Hd. Jones et al., GENOTYPE AND ENVIRONMENT INTERACT TO CENTRAL DORMANCY AND DIFFERENTIAL EXPRESSION OF THE VIVIPAROUS-1 HOMOLOG IN EMBRYOS OF AVENA-FATUA, Plant journal, 12(4), 1997, pp. 911-920
Embryo dormancy is a reversible developmental state during which germi
nation is repressed. In this study, inbred lines of Avena fatua were u
sed to analyse the influence of genotype and environment on the dorman
t phenotype, and on expression of the homologue of the maize transcrip
tion factor VIVIPAROUS 1 (afVP 1). The cDNA for afVP 1 was cloned from
mature embryos. Analysis of the predicted protein sequence revealed a
high degree of similarity to other VP 1/ABI 3-related transcription f
actors, in particular in four regions previously shown to be highly co
nserved, including the BR2 region that has been shown to interact with
several classes of sequence-specific DNA binding proteins. The potent
ial of imbibed mature embryos for dormancy was analysed and shown to b
e determined primarily by genotype and secondarily by previous environ
mental experience of the mature seed acting on embryo genotype. Under
all conditions studied, expression of afVP 1 and the A. fatua homologu
e of Pm (shown in maize to be regulated by VP 1 during embryo maturati
on) were positively correlated with the dormant phenotype, whereas exp
ression of A. fatua AMY-related RNAs was negatively correlated with do
rmancy (in barley AMY 6-4 has been shown to be repressed by VP 1). Exp
ression of afVP 1 RNA was also shown in the dry seed to be positively
correlated with the length of time required for seeds of the inbred li
nes to after-ripen. These results suggest new functions for the VP 1 t
ranscription factor family in the control of dormancy-related processe
s in embryo cells of mature seeds, and the up-regulation of afVP 1 and
afEm RNAs in the dormant state suggests that they are regulated by a
switching mechanism in the mature seed that shows some aspects of reve
rsibility.