The colonization characteristics of Paenibacillus jamilae QHZ11-gfp in potato plants and its growth-promoting effect

Abstract:

[Background] The effective colonization of biocontrol bacteria in crop roots is the prerequisite for their functions, and intuitive tracking technology and effective quantitative methods are important tools for studying the roots' distribution of biocontrol bacteria.[Objective] To study the colonization characteristics of QHZ11 (antagonistic bacteria of Rhizoctonia solani JT18) in potato plants and its growth-promoting effect on potato. [Methods] Using green fluorescent protein (GFP) to label QHZ11, and separately inoculating the labeled bacterial suspension, bio-organic fertilizer and sterile water into the sterilized soil. Using laser confocal microscopy technology and real-time fluorescent quantitative PCR to study the colonization characteristics and quantitative changes of labeled strain in different parts of potato plants and its growth-promoting effect on potato. [Results] The pHAPII plasmid was successfully transformed into QHZ11 and could be inherited stably for 40 generations in QHZ11-gfp, recorded as QHZ11-gfp; the colony morphology, growth curve and antagonistic ability against R. solani JT18 of strain before and after the labeling were basically same. Starting from the 7th day, green fluorescence successively were found on the potato buds and roots, indicating that QHZ11-gfp successfully colonized on the potato buds, roots, etc. The quantity of colonization of QHZ11-gfp in the roots and stolons both showed a trend of first increasing to the peak in tuber formation period and then decreasing and in the whole growth period, the quantity of colonization of QHZ11-gfp in the roots was always>stolons. Both bacterial suspension and bio-organic fertilizer treatments significantly promoted the growth of potato roots, increased the tuber yield by increasing plant height, etc. The fluorescence intensity, the quantity of colonization and the growth-promoting effect on potato of bio-organic fertilizer treatment were significantly better than those of bacterial suspension. [Conclusion] QHZ11-gfp can be successfully colonized on potato plants and has a good growth-promoting effect on potatoes. Making it into bio-organic fertilizer promotes its colonization and makes the growth-promoting effect better.