Auxin is a key regulator of plant growth and development. Within the root tip, auxin distribution plays a crucial role specifying developmental zones and coordinating tropic responses. Determining how the organ-scale auxin pattern is regulated at the cellular scale is essential to understanding how these processes are controlled. In this study, we developed an auxin transport model based on actual root cell geometries and carrier subcellular localizations. We tested model predictions using the DII-VENUS auxin sensor in conjunction with state-of-the-art segmentation tools. Our study revealed that auxin efflux carriers alone cannot create the pattern of auxin distribution at the root tip and that AUX1/LAX influx carriers are also required. We observed that AUX1 in lateral root cap (LRC) and elongating epidermal cells greatly enhance auxin's shootward flux, with this flux being predominantly through the LRC, entering the epidermal cells only as they enter the elongation zone. We conclude that the nonpolar AUX1/LAX influx carriers control which tissues have high auxin levels, whereas the polar PIN carriers control the direction of auxin transport within these tissues.
Red-fleshed
apples are popular as a result of their high anthocyanin content. MdMYB10 and its homologues are known to be important regulators
of anthocyanin synthesis in apple, but the roles of other transcription
factors are not well-understood. Here, we explored the role of MdWRKY11 in regulating anthocyanin synthesis in apple flesh.
Overexpression of MdWRKY11 in apple callus could
significantly promote anthocyanin accumulation, and the expression
of some MYB transcription factors and structural genes increased significantly.
In binding analyses, MdWRKY11 bound to W-box cis-elements
in the promoters of MdMYB10, MdMYB11, and MdUFGT. However, MdWRKY11 did not interact
with MdMYB10, MdbHLH3, or MdWD40 proteins, the members of the MBW
complex. Sequence analyses revealed that another W-box cis-element was present in the promoter of MdHY5 (encoding
a photoresponse factor), and MdWRKY11 was able to bind to the promoter
of MdHY5 and promote its activity. Our findings clarify
the role of MdWRKY11 in anthocyanin synthesis in
red-fleshed apple and imply that other novel genes may be involved
in anthocyanin synthesis.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.