Priestia Endophytica Bacteria Stimulate Rhodiola rosea L. in vitro Growth

Abstract

Soil microorganisms, in particular so-called plant growth promoting rhizobacteria (PGPR), can positively affect plants, stimulating growth by changing their metabolism. In addition, these bacteria synthesize hormone-like chemicals that can influence the formation of primary roots. This work was aimed to determine the possibility of using the sterile cell-free cultural medium obtained after the growth of endophytic bacteria Priestia endophytica UKM B-7515 strain (test solution) to stimulate the rooting of a valuable medicinal plant Rhodiola rosea L. (golden root) shoots in in vitro conditions and to study the physiological characteristics of the response of plants to treatment with such a medium. Single treatment of golden root shoots with a sterile cultural fluid has led to stimulation of the growth of the root system. The stimulating effect was manifested already at the beginning of cultivation. In particular, in seven days, the average number of formed roots on one shoot was 3.6 ±0.7 in the control and 7.5 ±2.1 in the experimental variant. After 28 days, the rooting of shoots that were treated with the test solution occurred more intensively. Thus, the number of roots formed on one shoot in the control and experimental variants was 7.9 ±1.2 and 16.2 ±4.8, respectively. Treated plants exceeded the control one in parameters of root weight. In particular, the weight of the roots in the control was 10.1 ±4.0 and in the experimental plants – 18.6 ±6.3. Thus, the culture medium obtained after the cultivation of P. endophytica UKM B-7515 bacteria without the microorganisms themselves was able to stimulate the process of rooting. Therefore, such a solution can be used for rooting plant shoots that need to be propagated in in vitro culture.