Root hairs (RHs) are mixed tip- and non-tip-growing protrusions derived from root epidermal cells that play essential roles in nutrient and water uptake, root anchorage, and interactions with soil microorganisms. Nutrient availability and temperature are critical and interconnected factors for sustained plant growth, but the molecular mechanisms that underlie their perception and downstream signaling pathways remain unclear. Here, we show that moderately low temperature (10°C) induces a strong RH elongation response mediated by several molecular components of the auxin pathway. Specifically, auxin biosynthesis mediated by TAA1/YUCCAs, auxin transport via PIN2, PIN4, and AUX1, and auxin signaling regulated by TIR1/AFB2 in conjunction with specific ARFs (ARF6/ARF8 and ARF7, but not ARF19) contribute to the RH response under moderately low temperature. These findings establish the auxin biosynthesis and signaling pathway as a central regulatory process driving RH growth under moderate low-temperature conditions in roots. Our work underscores the importance of moderately low temperature as a stimulus that interacts with complex nutritional signaling originating from the growth medium and the plant nutritional status; this process has the potential to be fine-tuned for future biotechnological applications to enhance nutrient uptake.

• Klíčová slova
• Arabidopsis, auxin, moderately low temperature, root hairs,
• MeSH
• Arabidopsis * růst a vývoj   metabolismus   genetika   fyziologie   MeSH
• kořeny rostlin * růst a vývoj   metabolismus   genetika   MeSH
• kyseliny indoloctové * metabolismus   MeSH
• nízká teplota MeSH
• proteiny huseníčku metabolismus   genetika   MeSH
• regulace genové exprese u rostlin MeSH
• signální transdukce * MeSH
• Publikační typ
• časopisecké články MeSH
• Názvy látek
• kyseliny indoloctové * MeSH
• proteiny huseníčku MeSH

Roots are sensors evolved to simultaneously respond to manifold signals, which allow the plant to survive. Root growth responses, including the modulation of directional root growth, were shown to be differently regulated when the root is exposed to a combination of exogenous stimuli compared to an individual stress trigger. Several studies pointed especially to the impact of the negative phototropic response of roots, which interferes with the adaptation of directional root growth upon additional gravitropic, halotropic or mechanical triggers. This review will provide a general overview of known cellular, molecular and signalling mechanisms involved in directional root growth regulation upon exogenous stimuli. Furthermore, we summarise recent experimental approaches to dissect which root growth responses are regulated upon which individual trigger. Finally, we provide a general overview of how to implement the knowledge gained to improve plant breeding.

• Klíčová slova
• ABA, SnRK1, SnRK2, TOR, auxin, green systems biology, metabolomics, panomics,
• Publikační typ
• časopisecké články MeSH
• přehledy MeSH

Directional root growth control is crucial for plant fitness. The degree of root growth deviation depends on several factors, whereby exogenous growth conditions have a profound impact. The perception of mechanical impedance by wild-type roots results in the modulation of root growth traits, and it is known that gravitropic stimulus influences distinct root movement patterns in concert with mechanoadaptation. Mutants with reduced shootward auxin transport are described as being numb towards mechanostimulus and gravistimulus, whereby different growth conditions on agar-supplemented medium have a profound effect on how much directional root growth and root movement patterns differ between wild types and mutants. To reduce the impact of unilateral mechanostimulus on roots grown along agar-supplemented medium, we compared the root movement of Col-0 and auxin resistant 1-7 in a root penetration assay to test how both lines adjust the growth patterns of evenly mechanostimulated roots. We combined the assay with the D-root system to reduce light-induced growth deviation. Moreover, the impact of sucrose supplementation in the growth medium was investigated because exogenous sugar enhances root growth deviation in the vertical direction. Overall, we observed a more regular growth pattern for Col-0 but evaluated a higher level of skewing of aux1-7 compared to the wild type than known from published data. Finally, the tracking of the growth rate of the gravistimulated roots revealed that Col-0 has a throttling elongation rate during the bending process, but aux1-7 does not.

• Klíčová slova
• AUX1, AUXIN-RESISTANT 1, D-root system, directional root growth, gravitropic response, mechanoadaptation, mechanostimulus, root elongation rate, root penetration assay, root skewing,
• Publikační typ
• časopisecké články MeSH

The root is the below-ground organ of a plant, and it has evolved multiple signaling pathways that allow adaptation of architecture, growth rate, and direction to an ever-changing environment. Roots grow along the gravitropic vector towards beneficial areas in the soil to provide the plant with proper nutrients to ensure its survival and productivity. In addition, roots have developed escape mechanisms to avoid adverse environments, which include direct illumination. Standard laboratory growth conditions for basic research of plant development and stress adaptation include growing seedlings in Petri dishes on medium with roots exposed to light. Several studies have shown that direct illumination of roots alters their morphology, cellular and biochemical responses, which results in reduced nutrient uptake and adaptability upon additive stress stimuli. In this review, we summarize recent methods that allow the study of shaded roots under controlled laboratory conditions and discuss the observed changes in the results depending on the root illumination status.

• Klíčová slova
• D-rootsystem, abiotic stress, auxin, cytokinin, dark-grown roots, direct root illumination, flavonols, light escape mechanism, reactive oxygen species, root growth,
• MeSH
• fyziologická adaptace * MeSH
• kořeny rostlin metabolismus   účinky záření   MeSH
• regulace genové exprese u rostlin účinky záření   MeSH
• rostlinné proteiny genetika   metabolismus   MeSH
• rostliny metabolismus   účinky záření   MeSH
• semenáček metabolismus   účinky záření   MeSH
• světlo * MeSH
• Publikační typ
• časopisecké články MeSH
• přehledy MeSH
• Názvy látek
• rostlinné proteiny MeSH

Plant growth is continuously modulated by endogenous and exogenous stimuli. By no means the only, but well described, signaling molecules produced in plants and distributed through the plant body to orchestrate efficient growth are photosynthates. Light is a potent exogenous stimulus that determines, first, the rate of photosynthesis, but also the rate of plant growth. Root meristem activity is reduced with direct illumination but enhanced with increased sugar levels. With reduced cotyledon illumination, the seedling increases hypocotyl elongation until adequate light exposure is again provided. If endogenous carbon sources are limited, this leads to a temporary inhibition of root growth. Experimental growth conditions include exogenous supplementation of sucrose or glucose in addition to culturing seedlings under light exposure in Petri dishes. We compared total root length and hypocotyl elongation of Arabidopsis thaliana wild type Col-0 in response to illumination status and carbon source in the growth medium. Overall, sucrose supplementation promoted hypocotyl and root length to a greater extent than glucose supplementation. Glucose promoted root length compared to non-supplemented seedlings especially when cotyledon illumination was greatly reduced.

• Klíčová slova
• Arabidopsis thaliana, carbon source, dark grown root, drootsystem, etiolated, hypocotyl growth, illumination, root growth, shaded cotyledons,
• MeSH
• adaptace oční fyziologie   MeSH
• Arabidopsis růst a vývoj   metabolismus   MeSH
• glukosa metabolismus   MeSH
• hypokotyl růst a vývoj   metabolismus   MeSH
• kořeny rostlin růst a vývoj   metabolismus   MeSH
• kotyledon růst a vývoj   metabolismus   MeSH
• sacharosa metabolismus   MeSH
• uhlík metabolismus   MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH
• Názvy látek
• glukosa MeSH
• sacharosa MeSH
• uhlík MeSH