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Characterization of tub4 P287L , a β‐tubulin mutant, revealed new aspects of microtubule regulation in shade
Author(s) -
Yu Jie,
Qiu Hong,
Liu Xin,
Wang Meiling,
Gao Yongli,
Chory Joanne,
Tao Yi
Publication year - 2015
Publication title -
journal of integrative plant biology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.734
H-Index - 83
eISSN - 1744-7909
pISSN - 1672-9072
DOI - 10.1111/jipb.12363
Subject(s) - hypocotyl , mutant , microtubule , auxin , biology , arabidopsis , elongation , microbiology and biotechnology , tubulin , gibberellin , arabidopsis thaliana , wild type , shade avoidance , botany , biochemistry , gene , materials science , ultimate tensile strength , metallurgy
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 s hade av oidance2 ( 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 tub4 P287L represents 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.