An Improved Mesocotyl Elongation Assay for the Rapid Identification and Characterization of Strigolactone-Related Rice Mutants

Abstract

Strigolactones (SLs) constitute an important class of plant hormones involved in diverse developmental activities in plant growth and host-parasite interaction. Although substantial progress has been made to understand this pathway, the mechanism of action is still elusive especially with its interaction with other phytohormones and downstream targets. Here we have utilized the negative role of strigolactones in rice (Oryza sativa L.) mesocotyl elongation as a morphological marker for the identification and characterization of new developmental mutants. We observed that deep sown seeds develop longer mesocotyl compared with the surface-grown seeds in the dark condition. Based on this observation, we have developed a method to access mesocotyl elongation consisting of the glass vessel and vermiculite as a growth media. Mesocotyl elongation in the modified deep sown system results in a many-fold increase compared to the surface-grown seeds in the dark condition. External application of SLs analog rac-GR24 rescued the elongated mesocotyl phenotype in the mutant defective in SLs synthesis but not the signaling mutant, demonstrating its applicability in the physiological experiments. The modified mesocotyl elongation assay can be used as a rapid method for characterization and identification of suppressors/enhancers and new developmental mutants in the SLs or its associated pathway saving a huge amount of time and space.

Sucrose promotes D53 accumulation and tillering in rice

“…This observation suggests that D3/MAX2 may retain an inhibitory effect on bud outgrowth, even in the absence of SL perception. In field conditions, the d3 (s2-215) mutant 50 showed a more severe dwarf and high tillering phenotype compared with the d14 (htd-2) mutant 51 both being loss-of-function mutants developed from the same background (Nipponbare) (Supplementary figure S4). This stronger impact of D3/MAX2/RMS4 mutation compared with D14/RMS3 mutation or SL-deficiency has been reported in different species and in different developmental processes 52–55 , showing that our observations are not due to a specific allele, and the difference between D3 and D14 mutations is conserved in diverse species.…”

“…For rice, the tiller development assay in response to sucrose and GR24 was performed using HuaiDao5 as wild type and hd118 L97P (d27) as a SL-deficient mutant 50 . The seeds were sterilised as per the method described earlier 29 with slight modifications.…”

“…For rice, available lines created in different backgrounds were used as indicated in the figure legends, and the corresponding wild types were used as controls. The tiller development assay in response to sucrose and GR24 was performed using the japonica cultivar HuaiDao5 (Patil et al, 2019). The seeds were sterilised as per the method described earlier (Zhao et al, 2014) with slight modifications.…”

“…The lines were maintained in field condition at the experimental station of Shandong Rice Research Institute, Shandong, China. The lines used for sucrose sensitivity assay consisted of d3 (s2-215 Q393Stop ) (Patil et al, 2019) and d14 (htd-2) (Liu et al, 2009) mutants in the Nipponbare WT background.…”

Comparative transcriptome analysis identified important genes and regulatory pathways for flower color variation in Paphiopedilum hirsutissimum

“…6). Strigolactone is an important phytohormone derived from carotenoids and function in various plant developmental processes [29,45]. Genes encoding CCD8 and DWARF27 were strongly upregulated in albino flower tissues (Fig.…”