Natural variation of rice strigolactone biosynthesis is associated with the deletion of two MAX1 orthologs.
Rice (Oryza sativa) cultivar Azucena--belonging to the Japonica subspecies--exudes high strigolactone (SL) levels and induces high germination of the root parasitic plant Striga hermonthica. Consistent with the fact that SLs also inhibit shoot branching, Azucena is a low-tillering variety. In contrast, Bala, an Indica cultivar, is a low-SL producer, stimulates less Striga germination, and is highly tillered. Using a Bala × Azucena F6 population, a major quantitative trait loci--qSLB1.1--for the exudation of SL, tillering, and induction of Striga germination was detected on chromosome 1. Sequence analysis of the corresponding locus revealed a rearrangement of a 51- to 59-kbp stretch between 28.9 and 29 Mbp in the Bala genome, resulting in the deletion of two cytochrome P450 genes--SLB1 and SLB2--with high homology to the Arabidopsis SL biosynthesis gene, MAX1. Both rice genes rescue the Arabidopsis max1-1 highly branched mutant phenotype and increase the production of the SL, ent-2'-epi-5-deoxystrigol, when overexpressed in Bala. Furthermore, analysis of this region in 367 cultivars of the publicly available Rice Diversity Panel population shows that the rearrangement at this locus is a recurrent natural trait associated with the Indica/Japonica divide in rice.
Laboratory of Plant Physiology, Wageningen University, 6708 PB, Wageningen, The Netherlands.
Catarina
C
Cardoso
Yanxia
Y
Zhang
Muhammad
M
Jamil
Jo
J
Hepworth
Tatsiana
T
Charnikhova
Stanley O N
SO
Dimkpa
Caroline
C
Meharg
Mark H
MH
Wright
Junwei
J
Liu
Xiangbing
X
Meng
Yonghong
Y
Wang
Jiayang
J
Li
Susan R
SR
McCouch
Ottoline
O
Leyser
Adam H
AH
Price
Harro J
HJ
Bouwmeester
Carolien
C
Ruyter-Spira
D032461:Chromosomes, Plant; D017353:Gene Deletion; D017343:Genes, Plant; D014644:Genetic Variation; D007783:Lactones / Q000378:metabolism*; D008969:Molecular Sequence Data; D012275:Oryza / Q000235:genetics / Q000378:metabolism*; D010940:Plant Proteins / Q000235:genetics*; D040641:Quantitative Trait Loci
D007783:Lactones; D010940:Plant Proteins
CYP450; QTL; plant hormone