the solvothermal precursors, making the com-
posite promising for up-scaling (fig. S44).
Collectively, (CsPbI 3 )0.25(agZIF-62)0.75offers
substantial advantages over LHP composites
with other substrates (fig. S45 and table S2).
Last, an array of composites were formed
from CsPbX 3 (X = Cl, Br, and mixed halide
ions) and agZIF-62, showing a wide color
gamut with narrow PL peaks (Fig. 4, B and C,
and table S3). For all the CsPbX 3 composites,
their absolute PL intensities were at least two
orders of magnitude higher than those of the
corresponding pure CsPbX 3 samples, either as
synthesized or after being treated with identi-
cal sintering (fig. S46). These properties, to-
gether with the high processibility (Fig. 4D),
render these monolithic materials ideal can-
didates for downshifting white LEDs (fig. S47).
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ACKNOWLEDGMENTS
We acknowledge D. D’Alessandro and Y. Sun for discussions.
Funding:This work was supported by the Australian Research
Council (DE190100803, DE210100930, DP180103874,
DE190101152, DP200101900, and FL190100139); Department of
Industry, Innovation and Science (AISRF53765); University of
Queensland (UQECR2057677); Australian Centre for Advanced
Photovoltaics fellowship and Australian Renewable Energy Agency;
Henry Royce Institute for a summer undergraduate internship;
National Natural Science Foundation of China (51772326); RIKEN
Information Systems and Cybersecurity (Project Q20266);
Slovenian Research Agency (research core funding P1-0021);
Ras al Khaimah Center for Advanced Materials; Royal Society and
Leverhulme Trust for a University Research Fellowship (UF150021)
and Philip Leverhulme Prize (2019); European Union’s Horizon2020 research and innovation program (823717–ESTEEM3); and
the National Agency for Research future investment TEMPOS-
CHROMATEM (ANR-10-EQPX-50). Part of this research was
undertaken on the THz/Far-IR, SAXS, and PD beamlines at the
Australian Synchrotron, part of ANSTO (M15988 and M15433).
The authors acknowledge the Centre for Microscopy and
Microanalysis and the Australian National Fabrication Facility, the
University of Queensland; the Leeds EPSRC Nanoscience and
Nanotechnology Facility (LENNF); ESRF / ID31 beamline; and the
Diamond Light Source for access and support in the use of
the electron Physical Sciences Imaging Centre (MG21980 and
MG25140).Author contributions:Conceptualization: J.H. and
T.D.B. Methodology: J.H., P.C., T.W., S.M.C., Z.W., and T.U.S.
Investigation: J.H., A.S., S.-C.L., T.W., E.B.N., A.K., G.M., R.D.,
L.H.G.T., D.N.J., M.S’A., S.M.C., B.C., X.L., R.L., S.L., M.L., I.M., and
D.A. Funding acquisition: J.H., S.M.C., G.M., A.K.C., V.C., L.W.,
and T.D.B. Project administration: J.H., S.M.C., L.W. Writing,
original draft: J.H., A.K.C., V.C., L.W., and T.D.B. Writing, review and
editing: all authors.Competing interests:. J.W., V.C., and L.W.
are inventors on Australian Provisional Patent Application no.
2021902824 held by the University of Queensland, titled
“Composite Material”and related to composite glass material
and methods of making composite glass materials.Data and
materials availability:All data are available in the manuscript or
the supplementary materials. The composite glass samples are
available from J.W. and L.W. under a materials transfer agreement
with the University of Queensland.SUPPLEMENTARY MATERIALS
science.org/doi/10.1126/science.abf4460
Materials and Methods
Supplementary Text
Figs. S1 to S47
Tables S1 to S3
References ( 29 Ð 61 )
27 October 2020; resubmitted 28 May 2021
Accepted 17 September 2021
10.1126/science.abf4460PLANT SCIENCE
NIN-like protein transcription factors regulate
leghemoglobin genes in legume nodules
Suyu Jiang^1 , Marie-Françoise Jardinaud^2 , Jinpeng Gao^1 , Yann Pecrix2,3, Jiangqi Wen^4 ,
Kirankumar Mysore^4 , Ping Xu^5 , Carmen Sanchez-Canizares^6 , Yiting Ruan^1 , Qiujiu Li^1 , Meijun Zhu^1 ,
Fuyu Li^1 , Ertao Wang^1 , Phillip S. Poole^6 , Pascal Gamas^2 , Jeremy D. Murray1,7*
Leghemoglobins enable the endosymbiotic fixation of molecular nitrogen (N 2 ) in legume nodules by channeling
O 2 for bacterial respiration while maintaining a micro-oxic environment to protect O 2 -sensitive nitrogenase.
We found that the NIN-like protein (NLP) transcription factors NLP2 and NIN directly activate the expression of
leghemoglobins through a promoter motif, resembling a“double”version of the nitrate-responsive elements
(NREs) targeted by other NLPs, that has conserved orientation and position across legumes. CRISPR knockout
of the NRE-like element resulted in strongly decreased expression of the associated leghemoglobin. Our
findings indicate that the origins of the NLP-leghemoglobin module for O 2 buffering in nodules can be traced
to an ancient pairing of NLPs with nonsymbiotic hemoglobins that function in hypoxia.
M
ost legume species can form an endo-
symbiosis with rhizobia bacteria, form-
ing highly specialized root nodules
containing cells in which rhizobial ni-
trogenase reduces dinitrogen to am-
monia. Nitrogenase is rapidly and irreversibly
deactivated by oxygen, whereas N 2 fixation
is energy-intensive, so the rate of N 2 fixation
is a compromise between the O 2 required to
support the energy demands of the symbionts
and the poisoning of nitrogenase by O 2 , the so-
called“oxygen paradox”( 1 ). To address this
constraint, up to 40% of nodule protein con-
sists of leghemoglobins (LgHbs), which con-
tain an O 2 -binding heme group that colors the
nodule red. LgHbs feature an extremely fast
O 2 association rate and a relatively slow O 2
dissociation rate, allowing them to buffer the
free oxygen concentration at ~10 nM and there-
by maintain O 2 levels compatible with N 2 fix-
ation. Notwithstanding the central role of LgHbs
in N 2 fixation, their transcriptional regulation
and the manner of their recruitment to nod-
ulation have not been elucidated.The founding member of the NIN-like pro-
tein family, NIN (Nodule Inception), is re-
quired for infection by rhizobia as well as for
nodule formation ( 2 ). In contrast,Medicago
truncatulaNLP1 andLotus japonicusNLP4
are required for nitrate suppression of nod-
ulation ( 3 , 4 ).NINandNLP2, however, are
the only NLPs expressed in medicago nodules
(Fig. 1A and fig. S1A). The expression ofNLP2
and severalLgHbs was strongly reduced in
nodules induced by the rhizobia mutantsbacA
andfixJ; in these mutants, N 2 fixation is defec-
tiveasaresultoflackofsymbiosomesornitro-
genase activity, respectively, indicating a tight
connection ofNLP2with N 2 fixation (Fig. 1B).
To investigate NLP2’s role, we used an
aeroponic system to evaluate nodulation on
NLP2-knockout roots. The resultant nodules
had normal zonation but were smaller and had
reduced N 2 fixation potential (Fig. 1, C and D).
We then isolated two mutants,nlp2-1andnlp2-2
(fig. S1B). Thenlp2-1mutant had smaller nodules
in aeroponics, matching the CRISPR knockout
phenotype (Fig. 1E), and had a greatly reduced
plant biomass but developed a normal number
of nodules (Fig. 1F). However, when grown in
substrate, the mutant developed normal-sized
nodules (fig. S1C). The increase in phenotype
severity seen in aeroponics versus substrate con-
ditions may reflect the much larger and more
extensively nodulated root system that develops
under aeroponics, which may exaggerate theSCIENCEscience.org 29 OCTOBER 2021•VOL 374 ISSUE 6567 625
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