GENE-EXPRESSION IN DEVELOPING KERNELS OF SOME ENDOSPERM MUTANTS OF MAIZE

A number of endosperm mutants of maize (Zea mays L.) have altered kern el composition as the result of single locus mutations. We have examin ed eight different mutants to determine how these mutations might affe ct expression of eight different genes in developing kernels. We found that the abundance of aldolase, Shrunken-2, Brittle-2, Opaque-2 and W axy transcripts were stimulated by the mutations. The abundance of all of these transcripts, except for Shrunken-2, was correlated with the sucrose concentration in the kernel. Sucrose may modulate expression o f these genes. Transcript abundance of the zein genes was lower in mos t of the mutants. A correlation between a-zein transcript abundance an d mature kernel zein protein content suggested that zein accumulation is controlled by transcript abundance. A correlation between a-zein tr anscript abundance and mature kernel dry weight suggested that zein ge ne expression is in some way linked with carbohydrate formation. The i nverse relationship between sugar concentration in immature kernels an d mature kernel dry weight supports the concept that the failure of de veloping kernels to utilize nutrients in the biosynthesis of storage p roducts results in the accumulation of these nutrients. The accumulati on of sugars and amino acids may then contribute to the observed chang es in overall gene expression.