Distinction between the Responses of Developing Maize Kernels to Fluridone and Desiccation in Relation to Germinability, α-Amylase Activity, and Abscisic Acid Content

Abstract

Developing kernels of the maize (Zea mays) hybrid W64A x W182E germinated precociously following fluridone treatment.

Integrated control of seed maturation and germination programs by activator and repressor functions of Viviparous-1 of maize.

“…2). Our results are consistent with findings that a-amylase genes are not expressed in the developing seed (Nicholls 1979;Cornford et al 1986;Garcia-Maya et al 1990;Oishi and Bewley 1990). Hence, cessation of VP1 expression prior to germination may be necessary to allow induction of a-amylase genes in the germinating seed.…”

“…Although we cannot rule out the possibility that maternal ABA derived from the vp5/ + parent plant is sufficient for VP1 function, we suggest that VP1-mediated repression of Amy-GUS expression does not require ABA. This is also consistent with the finding that VPl also functions in aleurone of germinating seeds (see below] where ABA levels are very low (Oishi and Bewley 1990). Taken together, these data indicate that ABA and VP1 inhibit Amy-GUS expression independently.…”

“…5). This suggests that expression of VP1 in the developing seed may be, at least in part, responsible for the GA insensitivity of cereal and maize a-amylase genes prior to seed maturity (Nicholls 1979;Cornford et al 1986;Garcia-Maya et al 1990;Oishi and Bewley 1990). In our experiments, VP1 displayed full repressing activity in sln mutant barley seeds (Fig.…”

“…It has been suggested that the presence of ABA in developing seeds is responsible for the inhibition of a-amylase genes at this developmental stage (King 1976). However, treatment of developing maize seeds with the ABA synthesis inhibitor flouridone was not sufficient to sensitize the aleurone cells to GA, suggesting the action of additional factors in repressing a-amylase genes in the developing seed (Oishi and Bewley 1990).…”

“…In the developing seed, a-amylase activity is absent prior to seed maturity (Wilson et al 1973;Evans et al 1975). Moreover, a-amylase genes are unresponsive to applied GA (Nicholls 1979;Cornford et al 1986;Garcia-Maya et al 1990;Oishi and Bewley 1990). It has been suggested that the presence of ABA in developing seeds is responsible for the inhibition of a-amylase genes at this developmental stage (King 1976).…”