| There is huge heterosis over the better parent between indica and japonica rice. Application of the heterosis between indica and japonica subspecies has been considered to be one of the primary method for breeding super hybrid rice. Many people think that it will bring about a break through in rice breeding, and more and more people are interested in studying it. In this study, in order to overcome the handicap of fertility between indica and japonica rice and breed new indica-compatible male sterile lines (ICMSLs), a breeding route was designed based on the genetic analysis of hybrid fertility between indica and japonica rice. The genetic basis of hybrid fertility in the ICMSLs was verified using molecular markers. The application values of the ICMSLs and the feasibility and efficiency of the breeding technologies used in this study were evaluated. The study will provide scientific evidence for application of heterosis between indica and japonica rice and will be helpful to understand the genetic basis of heterosis between indica and japonica rice. The main results are as follows:1.9 indica rice and 8 japonica rice were picked out, then 72 F1 were obtained using imperfection double cross design. The genetic effect, heterosis and genetic correlation of pollen fertility and spikelet fertility in those F1 were analyzed systematically by the addictive-dominant genetic model (AD model) and statistical analysis. The result indicates that:The declining of fertility between Indica and Japonica is controlled by dominant effect of the genes. The correlation coefficient of the phenotype, genetic, additive and dominant between the pollen fertility and spikelet fertility are 0.598,0.612,0.988 and 0.581 respectively, and all of them are significant difference. The result indicates that increasing of the pollen fertility could improve spikelet fertility of the offspring, but the spikelet ferility is affected by other factors. The fertility of F1 derived from the cross between the xiushui and indica is obviously higher than that of F1 derived from the cross between the northern japonica and indica.2. Two genetic linkage map were constructed using two F2 populations, Zhenshan 97B /xiushui 13 and the Zhenshan 97B/Liao 91B, and QTLs of the pollen fertility and spikelet fertility were analyzed in genome-wide level by QTL Network2.0, the effect and the contribution rate of QTLs were compared to understanding the genetic basis of fertility. The results indicate that:there were different results between two F2 populations. Confferring the pollen fertility, there is a QTL qPF5-1 locating in region of RM421 and RM26 on chromosome 5 among the population derived from Zhenshan 97B and xiushui 13, the genetic contribution rate of which is 11.25%, and the value of additive effect is -8.65. There are two QTLS, qPF3 and qPF5-2, detected from the population of Zhenshan 97B/Liao 91B, qPF3 is located between markers RM3436-RM293 on chromosome 3, the additive effect is the major factor and the genetic contribution rate of which is 15.35%. qPF5-2,which is located in the regions of RM289-RM169 on chromosome 5,whose location is different from that of qPF5-1, is interacted by the additive effect and dominant effect, theirs genetic contribution rate are 8.80% and 6.39% respectively, there are two QTLs conferring the spikelet fertility, qSPF6-1 and qSPF6-2, detected around RM402 on chromosome 6 in both populations. The additive effect value of the qSPF6-1 in the population derived from Zhenshan 97B/xiushui 13 is -0.855, the genetic contribution rate is 16.31%, and the dominant effect value is 3.97 and the genetic contribution rate is only 1.01%, the QTL was considered to be the wide compatible gene S-5n. The dominant effects of qSPF6-2 is-8.43,which detected in the population derived from Zhenshan 97B/ Liao 91B, and the genetic contribution rate is 9.68%, and the heterozygous allele in the loci leads to declining the spikelet fertility. There are two QTLS, qPF5 and qPF8, detected from both population respectively, the additive effect is the major factor(-5.95 and -5.48), and the genetic contribution rate of qSPF5 is 9.11%, and that of qPF8 is 9.70% respectively, there are a pair of QTLs conferring the epistasis of fertility in two populations respectively, but the contribution rate is low, and the interaction is complicated.3. Based on the genetic analysis of fertility between Indica and japonica rice, the population derived from Zhenshan 97B/xiushui 13 was chosen for breeding new CMS lines with the wide compatible gene and the high seed setting rate. It can create the Specific indicaljaponica Germpiasm with the wide compatible gene. A series of Indica-compatibility CMS lines were bred rapidly by pedigree method and backcrossing in five years. There are good agronomic characters with complete pollen abortion and stable fertility in those CMS lines,and high seed setting rate between those CMS lines and the indica restorer lines could be get. The stability of fertility of Indica-clinious, Japonica-clinious and Japonica was indentified under two different temperature. The results indicates that the pollen fertility and the spikelet fertility of descendants derived from the cross between japonica and indica declines obviously under low temperature, so the Japonica-clinious lines with stable fertility should be a top priority in breeding.4. There are 7 representative CMS lines were picked out according to Clustering Analysis by SSR and fertility analyzing under high altitude condition. Based on analyzing of the main characters and the genetic constitution of the CMS lines and combining QTL analysis of fertility and the fertility of F1 derived from the selected CMS lines, the spikelet fertility of F1 between Indica and japonica rice were verified by molecular technologies. The result are as the fellow:The fertility of F1 were decreased obviously in the breeding population with high-japonica genetic constitution, the related QTL of fertility in the Indica-compatibility Male Sterile Line can overcame the handicap of fertility between indiaca and japonica, and the genetic effect of fertility SiSi was higher than that of SiSn, the wide compatible gene qSPF 6-1 in xiushuil3 can increase the seed setting of the F1 between indiaca and japonica, but fertility is a complicated trait and it is effected by qSPF 5 obviously.5. Seven representative intermediate CMS and six restorer lines were screened out, and 11-32A was chosen as the control CMS line too. According to imperfection double cross design (6X8), a suit of genetic materials including parents and 48 F1 was selected,using the addictive-dominant genetic model(AD model) and statistical analysis method, the genetic effect, heterosis and genetic correlation heterosis concerning yielding of the selected CMS line were analyzed, and their value in breeding were appraised too. The results indicates that:(1)The general combining ability of grain weight of per plant in line 08cmg132 is the best among the 7 CMS lines, and the specific combining ability of F1 which derived from 08cmg164 was the greatest. The seed setting rate of 26 combinations are more than 77% in 42 Indica-japonica combinations, and the grain weight of per plant in 16 combinations are heavier than that ofâ…¡-you63.The heterosis of indiaca and japonica are mainly embodied in weight of per plant, plant height, total grain number, real grain number and total grain number of per fringe. (2) The most of the main characters concerning yield in the hybrids are effected by additive effect and dominant effect of alleles. Yield is a complicated and integrated character, it can not be selected by other concerning related character, there are negative correlated in phenotypic correlation, additive and dominance correlation among plant height, the main panicle length,1000-grain weight, growth period and seed setting rate, so those traits should be emphasized in breeding process to increase seed setting rate between indiaca and japonica hybrids. (3) The narrow- sense heritability of plant height, main ear length, total grain number and seed setting rate were higher, those can be selected effectively in early generation, but the narrow- sense heritability of grain weight of per plant, panicle number, total grain number and seed setting rate were lower, those should be selected in later generations because of serious segregating.Based on the genetic analyse of fertility between Indica and japonica rice, a series of Indica-compatible Male Sterile Lines were bred rapidly and effectively by combining molecular and conventional technologies. The breeding project was correct and the breeding route was available, the Indica-compatibility Male Sterile Line has good prospects in application of heterosis hybrids between Indica and Japonica. |
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