ERECTA Regulates Cell Elongation by Activating Auxin Biosynthesis in Arabidopsis thaliana

Abstract

The ERECTA family genes, ERECTA (ER), ERECTA-LIKE1 (ERL1), and ERECTA-LIKE2 (ERL2), encode leucine-rich repeat receptor-like kinases in Arabidopsis thaliana. Knocking out these three genes can cause severe phenotypes, which indicates that they play significant roles in plant growth and development. However, the molecular mechanism within remains unclear. Here we show that the short hypocotyl phenotypes of er erl1 erl2 mutants are mainly due to the defects of cell elongation rather than the cell division. In contrast, in the ERECTA overexpression transgenic plants, the hypocotyl length is increased with elongated cells. Moreover, we show that the er erl1 erl2 triple mutant contains a low level of auxin, and the expression levels of the key auxin biosynthesis genes are significantly reduced. Consistent with this observation, increasing exogenous or endogenous auxin levels could partially rescue the cell elongation defects of the er erl1 erl2 triple mutant. Therefore, our results provide a molecular basis for auxin mediated ERECTA control of the hypocotyl length in Arabidopsis thaliana.

Auxin and Gibberellins Are Required for the Receptor-Like Kinase ERECTA Regulated Hypocotyl Elongation in Shade Avoidance in Arabidopsis

“…Thirdly, it is known that high temperature can increase the endogenous auxin levels to promote the hypocotyl elongation of Arabidopsis and the expression of auxin biosynthesis gene YUC9 is also induced by shade ( Gray et al, 1998 ; Müller-Moulé et al, 2016 ), our results revealed that high temperature can enhance the hypocotyl elongation of er-3 similar to that of Col-0 in the white light condition ( Supplementary Figure S3 ) and auxin biosynthesis gene YUC9 is less induced by shade in er-3 than that in Col-0 ( Figure 5 ), indicating that endogenous auxin homeostasis makes an important contribution to ER-mediated hypocotyl elongation in the shade. This conclusion also supported by another recent study which revealed that auxin biosynthesis is essential for ER regulated cell elongation in the hypocotyl under white light ( Qu et al, 2017 ). It is reported that VAS2 controls the endogenous free IAA levels by conversion from IAA-Glu in the hypocotyl epidermis to promote the hypocotyl elongation ( Zheng et al, 2016 ).…”

Breaking the Summer Dormancy of Pinellia ternata by Introducing a Heat Tolerance Receptor-Like Kinase ERECTA Gene

“…The ER gene has been characterized as an important heat and drought stress regulator in plants. It controls plant growth from the early stages, throughout the developmental processes to the maturity of the plants in Arabidopsis (Qu et al, 2017), tomato and rice (Shen et al, 2015) and poplar (Xing et al, 2011). Similarly, ER-OE P. ternata lines showed a significantly improved plant growth performance, heat stress survival and recovery rates as compared to the EV controls in this study.…”

Auxin homeostasis and signaling alterations result in the aberrant phenotype in scl mutant of cotton (Gossypium hirsutum L.)

“…Abnormalities in auxin biosynthesis, accumulation, transport, signaling and other aspects could result in defective development and altered IAA contents in plants. The application of exogenous auxin can completely or partially restore the defects in auxin deficient mutants (Li et al 2015;Qu et al 2017). On the other hand, some of the auxin deficient mutants, for example the auxin signaling and transport deficient mutant pid, showed extremely weak response to exogenous auxin (Cui et al 2016).…”