| Rice is an important food crop, and lodging is an important limiting factor to rice high and stable yield. Therefore, it’s significant to study the rice core germplasm for the identification of genes involved in the lodging-related traits. The study was carried out in the potted experiment field of the National Key Laboratory of Crop Genetic Improvement in Huazhong Agricultural University from April to November,2012and April to November,2013.245rice core germplasm resources were used in the experiment during2012, the related characters of the basal two elongated internode at the late rice ripening period were determined and analyzed by simple statistics and GWAS.512rice core germplasm resources were used in the experiment during2013, the lodging-related traits were determined at the25th day after rice full heading, and lodging index was used to evaluate the lodging resistance ability. The rice core germplasm were classified into4types by the Fast Clustering analysis method. The lodging-related traits and lodging index and analyzed by simple statistics, variance analysis, correlation and path analysis and GWAS.1. The results of the simple statistics to the agronomic traits determined in2012: The plant height(PH) range from57.75cm to213.25cm, and average is132.96cm; the effective tiller number range from6.5to37.75, and average is17.2; the first elongated internode length(FIL) range from1.18cm to17.28cm, and average is5.58cm; the second elongated internode length(SIL) range from2.84cm to31.5cm, and average is11.8cm; the first elongated internode long axis(FLA), short axis(FSA) and wall thickness(FIT) range from2.64mm to8.28mm (average is5.38mm),2.1mm to6.64mm (average is4.13mm) and0.41mm to1.62mm (average is0.9mm); the second elongated internode long axis(SLA), short axis(SSA) and wall thickness(SIT) range from2.08mm to8.22mm (average is5.1mm),1.57mm to6.95mm (average is4.26mm) and0.32mm to1.36mm (average is0.7mm). The coefficient of variation of FIL is the largest, at58.65%; followed by SIL, the variation coefficient was50.44%; the variation coefficient of PH and ETN were higher, at26.12%and31.84%respectively.; the variation coefficient of the first and second elongated internode long axis, short axis and wall thickness are all more than16%.2. The512rice core germplasm with complete data are divided into four types through cluster analysis: high lodging resistance type (lodging index:0.24-0.24), medium lodging resistance type (lodging index:0.53-0.53), low lodging resistance type (lodging index:0.94-1.5) and lodging type (lodging index:1.52to6.66).3. The simple statistics and analysis of variance to different lodging resistance types of rice core germplasm showed that, the variable coefficient of the breaking-resistant strength in the basal stem10cm is the largest, the second is the fresh weight from the basal stem10cm broken place to the top of the panicle and panicle fresh weight, the variable coefficient of the plant height, panicle length and basal stem5cm long axis, short axis, wall thickness and stem thick are relatively small, but are also larder than14%. Plant height and the breaking-resistant strength in the basal stem10cm among the four types have extremely significant differences, and the high lodging resistance type is also existed in high plant height varieties.4. The correlation and path analysis demonstrated that, among the traits related to lodging index, the correlation coefficient of the the breaking-resistant strength in the basal stem10cm(r=-0.45761**) is the largest, the second is the plant height (r=0.21108**), the correlation coefficient of the panicle fresh weight, the fresh weight from the basal stem10cm broken place to the top of the panicle and the basal stem5cm wall thickness and stem thick are also extremely significance. The direct path coefficient of the breaking-resistant strength in the basal stem10cm is the largest(P=-0.71809**), the second is the fresh weight from the basal stem10cm broken place to the top of the panicle(P=0.31484**) and plant height(P=0.23105**). The direct path coefficient of the panicle fresh weight(P=0.03339*) and the basal stem5cm wall thickness(P=-0.04298*) and lodging index are also significant. The direct path coefficient of the basal stem5cm stem thick and the lodging index had no significant (P=0.01692).5. According to the GWAS:there are48SNPs detected at the chromosomal level (threshold of1.21×10-6) are significant with the6rice core germplasm resources quantitative traits (PH, ETN, FIL, SIL, FSA, FIT) significantly correlated, other measured traits associated SNPs loci in2012are not found in the chromosome level, and the significant SNPs of plant height in the1st chromosome is near the famous dwarfing gene sdl.There are74SNPs are significant with the9rice core germplasm resources quantitative traits (plant height, panicle length, basal stem5cm long axis, basal stem5cm short axis, basal stem5cm wall thickness, the breaking-resistant strength in the basal stem10cm, panicle fresh weight, tillering angle, full heading time) in2013. The significant SNPs of plant height in the1st chromosome is near the famous dwarfing gene sdl. The significant SNPs of tillering angle in the1st chromosome is near the cloned gene log which is associated with tillers of rice.The significant SNPs of tillering angle in the9th chromosome is near the cloned gene TAC1, TAC1is a tillering angle control genes. The significant SNPs of full heading time in the1st chromosome is near the cloned gene OsMADS51, OsMADS51relate to the rice flowering time under short day conditions. The significant SNPs of full heading time in the6th chromosome is near the cloned gene OsMADS5which relate to the formation of flower organ. The significant SNPs of basal stem5cm wall thickness in the6th chromosome and the significant SNPs of full heading time in the9th chromosome have neat peaks where nearby correlated SNPs all show the same signal and high P values are the important locus need to focus on. |
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