Probabilities of Multilocus Genotypes in SIB Recombinant Inbred Lines

Probabilities of multilocus genotypes in SIB recombinant inbred lines

10.1101/697144 ◽

2019 ◽

Author(s):

Kamel Jebreen ◽

Marianyela Petrizzelli ◽

Olivier C. Martin

Keyword(s):

Computer Program ◽

Recombinant Inbred ◽

Average Rate ◽

Recombinant Inbred Lines ◽

Linear Equations ◽

Inbred Lines ◽

Male Meiosis ◽

General Situation ◽

Recombination Rates ◽

Multilocus Genotypes

ABSTRACTRecombinant Inbred Lines (RILs) are obtained through generations of inbreeding until all alleles are fixed. In 1931 Haldane and Waddington published a landmark paper where they provided the probabilities of achieving any combination of alleles in 2-way RILs for 2 and 3 loci. In the case of SIB RILs where sisters and brothers are crossed at each generation, there has been no progress in treating 4 or more loci, a limitation we overcome here without much increase in complexity. In the general situation of L loci, the task is to determine 2L probabilities, but we find that it is necessary to first calculate the 4L “identical by descent” (IBD) probabilities that a RIL inherits at each locus its DNA from one of the four originating chromosomes. We show that these 4L probabilities satisfy a system of linear equations that follow from self consistency. In the absence of genetic interference – crossovers arising independently –, the associated matrix can be written explicitly in terms of the recombination rates between the different loci. We provide the matrices for L up to 4 and also include a computer program to automatically generate the matrices for higher values of L. Furthermore, our framework can be generalized to recombination rates that are different in female and male meiosis which allows us to show that the Haldane and Waddington 2-locus formula is valid in that more subtle case if the meiotic recombination rate is taken as the average rate across female and male. Once the 4L IBD probabilities are determined, the 2L probabilities of RIL genotypes are obtained via summations of these quantities. In fine, our computer program allows to determine the probabilities of all the multilocus genotypes produced in such sibling-based RILs for L ≤ 10, a huge leap beyond the L = 3 restriction of Haldane and Waddington.

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Diverse sources of resistance to Spodoptera litura (F.) in groundnut

Indian Journal of Genetics and Plant Breeding (The) ◽

10.31742/ijgpb.79s.1.8 ◽

2019 ◽

Vol 79 (01S) ◽

Author(s):

M. A. Saleem ◽

G. K. Naidu ◽

H. L. Nadaf ◽

P. S. Tippannavar

Keyword(s):

Recombinant Inbred ◽

Spodoptera Litura ◽

Hot Spot ◽

Recombinant Inbred Lines ◽

Insect Pest ◽

Inbred Lines ◽

Leaf Damage ◽

Botanical Variety ◽

Resistant Genotypes ◽

Botanical Varieties

Spodoptera litura an important insect pest of groundnut causes yield loss up to 71% in India. Though many effective chemicals are available to control Spodoptera, host plant resistance is the most desirable, economic and eco-friendly strategy. In the present study, groundnut mini core (184), recombinant inbred lines (318) and elite genotypes (44) were studied for their reaction to Spodoptera litura under hot spot location at Dharwad. Heritable component of variation existed for resistance to Spodoptera in groundnut mini core, recombinant inbred lines and elite genotypes indicating scope for selection of Spodoptera resistant genotypes. Only 29 (15%) genotypes belonging to hypogaea, fastigiata and hirsuta botanical varieties under mini core set, 15 transgressive segregants belonging to fastigiata botanical variety among 318 recombinant inbred lines and three genotypes belonging to hypogaea and fastigiata botanical varieties under elite genotypes showed resistance to Spodoptera litura with less than 10% leaf damage. Negative correlation existed between resistance to Spodoptera and days to 50 per cent flowering indicating late maturing nature of resistant genotypes. Eight resistant genotypes (ICG 862, ICG 928, ICG 76, ICG 2777, ICG 5016, ICG 12276, ICG 4412 and ICG 9905) under hypogaea botanical variety also had significantly higher pod yield. These diverse genotypes could serve as potential donors for incorporation of Spodoptera resistance in groundnut.

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