Bacterial endophytes from rice cut grass (Leersia oryzoides L.) increase growth, promote root gravitropic response, stimulate root hair formation, and protect rice seedlings from disease

Editorial special issue: the soil, the seed, the microbes and the plant

“…As a global strategy to reduce chemical fertilizers and pesticides, some endophytes and other members of the phytosphere can be used for plant growth promotion and health. In this Special Issue, Verma et al (2018) demonstrate that some seed endophytes of the monocotyledonous plant Leersia oryzoides (L.) Sw., a wild relative of rice (Oryza sativa L.), can produce auxins, solubilize phosphate, have antifungal activities and increase root and shoot growth of rice and Bermuda grass (Cynodon dactylon (L.) Pers.) seedlings.…”

Review: Endophytic microbes and their potential applications in crop management

“…The widespread capacity of many microbes to produce plant signal molecules (such as nitric oxide) growth regulators (such as auxins and ethylene) could be another reflection of co‐evolutionary association of microbes and plants. Controlled experiments revealed that seedlings of grasses cleaned of most of their endophytic microbes lose the root gravitropic response ( i.e ., roots do not grow downward), and seedlings frequently are diminished in size with reduced or no root hair formation . The re‐inoculation of axenic or near axenic seedlings with microbes that internally colonize seedlings results in reacquisition of gravitropic response of roots and increased plant stature and root hair development .…”

“…The loss of individual components of the natural endophytic community could alter how the seed community of microbes functions and result in seeds that are less capable of growth and survival. To remedy losses of essential endophytic microbes and reduce reliance on agrochemicals in crop cultivation, it could be necessary to obtain endophytic microbes from wild relatives of crops and reintroduce them into crops—perhaps as seed treatments …”

“…3,4 Other endophytes may be recruited from the soil but similarly benefit plants. 4 Endophytic microbes are important components of plants, and they function in the following ways: (i) increase nutrients acquired by plants, [5][6][7][8] (ii) defend plants from pathogens and insects, [9][10][11] (iii) increase stress tolerance in plants, 12,13 (iv) modulate plant development, [13][14][15] and (v) suppress weed growth. 16 The particular mechanisms by which endophytic microbes fill the various functions in plants likely differ depending on the microbe and plant.…”

“…14,15 The re-inoculation of axenic or near axenic seedlings with microbes that internally colonize seedlings results in reacquisition of gravitropic response of roots and increased plant stature and root hair development. 14,15 Several experiments suggest that root hairs elongate until all microbes have been ejected from hairs. 21 Root hair elongation may be triggered by nitric oxide or ethylene production by the intracellular microbe protoplasts that cluster in the tip of the elongating hair, but this has not been proven.…”