The cooperation effects of GA3, IAA and uniconazole-P were studied on the gravitropism and wood formation in Fraxinus mandshurica Rupr. var.japonica Maxim. Seedlings using traditional paraffin section technology. Our ...The cooperation effects of GA3, IAA and uniconazole-P were studied on the gravitropism and wood formation in Fraxinus mandshurica Rupr. var.japonica Maxim. Seedlings using traditional paraffin section technology. Our results are： （1） Gravitropism of stems was strongly inhibited only in B, whereas promoted significantly in D, E, F, H and I treatments; （2） Xylem formation was increased on both sides in H, I and J treatments and on the lower side in E and F which also show the synergistic effect; （3） On the radial direction, cell wall thickness was enhanced on the upper side, whereas decreased on the lower side in C, and was also significantly promoted on the upper in E, G, H, I and J treatments. On the tangential direction, cell wall thickness was increased on the lower side in E, H, I and J treatments respectively; （4） Gelatinous layer of wood fibers was observed on the upper side in all treatments. These results suggest that both GA3 and IAA affected negative gravitropism and wood formation significantly. However, appliedor unapplited-uniconazole-P does not affect G-layer formation, indicating GA does not play the key role on G-layer formation, and ratio of GA3/IAA or IAA may be more important in regulating G-layer formation.展开更多
GA3 and GA4 （gibberellins） play an important role in controlling gravitropism and tension wood formation in woody angiosperms. In order to improve our understanding of the role of GA3 and GA4 on xylem cell formation...GA3 and GA4 （gibberellins） play an important role in controlling gravitropism and tension wood formation in woody angiosperms. In order to improve our understanding of the role of GA3 and GA4 on xylem cell formation and the G-layer, we studied the effect of GA3 and GA4 and uniconazole-P, which is an inhibitor of GA biosynthesis, on tension wood formation by gravity in Fraxinus mandshurica Rupr. var. japonica Maxim. seedlings. Forty seedlings were divided into two groups; one group was placed upright and the other tilted. Each group was further divided into four sub-groups subjected to the following treatments： 3.43 x 10-9 lunol acetone as control, 5.78 x 10-8 lunol gibberellic acid （GA3）, 6.21 x 10-8 lunol GA4, and 6.86 x 10-8 lunol uniconazole-P. During the experimental period, GAs-treated seedlings exhibited negative gravitropism, whereas application of uniconazole-P inhibited negative gravitropic stem bending. GA3 and GA4 promoted wood fibers that possessed a gelatinous layer on the upper side, whereas uniconazole-P inhibited wood formation but did not inhibit the differentiation of the gelatinous layer in wood fibers on the upper side. These results suggest that： （i） both the formation of gelatinous fibers and the quantity of xylem production are important for the negative gravitropism in horizontally-positioned seedlings; （ii） GA3 and GA4 affect wood production more than differentiation of the gelatinous layer in wood fibers; G-layer development may be regulated by other hormones via the indirect-role of GA3 and GA4 in horizontally-positioned F. mandshurica seedlings rather than the direct effect of GAs; and （iii） the mechanism for upward wood stem bending is different to the newly developed shoot bending in reaction to gravity in this species.展开更多
基金This research was supported by the scholarship from the Japanese Ministry of Education （No. 07456073）, Scientific Research Foundation for the Returned Oversea Chinese Scholars, State Education Ministry of China, Natural Science Foundation of Tianjin, China （No. 07JCYBJCI2400 and No. 07JCYBJCI2500） and National Key Basic Research Plan Proiect （No. 2007CB 106802）.
文摘The cooperation effects of GA3, IAA and uniconazole-P were studied on the gravitropism and wood formation in Fraxinus mandshurica Rupr. var.japonica Maxim. Seedlings using traditional paraffin section technology. Our results are： （1） Gravitropism of stems was strongly inhibited only in B, whereas promoted significantly in D, E, F, H and I treatments; （2） Xylem formation was increased on both sides in H, I and J treatments and on the lower side in E and F which also show the synergistic effect; （3） On the radial direction, cell wall thickness was enhanced on the upper side, whereas decreased on the lower side in C, and was also significantly promoted on the upper in E, G, H, I and J treatments. On the tangential direction, cell wall thickness was increased on the lower side in E, H, I and J treatments respectively; （4） Gelatinous layer of wood fibers was observed on the upper side in all treatments. These results suggest that both GA3 and IAA affected negative gravitropism and wood formation significantly. However, appliedor unapplited-uniconazole-P does not affect G-layer formation, indicating GA does not play the key role on G-layer formation, and ratio of GA3/IAA or IAA may be more important in regulating G-layer formation.
基金Supported by a Scholarship from the Japanese Ministry of Education(07456073)Scientific Research Foundation for the Returned Overseas Chinese Scholars.
文摘GA3 and GA4 （gibberellins） play an important role in controlling gravitropism and tension wood formation in woody angiosperms. In order to improve our understanding of the role of GA3 and GA4 on xylem cell formation and the G-layer, we studied the effect of GA3 and GA4 and uniconazole-P, which is an inhibitor of GA biosynthesis, on tension wood formation by gravity in Fraxinus mandshurica Rupr. var. japonica Maxim. seedlings. Forty seedlings were divided into two groups; one group was placed upright and the other tilted. Each group was further divided into four sub-groups subjected to the following treatments： 3.43 x 10-9 lunol acetone as control, 5.78 x 10-8 lunol gibberellic acid （GA3）, 6.21 x 10-8 lunol GA4, and 6.86 x 10-8 lunol uniconazole-P. During the experimental period, GAs-treated seedlings exhibited negative gravitropism, whereas application of uniconazole-P inhibited negative gravitropic stem bending. GA3 and GA4 promoted wood fibers that possessed a gelatinous layer on the upper side, whereas uniconazole-P inhibited wood formation but did not inhibit the differentiation of the gelatinous layer in wood fibers on the upper side. These results suggest that： （i） both the formation of gelatinous fibers and the quantity of xylem production are important for the negative gravitropism in horizontally-positioned seedlings; （ii） GA3 and GA4 affect wood production more than differentiation of the gelatinous layer in wood fibers; G-layer development may be regulated by other hormones via the indirect-role of GA3 and GA4 in horizontally-positioned F. mandshurica seedlings rather than the direct effect of GAs; and （iii） the mechanism for upward wood stem bending is different to the newly developed shoot bending in reaction to gravity in this species.
