. The Biological bulletin. Biology; Zoology; Biology; Marine Biology. 68 A. L. MILLER. Figure 4. The enhanced rooi-generated current induced by 10 6 M FC at pH (A). (D). and (O) are compared with their respec- tive APW controls (A). (•) and (•). Six-day-old seedlings were utilized. effective at pH , where it induced more that a dou- bling of the elongation rate. At the upper (pH ) and lower (pH ) limits of the pH range, the promotive effects of fusicoccin on growth were not so apparent in comparison with controls (Table I). It was clear that the absence of K+ had little ef
. The Biological bulletin. Biology; Zoology; Biology; Marine Biology. 68 A. L. MILLER. Figure 4. The enhanced rooi-generated current induced by 10 6 M FC at pH (A). (D). and (O) are compared with their respec- tive APW controls (A). (•) and (•). Six-day-old seedlings were utilized. effective at pH , where it induced more that a dou- bling of the elongation rate. At the upper (pH ) and lower (pH ) limits of the pH range, the promotive effects of fusicoccin on growth were not so apparent in comparison with controls (Table I). It was clear that the absence of K+ had little effect on the enhanced inward current density over the length of the root examined (Fig. 5). Effects of I.'LA on the root-generated ion current and root growth exogenous presence of 10"6 A/IAA ~.u reduced the density of the in- also induced a shift towards the r 5-over point (, acrope- tally comprt ird current). The effects of IAA were the pH of the experi- mental med of growth rates mea- sured at pH 3 -a roots was inhib- ited by the pres i. This inhibition ap- peared to be ph ,eater inhibition at high pH. As shou i, the reduction in growth rate resulting PH of the bathing medium (in the absence of IAA) was also associated with a reduction in inward current density and an acropetal compression of the region of the root associated with in- ward current. Discussion The ion current pattern detected in the medium sur- rounding primary root tips of Zea indicated clearly that positive current flowed into those parts of the root that were responsible for division, differentiation, and growth: the meristematic and elongating tissues. Mature root regions were responsible for generating the bulk of the outward current. These results are consistent with previous investigations of root growth made with vibrat- ing electrodes (Weisensed et al, 1979; Behrens et ai, 1982; Miller et al, 1986, 1988; Miller and Gow, 1989). The suggestion that H+ ions may be a major component carrying
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Keywords: ., bookauthorlilliefrankrat, booksubjectbiology, booksubjectzoology
