Identification of molecular markers for resistance to taro leaf blight in colocasia esculenta (L.) schott (Record no. 163850)
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| 000 -LEADER | |
|---|---|
| fixed length control field | 07356nam a22001697a 4500 |
| 082 ## - DEWEY DECIMAL CLASSIFICATION NUMBER | |
| Classification number | 660.6 |
| Item number | ANJ/ID |
| 100 ## - MAIN ENTRY--PERSONAL NAME | |
| Personal name | Anjitha Nair U M |
| 245 ## - TITLE STATEMENT | |
| Title | Identification of molecular markers for resistance to taro leaf blight in colocasia esculenta (L.) schott |
| 260 ## - PUBLICATION, DISTRIBUTION, ETC. (IMPRINT) | |
| Place of publication, distribution, etc | Vellayani |
| Name of publisher, distributor, etc | Department of Plant Biotechnology, College of Agriculture |
| Date of publication, distribution, etc | 2018 |
| 300 ## - PHYSICAL DESCRIPTION | |
| Extent | ix,146p |
| 502 ## - DISSERTATION NOTE | |
| Dissertation note | MSc |
| 520 3# - SUMMARY, ETC. | |
| Abstract | The study entitled “Identification of molecular markers for resistance to taro leaf blight in Colocasia esculenta (L.) Schott” was carried out at the Division of Crop Improvement, ICAR-CTCRI, Sreekariyam, during 2017-18 with the objective to identify molecular markers associated with leaf blight resistance in taro, sequencing and analysis using BLAST. RAPD, ISSR and SSR markers were used for the study. A total of 36 taro genotypes were selected consisting of 18 each susceptible and 18 resistant genotypes. DNA was isolated by employing the CTAB method of Sharma et al. (2008). Out of 10 RAPD primers screened, 7 were selected whose annealing temperature were optimized at 32⁰C and the presence of amplicons were confirmed in 2% agarose gel. For the selected primers, percent polymorphism ranged from 50 to 100% where, OPW12 recorded the least polymorphism (50%) followed by OPW6 (81.8%). The highest was shown by OPW1 and OPW16. The average percent polymorphism was 86.22%. The PIC values were highest for OPW8 (0.888) followed by OPW2 (0.886) and OPW1 (0.885) while least with OPW16 (0.615). Number of alleles per locus varied from 4-8.19 with the maximum by OPW8 and minimum by OPW5. The He values ranged between 0.66 (OPW16) to 0.89 (OPW1, OPW2, OPW8) and mostly found to be >0.8. Dendrogram generated using UPGMA analysis grouped the 36 genotypes into two major clusters. Cluster I with four susceptible varieties includes Bhu Sree, Bhu Kripa and Sree Rashmi where, Bhu Sree and Bhu Kripa pooled together showing 88% similarity. The resistant line, IC310104 and a susceptible line, L-12 expressed 91% similarity. Similarity index values varied from 0.47 to 0.88 with lowest (0.47) between 557 (S3) and 370 (R13) and between Sree Pallavi (S9) and 370 (R13) while, the highest similarity index (0.91) was observed between IC310104 (R11) and L12 (R14). Fourteen ISSR primers were selected whose annealing temperature was optimized at 56.3⁰C and amplicons were confirmed in 1.8% agarose gel. Percent polymorphism of primers varied from 60 to 100% where UBC 827 recorded lowest (60%) while UBC 818 recorded the 80% polymorphism. Rest of the primers showed 100% polymorphism with an average polymorphism of 95.7%. The PIC values of the primers were highest for UBC 818 (0.862) followed by UBC 811 (0.861) and UBC 809 (0.857) while UBC 827 (0.709) recorded lowest PIC content of <0.8. Number of alleles per locus varied from 2.38 - 6.13, where the maximum was shown by UBC 811 and minimum by UBC 817. He values varied between 0.75 (UBC 827) to 0.87 (UBC 809, UBC 818 and UBC 811). Similarity matrix index values varied from 0.50 to 0.88 with lowest (0.50) shown between Sree Rashmi (S1) and B-2 (SVP) (S18) and highest (0.88) between Sree Rashmi (S1) and E-10 (R9). A dendrogram was constructed using UPGMA, which grouped the genotypes into two major clusters. In the first cluster susceptible variety, Sree Rashmi (S1) pooled together with resistant, E-10 (R9) and it revealed 88% similarity. Out of 14 primers tested, the primer (UBC 811) gave an extra band for 7 resistant genotypes (IC012601, IC089624, TCR 429, 679, 370, 84 and 565) out of the total 18 selected in 1270 bp region and it included the three resistant lines, 679, 370 and 84 which showed consistency in resistance reaction for the last four years under artificial screening. For primer UBC836, a resistant genotype IC089624 expressed a unique band at 1000 bp. The primer (GA)9AC also produced a unique band for the resistant genotype, IC089624 at 800 bp. For primer, UBC824, a resistant line, 565 showed a different banding pattern. From these primers, the one showing unique bands for the maximum genotypes viz., UBC811 was selected. The band of size 1270 bp was cut and eluted. However, as the size of the band was very high and concentration was less, it was reamplified with the same primer. For reamplification, only four resistant genotypes (IC012601- R2; 370 - R13; 679 - R16 and 84 - R17) were selected based on the band intensity. This product was then checked in agarose gel, which gave two bands of which, one was very prominent at approximately 280 bp. This band was isolated and sequenced. Sequence data showed that the product size ranged from 242 bp, 252 bp, 247 bp and 252 bp, respectively. The sequences obtained were used for similarity search in BLASTn and 100% identity and 8% query cover with Arabidopsis lyrata subsp. lyrata disease resistance protein RML1B (LOC9323997), mRNA was obtained for the DNA sequence from R13 (370). The following sequence (TTTGAAGAAGATAGCCT - 17 bp) showed similarity with the above mRNA. Nine out of ten SSR primers screened were selected based on their agarose gel profile whose annealing temperatures were optimized at 56⁰C and presence of amplicons was confirmed in 2.5% agarose gel. The percent polymorphism of the nine primers ranged from 33.33% to 100%, Uq 73-164 with the lowest (33.33%) followed by Uq 201-302 (50%). Primers, Ce1 F12 and Uq 97-256 revealed 100% polymorphism with average polymorphism shown was 71.29%. The PIC values of the primers were highest for Uq 132-147 (0.69) and Uq 201-302 (0.69) followed by Uq 97-256 (0.61) and Uq 73-164 (0.59). Primer, Uq 84-207, recorded the lowest PIC (0.30). Number of alleles per locus varied from 1.08 - 6.22 with maximum for Uq 97-256 and minimum with Ce1 B03. The He values varied between 0.33 (Uq 84-207) to 0.74 (Uq 132-147 and Uq 201-302) whereas similarity coefficient values ranged from 0.49 to 0.89 concentrating between 0.56 to 0.86 with lowest (0.49) between 485 (S11) and 450 (R1) while highest (0.89) between 679 (R16) and TCR 961 (S17). In present study with three marker systems, the 30 odd primers did not produce any trait specific band(s) in all the resistant genotypes tested. However, with ISSR markers, primer UBC 811, expressed unique band in seven resistant genotypes which was completely absent in the susceptible ones. The specific band obtained were eluted and sequenced. The sequence showed 100% identity and 8% query cover with Arabidopsis lyrata subsp. lyrata disease resistance protein RML1B (LOC9323997), mRNA. This was obtained for the DNA sequence from R13 (370). The following is the sequence which showed similarity with the above mRNA - TTTGAAGAAGATAGCCT (17 bp). Mantel’s test established no correlation between the marker systems employed since they did not reveal any trait specific marker and only the genetic diversity was revealed. Therefore, further studies must be performed by employing more genotypes with increased primers to arrive at a definite consensus. The sequence obtained can be converted to a SCAR marker and validated with more resistant genotypes. |
| 650 ## - SUBJECT ADDED ENTRY--TOPICAL TERM | |
| Topical term or geographic name as entry element | Plant Biotechnology |
| 700 ## - ADDED ENTRY--PERSONAL NAME | |
| Personal name | Asha Devi A (Guide) |
| 856 ## - ELECTRONIC LOCATION AND ACCESS | |
| Uniform Resource Identifier | http://krishikosh.egranth.ac.in/handle/1/5810149217 |
| 942 ## - ADDED ENTRY ELEMENTS (KOHA) | |
| Source of classification or shelving scheme | |
| Item type | Theses |
| Not for loan | Collection code | Permanent location | Current location | Shelving location | Date acquired | Full call number | Barcode | Date last seen | Koha item type |
|---|---|---|---|---|---|---|---|---|---|
| Not For Loan | Reference Book | KAU Central Library, Thrissur | KAU Central Library, Thrissur | Theses | 2019-02-21 | 660.6 ANJ/ID | 174451 | 2019-02-21 | Theses |