Abstract:
Yellow mosaic disease (YMD) is one of the major devastating constraints to
soybean production in Pakistan. In the present study, we report the identification
of resistant soybean germplasm and a novel mutation linked with disease
susceptibility. Diverse soybean germplasm were screened to identify YMDresistant lines under natural field conditions during 2016-2020. The severity of
YMD was recorded based on symptoms and was grouped according to the
disease rating scale, which ranges from 0 to 5, and named as highly resistant (HR),
moderately resistant (MR), resistant (R), susceptible (S), moderately susceptible
(MS), and highly susceptible (HS), respectively. A HR plant named “NBG-SG
Soybean” was identified, which showed stable resistance for 5 years (2016-
2020) at the experimental field of the National Institute for Biotechnology and
Genetic Engineering (NIBGE), Faisalabad, Pakistan, a location that is a hot spot
area for virus infection. HS soybean germplasm were also identified as NBG-47
(PI628963), NBG-117 (PI548655), SPS-C1 (PI553045), SPS-C9 (PI639187), and cv.
NARC-2021. The YMD adversely affected the yield and a significant difference
was found in the potential yield of NBG-SG-soybean (3.46 ± 0.13a t/ha) with HS
soybean germplasm NARC-2021 (0.44 ± 0.01c t/ha) and NBG-117 (1.12 ± 0.01d t/
ha), respectively. The YMD incidence was also measured each year (2016-2020)
and data showed a significant difference in the percent disease incidence in the
year 2016 and 2018 and a decrease after 2019 when resistant lines were planted.
The resistance in NBG-SG soybean was further confirmed by testing for an
already known mutation (SNP at 149t h position) for YMD in the
Glyma.18G025100 gene of soybean. The susceptible soybean germplasm in
the field was found positive for the said mutation. Moreover, an ortholog of the
CYR-1 viral resistance gene from black gram was identified in soybean asGlyma.13G194500, which has a novel deletion (28bp/90bp) in the 5`UTR of
susceptible germplasm. The characterized soybean lines from this study will
assist in starting soybean breeding programs for YMD resistance. This is the first
study regarding screening and molecular analysis of soybean germplasm for
YMD resistance.
