Formation of lateral roots and root hairs of Ciherang rice as a result of Nostoc colonization

We performed an interaction study between the cyanobacteria Nostoc sp. CPG24 and GIA13a and the roots of Ciherang rice (Oryza sativa var. Ciherang) in a hydroponic system. For this purpose,14-day-old rice seedlings were cultivated in 10× BG11 N-free, aerated liquid medium. The plants were incubated at room temperature and grown in a 12:12 light-dark cycle. To better understand the role of Nostoc colonization on root growth, we exposed the rice samples to four different treatments: P1 (0.4 g Nostoc CPG24 strain inoculum), P2 (0.4 g Nostoc GIA13a strain inoculum), K1 (no inoculation of Nostoc and IAA), and K2 (addition of 15 ppm IAA). Regardless of the strain, we found that Nostoc filaments were attached to the root surface, particularly in the regions of formation and elongation of lateral roots and root hairs. The root elongation and number of lateral roots were high under the K2 and P2 treatments, whereas they were substantially reduced under the P1 treatment. We demonstrate that the Nostoc strain GIA13a induces the formation of new lateral roots, whereas the Nostoc strain CPG24 stimulates the formation of root hairs.