PHENOTYPIC AND MARKER ASSISTED SELECTION FOR COMBINING THE TRAITS; TOLERANCE TO LOW SOIL PHOSPHOROUS, RESISTANCE AGAINST BACTERIAL BLIGHT AND BLAST INTO THE ELITE RICE VARIETY, MTU1010
Loading...
Date
2018
Authors
Journal Title
Journal ISSN
Volume Title
Publisher
PROFESSOR JAYASHANKAR TELANGANA STATE AGRICULTURAL UNIVERSITY
Abstract
Bacterial blight and blast diseases limit rice production in many rice growing
areas significantly. Breeding for tolerance to both the major diseases of rice is the
economically feasible and environmentally friendly option for managing them. Due to
the inherent nature of many rice growing soils in terms of fixing phosphorus (P) to nonavailable form and due to increasing cost of phosphatic fertilizers, a significant
proportion of rice growing soils have limiting levels of P and hence are poor in
productivity. Breeding for tolerance to low soil phosphorous assumes great significance
in such soils. MTU1010 (also known as Cotton Dora Sannalu) is a mega variety of rice
grown in many parts of India including Telangana. MTU1010 is highly susceptible to
bacterial blight and blast diseases and does not have tolerance to low soil P conditions.
Keeping in view these points, the present study entitled “Phenotypic and marker
assisted selection for combining the traits; tolerance to low soil phosphorous, resistance a
gainst bacterial blight and blast into the elite rice variety, MTU 1010” was carried out
with an objective to combine the major QTL associated with tolerance to low soil
phosphorus (P) and the major bacterial blight and blast resistance genes, Xa21 and Pi54,
xiii
respectively into the genetic background of MTU1010 through marker-assisted breeding
coupled with phenotype-based selection for agromorphological traits specific for
MTU1010.
An improved breeding line (i.e. NIL) of MTU1010 (RP5973-20-9-8-24-12-7),
possessing tolerance against low soil P conferred by Pup1 (developed by ICAR-IIRR
(Anila et al., 2014)) was used as the female parent for improving low soil P tolerance and
a breeding line of the high-yielding rice variety, Akshayadhan named RP6132,
possessing the major, broad spectrum resistance genes against bacterial blight (i.e. Xa21)
and blast (i.e. Pi54) was used as the male parent in the present study. In order to combine
the three traits mentioned above, a cross was carried out between NIL of MTU1010
(RP5973-20-9-8-24-12-7) and NIL of Akshayadhan (RP6132) during kharif 2016. At
each generation, the resultant F1, F2 and F3 obtained were screened through foreground
selection for confirmation of presence of target trait specific genes/QTL, viz., for low P
tolerance (Pup1), bacterial blight resistance (Xa21) and blast resistance (Pi54).
Foreground selection was carried out with co-dominant CAPS marker, K20-2 for
identifying the presence of Pup1, gene specific co-dominant markers viz., pTA248 and
Pi54-MAS for checking the presence of Xa21and Pi54 respectively.
In F1 generation, 76 plants heterozygous for all the three target traits were
identified through analysis with the marker(s) specific for the target gene and they were
then forwarded to F2 generation by selfing. In F2 generation, 15 plants homozygous for
the three target traits were identified based on foreground selection using the codominant markers mentioned above. The 15 homozygous F2 plants (possessing Xa21,
Pi54 and Pup1) were selfed to F3 generation and the F3 lines were screened for their
resistance against bacterial blight in the field, blast in uniform blast nursery and low soil
P tolerance in low P plot. Analysis of variance among the F3 lines in the present study,
revealed the presence of significant difference between the parents and breeding lines for
days to fifty percent flowering, plant height, number of productive tillers, panicle length,
root length, root volume, dry root weight, thousand grain weight, grain yield per plant, P
content in shoots and roots under low soil P condition, but significant difference was not
found for dry shoot weight. Stress indices like stress tolerance index, tolerance index,
yield reduction ratio, yield index, stress susceptibility index, yield stability index and
percent yield reductions were worked out based on the yield under normal condition and
yield under low soil P condition. Breeding lines with Pup1 possessed high YI value than
xiv
RP6132. In particular, the breeding line LPK 49-1-21 (possessing Pup1, Xa21 &Pi54)
were observed to have lower percent of yield reduction under low soil P condition
followed by the other breeding lines possessing Pup1,
All the 15 F3 lines were also observed to be resistant to bacterial blight and blast
through phenotypic screening and possessed grain yields and grain quality equivalent to
or better than the MTU1010 NIL. Two breeding lines viz., LPK 30-18-16 and LPK 49-
15-22 respectively, exhibited good performance with high level of resistance to all the
three stresses viz., BB, blast and low soil P and possessed high yield under both normal
soil P and low soil P with highly desirable long slender grain type like MTU1010. The
results obtained in the preent study indicate the success of the strategy of combining
marker-assisted breeding with phenotypic selection and the two lines mentioned above
are expected to perform well in areas prone to the two diseases and also in problematic
soils with low soil phosphorous levels. Cultivation of the biotic and abiotic stress
resistance/tolerant breeding lines developed in this study would be of great advantage in
BB and blast endemic areas and also in low P affected rice growing areas, particularly
upland conditions in the country and can be helpful to expand the area under MTU1010.
Description
Keywords
Citation
D10,322