Functional Genomics can Assist Molecular Breeding of Maize

Tissue-culture-based genetic transformation, a commonly used maize breeding technique, however, is limited by two major roadblocks: First, the relative unavailability of genome sequences of inbred lines that show stark phenotypic variations and second, difficulty in inducing callus from immature maize embryos on tissue culture media—the initial step of genetic transformation.

Dr. Yaou Shen of Sichuan Agricultural University, lead author of the study and one of the corresponding authors, explains: “A188 also shows excellent callus induction from the immature embryo, and therefore, we sought to determine the candidate genes responsible for this highly desirable trait.” First, they compared the phenotypic variations of A188 with those of three other reference maize inbred lines, B73, Mo17, and W22. Whereas, Dr. Langlang Ma, the other corresponding author of the study explains, “We assembled a 2210-Mb genome for A188 with a scaffold N50 size of 11.61 million bases (Mb), a value much larger compared to 9.73 Mb for B73 and 10.2 Mb for Mo17 lines.” Interestingly, almost 30% of the predicted A188 genes were structurally very different from other maize lines, accounting for the high protein divergence and phenotypic variations seen in A188.

In their study published in The Crop Journal, they explored the genome of maize inbred line A188, known for having many unique traits compared to other lines, to elucidate the linkage between genotype and phenotype.

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