Marker Assisted Backcross Breeding to Enhance Lysine and Tryptophan Content of Parental Lines of Shalimar Maize Hybrid-5
| dc.contributor.advisor | Rather, M. Ashraf | |
| dc.contributor.author | Shamshir ul Hussan | |
| dc.date.accessioned | 2023-12-18T10:57:54Z | |
| dc.date.available | 2023-12-18T10:57:54Z | |
| dc.date.issued | 2023 | |
| dc.description.abstract | This study was carried out to convert parental lines of Shalimar maize hybrid 5 (IML-187 and BML-6) by crossing with donor inbred lines (DQL-2029-1 and DQL-779-2-9) having quality protein trait and subsequent backcrossing of resultant F1s with recurrent parents using marker assisted backcross breeding technique. The above said inbred lines were analyzed for polymorphism with opaque-2 gene specific SSR markers at the opaque-2 locus. The objectives of this study were (i) Establishing a marker assisted backcrossing strategy for developing QPM version of SMH-5 (ii) SSR markers based foreground and background selection for confirmation of genetic background (iii) Phenotyping of backcross derived F1 and F2 generations. IML-187 was crossed with DQL-2029-1 and BML-6 was crossed with DQL-779-2-9 The first and second backcross generations involving IML-187 as recurrent parent as marked as BC1F1 (A) and BC2F1 (A) respectively, whereas those involving BML-6 were designated as BC1F1 (B) and BC2F1 (B) respectively. The BC2F2 lines derived from two generation of backcrossing coupled with marker and phenotypic assisted selection were further phenotyped for endosperm modification and selection of lines with desirable modifications was done which were further analyzed for protein, tryptophan and lysine content. The two BC1F1 populations were genotyped at the opaque-2 locus using phi057 SSR marker. The marker allele size at 02 locus for normal parents was 155 bp in IML-187(P1) and 160 bpBML-6(P2). 170bp in DQL-2029-1(P3) and DQL-779-2-9(P4) for QPM or donor parents. It was observed that out of 96 plants analyzed, 40 individuals were heterozygous at o2 locus in BC1F1 population derived from the cross BC1F1 (A) while 43 out of the 100 plant analyzed in cross BC1F1 (B) were heterozygous. About 200 plant population of each BC2F1 along with normal maize lines were raised and all the undesirable plants were roughed out from each population before flowering. Analyzed allelic form of individual plants at o2 locus using phi057 marker and plants heterozygous were tagged and those indicating allele in homozygous condition were rejected. Eighty nine plants from BC2F1 (A) and 103 plants from BC2F1 (B) were used in genotyping using phi 057 SSR for foreground selection. The BC2F1 plants heterozygous for o2 locus were 36 and 44 in BC2F1 (A) and BC2F1 (B) respectively. Heterozygous selected plants were also genotyped for recurrent parent genome using background 25 markers that were polymorphic. The number of plants used for background genotyping from BC2F1 (A) were 36 as we have used the DNA of all heterozygous plants for foreground trait from the lot. And 18 plants from this generation were selfed to produce BC2F1 ears. Similarly 16 plants from BC2F1 (B) were selfed after background MAS. Screening of kernels in light box categorized four degrees of opaqueness viz. <25%, 25%-50%, 50%-75% and 75%-100%. Sixteen selfed ears from BC2F2 (A) were used in kernel phenotyping and 6 were rejected for having more than 25% opaqueness and seeds from 10 cobs were selected for having 25% or less opaqueness confirming the presence of endosperm modifiers. Similarly, seeds of 14 cobs were utilized in kernel phenotyping in BC2F2 (B) and only 8 populations were selected for having 25% or less opaqueness. The protein quality content values of the converted lines developed from the cross between BC2F2 (A) and BC2F2 (B) were estimated. The results indicated that the lowest tryptophan value of 0.047 % was recorded in IML-187 x DQL-2029-1 BC2F2:12 line while the maximum value of 0.117% was found in BML-6 x DQl-779-2-9:12. The 04 parents namely IML-187, DQL-2029-1, BML-6 and DQL-779-2-9 used in conversion programme had 0.045, 0.042, 0.074 and 0.090 % tryptophan, respectively. Eight lines namely IML-187 x DQL-2029-1- BC2F2:06, 07 and 23: BML-6 x DQl-779-2-9: 02,04,09,20 and 13 were identified to have tryptophan higher than 0.075%. Line IML-187 x DQL-2029-1- BC2F2:17 was also selected due to better lysine and overall protein content despite having 0.074% tryptophan content. In the present study we were able to recover approx. 88-90% genome in the selected BC2F1 plants based on 25 polymorphic SSR markers that were used. These selected entries can be used for developing QPM version of SMH-5, can be further selfed or one more backcross can be attempted to increase the proportion of recurrent parent genome in these lines. | |
| dc.identifier.uri | https://krishikosh.egranth.ac.in/handle/1/5810203690 | |
| dc.keywords | Maize | |
| dc.keywords | conversion | |
| dc.keywords | QPM | |
| dc.keywords | MABC | |
| dc.keywords | lysine | |
| dc.keywords | tryptophan | |
| dc.keywords | Genetics and Plant Breeding | |
| dc.language.iso | English | |
| dc.pages | 77 | |
| dc.publisher | SKUAST Kashmir | |
| dc.research.problem | Marker Assisted Backcross Breeding to Enhance Lysine and Tryptophan Content of Parental Lines of Shalimar Maize Hybrid-5 | |
| dc.sub | Genetics and Plant Breeding | |
| dc.subject | Maize | |
| dc.subject | conversion | |
| dc.subject | QPM | |
| dc.subject | MABC | |
| dc.subject | lysine | |
| dc.subject | tryptophan | |
| dc.subject | Genetics and Plant Breeding | |
| dc.theme | Marker Assisted Backcross Breeding to Enhance Lysine and Tryptophan Content of Parental Lines of Shalimar Maize Hybrid-5 | |
| dc.these.type | Ph.D | |
| dc.title | Marker Assisted Backcross Breeding to Enhance Lysine and Tryptophan Content of Parental Lines of Shalimar Maize Hybrid-5 | |
| dc.type | Thesis |