Biology subjects

McCaskey, E. N.

Publications and source records attributed to McCaskey, E. N..

2 recordsLinked to original sources

bioRxiv2020

Mechanism and function of root circumnutation

AbstractEarly root growth is critical for plant establishment and survival. We have identified a molecular pathway required for oscillatory root tip movement known as circumnutation. Here we report a multiscale investigation of the regulation and function of this phenomenon. We identify key cell signaling events comprising interaction of the ethylene, cytokinin, and auxin hormone signaling pathways. We identify the gene Oryza sativa Histidine Kinase-1/OsHK1, as well as the auxin influx carrier gene OsAUX1, as essential regulators of this process in rice. Robophysical modelling demonstrated the benefits of tip movement for navigating past obstacles, prompting us to challenge mutant and wild-type plants with different substrates. Consistent with model behavior, root circumnutation facilitated exploration of a solid surface and promoted seedling establishment in rocky soil. Thus, the integration of robotics, physics and biology elucidated the functional importance of root circumnutation and uncovered the molecular mechanisms underlying its regulation. One sentence summaryCircumnutation facilitates root exploration.

plant biology↗

bioRxiv2018

A histidine kinase gene is required for large radius root tip circumnutation and surface exploration in rice

The intricate growth patterns that accompany plant organ elongation have long intrigued biologists 1. Circumnutation refers to the circular or elliptical growth of the tip of a plant organ around a central axis. While the utility of circumnutation for climbing plants is clear, its function in roots is less obvious. Additionally, the genetic requirements for root circumnutation are not known. Here we show that mutations in a gene encoding a histidine kinase abolish large radius root tip circumnutation in rice. Using a gel-based imaging system and a whole genome sequenced mutant population, we identified three different mutant alleles of the gene OsHK1 that exhibit increased seedling root depth. Time-lapse imaging indicated that this phenotype is likely due to a lack of large radius root tip circumnutation in OsHK1 mutants. Treatment of mutant roots with the plant hormone zeatin rescues circumnutation, indicating that OsHK1 functions in a cytokinin-related signaling pathway. We found that OsHK1 mutants are impaired in their ability to explore flat surfaces, suggesting that circumnutation facilitates root exploration at the interface of compacted soil horizons.

plant biology↗