Regulation of Nod factor biosynthesis by alternative NodD proteins at distinct stages of symbiosis provides additional compatibility scrutiny

TY - JOUR

T1 - Regulation of Nod factor biosynthesis by alternative NodD proteins at distinct stages of symbiosis provides additional compatibility scrutiny

AU - Kelly, Simon

AU - Sullivan, John T

AU - Kawaharada, Yasuyuki

AU - Radutoiu, Simona

AU - Ronson, Clive W

AU - Stougaard, Jens

N1 - © 2017 Society for Applied Microbiology and John Wiley & Sons Ltd.

PY - 2018/1

Y1 - 2018/1

N2 - The Lotus japonicus symbiont Mesorhizobium loti R7A encodes two copies of nodD and here we identify striking differences in Nod factor biosynthesis gene induction by NodD1 and NodD2 both in vitro and in planta. We demonstrate that induction of Nod factor biosynthesis genes is preferentially controlled by NodD1 and NodD2 at specific stages of symbiotic infection. NodD2 is primarily responsible for induction in the rhizosphere and within nodules, while NodD1 is primarily responsible for induction within root hair infection threads. nodD1 and nodD2 mutants showed significant symbiotic phenotypes and competition studies establish that nodD1 and nodD2 mutants were severely outcompeted by wild-type R7A, indicating that both proteins are required for proficient symbiotic infection. These results suggest preferential activation of NodD1 and NodD2 by different inducing compounds produced at defined stages of symbiotic infection. We identified Lotus chalcone isomerase CHI4 as a root hair induced candidate involved in the biosynthesis of an inducer compound that may be preferentially recognized by NodD1 within root hair infection threads. We propose an alternative explanation for the function of multiple copies of nodD that provides the host plant with another level of compatibility scrutiny at the stage of infection thread development.

AB - The Lotus japonicus symbiont Mesorhizobium loti R7A encodes two copies of nodD and here we identify striking differences in Nod factor biosynthesis gene induction by NodD1 and NodD2 both in vitro and in planta. We demonstrate that induction of Nod factor biosynthesis genes is preferentially controlled by NodD1 and NodD2 at specific stages of symbiotic infection. NodD2 is primarily responsible for induction in the rhizosphere and within nodules, while NodD1 is primarily responsible for induction within root hair infection threads. nodD1 and nodD2 mutants showed significant symbiotic phenotypes and competition studies establish that nodD1 and nodD2 mutants were severely outcompeted by wild-type R7A, indicating that both proteins are required for proficient symbiotic infection. These results suggest preferential activation of NodD1 and NodD2 by different inducing compounds produced at defined stages of symbiotic infection. We identified Lotus chalcone isomerase CHI4 as a root hair induced candidate involved in the biosynthesis of an inducer compound that may be preferentially recognized by NodD1 within root hair infection threads. We propose an alternative explanation for the function of multiple copies of nodD that provides the host plant with another level of compatibility scrutiny at the stage of infection thread development.

KW - Journal Article

UR - http://www.scopus.com/inward/record.url?scp=85040086820&partnerID=8YFLogxK

U2 - 10.1111/1462-2920.14006

DO - 10.1111/1462-2920.14006

M3 - Journal article

C2 - 29194913

SN - 1462-2912

VL - 20

SP - 97

EP - 110

JO - Environmental Microbiology

JF - Environmental Microbiology

IS - 1

ER -