Mapping and validation of QTLs for cold tolerance at seedling stage in rice from an indica cultivar Habiganj Boro VI (Hbj.BVI)

Abstract

Yellowing, stunting, and seedling death associated with cold stress is a common problem in many Asian countries for winter rice cultivation. Improvement of cultivars through marker-assisted selection of QTLs for cold tolerance at seedling stage from locally adapted germplasm/cultivar is the most effective and sustainable strategy to resolve this problem. A study was undertaken to map QTLs from 151 progenies of a cross between a cold susceptible variety, BR1 and a locally adapted traditional cultivar, Hbj.BVI. A total of six significant QTLs were identified for two cold tolerance indices-cold-induced leaf discoloration and survival rate after a recovery period of seven days on chromosomes 6, 8, 11, and 12. Among these QTLs,-- and -- being co-localized into RM7027-RM339 on chromosome 8 and -- and -- into RM247-RM2529 on chromosome 12 showed 12.78 and 14.96% contribution, respectively, to the total phenotypic variation for cold tolerance. Validation of QTL effect in BCF population derived a cross between a cold susceptible BRRI dhan28 and Hbj.BVI showed dominating effect of -- on cold tolerance at seedling stage and it became stronger when one or more other QTLs were co-segregated with it. These results suggest that the QTLs identified in this study are stable and effective on other genetic background also, which warrant the use of these QTLs for further study aiming to cultivar development for seedling stage cold tolerance.

Using Agumented design for screening of cold tolerant rice genotypes for seedling traits under low temperature condition [Oryza sativa (L.)]

“…Positive and significant associations were also noticed for cold tolerance scoring with root length and cold stress tolerance index Cruz and Milach (2013) [5] , chlorophyll content with seedling height and shoot length Farzin et al (2013) [8] , shoot length with seedling height Siddi et al (2020) [20] . Negative and significant associations were in contrast observed for cold tolerance scale with chlorophyll content ~ 190 ~ Biswas et al (2017) [3] , chlorophyll content with cold stress tolerance index Kim et al (2009) [14] , root length with shoot length. A perusal of these results indicated the need for balanced selection while effecting simultaneous improvement for these traits.…”

Molecular and Phenotypic Characterization for Cold Tolerance in Rice (Oryza sativa L.)

“…At 3-leaf stage (approximately 12 -15 days after seeding), the plastic trays were placed in the cold water tank pre-set at 13°C. Sensitivity to cold stress was recorded using an arbitrary leaf discoloration (LD) scores (1 to 9) as described in Biswas et al (2017). LD scores were recorded at seven days after cold treatment or when the susceptible check variety (BR1) died.…”

Mapping of QTLs for Yield Traits Using F2:3:4 Populations Derived From Two Alien Introgression Lines Reveals qTGW8.1 as a Consistent QTL for Grain Weight From Oryza nivara

“…Similarly, QTLs were reported in the F 2 population derived from a cross between a back cross inbred line ( japonica × indica ) and a japonica cultivar Z550 ( Wang et al, 2018 ). Various studies reported QTLs for yield traits in rice using primary mapping populations like F 2:3 ( Sabouri et al, 2009 ; Zhang et al, 2010 ; Kim et al, 2014 ; Tian et al, 2015 ; Biswas et al, 2017 ; Kumar et al, 2019 ) and F 2:4 ( Rabiei et al, 2015 ; Verma et al, 2017 ; Jeon et al, 2018 ; Kumar et al, 2019 ). Crossing of two wild-derived back cross inbred lines generate hybrid lines which can closely resemble the parental lines ( Wang et al, 2018 ) with combination of improved traits.…”