Abstract
rrd1, rrd2, and rid4 are temperature-sensitive mutants of Arabidopsis that are characterized by forming fasciated lateral roots at the restrictive temperature. The RID4 and RRD1 genes encode a pentatricopeptide protein (PPR) and a poly(A)-specific ribonuclease-like protein, respectively.
RRD1 is assumed to function as a deadenylase to remove mRNA poly(A) tails at the first step of mRNA degradation. If so, target mRNAs of RRD1 might accumulate at the restrictive temperature in the rrd1 mutant. To test this hypothesis, by microarray analysis, we compared mRNA profiles between the rrd1 and wild-type explants that were induced to form lateral roots at the restrictive temperature. The result showed that mRNAs of mitochondrial respiratory chain-related proteins over-accumulated in the rrd1 mutant.
Crossing experiments with rrd1, rrd2, and rid4 revealed that any double mutation caused embryonic lethality, which suggested close functional relations among their responsible genes. Thus the possibility has arisen that RRD1, RRD2, and RID4 cooperate in the control of degradation of a particular set of mRNAs required for proper development.
