PagGRF12a interacts with PagGIF1b to regulate secondary xylem development through modulating PagXND1a expression in Populus alba × P. glandulosa

Rab GTPases are the subfamily of the small guanosine triphosphate (GTP)-binding proteins which participated in the regulation of various biological processes. Recent studies have found that plant Rabs play some specific functions. However, the functions of Rabs in xylem development in trees remain unclear. In this study, functional identification of PagRabE1b in Populus was performed. Quantitative reverse transcription PCR (qRT-PCR) results showed that PagRabE1b was highly accumulated in stems, especially in phloem and xylem tissues. Overexpression of PagRabE1b in poplar enhanced programmed cell death (PCD) and increased the growth rate and the secondary cell wall (SCW) thickness. Quantitative analysis of monosaccharide content showed that various monosaccharides were significantly increased in secondary xylem tissues of the overexpressed lines. Flow cytometry analysis revealed that the number of apoptotic cells in PagRabE1b-OE lines is more than a wild type (WT), which indicated that PagRabE1b may play an important role in PCD. Further studies showed that overexpression of PagRabE1b increased the expression level of genes involved in SCW biosynthesis, PCD, and autophagy. Collectively, the results suggest that PagRabE1b plays a positive role in promoting the xylem development of poplar.

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Effects of Light Intensity on Early Periderm and Xylem Development in Pinusresinosa, Fraxinuspennsylvanica, and Robiniapseudoacacia

Canadian Journal of Forest Research ◽

10.1139/x72-033 ◽

1972 ◽

Vol 2 (3) ◽

pp. 190-197 ◽

Cited By ~ 5

Author(s):

G. A. Borger ◽

T. T. Kozlowski

Keyword(s):

Seed Germination ◽

Light Intensity ◽

Secondary Xylem ◽

Xylem Development

The influence of light intensity on development of the first periderm and xylem in seedlings of Pinusresinosa, Fraxinuspennsylvanica, and Robiniapseudoacacia up to 56 days after seed germination was studied. Dark-grown seedlings of all three species lacked periderm at the end of the experimental periods, emphasizing the essentiality of light for periderm development. P. resinosa seedlings grown for 56 days following germination at 70 ft-c (1 ft-c = 10.76 lm/m2) of light and R. pseudoacacia seedlings grown at 70 or 300 ft-c of light for 30 days following germination failed to develop periderm. Seedlings of F. pennsylvanica grown at 70, 300, 600 or 1200 ft-c of light for 30 days following germination developed periderm. Periderm increments did not differ in 56-day-old P. resinosa seedlings grown at 600 or 1200 ft-c or in 30-day-old F. pennsylvanica seedlings grown at 70 or 300 ft-c of light. Phellogen formed sooner and was more active in 30-day-old R. pseudoacacia seedlings grown at 1200 ft-c than in those grown at 600 ft-c. Time to periderm initiation decreased and phellem increment increased in 30-day-old F. pennsylvanica seedlings with each increase in light intensity from 300 to 1200 ft-c. Secondary xylem was absent in dark-grown seedlings of all three species and in P. resinosa and F. pennsylvanica seedlings grown at 70 ft-c of light. In other treatments xylem increment increased significantly with each increase in light intensity up to 1200 ft-c.

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