Infection, colonization and growth-promoting effects of tea plant (Camellia sinensis L.) by the endophytic bacterium Herbaspirillum sp. WT00C

The endophytic Herbaspirillum sp. WT00C, isolated from tea plant, seems to have a potential ability to promote tea-plant rooting and budding due to its capability of producing indole-3-acetic acid (IAA), ammonia and siderophores. Thus, the present study was aimed to verify whether this bacterium could be used for tea cultivation as an environment-friendly bioaccelerator. To evaluate its potential use in promoting tea-plant rooting and bud growth, Herbaspirillum sp. WT00C was characterized using several methods. Observation by bacterial infection found that the bacterium only went into plants via plant vulnus when irrigation, sprinkling and traumatic infection were applied. Whatever irrigation, sprinkling or traumatic infection was applied, all tea plant, vegetables, rice and wheat tested in this study did not show any growth inhibition or disease symptom. Observation by bacterial count test also found that the bacterium colonized only in tea plant, but not in vegetables, rice or wheat. To test the effect of Herbaspirillum sp.WT00C on tea-cutting rooting and budding, tea cuttings were soaked with the diluted bacterial culture. Observation at 280 day postinoculation found that the tea-seedling rate approached to 100%, and average newborn shoot length and lateral root number of tea seedlings increased 88% compared to control groups. In addition, the bacterium was found only in those tea cuttings treated with the bacterium, but not in their newborn shoots and leaves. Inoculating the bacterium to the upper incision of tea twigs in the field also enhanced the growth of newborn shoots. Our studies demonstrated that Herbaspirillum sp.WT00C was a tea-specific endophyte with the ability to stimulate the lateral root formation and bud growth of tea cuttings, and paved the way for its application in propagation of tea cuttage as a novel bioaccelerator.