植物學(xué)

來(lái)源出版物：Journal of Integrative Plant Biology, 2015, 57(9): 757-769聯(lián)系郵箱：TAO Yi, yitao@xmu.edu.cn

封面介紹：When plants such as Arabidopsis are under canopy shade, the most prominent response is the elongations of stems/petioles. In this issue, Yu et al. (pp. 757-769) report that shade avoidance 2 (sav2) mutant (the bottom one in two SEM photos, and the right one in two seedlings) exhibits short and swollen hypocotyls when grown in shade. SAV2 encodes a β-tubulin, suggesting cMTs is cortical in regulating anisotropic cell growth.

Characterization oftub4P287L, a β-tubulin mutant, revealed new aspects of microtubule regulation in shade

Jie Yu, Hong Qiu, Xin Liu, et al.

When sun plants, such as Arabidopsis thaliana, are under canopy shade, elongation of stems/petioles will be induced as one of the most prominent responses. Plant hormones mediate the elongation growth. However, how environmental and hormonal signals are translated into cell expansion activity that leads to the elongation growth remains elusive. Through forward genetic study, we identified shade avoidance2 (sav2) mutant, which contains a P287L mutation in β-TUBULIN 4. Cortical microtubules (cMTs) play a key role in anisotropic cell growth. Hypocotyls of sav2 are wild type-like in white light, but are short and highly swollen in shade and dark. We showed that shade not only induces cMT rearrangement, but also affects cMT stability and dynamics of plus ends. Even though auxin and brassinosteroids are required for shade-induced hypocotyl elongation, they had little effect on shade-induced rearrangement of cMTs. Blocking auxin transport suppressed dark phenotypes of sav2, while overexpressing EB1b-GFP, a microtubule plus-end binding protein, rescued sav2 in both shade and dark, suggesting that tub4P287Lrepresents a unique type of tubulin mutation that does not affect cMT function in supporting cell elongation, but may affect the ability of cMTs to respond properly to growth promoting stimuli.

Arabidopsis; microtubules; plant hormones; shade