Molecular diversity and differential expression of starch-synthesis genes in developing kernels of three maize inbreds.

The maize genome remains abundant in molecular diversity, and the rich genetic diversity of maize starch-synthesis genes is crucial for controlling various grain traits. To explore the unique mechanism controlling the advantageous waxy trait and characterize the molecular feature of genes relevant to starch composition in two elite waxy inbreds, expression profiling combined with gene organization analysis was performed in them as compared to one normal inbred. Genotype-specific expression patterns were observed for most genes studied. The waxy inbreds were shown to contain mutations in multiple starch-synthesis genes, namely gbssI (wx), gbssIIb and isa2 (potentially isa3 too).The mis-splicing events directly accounted for wx loss of function. Contrarily, disruption of 5' and 3' transcript sequence may contribute to the absence of GbssIIb and Isa2 transcripts in waxy inbreds, respectively. Besides, the splicing of Sugary1 transcript was developmentally regulated in the normal inbred, and DNA polymorphisms were detected within SSIIIb-1 gene in waxy inbreds.