TY - JOUR
T1 - Three classes of hemoglobins are required for optimal vegetative and reproductive growth of Lotus japonicus
T2 - genetic and biochemical characterization of LjGlb2-1
AU - Villar, Irene
AU - Rubio, Maria C
AU - Calvo-Begueria, Laura
AU - Pérez-Rontomé, Carmen
AU - Larrainzar, Estibaliz
AU - Wilson, Michael T
AU - Sandal, Niels
AU - Mur, Luis A
AU - Wang, Longlong
AU - Reeder, Brandon
AU - Duanmu, Deqiang
AU - Uchiumi, Toshiki
AU - Stougaard, Jens
AU - Becana, Manuel
N1 - © The Author(s) 2021. Published by Oxford University Press on behalf of the Society for Experimental Biology.
PY - 2021/12
Y1 - 2021/12
N2 - Legumes express two major types of hemoglobins, namely symbiotic (leghemoglobins) and non-symbiotic (phytoglobins), with the latter being categorized into three classes according to phylogeny and biochemistry. Using knockout mutants, we show that all three phytoglobin classes are required for optimal vegetative and reproductive development of Lotus japonicus. The mutants of two class 1 phytoglobins showed different phenotypes: Ljglb1-1 plants were smaller and had relatively more pods, whereas Ljglb1-2 plants had no distinctive vegetative phenotype and produced relatively fewer pods. Non-nodulated plants lacking LjGlb2-1 showed delayed growth and alterations in the leaf metabolome linked to amino acid processing, fermentative and respiratory pathways, and hormonal balance. The leaves of mutant plants accumulated salicylic acid and contained relatively less methyl jasmonic acid, suggesting crosstalk between LjGlb2-1 and the signaling pathways of both hormones. Based on the expression of LjGlb2-1 in leaves, the alterations of flowering and fruiting of nodulated Ljglb2-1 plants, the developmental and biochemical phenotypes of the mutant fed on ammonium nitrate, and the heme coordination and reactivity of the protein toward nitric oxide, we conclude that LjGlb2-1 is not a leghemoglobin but an unusual class 2 phytoglobin. For comparison, we have also characterized a close relative of LjGlb2-1 in Medicago truncatula, MtLb3, and conclude that this is an atypical leghemoglobin.
AB - Legumes express two major types of hemoglobins, namely symbiotic (leghemoglobins) and non-symbiotic (phytoglobins), with the latter being categorized into three classes according to phylogeny and biochemistry. Using knockout mutants, we show that all three phytoglobin classes are required for optimal vegetative and reproductive development of Lotus japonicus. The mutants of two class 1 phytoglobins showed different phenotypes: Ljglb1-1 plants were smaller and had relatively more pods, whereas Ljglb1-2 plants had no distinctive vegetative phenotype and produced relatively fewer pods. Non-nodulated plants lacking LjGlb2-1 showed delayed growth and alterations in the leaf metabolome linked to amino acid processing, fermentative and respiratory pathways, and hormonal balance. The leaves of mutant plants accumulated salicylic acid and contained relatively less methyl jasmonic acid, suggesting crosstalk between LjGlb2-1 and the signaling pathways of both hormones. Based on the expression of LjGlb2-1 in leaves, the alterations of flowering and fruiting of nodulated Ljglb2-1 plants, the developmental and biochemical phenotypes of the mutant fed on ammonium nitrate, and the heme coordination and reactivity of the protein toward nitric oxide, we conclude that LjGlb2-1 is not a leghemoglobin but an unusual class 2 phytoglobin. For comparison, we have also characterized a close relative of LjGlb2-1 in Medicago truncatula, MtLb3, and conclude that this is an atypical leghemoglobin.
KW - Hemoglobins
KW - Lotus japonicus
KW - Medicago truncatula
KW - mutants
KW - nitric oxide
KW - symbiosis
UR - http://www.scopus.com/inward/record.url?scp=85122584677&partnerID=8YFLogxK
U2 - 10.1093/jxb/erab376
DO - 10.1093/jxb/erab376
M3 - Journal article
C2 - 34387337
SN - 0022-0957
VL - 72
SP - 7778
EP - 7791
JO - Journal of Experimental Botany
JF - Journal of Experimental Botany
IS - 22
ER -