TY - JOUR
T1 - NODULE INCEPTION Recruits the Lateral Root Developmental Program for Symbiotic Nodule Organogenesis in Medicago truncatula
AU - Schiessl, Katharina
AU - Lilley, Jodi L.S.
AU - Lee, Tak
AU - Tamvakis, Ioannis
AU - Kohlen, Wouter
AU - Bailey, Paul C.
AU - Thomas, Aaron
AU - Luptak, Jakub
AU - Ramakrishnan, Karunakaran
AU - Carpenter, Matthew D.
AU - Mysore, Kirankumar S.
AU - Wen, Jiangqi
AU - Ahnert, Sebastian
AU - Grieneisen, Veronica A.
AU - Oldroyd, Giles E.D.
PY - 2019/11/4
Y1 - 2019/11/4
N2 - To overcome nitrogen deficiencies in the soil, legumes enter symbioses with rhizobial bacteria that convert atmospheric nitrogen into ammonium. Rhizobia are accommodated as endosymbionts within lateral root organs called nodules that initiate from the inner layers of Medicago truncatula roots in response to rhizobial perception. In contrast, lateral roots emerge from predefined founder cells as an adaptive response to environmental stimuli, including water and nutrient availability. CYTOKININ RESPONSE 1 (CRE1)-mediated signaling in the pericycle and in the cortex is necessary and sufficient for nodulation, whereas cytokinin is antagonistic to lateral root development, with cre1 showing increased lateral root emergence and decreased nodulation. To better understand the relatedness between nodule and lateral root development, we undertook a comparative analysis of these two root developmental programs. Here, we demonstrate that despite differential induction, lateral roots and nodules share overlapping developmental programs, with mutants in LOB-DOMAIN PROTEIN 16 (LBD16) showing equivalent defects in nodule and lateral root initiation. The cytokinin-inducible transcription factor NODULE INCEPTION (NIN) allows induction of this program during nodulation through activation of LBD16 that promotes auxin biosynthesis via transcriptional induction of STYLISH (STY) and YUCCAs (YUC). We conclude that cytokinin facilitates local auxin accumulation through NIN promotion of LBD16, which activates a nodule developmental program overlapping with that induced during lateral root initiation.
AB - To overcome nitrogen deficiencies in the soil, legumes enter symbioses with rhizobial bacteria that convert atmospheric nitrogen into ammonium. Rhizobia are accommodated as endosymbionts within lateral root organs called nodules that initiate from the inner layers of Medicago truncatula roots in response to rhizobial perception. In contrast, lateral roots emerge from predefined founder cells as an adaptive response to environmental stimuli, including water and nutrient availability. CYTOKININ RESPONSE 1 (CRE1)-mediated signaling in the pericycle and in the cortex is necessary and sufficient for nodulation, whereas cytokinin is antagonistic to lateral root development, with cre1 showing increased lateral root emergence and decreased nodulation. To better understand the relatedness between nodule and lateral root development, we undertook a comparative analysis of these two root developmental programs. Here, we demonstrate that despite differential induction, lateral roots and nodules share overlapping developmental programs, with mutants in LOB-DOMAIN PROTEIN 16 (LBD16) showing equivalent defects in nodule and lateral root initiation. The cytokinin-inducible transcription factor NODULE INCEPTION (NIN) allows induction of this program during nodulation through activation of LBD16 that promotes auxin biosynthesis via transcriptional induction of STYLISH (STY) and YUCCAs (YUC). We conclude that cytokinin facilitates local auxin accumulation through NIN promotion of LBD16, which activates a nodule developmental program overlapping with that induced during lateral root initiation.
KW - auxin
KW - CYTOKININ RESPONSE FACTOR
KW - endosymbiosis
KW - LATERAL ORGAN BOUNDARIES DOMAIN
KW - lateral root/nodule organogenesis
KW - Medicago truncatula
KW - nitrogen
KW - NODULE INCEPTION
KW - rhizobia
KW - YUCCA
U2 - 10.1016/j.cub.2019.09.005
DO - 10.1016/j.cub.2019.09.005
M3 - Article
AN - SCOPUS:85074085878
SN - 0960-9822
VL - 29
SP - 3657-3668.e5
JO - Current Biology
JF - Current Biology
IS - 21
ER -