Selection for seedling cold vigor in grain sorghum
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Sorghum is the fifth most widely grown cereal grown in the world, but one limitation to sorghum production is the restriction of cool temperatures on crop growth and development. The primary objective of the current study was to validate five previously identified markers of cold tolerance in sorghum by deriving a recombinant inbred line population from a cross between BTx623, a warm season elite sorghum line, and Hong Ke Zi, a Chinese sorghum landrace with increased cold tolerance. We conducted controlled environment screening testing of 307 recombinant inbred lines (RILs), followed by field-based phenotypic testing early-planted sorghum for 31 selected lines. Genotyping of the 31 F4 RILS using the KASP genotyping technology indicated that only two of the five markers tested showed segregation for the HKZ, BTx623, and the heterozygous genotype. Using the genotype data obtained, the genotype of each of the 31 RILS was compared to the various growth parameters measured by performing a one-way ANOVA analysis. Significant separation of the three genotypic groups (homozygous for HKZ allele, homozygous for BTx623 allele, and heterozygous for both alleles) was seen with the root biomass per plot (RBM/plot) phenotype only. That is, RILS that contained the homozygous HKZ (cold-tolerant) allele had significantly more root biomass than did RILS that were homozygous for the BTx623 allele or heterozygous for both alleles (Table 3.2). This result indicates that the two markers tested could be potential candidates in selecting for the seedling cold vigor trait using marker assisted selection (MAS). Though this result is promising, the markers need to be tested against a larger pool of diverse individuals to observe if the markers are truly viable as a selection tool.