Fig. 4: ZmACO2 is expressed in developing ears and shows enzyme activity in ethylene biosynthesis in vivo.
From: An ethylene biosynthesis enzyme controls quantitative variation in maize ear length and kernel yield
ZmACO2 expression is highly localized in developing ears, revealed by RNA in situ hybridization; black arrowheads indicate SPMs (a), SMs (b), and the junction between glumes and FMs (c); the experiment was performed three times with similar results, using ears from at least three independent plants per experiment; negative control using sense probes (d); scale bars = 100 μm. e ACC oxidase (ACO) converts ACC to ethylene in the final pathway step of methionine-dependent ethylene biosynthesis in plants24. f Enzymatic activity of ZmACO2 and the H186Q protein isoforms at various concentrations of ACC; H186Q represents an isoform of ZmACO2 with a substitution at amino acid 186 from a histidine (H) to a glutamine (Q); experimental data are fit to a line representing Michaelis–Menten kinetics. Error bars represent SD; three biological replicates for each. Measurement of endogenous ethylene levels in 2 and 5 mm ears of qEL7SL17 (orange bar) and qEL7Ye478 (blue bar) (g) (p = 6.37 × 10−5 and 2.67 × 10−4 respectively), and 5 mm ears of aco2-cr1 (dark blue bar) and ACO2-OE3 (dark green bar) and their controls (orange bar) (p = 5.50 × 10−4 and 5.42 × 10−4 respectively). For g, h data are presented as means ± SD. ***p-value ≤ 0.001, from a two-tailed, two-sample t-test, three biological replicates for each, and approximately 30 ears were used in each biological replicate.
