The use of hair roots as experimental samples has been a research focus for understanding the effects of spaceflight on astronauts, because it has many advantages, one of which is the fact that hair matrix cells activ...The use of hair roots as experimental samples has been a research focus for understanding the effects of spaceflight on astronauts, because it has many advantages, one of which is the fact that hair matrix cells actively divide in a hair follicle and sensitively reflect the physical conditions of the human body. In 2009, a research program focusing on the analysis of astronauts’ hairs was initiated to examine the effects of long-term spaceflight on the gene expression and mineral metabolism in the human body. Since the number of samples per astronaut is limited to 5 strands of hairs at each sampling point, due to the ethical viewpoint of astronauts or limited resources in space, it is important to develop an effective method for the molecular analysis of small amounts of hair roots. In this study, mRNA successfully extracted from 1, 5, and 10 hair follicles was amplified and subjected to the DNA microarray analysis to compare the gene expression within subjects. The results indicated that (1) it was possible to perform the genetic analysis on hair samples stored at -80℃, even without a fixation buffer and (2) the newly modified method of mRNA extraction and analysis was effective in detecting differential gene expression in samples containing only 5 hairs. In conclusion, RNA was efficiently extracted from 5 hair roots, which is the same number of hair roots used in the space experiment;therefore, this method can be applied to genetically analyze astronauts’ hair samples.展开更多
A system to control the release of phosphate in water was successfully established, based on solubility product of [Ca^2＋] and [PO4^3-] using tricalcium phosphate as P source in the hydroponic solution, and adding Ca...A system to control the release of phosphate in water was successfully established, based on solubility product of [Ca^2＋] and [PO4^3-] using tricalcium phosphate as P source in the hydroponic solution, and adding CaCl2 for supplementing extra Ca^2＋. The system, similar to soil solutions, was a P nutrient buffer solution with very low bioavailable P. The buffer solution induced the roots of both monocotyledon and dicotyledon species to grow abundant root hairs, 3 mm in maximum length. The monocotyledons were corn （Zea mays L.） （var. Yellow Rose）, wheat （Triticum aestivum L.） （var. Yanzhong 144）, Triticale secale L. （vat. Jingsong 5）, and ryegrass （Lolium rigidum L.） （var. Ruanni）, and the dicotyledons were Arabidopsis thaliana L. （var. Columbia）, white clover （Trifolium repens） （var. Kopu）, Lotus （Lotus peduncucatus Cav. Luliginosus Schkuhr） （var. Grasslands Maku）. For these species we proved that the root environment controls the induction of root hair formation. However, the hydroponic buffer solution failed to induce root hairs on the roots of onion （Allium cepa L.）. Other investigators have concluded that corn does not form root hairs in hydroponics, but abundant long root hairs on corn were induced by this buffer system. The roots with abundant long root hairs are called ＂hedgehog roots＂ because they have hairs everywhere just like a hedgehog.展开更多
Peanut root invasion by Bradyrhizobia is through a crack entry, which is different from many other legumes applying an infection thread entry in root hair. Understanding the role of root hair in the crack entry of Bra...Peanut root invasion by Bradyrhizobia is through a crack entry, which is different from many other legumes applying an infection thread entry in root hair. Understanding the role of root hair in the crack entry of Bradyrhizobia invasion of peanut root and subsequent peanut nodulation would facilitate improvement of biological nitrogen fixation in cultivated peanut. The objective of this study was to investigate the involvement of root hair in Bradyrhizobial invasion of peanut. Seedling roots of a nodulating peanut cultivar were observed for root hair emergence, its life span, and nodule formation at the base of the lateral roots with and without rhizobia inoculation for 14 days after germination (DAG). Scanning electron microscopy (SEM) was utilized to observe rhizobia accumulation at lateral roots at 24 hours after inoculation (HAI) before the emergence of root hair. Root hair emerged at 7 DAG with or without rhizobia inoculation. Two variations of rosette hair (RoH) were observed, the transient-thin RoH had life span of 3 days after root hair emergence and the thick and densely distributed RoH type stayed till the time of nodule emergence (9 days after inoculation). The lateral root devoid of root hair at the top 2 cm region was found to produce nodules. The SEM observation of seedling roots at 24 HAI showed that Bradyrhizobia invaded the roots at epidermis, protoplasm of cortical cell, and cortical cells of the main root near the newly emerged lateral root in the absence of RoH. The observations validated that root hair is not required in the Bradyrhizobia invasion of peanut root in the crack entry mode. Results from this study provided important morphological information for the hypothesis of close relationship between RoH and peanut nodulation for further genetic study of crack entry mechanism and signaling pathway of symbiosis between Bradyrhizobia and peanut.展开更多
A hydroponic experiment was carried out to study the effect of elevated carbon dioxide(CO2) on root growth of tomato seedlings.Compared with the control(350 μL L-1),CO2 enrichment(800 μL L-1) significantly increased...A hydroponic experiment was carried out to study the effect of elevated carbon dioxide(CO2) on root growth of tomato seedlings.Compared with the control(350 μL L-1),CO2 enrichment(800 μL L-1) significantly increased the dry matter of both shoot and root,the ratio of root to shoot,total root length,root surface area,root diameter,root volume,and root tip numbers,which are important for forming a strong root system.The elevated CO2 treatment also significantly improved root hair development and elongation,thus enhancing nutrient uptake.Increased indole acetic acid concentration in plant tissues and ethylene release in the elevated CO2 treatment might have resulted in root growth enhancement and root hair development and elongation.展开更多
A root hair is a polarly elongated single-celled structure that derives from a root epidermal cell and func-tions in uptake of water and nutrients from the surrounding environment.Previous reports have demon-strated t...A root hair is a polarly elongated single-celled structure that derives from a root epidermal cell and func-tions in uptake of water and nutrients from the surrounding environment.Previous reports have demon-strated that short periods of high pH inhibit root hair extension;but the effects of long-term high-pH treat-ment on root hair growth are still unclear.Here,we report that the duration of root hair elongation is signicantly prolonged with increasing external pH,which counteracts the effect of decreasing root hair elongation rate and ultimately produces longer root hairs,whereas loss of actin-depolymerizing factor 8 and 11(ADF8/11)function causes shortening of root hair length at high pH(pH 7.4).Accumulation of ADF8/11 at the tips of root hairs is inhibited by high pH,and increasing environmental pH affects the actinlament(F-actin)meshwork at the root hair tip.At high pH,the tip-focused F-actin meshwork is absent in root hairs of the adf8/11 mutant,actinlaments are disordered at the adf8/11 root hair tips,and actin turn-over is attenuated.Secretory and recycling vesicles do not aggregate in the apical region of adf8/11 root hairs at high pH.Together,our results suggest that,under long-term exposure to high extracellular pH,ADF8/11 may establish and maintain the tip-focused F-actin meshwork to regulate polar trafcking of secretory/recycling vesicles at the root hair tips,thereby promoting root hair elongation.展开更多
文摘The use of hair roots as experimental samples has been a research focus for understanding the effects of spaceflight on astronauts, because it has many advantages, one of which is the fact that hair matrix cells actively divide in a hair follicle and sensitively reflect the physical conditions of the human body. In 2009, a research program focusing on the analysis of astronauts’ hairs was initiated to examine the effects of long-term spaceflight on the gene expression and mineral metabolism in the human body. Since the number of samples per astronaut is limited to 5 strands of hairs at each sampling point, due to the ethical viewpoint of astronauts or limited resources in space, it is important to develop an effective method for the molecular analysis of small amounts of hair roots. In this study, mRNA successfully extracted from 1, 5, and 10 hair follicles was amplified and subjected to the DNA microarray analysis to compare the gene expression within subjects. The results indicated that (1) it was possible to perform the genetic analysis on hair samples stored at -80℃, even without a fixation buffer and (2) the newly modified method of mRNA extraction and analysis was effective in detecting differential gene expression in samples containing only 5 hairs. In conclusion, RNA was efficiently extracted from 5 hair roots, which is the same number of hair roots used in the space experiment;therefore, this method can be applied to genetically analyze astronauts’ hair samples.
基金the National Natural Science Foundation of China through grant numbers 30270785 948 Project 0ffice, Ministry of Agriculture, China, through grant numbers 201068.
文摘A system to control the release of phosphate in water was successfully established, based on solubility product of [Ca^2＋] and [PO4^3-] using tricalcium phosphate as P source in the hydroponic solution, and adding CaCl2 for supplementing extra Ca^2＋. The system, similar to soil solutions, was a P nutrient buffer solution with very low bioavailable P. The buffer solution induced the roots of both monocotyledon and dicotyledon species to grow abundant root hairs, 3 mm in maximum length. The monocotyledons were corn （Zea mays L.） （var. Yellow Rose）, wheat （Triticum aestivum L.） （var. Yanzhong 144）, Triticale secale L. （vat. Jingsong 5）, and ryegrass （Lolium rigidum L.） （var. Ruanni）, and the dicotyledons were Arabidopsis thaliana L. （var. Columbia）, white clover （Trifolium repens） （var. Kopu）, Lotus （Lotus peduncucatus Cav. Luliginosus Schkuhr） （var. Grasslands Maku）. For these species we proved that the root environment controls the induction of root hair formation. However, the hydroponic buffer solution failed to induce root hairs on the roots of onion （Allium cepa L.）. Other investigators have concluded that corn does not form root hairs in hydroponics, but abundant long root hairs on corn were induced by this buffer system. The roots with abundant long root hairs are called ＂hedgehog roots＂ because they have hairs everywhere just like a hedgehog.
文摘Peanut root invasion by Bradyrhizobia is through a crack entry, which is different from many other legumes applying an infection thread entry in root hair. Understanding the role of root hair in the crack entry of Bradyrhizobia invasion of peanut root and subsequent peanut nodulation would facilitate improvement of biological nitrogen fixation in cultivated peanut. The objective of this study was to investigate the involvement of root hair in Bradyrhizobial invasion of peanut. Seedling roots of a nodulating peanut cultivar were observed for root hair emergence, its life span, and nodule formation at the base of the lateral roots with and without rhizobia inoculation for 14 days after germination (DAG). Scanning electron microscopy (SEM) was utilized to observe rhizobia accumulation at lateral roots at 24 hours after inoculation (HAI) before the emergence of root hair. Root hair emerged at 7 DAG with or without rhizobia inoculation. Two variations of rosette hair (RoH) were observed, the transient-thin RoH had life span of 3 days after root hair emergence and the thick and densely distributed RoH type stayed till the time of nodule emergence (9 days after inoculation). The lateral root devoid of root hair at the top 2 cm region was found to produce nodules. The SEM observation of seedling roots at 24 HAI showed that Bradyrhizobia invaded the roots at epidermis, protoplasm of cortical cell, and cortical cells of the main root near the newly emerged lateral root in the absence of RoH. The observations validated that root hair is not required in the Bradyrhizobia invasion of peanut root in the crack entry mode. Results from this study provided important morphological information for the hypothesis of close relationship between RoH and peanut nodulation for further genetic study of crack entry mechanism and signaling pathway of symbiosis between Bradyrhizobia and peanut.
基金supported by the National Natural Science Foundation of China (No.30871590)the National Key Basic Research Program (973 Program) of China (Nos.2009CB119003 and 2007CB109305)+1 种基金the Major Research Program of Zhejiang Province (No.2008C12061-1)the National "Eleventh Five Years Plan" Key Project on Science and Technology of China (No.2006BAD05B03)
文摘A hydroponic experiment was carried out to study the effect of elevated carbon dioxide(CO2) on root growth of tomato seedlings.Compared with the control(350 μL L-1),CO2 enrichment(800 μL L-1) significantly increased the dry matter of both shoot and root,the ratio of root to shoot,total root length,root surface area,root diameter,root volume,and root tip numbers,which are important for forming a strong root system.The elevated CO2 treatment also significantly improved root hair development and elongation,thus enhancing nutrient uptake.Increased indole acetic acid concentration in plant tissues and ethylene release in the elevated CO2 treatment might have resulted in root growth enhancement and root hair development and elongation.
基金supported by the National Natural Science Foundation of China (grants 31970195,31700161,32170331,32170330,and 6232300303)Hainan Yazhou Bay Seed Lab grant B23YQ1510,China Postdoctoral Science Foundation grant 2022M720058the Fundamental Research Funds for the Central Universities grants lzujbky-2022-ey06,lzujbky-2023-I02 and lzuibky-2023-pd10.
文摘A root hair is a polarly elongated single-celled structure that derives from a root epidermal cell and func-tions in uptake of water and nutrients from the surrounding environment.Previous reports have demon-strated that short periods of high pH inhibit root hair extension;but the effects of long-term high-pH treat-ment on root hair growth are still unclear.Here,we report that the duration of root hair elongation is signicantly prolonged with increasing external pH,which counteracts the effect of decreasing root hair elongation rate and ultimately produces longer root hairs,whereas loss of actin-depolymerizing factor 8 and 11(ADF8/11)function causes shortening of root hair length at high pH(pH 7.4).Accumulation of ADF8/11 at the tips of root hairs is inhibited by high pH,and increasing environmental pH affects the actinlament(F-actin)meshwork at the root hair tip.At high pH,the tip-focused F-actin meshwork is absent in root hairs of the adf8/11 mutant,actinlaments are disordered at the adf8/11 root hair tips,and actin turn-over is attenuated.Secretory and recycling vesicles do not aggregate in the apical region of adf8/11 root hairs at high pH.Together,our results suggest that,under long-term exposure to high extracellular pH,ADF8/11 may establish and maintain the tip-focused F-actin meshwork to regulate polar trafcking of secretory/recycling vesicles at the root hair tips,thereby promoting root hair elongation.
