ABSTRACT
Rice starch properties of apparent amylose content (AAC), amylose content (AC), and amylopectin content (AP) are considered as the most important factors influencing grain quality as they are highly correlated with eating quality. This report is the first effort of predicting AC and AP values in rice flours, and recognizing waxy rice from non-waxy rice using NIRS technique. Calibration models generated by different mathematical, preprocessing treatments and combinations of wavelengths and signals were compared and optimized. The model established by modified partial least squares (MPLS) with "2, 8, 8, 2"/ Inverse MSC and â¼138 wavelengths signals yielded high RSQ of 0.977, 0.928, and 0.912 for AAC, AC and AP, respectively, as simultaneous measurement. MPLS-DA (discriminant analysis) could classify waxy and non-waxy rice with 100% accuracy. This high-throughput technology is valuable for breeding programs, and for the purposes of quality control in the food industry.
Subject(s)
Amylose , Oryza , Amylopectin/chemistry , Amylose/chemistry , Oryza/chemistry , Plant Breeding , Spectroscopy, Near-Infrared , Starch/chemistry , WaxesABSTRACT
In rice, the contents of protein and amino acids are the major parameters of nutritional quality. Co-localization of quantitative trait loci (QTLs) for heading date and protein content were reported, but pleiotropism of heading-date genes on protein contents has not been investigated. Here, we reported that rice florigen gene RFT1 plays an important role in controlling amino acid contents of rice grain. Firstly, 73 QTLs for the contents of 17 amino acids in unmilled rice were detected using recombinant inbred lines (RILs) of the indica rice cross Zhenshan 97 (ZS97)/Milyang 46 (MY46). Then, the effect of the largest cluster consisting of 14 QTLs, located in proximity to the rice florigen genes RFT1 and Hd3a, was validated using three populations consisting of near isogenic lines (NILs) that only segregated a region covering the target QTL. The first and second NIL populations were derived from a residual heterozygote identified from the ZS97/MY46 RIL population, consisting of homozygous lines that were only segregated in a 29.9-kb region covering the two florigen genes and a 1.7-kb region for RFT1, respectively. The third NIL population was segregated for the RFT1 ZS97 transgene in the background of japonica rice cultivar Zhonghua 11. In all the three NIL populations, RFT1 was shown to have a strong effect on the contents of most amino acids, with the ZS97 allele always having the reducing effects. By comparing QTLs for amino acid contents detected in the ZS97/MY46 RIL population and genes/QTLs previously identified for heading date difference between ZS97 and MY46, possible pleiotropism on amino acid contents was also shown for other key heading-date genes including Hd1, Ghd7, and OsGI.
ABSTRACT
A recombinant inbred line (RIL) population bred from a cross between a javanica type (cv. D50) and an indica type (cv. HB277) rice was used to map seven quantitative trait loci (QTLs) for thousand grain weight (TGW). The loci were distributed on chromosomes 2, 3, 5, 6, 8 and 10. The chromosome 3 QTL qTGW3.2 was stably expressed over two years, and contributed 9-10% of the phenotypic variance. A residual heterozygous line (RHL) was selected from the RIL population and its selfed progeny was used to fine map qTGW3.2. In this "F2" population, the QTL explained about 23% of the variance, rising to nearly 33% in the subsequent "F2:3" generation. The physical location of qTGW3.2 was confined to a ~556 kb region flanked by the microsatellite loci RM16162 and RM16194. The region also contains other factors influencing certain yield-related traits, although it is also possible that qTGW3.2 affects these in a pleiotropic fashion.
Subject(s)
Genes, Plant , Oryza/genetics , Seeds/genetics , Alleles , Chromosome Mapping , Chromosomes, Plant/genetics , Crops, Agricultural/anatomy & histology , Crops, Agricultural/genetics , Genetic Linkage , Inbreeding , Oryza/anatomy & histology , Quantitative Trait Loci , Seeds/anatomy & histologyABSTRACT
The genetic diversity in 370 aromatic rice germplasms introduced from home and abroad, was investigated by using a total of 60 SSR markers. 361 alleles were detected, with the number of alleles (Na) per loci ranging from 2 to 10. The Nei's genetic diversity index (He) among loci varied widely from 0.104 at RM308 to 0.885 at RM2634 with an average value of 0.663. There was an obvious difference in SSR allelic diversity between indica and japonica rice. Indica rice showed more variation than japonica rice both for Na and He. Meanwhile, the genetic diversity of the landraces was higher than that of the improved varieties, and Na of the improved varieties was 86.5% of the landraces. Analysis of molecular variance indicated that 43.08% of the variation was from genetic differences between subspecies. It was also demonstrated that the genetic differentiation among different rice ecological regions ranged from 1.69% to 14.40%. There was significant differentiation between Southern China and Southwestern China, Central China and Southwestern China, respectively. Cluster analysis showed that 370 aromatic rice varieties were mainly classified into indica and japonica, and aromatic rice varieties from the same areas or the neighboring provinces were basically assigned to the same group.