ABSTRACT
The pentatricopeptide repeat (PPR) gene family represents one of the largest gene families in higher plants. Accumulating data suggest that PPR proteins play a central and broad role in modulating the expression of organellar genes in plants. Here we report a rice (Oryza sativa) mutant named young seedling albino (ysa) derived from the rice thermo/photoperiod-sensitive genic male-sterile line Pei'ai64S, which is a leading male-sterile line for commercial two-line hybrid rice production. The ysa mutant develops albino leaves before the three-leaf stage, but the mutant gradually turns green and recovers to normal green at the six-leaf stage. Further investigation showed that the change in leaf color in ysa mutant is associated with changes in chlorophyll content and chloroplast development. Map-based cloning revealed that YSA encodes a PPR protein with 16 tandem PPR motifs. YSA is highly expressed in young leaves and stems, and its expression level is regulated by light. We showed that the ysa mutation has no apparent negative effects on several important agronomic traits, such as fertility, stigma extrusion rate, selfed seed-setting rate, hybrid seed-setting rate, and yield heterosis under normal growth conditions. We further demonstrated that ysa can be used as an early marker for efficient identification and elimination of false hybrids in commercial hybrid rice production, resulting in yield increases by up to approximately 537 kg ha(-1).
Subject(s)
Oryza/metabolism , Phenotype , Plant Proteins/genetics , Seedlings/metabolism , Seeds/metabolism , Amino Acid Motifs , Amino Acid Sequence , Biomarkers , Chimera/genetics , Chimera/metabolism , Chlorophyll/metabolism , Chloroplasts/metabolism , Chloroplasts/ultrastructure , Chromosome Mapping , Chromosomes, Plant/genetics , Chromosomes, Plant/metabolism , Cloning, Molecular , Crosses, Genetic , Fertility , Genes, Plant , Hybrid Vigor , Microscopy, Electron, Transmission , Molecular Sequence Data , Mutation , Oryza/anatomy & histology , Oryza/genetics , Photoperiod , Plant Leaves/anatomy & histology , Plant Leaves/metabolism , Plant Proteins/metabolism , Plant Stems/metabolism , Plant Stems/physiology , Plants, Genetically Modified/genetics , Plants, Genetically Modified/metabolism , Seedlings/genetics , Seeds/genetics , Transcription, GeneticABSTRACT
A mapping population of 81 F11 lines (Recombinant Inbred Lines, RILs), derived from a cross between a japonica variety Kinmaze and an indica variety DV85 by single-seed descent method, was used to detect quantitative trait loci (QTL) for traits associated with photosynthetic functions. Total leaf nitrogen content (TLN), chlorophyll a/b ratio (Chl. a:b) and chlorophyll content (Chl) were measured in leaves of rice (Oryza sativa L.) at the 7th day after heading. A total of six putative QTLs were detected with percentage of variance explained (PVE) ranging between 11.2% -29.6%, and LOD of QTLs 2.66-4.81. Of those putative QTLs, three for TLN were detected on chromosomes 1,2 and 11, with PVE of 17.3%, 15.3% and 13.7%, respectively;Two controlling Chl. a:b on chromosomes 3 and 4, PVE of 13.8% and 29.6%, one for Chl on chromosome 1, PVE of 11.2%. Four of those detected QTLs were newly reported in this study. Interestingly, the QTL controlling chlorophyll content,namely qCC-1 reported here,was detected in the region of the RFLP marker C122 on chromosome 1, where harbored NADH-glutamate synthase structure gene according to a previous study. Because the biosynthesis of chlorophyll begins with glutamate, qCC-1 would play a vital role in photosynthetic functions. Whereas,no QTL controlling chlorophyll content were detected at the 30th day after heading, suggesting that the effect of the QTL controlling chlorophyll content decreased during leaf senescence.
Subject(s)
Oryza/genetics , Photosynthesis/genetics , Quantitative Trait Loci/genetics , Chlorophyll/analysis , Chromosome Mapping , Chromosomes, Plant/genetics , Lod Score , Nitrogen/analysis , Oryza/chemistry , Oryza/physiology , Plant Leaves/chemistry , Plant Leaves/genetics , Plant Leaves/physiologyABSTRACT
It is meaningful to study the genetics of the traits associated with photosynthesis such as leaf chlorophyll and H2O2 contents for high yield breeding in rice. A mapping population of 98 BC1F9 lines (backcross Inbred Lines, BIL), derived from a backcross of Nipponbare (japonica)/Kasalath(indica)//Nipponbare by the single-seed-descent methods, was employed to map quantitative trait loci (QTL) underlying such rice traits as leaf chlorophyll and H2O2 contents. Five and two QTLs were detected for leaf Chlorophyll and H2O2 content variation, respectively. Among the QTLs detected, q-Chl1 on chromosome 1 accounted for 22% variation for leaf chlorophyll content variation. The alleles from Nipponbare increased stature at the locus; On the other hand, q-H2O2(1) which associated with H2O2 content was also located on the same region as q-Chl1. The alleles from Nipponbare decreased stature at this locus. The 2 traits have the 2 QTL sharing the same chromosome locations, which was located between C86 and C813 on chromosome 1. Epistasis analysis showed QTL with interaction distributed on chromosome 2, 6, 11 and 12. However, no QTL interacted with q-Chl1 or q-H2O2(1) was detected. It can be deduced that alleles from Nipponbare at the region between C86 and C813 on chromosome 1 increases leaf chlorophyll content and decreases H2O2 content at the mean time with significant additive effect but little epistasis.
