| Rapeseed (Brassica napus) is one of the most important oilseed crops, and it is cultivated over alarge area around the world. A1%increase in the seed oil content of rapeseed is equivalent to a2.3~2.5%increase in seed yield. Therefore, it is very important to improve the seed oil content inrapeseed.The major research contents in the study are as follows:1. Transcriptome sequencing of high-/low-oil content mixtures in DH population. A total of2370differentially expressed genes including1586up-regulated genes and1144down-regulatedgenes were detected. They were found according to the result of transcriptome sequencing ofextremely high-/low-oil content mixtures (10single plants of DH population with extremely high oilcontent were chosen as high-oil mixture and10single plants of DH population with extremely low oilcontent were chosen as low-oil mixture).2. Primer design and primer polymorphism aplificatoin. To address the deficiency inpolymorphic markers, we designed2244pairs of publicly available primers,5944pairs of newlydeveloped genome-sourced primers, and443pairs newly developed primers related to oil-contentgenes. Primer screened for polymorphisms in the parents zy036and51070, for the2244pairs ofpublicly available primers,5944pairs of newly developed genome-sourced primers, and443pairs ofnewly developed primers related to oil-content genes,400(17.83%),718(12.08%), and73(16.48%)amplified polymorphisms.3. Construction of the genetic linkage map. A genetic linkage map was constructed with527markers using our DH population. The map included181publicly available markers,298newlydeveloped genome-sourced markers and48newly developed markers related to oil-content genes.The total length of the19linkage groups was2,265.54cM, with an average length of119.34cM foreach linkage group and an average distance of4.30cM between markers.4. Mapping of QTLs and screening of candidate genes for seed oil content.17QTLs for oilcontent were detected using software WinQTL Cartographer2.5. By QTL mapping, the mount ofphenotype variation (R2) in seed oil content explained by an individual QTL ranged from9.15%to24.56%. The additive effect of an individual QTL varied from0.35to2.05. Seven candidate genesrelated with oil content was found by combining the information of gene-sourced primers based on50differentially expressed genes with17oil content QTLs regions.5. Analysis of correlation between oil content and yield of main inflorescence and itscomponents. It was shown that there were no significant correlation (P>0.05) between oil content andthe yield of main inflorescence, the number of effective siliques on main inflorescence, the number ofseeds per silique and thousand seeds weight.13QTLs of the yield of main inflorescence,10QTLs ofthe number of effective siliques on main inflorescence,15QTLs of the number of seeds per silique and23QTLs of thousand seeds weight were mapped.The points of innovation in the study are as follows:1. The B. napus DH population whose parents (10percentage points) with big difference in oilcontent were constructed. Many newly developed genome-and gene-sourced primers were designed.QTLs for oil content were detected, especially high-oil QTLs, which were laid foundation for finelyQTL mapping related to oil content and yield traits, genes cloning and molecular marker assistedselection (MAS) in B. napus.2. Many candidate genes in many QTL regions could be detected at same time by combiningdesign of gene primers using differentially expressed genes obstaining from result of transcriptomesequencing of high-/low-oil content mixtures in DH population, which supplied possibility to findquickly candidate genes related to the quantitative traits with high-throughput.3. It was shown that oil content and yield of main inflorescence had no significant correlationshipbetween each other by analysis of correlation between oil content and yield of main inflorescence andits components, which indicated that oil content and yield could be increased at same time. |
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