| Most of the photosynthesis-related traits of maize, such as Chlorophyll content, photosynthetic function, and yield, are quantitative traits controlled by many genes. In order to explore the genetic mechanism of maize photosynthetic traits, two F2 populations (GY and FR) with different genetic background were used in this study. Chlorophyll content, photosynthetic traits and yield traits were measured and QTL analysis was made at molecule level. The main results were as follows:(1) Two genetic linkage maps of F2 populations were constructedFor GY population,193 SSR markers were used to develop the maize genetic linkage maps covering 1164.6cM of the whole genome with an average interval of 6.10cM. For FR population, 212 SSR markers were selected to construct the maize genetic linkage maps covering 1153.3cM of the whole genome with an average interval of 5.44cM. That can achieve the basic requirements of the QTL mapping.(2) 21 QTLs for chlorophyll content were detectedThree traits associated with chlorophyll content were detected at the five-leaf stage and at the Postulation stage. Total 21 QTLs were detected on the chromosomes of 1,4,6 and 10.In GY population, One QTL for chlorophyll-a content (FChla), one QTL for chlorophyll-b content (FChlb) and one QTL for total chlorophyll content (FChlt) at five-leaf stage on the marker interval umc2391-mmc0371 of chromosome 4, respectively; Each QTL can explained phenotypic variance 8.65%-9.87%. One QTL for chlorophyll-a content (PChla), one QTL for chlorophyll-b content (PCh1b) and one QTL for total chlorophyll content (PChlt) at the Postulation stage on the marker interval mmc0501-bn1g1451 of chromosome 10, respectively; Each QTL can explain phenotypic variance 6.77%-6.93%.In FR population, fifteen putative QTLs were detected with percentage of variance explained (PVE) running between 5.25%-10.22%,and LOD of QTLs 2.60-4.71. Of those Putative QTLs, three for chlorophyll-a content at the five-leaf stage (FChla) were detected on chromosomes 1,1 and 10, with PVE of 7.50%,9.77% and 6.17%,respectively; Three controlling total chlorophyll content at the five-leaf stage (FChlt) on chromosomes 1,1 and 10, PVE 7.86%,10.22% and 5.47%. Two for chlorophyll-b content at the five-leaf stage (FChlb) on chromosome 1,PVE 8.64% and 7.17%;Two controlling chlorophyll-a content at the postulation stage (PChla) on chromosome 1, PVE 6.62% and 9.87%; Two controlling total chlorophyll content at the postulation stage (PChlt) on chromosome 1, PVE 7.20% and 9.48%. Three controlling chlorophyll-b content at the postulation stage (PChlb) on chromosomes 1,1 and 6, PVE 8.08%,6.87% and 5.25%. There was a major QTL for chlorophyll content at the five-leaf stage (FChlt) on the marker interval umc1073-bn1g1803 of chromosome 1, which explained 10.22% of the phenotypic variance.(3) 11 QTLs for photosynthetic traits were detectedIn total, eleven QTLs were detected on chromosomes1,2,3,5,7,8 and 9. There has detected not the "consistency" QTL in the two populations.In GY population, six photosynthetic traits QTL were detected which located on chromosomes 1,4,6 and 10, respectively; Of those Putative QTLs, one QTL for net photosynthetic rate (Pn), one OTL for stomata conductance (Sc), two OTL for intercellular CO2 concentration (Ci), two OTL for transpiration rate (Tr), the phenotypic variation of a single QTL was 5.64%-7.73%.In FR population, five photosynthetic traits QTL were detected which located on chromosomes 1,4,6 and 10, respectively; of those Putative QTLs, Two QTL for net photosynthetic rate (Pn), one OTL for stomata conductance (Sc), two OTL for intercellular CO2 concentration (Ci), two OTL for transpiration rate (Tr), the phenotypic variation of a single QTL was 5.79%-9.24%.(4) 26 QTLs for yield traits were detected26 QTLs were investigated on all the chromosomes except for chromosomes 8. In the two populations, a major QTL for kernel weight was detected on the marker interval umc1408-umcl944 of chromosome 7.13 QTLs were detected in the GY population, which distributed in chromosomes 1,2,4,6,7 and 10. Of those Putative QTLs, two major QTL for ear length (EL), one major QTL for rows per ear (RPE), two major QTL for kernel per row (KPR), two major QTL for 100-kernel weight (HKW), two major QTL for Cob diameter (CD), a single major QTL contribution rate of 10.15%-18.25%.13 QTLs were detected in the FR population, which distributed in chromosomes 1,3,4,5,7,9 and 10. Four QTL for ear length (EL), one QTL for rows per ear (RPE), two QTL for kernel per row (KPR), two QTL for 100-kernel weight (HKW), four QTL for Cob diameter (CD), a single QTL could explain the phenotypic variation of 5.83%-12.14%. There were two major QTLs for KPR and CD, which explained 12.14% and 10.25% of the phenotypic variance, respectively.(5) Markers close to the major QTLs.SSR marker mmc0371 was the nearest marker close to qYFCa-4 and qYFCt-4.umc1590 link with qYEL-1 closely, nc012 link with qYEL-6-2. umc1051 was the nearest marker close to qYKPE-4.vmc1248 link with qYKPR-6, bnlg2190 link with qYKPR-10. bnlg1265 link with qYHKW-4, umc1944 link with qYHKW-7. umc2005 was the nearest marker close to qYCD-2b, mmc0481 was the nearest marker close to qYCD-5.SSR marker umc1073 were the nearest marker close to qRFCa-1-2 and qRFCt-1-2. bnlg1007 were the nearest marker close to qRPCa-1-2 and qRPCt-1-2. umc1702 link with qRKPR-4 phi050 was the nearest marker close to qRCD-10. |
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