Heterotic Loci Analysis For Internode Length Under Ear Basing On Test Cross Population Of The Single Segment Substitution Lines In Maize

Heterosis,an important genetic phenomenon in biology,was widely applied in improving the crops’ yield and quality.Because the genetic mechanisms of heterosis may be different in different traits,to analysis the mechanism of heterosis of different traits was of great significance for comprehensive understanding heterosis.Ear height(EH)was an important agronomic trait,which was closely related to the maize yield and lodging.And EH consisted of internode number and internode length under ear.Because internode number under ear in different inbred lines and hybrids was essentially constant,ear height mainly was decided by different internode length under ear jointly.According to the result of our laboratory’s early research,the seventh、eighth and ninth internode length under ear play a decisive role in ear height and show strong heterosis in maize.In this study,the genetic background of lx9801 of the Chang 7-2 chromosome single segment substitution lines(Single segment substitution lines,SSSLs)groups were used as materials to construct testcross populations with inbred line Z58 and 9058 respectively.The QTL and HL of seventh、eighth、ninth internode length and EH were detected in 2 years and 2 sites.1.Using these SSSL groups for QTL mapping,we detected 18 seventh internode length QTLs,23 eighth internode length QTLs and 17 ninth internode length QTLs.There are 8 common QTL of seventh、eighth、ninth internode length.Compared with the 20 ear height QTL,we found that 12(60%)of QTL distributed on the same SSSLs.These show that the seventh,eighth,ninth internode length were the important secondary components factor of ear height.2.By use of SSSL x Z58 and SSSL x 9058 testcross population,we detected 18 and18 seventh internode length HL,20 and 23 eighth internode length HL,17 and 19 ninth internode length HL;Compared with the ear height HL,only 29% of HL were in the same SSSLs.The result showed that EH heterosis was a complex trait,and heterosis of the seventh,eighth and ninth internode length were components factors for ear height heterosis.In addition,only 7(6%)HL in the two testcross groups was same,that showed that heterotic loci among different groups may be quite different,so heterotic loci in the site of single gene level were allele interaction performance in specific hybridization combination.3.Compared with results of HL and QTL,we found that only 23(20%)HL and thesame traits QTL were commen,Most of the QTL locus has nothing to do with the performance of the heterosis,which showed that character expression and the expression of heterosis may have different genetic mechanisms.