Overexpression of DWARF4 in the brassinosteroid biosynthetic pathway results in increased vegetative growth and seed yield in Arabidopsis

Choe, S Fujioka, S Noguchi, T Takatsuto, S Yoshida, S Feldmann, KA

S. Choe et al., Overexpression of DWARF4 in the brassinosteroid biosynthetic pathway results in increased vegetative growth and seed yield in Arabidopsis, PLANT J, 26(6), 2001, pp. 573-582

37

INGLESE

Article

Plant Sciences","Animal & Plant Sciences

PLANT JOURNAL

0960-7412 → ACNP

26

6

2001

573 - 582

ISI

0960-7412(200106)26:6<573:OODITB>2.0.ZU;2-3

Plants unable to synthesize or perceive brassinosteroids (BRs) are dwarfs. Arabidopsis dwf4 was shown to be defective in a steroid 22 alpha hydroxylas e (CYP90B1) step that is the putative rate-limiting step in the BR biosynth etic pathway. To better understand the role of DWF4 in BR biosynthesis, tra nsgenic Arabidopsis plants ectopically overexpressing DWF4 (AOD4) were gene rated, using the cauliflower mosaic virus 35S promoter, and their phenotype s were characterized. The hypocotyl length of both light- and dark-grown AO D4 seedlings was increased dramatically as compared to wild type. At maturi ty, inflorescence height increased >35% in AOD4 lines and >14% in tobacco D WF4 overexpressing lines (TOD4), relative to controls. The total number of branches and siliques increased more than twofold in AOD4 plants, leading t o a 59% increase in the number of seeds produced. Analysis of endogenous BR levels in dwf4, Ws-2 and AOD4 revealed that dwf4 accumulated the precursor s of the 22 alpha -hydroxylation steps, whereas overexpression of DWF4 resu lted in increased levels of downstream compounds relative to Ws-2, indicati ve of facilitated metabolic flow through the step. Both the levels of DWF4 transcripts and BR phenotypic effects were progressively increased in dwf4, wild-type and AOD4 plants, respectively. This suggests that it will be pos sible to control plant growth by engineering DWF4 transcription in plants.