU/ml)at the same stage of germination afterα-cyclodextrin pretreatment.The increase ofβ-amylase activity in the early stage of germination is one of the important reasons for B.subtilis QM3 to promote the germination of wheat seeds.(3)Theβ-amylase Isozyme in early period of wheat seed germination was measured by native polyacrylamide gel electrophoresis.The results showed that the band width and brightness ofβ-amylase isoenzyme of wheat seeds tested by B.subtilis QM3 increased during three to six hours of germination,and especially the effect was significant at six hours.In the early period,the band ofα-amylase isoenzyme could not be detected.It is suggested that the increase ofβ-amylase isoenzyme early band may be one of the main reasons for B.subtilis QM3 to promote wheat seed germination.Through the combination of B.subtilis QM3 with free and binding states ofβ-amylase,it was found that the former can increase the activity ofβ-amylase by either increasing freeβ-amylase or releasing bindingβ-amylase.β-amylase inhibitors can significantly inhibitβ-amylase activity,neverthelessα-amylase activators and inhibitors have no significant effect onβ-amylase,which further proved that theβ-amylase exerted the effects in the early period of wheat seed germination.(4)The characteristics ofβ-amylase isoenzyme in the early period of wheat germination induced by B.subtilis QM3 showed that the activity ofβ-amylase isoenzyme was the highest at 40℃,but it could not be detected at 70℃;The activity ofβ-amylase at p H 4-7 was stable,andβ-amylase isoenzyme only in strong acid or alkali would lose its activity.To sum up,B.subtilis QM3 can promote the growth of wheat seeds by enhancing the germination rate,germination potential,root length,bud length,dry weight,fresh weight and other morphological indicators;B.subtilis QM3 can promote the germination of wheat seeds by rapidly increasing the activity ofβ-amylase in the early stage of wheat germination.B.subtilis QM3 induced rise ofβ-amylase can be activated either by freeβ-amylase or by binding Caused by the release of beta-amylase.It provides a theoretical basis for B.subtilis QM3 to promote seed germination and apply it to agricultural production.