Dataset Information

Axillary meristems and the development of epicormic buds in wollemi pine (Wollemia nobilis).

ABSTRACT: Intact trees of Wollemia nobilis Jones, Hill and Allen (Araucariaceae) routinely develop multiple coppice shoots as well as orthotropic epicormic shoots that become replacement or additional leaders. As these are unusual architectural features for the Araucariaceae, an investigation was made of the axillary meristems of the main stem and their role in the production of epicormic and possibly coppice shoots. Leaf axils, excised from the apex to the base of 2-m-high W. nobilis plants (seedling origin, ex situ grown), were examined anatomically. Small, endogenous, undifferentiated (no leaf primordia, no vascular or provascular connections) meristems were found in the axils from near the shoot apex. In the more proximal positions about half the meristems sampled did not differentiate further, but became tangentially elongated to compensate for increases in stem diameter. In the remaining axils the meristems slowly developed into bud primordia, although these buds usually developed few leaf primordia and their apical 'domes' were wide and flat. Associated vascular development was generally restricted to provascular dedifferentiation of the cortical parenchyma, with the procambium usually forming a 'closed loop' that did not extend back to the secondary vascular tissues. Development of the meristems was very uneven with adjacent axils often at widely differing stages of development into buds. The study shows that, unlike most conifers, W. nobilis possesses long-lived meristematic potential in most, if not all, leaf axils. Unlike other araucarias that have been investigated, many of the meristems in the orthotropic main stem will slowly develop into bud primordia beneath the bark in intact plants. It appears likely that this slow but continued development provides a ready source of additional or replacement leaders and thus new branches and leaves.

SUBMITTER: Burrows GE

PROVIDER: S-EPMC4243624 | biostudies-literature | 2003 Dec

REPOSITORIES: biostudies-literature

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Axillary meristems and the development of epicormic buds in wollemi pine (Wollemia nobilis).

Burrows G E GE Offord C A CA Meagher P F PF Ashton K K

Annals of botany 20031201 6

Intact trees of Wollemia nobilis Jones, Hill and Allen (Araucariaceae) routinely develop multiple coppice shoots as well as orthotropic epicormic shoots that become replacement or additional leaders. As these are unusual architectural features for the Araucariaceae, an investigation was made of the axillary meristems of the main stem and their role in the production of epicormic and possibly coppice shoots. Leaf axils, excised from the apex to the base of 2-m-high W. nobilis plants (seedling ori ...[more]

PMID: 14612379

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Project description:BACKGROUND:Rice ratooning has traditionally been an important component of the rice cropping system in China. However, compared with the rice of the first harvest, few studies on factors effecting ratoon rice yield have been conducted. Because ratoon rice is a one-season rice cultivated using axillary buds that germinate on rice stakes and generate panicles after the first crop's harvest, its production is mainly affected by the growth of axillary buds. The objectives of this study were to evaluate the sprouting mechanism of axillary buds to improve the ratoon rice yield. RESULTS:First, we observed the differentiation and growth dynamics of axillary buds at different nodes of Shanyou 63, and found that they differentiated from bottom to top before the heading of the mother stem, and that they developed very slowly. After heading they differentiated from top to bottom, and the ones on the top, especially the top 2nd node, developed much faster than those at the other nodes. The average length and dry weight of the axillary buds were significantly greater than those at other nodes by the yellow ripe stage, and they differentiated into pistils and stamens by 6 d after the yellow ripe stage. The morphology of vegetative organs from regenerated tillers of Shanyou 63 also suggested the superior growth of the upper buds, which was regulated by hormones, in ratoon rice. Furthermore, a comprehensive proteome map of the rice axillary buds at the top 2nd node before and after the yellow ripe stage was established, and some proteins involved in steroid biosynthesis were significantly increased. Of these, four took part in brassinosteroid (BR) biosynthesis. Thus, BR signaling may play a role in the germination of axillary buds of ratoon rice. CONCLUSIONS:The data provide insights into the molecular mechanisms underlying BR signaling, and may allow researchers to explore further the biological functions of endogenous BRs in the germination of axillary buds of ratoon rice.

Project description:Perennial rice is a new type of rice that allows the harvest of rice for multiple years without growing new seedlings annually. This technology represents a green and sustainable agricultural production mode with many advantages for balancing agricultural ecology and food security. However, the differences in regeneration patterns between perennial and annual rice and the gene regulatory pathways of the apical dominance in axillary bud growth after harvest in perennial rice are still unclear. In this study, perennial rice (PR23) and annual rice (Chugeng28) were used to investigate axillary bud growth patterns before and after apical spike removal. After elimination of apical dominance at different development stages, perennial rice rhizome axillary buds at the compression nodes germinated more rapidly than others and developed into new seedlings. The axillary buds at the high-position nodes in annual rice grew faster than those at other nodes. Furthermore, the global gene expression patterns of PR23 rhizome buds at compression nodes grown for 1, 3, 4, and 5 days after apical spike removal were analyzed by transcriptome sequencing. Compared with the control buds without apical removal, 264, 3,484, 2,095, and 3,398 genes were up-regulated, and 674, 3,484, 1,594, and 1,824 genes were down-regulated in the buds grown for 1, 3, 4, and 5 days after apical spike removal, respectively. Trend analysis of the expressed genes at different time points was performed and co-expression network was constructed to identify key genes in rhizome axillary bud regrowth. The results showed that 85 hub genes involved in 12 co-regulatory networks were mainly enriched in the light system, photosynthesis-antenna protein, plant hormone signal transduction, ABC transporter and metabolic pathways, which suggested that hormone and photosynthetic signals might play important roles in the regulation of rhizome axillary bud regeneration in perennial rice. Overall, this study clarified the differences in the regeneration patterns of axillary buds between perennial and annual rice and provided insight into the complex regulatory networks during the regeneration of rhizome axillary buds in perennial rice.

Dataset Information

Axillary meristems and the development of epicormic buds in wollemi pine (Wollemia nobilis).

Publications

Axillary meristems and the development of epicormic buds in wollemi pine (Wollemia nobilis).

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