MANISH KUMARMASAYE, SANDIP SURYAKANT2016-06-302016-06-302010http://krishikosh.egranth.ac.in/handle/1/68333ABSTRACT The studies on “Nature of gene action and molecular marker assisted selection for powdery mildew resistance in Pea (Pisum sativum L.)” was carried out at the Vegetable Research Farm, Department of Vegetable Science,YSPUHF, Nauni, Dist. Solan and at Vegetable Research Station, Kalpa, Dist. Kinnaur during 2008-2010.The experimental material for diallel analysis comprised of four genetically diverse lines/genotypes viz.,Lincoln, Azad Pea-1, Arka Ajit and IC252401. These genotypes were crossed in a half diallel fashion excluding reciprocals during Rabi, 2008. Each F1 was raised and selfed to obtain F2 generation as well as backcrosses (B1and B2) seed during Kharif, 2009. Thus, the experimental materials finally consisting of six generations viz. P1,P2, F1, F2, B1 and B2 of all these crosses were further planted for final evaluation and recording of observations in Rabi, 2009 and computing results on combining ability and gene action studies.On the basis of gca estimates, the Lincoln was rated as the best general combiner for number of pods per plant, pod weight (g), pod yield (g/plant) and shelling percentage (%), whereas, Azad Pea-1 for TSS (0B), Arka Ajit for pod length (cm), seeds per pod and total phenols (mg/100g) and IC252401 was found to be a good combiner for plant height (cm). Superior cross combinations which recorded high sca estimates are Arka Ajit ×IC252401 for plant height (cm), pod weight (g), number of pods per plant and pod yield (g/plant) followed by Azad Pea-1 × IC252401 for pod length (cm) and shelling percentage (%) while, cross Azad Pea-1 × Arka Ajit for seeds per pod and total soluble solids(0B). Combining ability and weighted analysis of generation means suggested the preponderance of additive variance for all traits in F1 and F2 generations except for pod length and number of seeds per pod in F2. Most of the traits showed significant and higher magnitude of additive gene action thus suggesting that simple selection procedures may be adopted for combinations of desirable genes. However, some crosses exhibited significant non-additive gene effects which can be further exploited by following recurrent selection or bi-parental mating between selected recombinants in early segregating generations and further using simple selection procedure. Genomic DNA of the parents and individual F2 plants was isolated using CTAB method. Polymorphism survey of the resistant and susceptible parents was done by amplifying their DNA using 30 decamer random primers. Of these, 10 decamer primers produced amplification and only two (OPO-18 and OPC-04) produced unique band of 1054.49bp and 771.86 bp between the parents and bulks in cross Lincoln × Arka Ajit and Azad Pea-1 × Arka Ajit, respectively. The linkage map was generated using “MAPMAKER”, Ver 3.0 and it was found that the OPO-18 is 2.1 cM and OPC-04 is 2.3 cM away from the powdery mildew resistance gene, which shows close linkage of this marker with the resistance gene. However, more closely linked marker(s) needed to be identified for undertaking Marker Assisted Selection (MAS) in developing powdery mildew resistant varieties of pea.enThesis