The seed-borne transmitted Southern bean mosaic virus hinders the early events of nodulation and growth of Rhizobium-inoculated Phaseolus vulgaris L.

MARIADANIELA LÓPEZ,; NACIRA MUÑOZ; HERNAN RAMIRO LASCANO; MARÍA LUISA IZAGUIRRE-MAYORAL

FUNCTIONAL PLANT BIOLOGY

CSIRO PUBLISHING

Lugar: Collingwood; Año: 2017 p. 208 - 218

1445-4408

Abstract. To simulate seed-borne virus transmission, a non-invasive protocol was designed to virus-infect the radicle of germinating seeds, with 100% effectiveness. The pre-infection of 24 h old black bean radicles by Southern bean mosaic virus (SBMV) followed by rhizobia inoculation 48 h later caused a drastic reduction in the root nodulation. Results were attributed to the active virus replication within the elongating zone of the radicle, at least 32 h prior to rhizobia-inoculation that elicited severe anatomical malformations, an abnormal accumulation of apoplastic ROS in the rizodermis, cortex, inner cortical and endodermic root cells, the formation of atypical root hair tips, and the collapse of 94% of the root hairs in the pre-SBMV infected radicles. Adult pre-SBMV infected plants showed exacerbated virus symptoms and an 80% growth reduction ascribed to virus-induced major ultrastructural alterations in the nodules. The accumulation of ureides, amino acids and total reducing sugars in the leaves and nodules of pre-SBMV infected plants are indicators of the hindering effects of the SBMV infection on N2 fixation and ureide catabolism, causing N starvation. The exogenous addition of 1 or 4 M naringenin, genistein or daidzein did not counteract the deleterious effects of the pre-SBMV infection on nodulation.