Abstract:
Salt tolerant QTLs at the seedling stage of rice was studied using
green shoot length as a parameter, which was measured after salinity stress.
Under salinity stress from electrical conductivity level 4 dS/m,
Hyogokithanishiki Japonica parent showed more tolerance than Hokuriku 142 Indica parent. QTLs associated with salt tolerance were identified using
163 recombinant inbred lines derived from these parents. A linkage map
constructed with 95 simple sequence repeat markers was integrated with
the bioassay data for QTL analysis. Dormancy broken seeds were surface
sterilized. Acceleration of uniform seed germination was performed by
keeping surface-sterilized seeds at 350C for 6 days in distilled water.
Germinated seeds were grown in 1 ppm Hyponex (N:P:K: 6:10:5) solution for
one week. Hyponex solution was refreshed on every other day for better
aeration. Saline Hyponex solutions were prepared with electrical
conductivity 5 dS/m by adding NaCl and plants were subjected to salinity
stress. Green shoot length was measured at the end of the experiment. A
salinity tolerant QTL was identified by composite interval mapping with
LOD score 9.6 on chromosome 4 after 8-day salinity stress at electrical
conductivity 5 dS/m. It indicated that this QTL explained 53.4% of the
phenotypic variance and indica parent contributed salinity tolerant alleles for
the QTL. According to the 1000 time permutation test at composite interval
mapping, this QTL exceed the threshold LOD value. Chromosome four has
been identified as a candidate chromosome possessing salinity tolerance in
this study and in previous studies for different traits.
