INTROGRESSION OF ANTHRACNOSE RESISTANCE GENES IN ELITE FRENCH BEAN (Phaseolus vulgaris L.) BACKGROUND USING LINKED MOLECULAR MARKERS
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Date
2020-01-07
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CSKHPKV. Palampur
Abstract
French bean is one of the most important staple foods in many parts of the world, where it
constitutes the main source of protein for human consumption. Several bacterial, fungal and
viral diseases attack French bean and among these anthracnose caused by Colletotrichum
lindemuthianum is one of the most widespread and severe. Many improved pencil type
varieties developed are available for cultivation by the farmers of Himachal Pradesh, however
most of these are susceptible to many prevalent races of bean anthracnose. Therefore, the
present study was undertaken with the objectives of introgression of important bean
anthracnose resistance genes in elite cultivars and validation of imparted resistance in the
derivatives. Hybridisation between resistant genotypes, TO, TU, G 2333 and Cornell 49242,
known to harbour bean anthracnose resistance genes, Co-4, Co-5, Co-42/Co-5/Co-7 and Co-2,
respectively and elite cultivars, Arka Komal and Contender revealed a low and differential
crossability rate (0-7.69 %) among gene donors and elite recipient parents as Arka Komal was
more easily crossable with resistance gene donors as compared to Contender. Two most
successful crosses, Cross Combination I (Arka Komal × TO) and Cross Combination II (Arka
Komal × TU) were further advanced to generate F1, BC1F1, BC2F1 and BC2F2 plants. Testing
of hybridity of the resultant F1, BC1F1, BC2F1 and BC2F2 plants/pods using gene linked SCAR
markers (SY20 for Co-4 and SAB3 for Co-5) resulted in identification of 46 gene-positive
BC2F2 plants of Cross Combination I and 36 of Cross Combination II. A total of 457 and 764
seedsof 46 and 36 selected gene-positive BC2F2 plants of Cross Combinations I and II,
respectively were raised as progeny rows. Foreground selection with linked marker, SY20 and
SAB3 in representative 10 plants of the each progeny revealed lack of segregation for the
target gene Co-4 and Co-5 in 16 and 12 progenies of Cross Combinations I and II,
respectively. Screening of progenies following detached pod and germinated seed dip
methods using race 3 of C. lindemuthianum validated Co-4 and Co-5 imparted resistance in
all the 28 BC2F3 progenies of 2 cross combinations. Agronomic evaluation of 16 Co-4 and 12
Co-5 gene-positive BC2F4 progenies for 8 qualitative traits and 9 quantitative traits identified
AKTO 4, AKTO 5, AKTO 7 and AKTO 43 progenies of Cross Combination I and AKTU 19
and AKTU 33 of Cross Combination II as having better elite background. These can either be
used as donors of resistance gene(s) for further introgression and gene pyramiding or can
further be advanced following backcrossing to develop essentially derived variety of elite
parent, Arka Komal.