Cellular expression of panicle exsertion and peduncle elongation in semidwarf oat
1990
Farnham, M.W. | Stuthman, D.D. | Biesboer, D.D.
Panicle exsertion genes partially reverse the phenotypic effects of the Dw6 dwarfing gene in oat (Avena sativa L.) by elongating the peduncle. The objectives of this study were to: (i) determine the cellular basis of peduncle elongation in semidwarfs exhibiting full panicle exsertion, (ii) determine GA-sensitivity of Dw6 semidwarfs, and (iii) attempt to mimic the action of exsertion genes with a boot-stage application of gibberellic acid (GA3) to nonexserted semidwarfs. Four pairs of divergent lines, each pair consisting of a nonexserted semidwarf with a short peduncle and an exserted semidwarf with an extended peduncle, were compared in greenhouse and field experiments along with OT207, the original source of Dw6, and OT184, the nondwarf parent of OT207. Peduncle epidermal cells of all lines were measured. The GA3 was applied to field-grown plants, and genetically nonexserted plants sprayed with GA, were cytologically compared to exserted controls having equal length peduncles. Peduncles of OT207 had fewer and shorter cells per vertical axis than peduncles of OT184. Similar differences were observed between exserted and nonexserted lines. Thus, the Dw6 gene and the panicle exsertion genes have an effect on both cell number and cell elongation. The GA3 application elongated the peduncles by enhancing both cell number and elongation as do exsertion genes; however, GA3 application and exsertion genes did not produce peduncles with identical cellular characteristics. Effects of GA3 application on peduncle elongation were more pronounced in OT207 and nonexserted semidwarfs than in respective longer peduncle lines. Results implicate the involvement of GA metabolism in the action of Dw6 and the exsertion genes.
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