GENETIC STUDIES ON HORTICULTURAL TRAITS AND MARKER ASSISTED SELECTION FOR POWDERY MILDEW RESISTANCE IN PEA (Pisum sativum L)
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Date
2017-11
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UHF,NAUNI
Abstract
ABSTRACT
The present investigations on “Genetic studies on horticultural traits and marker assisted selection for
powdery mildew resistance in pea (Pisum sativum L)” was carried out at the Vegetable Research Farm,
Department of Vegetable Science, Dr YSPUHF, Nauni, Solan and Vegetable Research Station, Kalpa, Kinnaur
during 2013-2015. The experimental material for partial diallel analysis comprised of five genetically diverse
genotypes viz., Lincoln, Azad Pea-1 (Susceptible), and EC-598604, EC-598620 and Azad Pea-4 (Resistant).
These genotypes were crossed excluding reciprocals during Rabi 2013-14. Each F1 was raised and selfed to
obtain F2 generation as well as backcrossed to obtain BCs (B1 and B2) seeds during Kharif 2014. Thus, the
experimental materials finally consisting of six generations namely P1, P2, F1, F2, B1 and B2 of all these crosses
which were further planted for final evaluation and recording of observations in Rabi 2014-15 and for
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 days to marketable maturity, number of pods per plant, pod yield
(g/plant), pod yield (q/ha), shelling percentage, powdery mildew severity (%) and TSS (0Brix) whereas, Azad
Pea-1 for days to 50% flowering and number of seeds per pod, EC-598604 and EC-598620 were found to be a
good combiners for plant height (cm), Azad Pea-4 for pod length (cm) and EC-598620 for both protein content
(%) and total phenols (mg/100g). The cross combinations which recorded high sca estimates are Azad Pea-1 ×
Azad Pea-4 for days to 50% flowering, days to marketable maturity, number of pods per plant, number of seeds
per pod, Pod length (cm), pod yield (g/plant), pod yield (q/ha) and total soluble solids (0Brix) whereas, crosss
Azad Pea-1 × EC-598604 recorded high for both plant height (cm) and powdery mildew severity (%), Lincoln ×
Azad Pea-4 recorded high sca for shelling percentage. Combining ability and generation mean analysis
suggested the presence of additive variance in all the traits in F1 and F2 generations. Most of the traits showed
significant and higher magnitude of additive gene action thus suggesting the adoption of simple selection
procedures may be helpful for combinations of desirable genes. However, the crosses exhibiting significant nonadditive
gene effects can be further exploited by following recurrent selection or bi-parental mating design
between selected recombinants in early segregating generations and further using simple selection procedure.
The chi-square analysis showed the monogenic recessive inheritance pattern for powdery mildew resistance.
Genomic DNA of the parents and individual F2 plants from one cross i.e. Lincoln × Azad Pea-4 was isolated
using CTAB method. Initially parents were screened using three validated SCAR viz., ScX171400 (er2),
SCW4637 (Er3) and SCAB1874 (Er3), and one SSR markers viz., PSMPSAD60 (er1). The marker PSMPSAD60
has shown the resistant banding pattern at 290 bp in the parent Azad Pea-4 whereas, SCAR markers did not
exhibit any polymorphism between resistant and susceptible genotypes. Simultaneously the banding pattern was
validated in F2 generation of a single cross Lincoln × Azad Pea-4 to study the inheritance of powdery mildew
resistance. Two genotypes namely EC-598604 and EC-598620 also exhibited resistance in field but did not
amplify for PSMPSAD60 marker for er1 gene. Bulk segregating analysis was done using 80 SSR primers for
identification of new gene for powdery mildew resistance using marker assisted selection (MAS). Further, the
cross Azad Pea-1 × Azad Pea-4 can be advanced with the help of marker assisted selection for precisely figuring
out stable plants for developing a powdery mildew resistant genotype.
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