A Medicago truncatula tobacco retrotransposon insertion mutant collection with defects in nodule development and symbiotic nitrogen fixation.
A Tnt1-insertion mutant population of Medicago truncatula ecotype R108 was screened for defects in nodulation and symbiotic nitrogen fixation. Primary screening of 9,300 mutant lines yielded 317 lines with putative defects in nodule development and/or nitrogen fixation. Of these, 230 lines were rescreened, and 156 lines were confirmed with defective symbiotic nitrogen fixation. Mutants were sorted into six distinct phenotypic categories: 72 nonnodulating mutants (Nod-), 51 mutants with totally ineffective nodules (Nod+ Fix-), 17 mutants with partially ineffective nodules (Nod+ Fix+/-), 27 mutants defective in nodule emergence, elongation, and nitrogen fixation (Nod+/- Fix-), one mutant with delayed and reduced nodulation but effective in nitrogen fixation (dNod+/- Fix+), and 11 supernodulating mutants (Nod++Fix+/-). A total of 2,801 flanking sequence tags were generated from the 156 symbiotic mutant lines. Analysis of flanking sequence tags revealed 14 insertion alleles of the following known symbiotic genes: NODULE INCEPTION (NIN), DOESN'T MAKE INFECTIONS3 (DMI3/CCaMK), ERF REQUIRED FOR NODULATION, and SUPERNUMERARY NODULES (SUNN). In parallel, a polymerase chain reaction-based strategy was used to identify Tnt1 insertions in known symbiotic genes, which revealed 25 additional insertion alleles in the following genes: DMI1, DMI2, DMI3, NIN, NODULATION SIGNALING PATHWAY1 (NSP1), NSP2, SUNN, and SICKLE. Thirty-nine Nod- lines were also screened for arbuscular mycorrhizal symbiosis phenotypes, and 30 mutants exhibited defects in arbuscular mycorrhizal symbiosis. Morphological and developmental features of several new symbiotic mutants are reported. The collection of mutants described here is a source of novel alleles of known symbiotic genes and a resource for cloning novel symbiotic genes via Tnt1 tagging.
Plant Biology Division, Samuel Roberts Noble Foundation, Ardmore, Oklahoma 73401, USA.
Catalina I
CI
Pislariu
Jeremy D
JD
Murray
JiangQi
J
Wen
Viviane
V
Cosson
RajaSekhara Reddy Duvvuru
RR
Muni
Mingyi
M
Wang
Vagner A
VA
Benedito
Andry
A
Andriankaja
Xiaofei
X
Cheng
Ivone Torres
IT
Jerez
Samuel
S
Mondy
Shulan
S
Zhang
Mark E
ME
Taylor
Million
M
Tadege
Pascal
P
Ratet
Kirankumar S
KS
Mysore
Rujin
R
Chen
Michael K
MK
Udvardi
D017343:Genes, Plant / Q000235:genetics; D046913:Medicago truncatula / Q000235:genetics* / Q000382:microbiology / Q000502:physiology; D009024:Morphogenesis / Q000235:genetics; D016254:Mutagenesis, Insertional / Q000235:genetics*; D009154:Mutation / Q000235:genetics; D038821:Mycorrhizae / Q000502:physiology; D009586:Nitrogen Fixation / Q000235:genetics*; D010641:Phenotype; D055170:Plant Root Nodulation / Q000235:genetics; D018626:Retroelements / Q000235:genetics*; D053204:Root Nodules, Plant / Q000254:growth & development*; D013559:Symbiosis / Q000235:genetics*; D014026:Nicotiana / Q000235:genetics*
D018626:Retroelements