Abstract
High sensitivity of rice coleoptile elongation length to exogenous gibberellin is a beneficial trait to utilize superior rice cultivars that could not be used originally under water direct-seeded conditions. In the present study, we mined favorable alleles for the trait by combining the phenotypic data of 358 rice accessions with their genotype data of 262 simple sequence repeat (SSR) markers via genome wide association mapping method. Totally, 17 SSR marker loci significantly associated with gibberellin sensitivity index (GSI) of coleoptile elongation length under 10 cm depth of water, were detected by general linear model and mixed linear model across two years, with percent phenotypic variation explained larger than 10%. Twenty nine favorable alleles for GSI on the 17 loci were discovered with phenotypic effect value (PEV) larger than 0.1 cm/cm and RM6869-110 bp showed the largest PEV (0.27 cm/cm). Based on PEV of marker-alleles having positive effects on GSI, seven parental combinations were predicted to improve GSI. In addition, 7 loci for GSI were co-located with loci associated with coleoptile elongation length per se, and one locus (RM1182 on chromosome 5) was co-located with that associated with coleoptile elongation length after gibberellin-soaked seed, under germination condition of 10 cm depth of water. These favorable allele(s) could be used to improve two target traits simultaneously.
Highlights
IntroductionDue to a lack of manpower and higher wages, rice growers turn to the direct seeding method (Angaji et al 2010)
Rice (Oryza sativa L.) is the most important cereal crop in the world
The phenotypic data of the control treatment (CL) and CLGS followed a normal distribution as showed in Fig. 1, which is confirmed by Kurtosis and Skewness values for both years (Table 1)
Summary
Due to a lack of manpower and higher wages, rice growers turn to the direct seeding method (Angaji et al 2010). Direct-seeded rice is a common production method in southern Louisiana and areas in Texas and California State, USA (Hardke and Scott 2013). Flooding creates hypoxic or anoxic condition resulting in poor germination and seedling establishment, even in some cases leads to plant death within few days of full submergence (IRRI 2016; Singh et al 2017). There are different categories of flooding; we are interested in submergence during germination known as anaerobic germination. On this condition, rapid seedling elongation can provide successful establishment, and escape
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