Journal of Horticultural Sciences

B. Padmakar ¹, C. Kanupriya ², P. Madhavi Latha ², C. Vasugi ², M. R. Dinesh ², D. Sailaja ³, C. Aswath ²

Affiliations
1 Center for Biotechnology, JNTU, Hyderabad, Telangana, IN
2 ICAR-Indian Institute of Horticultural Research, Hesaraghatta Lake Post, Bengaluru - 560089, Karnataka, IN
3 Department of Biotechnology, GRIET, Hyderabad, Telangana, IN

Abstract

The present research focuses mainly on molecular mining and morphological evaluation of guava genome within a full-sib population and, thereby, mapping of quantitative trait loci related to fruit quality traits, viz., seed strength (hardness/softness) and average fruit weight. Linkage maps were enriched for both parental lines, 'Kamsari' and 'Purple Local' using a set of 60 RAPD markers following the pseudo-testcross strategy on a panel of 94 progeny. A total of 480 scorable markers were identified, of which 131 were specific to 'kamsari' and 28 to 'Purple Local', segregating as test cross markers, and, 321 showing intercross pattern common to both. 'Kamsari' spanned a total length of 1959.1cM with average marker interval distance of 3.93cM, while 'Purple Local' spanned a length of 1537.9cM with average marker interval distance of 3.29cM, by forming 11 linkage groups. Estimated genome length observed was 93.02% and 92.77% in 'Kamsari' and 'Purple Local', respectively. Composite Interval Mapping (CIM) was computed at significance of 0.05 and LOD threshold greater than 3.0, which led to detection of one major QTL for the trait of average fruit weight, and, four QTLs for the trait of seed strength (hardness/softness). Of these, two were major and two minor QTLs. Our study provides molecular mapping information on marker-assisted selection for improvement of guava in a breeding program.

Keywords

Composite Interval Mapping, Guava, Linkage Map, Pseudo-Testcross, Quantitative Trait Loci (QTL).

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B. Padmakar ¹, D. Sailaja ², C. Aswath ³

Affiliations
1 Centre for Biotechnology, Jawaharlal Nehru Technological University, Hyderabad, Telangana, IN
2 Department of Biotechnology, Gokaraju Rangaraju Institute of Engineering and Technology, Hyderabad, Telangana, IN
3 Division of Ornamental Crops, ICAR-Indian Institute of Horticultural Research, Bangalore, Karnataka, IN

Abstract

In the present study, molecular evaluation of two guava mapping populations (MP), MPI comprising 94 F1 progenies and MPII comprising 46 F1 progenies, was carried out using simple sequence repeat (SSR) and random amplified polymorphic DNA (RAPD) markers. A pseudo-test cross strategy was implemented where 'Kamsari' X 'Purple Local' and 'Purple Local' X 'Allahabad Safeda' were crossed, and, these showed variation in fruit quality traits such as seedstrength (hardness/softness), fruit weight, TSS and pulp color. A set of 30 RAPD markers was used for genotyping MPI while a set of 55 SSR markers was used for genotyping MPII. In case of MPI, 30 RAPD markers generated 214 scorable markers, of which 80 markers were specific to 'Kamsari', 14 markers to 'Purple Local' and the remaining 120 were intercross markers. As for MPII, 55 polymorphic SSR markers resulted in generation of 207 alleles (with a maximum of 4 alleles and a minimum of 3 alleles per locus), of which 108 alleles were specific to 'Purple Local' while 99 were specific to 'Allahabad Safeda'. Genotypic data thus generated can be further exploited for constructing genetic linkage maps and mapping complex QTLs governing fruit quality traits in guava..

Keywords

Guava, Genotyping, M13-Tailed PCR, SSR, RAPD.

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K. Khandagale ¹, B. Padmakar ², D. C. Lakshmana Reddy ², Anuradha Sane ³, C. Aswath ²

Affiliations
1 University of Pune, Pune - 411007, IN
2 Division of Biotechnology, ICAR-Indian Institute of Horticultural Research, Hesaraghatta Lake Post, Bengaluru - 560 089, IN
3 Division of Plant Genetic Resources, ICAR-Indian Institute of Horticultural Research, Bengaluru – 5600089, IN

Abstract

Tuberose is one of the most important bulbous ornamentals grown commercially for loose as well as cut flowers. RAPD and ISSR markers used in the study revealed 53% and 73% polymorphism, respectively, among ten tuberose varieties. Polymorphic Information Content (PIC) and Resolving Power (RP) for RAPD varied from 0.35 - 0.46 and 0.8 - 3.6, respectively, and that for ISSR was 0.36 - 0.49 and 0.91 - 4.55, respectively. The dendrogram (UPGMA), based on Jaccards co-efficient as similarity index for RAPD and ISSR, grouped ten varieties into two major clusters, and, combined RAPD-ISSR cluster analysis formed three major clusters based on their genetic relatedness/variation. PCA revealed that the spatial arrangement of these 10 cultivars was congruent with dendrogram analysis. Mantel's test indicated very good correlation, with r = 0.86 for combination of ISSR and RAPD-ISSR. To facilitate identification of tuberose cultivars, a cultivar identification diagram (CID) was developed in which seven ISSR loci could differentiate all the ten cultivars used in the study. Barcodes were developed for five cultivars released by IIHR using 57 polymorphic loci generated by 11 ISSR primers. The size of these loci ranged from 252bp to 2.2kb. These barcodes can be used as a standard reference source for quick identification of cultivars.

Keywords

ISSR, Molecular Barcode, PCR, RAPD, UPGMA.

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B. Padmakar ¹, M. R. Dinesh ², K. V. Ravishankar ¹

Affiliations
1 Division of Biotechnology, ICAR-Indian Institute of Horticultural Research Hessaraghatta Lake Post, Bengaluru 560089, Karnataka, IN
2 Division of Fruit Crops, ICAR-Indian Institute of Horticultural Research Hessaraghatta Lake Post, Bengaluru 560089, Karnataka, IN

Abstract

In the present study, putative marker-trait associations were identified within a core collection of mango cultivars by simple-sequence-repeat marker based association study. A panel of 48 mango varieties which represented the core collection of the South-West region of India, were characterized at the molecular level using 31 simple sequence repeat markers. Morphological characterization included important fruit characteristics viz., fruit weight, total soluble solids (TSS), pulp content and acidity. The study on population structure revealed two sub-groups in the core collection. Association analysis, computed by General Linear Model (GLM), using TASSEL resulted in the identification of seven markers being associated with the trait titrable acidity where as one marker each of the traits fruit weight and TSS. These traitspecific markers were highly significant at p<0.05 and explained a good amount of phenotypic variation by exhibiting substantial R2 values ranging from 0.71 to 0.86 for acidity, 0.61 for TSS and 0.59 for fruit weight. This is the first report on marker-trait associations (MTA) in mango.

Keywords

Marker-Trait Association, Fruit Characters, Mango, Mangifera indica L.

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