Linkage map construction in guava F1 population of Allahabad Safeda x Arka Kiran using molecular markers

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Date
2018
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Punjab Agricultural University, Ludhiana
Abstract
Guava is a perennial fruit tree grown in tropical and sub-tropical regions of the world. As of now, there are about 160 cultivars available in India. Crop improvement work attempted in India has resulted in release of several superior selections or hybrids. However, the maximum area under guava cultivation is occupied by Allahabad Safeda. Being a cross-pollinated tree (25.7 to 41.3 % cross pollination) guava has a heterozygous genome. Molecular mapping can help us to find the relative positions of the markers as well as the markers co-segregating with the trait of interest that could finally be transferred to the cultivated species. In the present study we have attempted Linkage map construction in guava. A cross between white fleshed Allahabad Safeda and colored fleshed Arka Kiran was attempted in Fruit Science, PAU. We genotyped Allahabad Safeda and Arka Kiran using 167 genomic SSR, 22 EST based and 5 apple color specific markers. Forty eight markers showed polymorphism out of 194 total markers. Polymorphic markers applied on a population of 73 F1 individuals showed segregation. Pattern of marker segregation in the population was scored and analysed with software, MAPDISTO version 1.7.7.0.1.1 (XL 2007) and a genetic linkage map was constructed using stringency parameters of LOD score and recombination frequency set to 3.0 and 0.35, respectively. Out of 48 polymorphic markers, thirty markers were mapped on different linkage groups of guava genome and 6 linkage groups were obtained. The genetic linkage map covered a total of 538.68 cM of the guava genome. Fruits were not set on 2 year old F1 trees so color segregation was studied on leaves as a proxy for fruit color trait. Color in young and mature leaves was measured using miniature leaf spectrometer. The data recorded in terms of anthocyanin reflective index 1 (ARI1) was analysed with the help of mapping software. Two markers mPgCIR93 and mPgCIR21 were mapped to linkage group 2 on positions 54.3 cM and 10.3 cM for leaf color traits at young and mature stage.
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