Ethanol production from two varieties of henequen (Agave fourcroydes Lem)

This work demonstrates the significant differences in ethanol production of two henequen (Agave fourcroydes Lem) varieties. Yaax ki, or green henequen, surpasses Sac ki, or white henequen, in weight, sugar accumulation capability and ethanol production. The study was carried out with the ‘piña’ (stem and basal part of the leaves that remain attached to it after harvesting the leaves) of 5‐ and 9‐year‐old plants, cultivated in two localities of Yucatán, México. At 5 years of age, Yaax ki piñas are 33% larger than those of Sac ki, and at 9 years this difference can increase to 59%. Juice from 5‐year‐old piñas of Yaax ki contains 15.6% more reducing sugars, whereas in the must it can exceed 67%. Values obtained in the 9‐year‐old plants indicate that the Yaax ki variety accumulates 30.6% more reducing sugars than the Sac ki, whereas in the must the difference is in favor of Yaax ki is 21.7%. To produce 1 L of ethanol at 40% concentration by volume from 5‐year‐old plants, 48 kg of Sac ki piñas and 29 kg of Yaax ki are required, whereas with the 9‐year‐old plants, only 23 and 19 kg are needed, respectively.     

Island biogeography and landscape ecology of mammals inhabiting fragmented, temperate rain forests

• 1 We expanded the island biogeography paradigm to test whether mammalian communities of the heavily fragmented temperate rain forests of the Olympic Peninsula were influenced by local environmental conditions, biogeographic factors (fragment area and isolation) and characteristics of the surrounding landscape.
  • 2 We used live‐trapping, sign surveys and infra‐red triggered cameras to compare distributions of non‐volant mammals among fragments and between fragments and other principal landscape components (continuous old‐growth, riparian corridors, second‐growth forest and clearcuts).
    • 3 Of the 24 species of non‐volant mammals detected during our studies, 18 occurred in at least one fragment.
      • 4 Species richness of old‐growth mammals was not significantly correlated with fragment area or isolation, per se, but was significantly and positively correlated with the amount of old‐growth fragments and old second‐growth (41–159 years) in the surrounding landscape (r² = 0.95, P < 0.005).
        • 5 Distributions of three old‐growth dependent species [shrew‐mole (Neurotrichus gibbsii), Douglas squirrel (Tamiasciurus douglasii) and Trowbridge shew (Sorex trowbridgii)] were significantly associated with local environmental conditions within the fragment, with geographical isolation from continuous old‐growth and riparian corridors, and with the amount of old‐growth and old second growth in the adjacent matrix.

     

Enhanced inflammation and attenuated tumor suppressor pathways are associated with oncogene‐induced lung tumors in aged mice

Aging is often accompanied by a dramatic increase in cancer susceptibility. To gain insights into how aging affects tumor susceptibility, we generated a conditional mouse model in which oncogenic Kras^G12D was activated specifically in lungs of young (3–5 months) and old (19–24 months) mice. Activation of Kras^G12D in old mice resulted in shorter survival and development of higher‐grade lung tumors. Six weeks after Kras^G12D activation, old lung tissues contained higher numbers of adenomas than their young tissue counterparts. Lung tumors in old mice displayed higher proliferation rates, as well as attenuated DNA damage and p53 tumor suppressor responses. Gene expression comparison of lung tumors from young and old mice revealed upregulation of extracellular matrix‐related genes in young tumors, indicative of a robust cancer‐associated fibroblast response. In old tumors, numerous inflammation‐related genes such as Ccl7, IL‐1β, Cxcr6, and IL‐15ra were consistently upregulated. Increased numbers of immune cells were localized around the periphery of lung adenomas from old mice. Our experiments indicate that more aggressive lung tumor formation in older Kras^G12D mice may be in part the result of subdued tumor suppressor and DNA damage responses, an enhanced inflammatory milieu, and a more accommodating tissue microenvironment.     

Energy budgets of the Chinese green lacewing （Neuroptera： Chrysopidae） and its potential for biological control of the cotton aphid （Homoptera： Aphididae）

Energy budgets of larval stages of the Chinese green lacewing, Chrysopa sinica (Tjeder) (Neuroptera: Chrysopidae) were determined under laboratory conditions at photo‐period of 14:10 L:D, 27 ± 1°C and 75%± 2% RH. The energy used as ingestion, assimilation, respiration, productivity and feces was constructed for each developmental stage. In addition, under these experimental conditions, the potential of C. sinica as a biological control agent was evaluated according to the ingestion by this predator and the energy content of cotton aphid, Aphis gossypii (Glover) (Homoptera: Aphididae). The larval stage of C. sinica was able to consume 1281.4 1‐day‐old aphids, 1018.7 2‐day‐old aphids, 626.9 3‐day‐old aphids, 393.5 4‐day‐old aphids, 312.1 5‐day‐old aphids or 203.5 9‐day‐old aphids, respectively. No significant difference was detected between the estimated number of aphids consumed by the lacewings using energetic methods and the actual number of aphids consumed by the lacewings in this experiment. Our results showed that C. sinica is an important natural enemy of the cotton aphid, and energetic methods are very useful to quantify biological control efficacy of natural enemies.     

Stilbella aciculosa: A Potential Biocontrol Fungus against Rhizoctonia solani

A semi‐solid fermentation product of the potential biocontrol fungus Stilbella aciculosa was formulated on wheat bran: water (1:1, w/w) and incubated 5, 10 and 15 days before addition to soil infested with the pathogen Rhizoctonia solani. Generally, preparations did not reduce survival of the pathogen in infested beet seed but they did prevent saprophytic growth of the pathogen from beet seed into soil. The magnitude of reduction by the 15‐day‐old inoculum was greater than that by the 5‐day‐old inoculum. Ten‐day‐old bran preparations of S. aciculosa at rates of 0.5 and 1.0% (w/w) in soil prevented post‐emergence damping‐off of cotton, radish and sugar beet in the glasshouse and a rate of 1.0% gave stands similar to those in the non‐infested control soil. The antagonist, grown on perlite formulated with molasses, cornmeal, alfalfa tissue or corn stover, prevented damping‐off of cotton in a naturally infested soil. However, the stands were not as great as that in soil planted with pentachloronitrobenzene (PCNB)‐treated seed. Toxic metabolites, produced by S. aciculosa developing on various substrates, slightly inhibited the growth of R. solani in culture and induced cytoplasmic leakage of the pathogen mycelium.     

Circadian emergence and movement of captive juvenile tuatara (Sphenodon spp.)

Abstract

Knowledge of the circadian behaviour of young tuatara (Sphenodon spp.) is relatively scarce because tuatara are difficult to observe in the wild. We document diurnal, nocturnal and crepuscular emergence and movements (half‐body movement, walking and running) of three groups of captive juvenile tuatara (2‐ and 3‐year‐old Sphenodon guntheri, and 5‐year‐old S. punctatus). Juvenile tuatara emerge predominantly at night, but move around above ground, mainly during the day and around sunset. Differences in emergence andmove‐ment scores between the three study groups were evident, probably linked with age, species or housing conditions, which were inevitably coupled in our study. We found that 2‐year‐old tuatara in captive conditions emerged less frequently than, but once above ground, moved more than 3‐ and 5‐year‐olds in semi‐captive conditions. Activities in semi‐captive conditions were not correlated with temperature, light or humidity. We conclude that young tuatara may be primarily adapted to nocturnal activity, but thermal restrictions and possible hardwired adaptations to avoid predators and conspecifics may make day‐time movements safer.     

Pathogenic analyses of fungus strains isolated from medicinal Fritillaria przewalskii Maxim. bulb rot

Bulb rot causes a great loss of rare perennial medicinal Fritillaria przewalskii Maxim., which is exacerbated with growth year and seriously constrains the plant productivity, but the pathogens responsible for the disease were still unknown. In this paper, we attempted to explore the potential pathogens leading to bulb rotting and their occurrence patterns in artificial domesticated F. przewalskii. Fungus strains were isolated from the bulb rot spot of the 3‐ to 5‐year‐old diseased F. przewalskii plants by tissue separation, further assayed for pathogenicity according to Koch's law and finally identified by both morphological and molecular methods. Seven pathogenic strains (F1‐F7) were detected in 5‐year‐old rot bulbs, six (F1‐F6) in 4‐year‐old rot bulbs and four (F1, F2, F5, F6) in 3‐year‐old rot bulbs. All of the strains were able to infect bulbs by stabbing and some exhibited varying levels of aggressiveness. Relative to the non‐stabbing controls, the bulbs stab‐inoculated with F5, F2, F7, F4, F1, F6, and F3 showed 76.65%, 75.15%, 71.44%, 40.37%, 39.09%, 36.87%, and 34.93% rot after 8 days, respectively. Phylogenetic analysis revealed that these seven strains were clustered into Bionectria ochroleuca (F1, F3, F4), Fusarium oxysporum (F2, F7), Fusarium tricinctum (F5), and Clonostachys rosea (F6). The two species of Fusarium had the strongest pathogenicity, followed by Bionectria ochroleuca and Clonostachys rosea. Although leading to low bulb rot incidence by stab inoculation, F1 showed the highest isolation rate (48.9%) among all strains. Thus, the edible and medicinal bulbs of F. przewalskii are susceptible to synergetic contamination by these seven pathogens at some point after their third year of growth, which has contributed to the species endangered status, with the two strains of Fusarium being the predominant pathogens. To our knowledge, this is the first report on the seven strains of four fungal species causing F. przewalskii bulb rot in China.     

Height and Adiposity among Children

Objectives : Although BMI (kilograms per meter squared) is widely used as a surrogate measure of adiposity, it is moderately associated (r ～ 0.3) with height among children. We examined whether the resulting preferential classification of taller children as overweight, based on a BMI ≥95th percentile, is appropriate. Research Methods and Procedures : We assessed the cross‐sectional relation of height among 5‐ to 18‐year‐old subjects (n = 1180) to levels of BMI, the sum of 10 skinfold thicknesses, and percentage body fat as determined by DXA. Results : The prevalence of a BMI level ≥95th percentile was substantially higher among 5‐ to 11‐year‐old subjects who were relatively tall for their age than among shorter children. Among 5‐ to 8‐year‐old boys, for example, each SD increase in height‐for‐age was associated with a 4.6‐fold increase in the prevalence of overweight (p < 0.001). Height not only was associated with BMI but also showed similar correlations with the skinfold sum and with percentage body fat; furthermore, the magnitudes of these associations decreased with age. We also found that the association between percentage body fat and BMI (r = 0.85 to 0.90) was close to the maximum correlation that can be achieved by any weight‐height index. Discussion : The use of BMI, which preferentially classifies taller young children as overweight, is appropriate because height and adiposity are correlated before the age of 12 years.     

Distribution of N, Rubisco and photosynthesis in Pinus pinaster and acclimation to light

The light–nitrogen hypothesis suggests canopy photosynthesis is maximized when there is a positive relationship between irradiance received by foliage, its nitrogen content (per unit area N_area), and maximum rate of photosynthesis (A_max). Relationships among relative irradiance and N_area, allocation of nitrogen within the photosynthetic apparatus to Rubisco and chlorophyll, and A_max were examined in Pinus pinaster Ait. needles up to 6 years of age. Measurements were made before bud break in August 1998, and in May 1999 after the first ‘winter’ rains. In August, N_area in P. pinaster needles decreased from 5·1 to 5·7 g m^?2 in sunlit 1‐year‐old needles to 2·3 g m^?2 in shaded 6‐year‐old needles. In May, N_area was 5–40% less but spatial trends were the same. At both sampling dates, A_max was less in old shaded needles compared with young sunlit needles, and was thus consistent with the light–nitrogen hypothesis. Relationships between N_area and A_max were positive at both dates yet varied in strength and form. Allocation of nitrogen within the photosynthetic apparatus was qualitatively consistent with acclimation to light (i.e. Rubisco/Chl decreased with shading), but quantitatively suboptimal with respect to photosynthesis owing to consistent over‐investment in Rubisco. This over‐investment increased with height in the canopy and was greater in May than in August.     

Changes in the Proliferation and Differentiation of Neonatal Mouse Pink‐Eyed Dilution Melanocytes in the Presence of Excess Tyrosine

Changes in the proliferation and differentiation of epidermal melanocytes derived from newborn mice wild‐type at the pink‐eyed dilution (p) locus (P/P) and from congenic mice mutant at that locus (p/p) were investigated in serum‐free primary culture, with or without the addition of L‐Tyr. Incubation with added L‐Tyr inhibited the proliferation of P/P melanocytes in a concentration‐dependent manner and inhibition was gradually augmented as the donor mice aged. In contrast, L‐Tyr stimulated the proliferation of p/p melanoblasts–melanocytes derived from 0.5‐day‐old mice, but inhibited their proliferation when derived from 3.5‐ or 7.5‐day‐old mice. L‐Tyr stimulated the differentiation of P/P melanocytes. However, almost all cells were undifferentiated melanoblasts in control cultures derived from 0.5‐, 3.5‐ and 7.5‐day‐old p/p mice, but L‐Tyr induced their differentiation as the age of the donor mice advanced. The content of the eumelanin marker, pyrrole‐2,3,5‐tricarboxylic acid as well as the pheomelanin marker, 4‐amino‐3‐hydroxyphenylalanine in p/p melanocytes was greatly reduced compared with P/P melanocytes. However, the contents of eumelanin and its precursor, 5,6‐dihydroxyindole‐2‐carboxylic acid, as well as the contents of pheomelanin and its precursor, 5‐S‐cysteinyldopa in culture media from p/p melanocytes were similar to those of P/P melanocytes at all ages tested. L‐Tyr increased the content of eumelanin and pheomelanin two‐ to threefold in cultured cells and media derived from 0.5‐, 3.5‐ and 7.5‐day‐old mice. These results suggest that the proliferation of p/p melanoblasts–melanocytes is stimulated by L‐Tyr, and that the differentiation of melanocytes is induced by L‐Tyr as the age of the donor mice advanced, although eumelanin and pheomelanin fail to accumulate in p/p melanocytes and are released from them at all ages of skin development.     

Expression profiles of two thaumatin‐like protein (TmTLP) genes in responses to various micro‐organisms from Tenebrio molitor

It is well known that anti‐fungal thaumatin‐like proteins (TLPs) play important roles in plants. Here, we investigated the expression analysis of thaumatin‐like protein genes TmTLPs in response to various pathogens in Tenebrio molitor. Developmental expression patterns of TmTLPs show that TmTLPs are highly expressed in the early pupal and adult stages. Furthermore, tissue‐specific expression patterns of TmTLPs indicate that TmTLP1 is highly expressed in the integument and gut of last instar larvae and the integument and Malpighian tubules of 5‐day old adults. In contrast, TmTLP2 is highly expressed in the gut of both last instar larvae and 5‐day old adults. We hypothesize that the expression of TmTLP genes in developmental stages may be related to molting and body remodeling stresses. In addition, the induction patterns of TmTLP genes indicate that TmTLPs were slightly induced by Escherichia coli, Staphylococcus aureus, Candida albicans and Listeria monocytogenes. Furthermore, TmTLP1 and TmTLP2 were strongly induced in response to E. coli at 9 h post‐injection and L. monocytogenes at 3 h post‐injection. Our results suggest that TmTLPs may possess antimicrobial functions in T. molitor.     

Discoidin domain receptor 2 (DDR2) is required for maintenance of spermatogenesis in male mice

Discoidin domain receptor 2 (DDR2) is a receptor tyrosine kinase (RTK). We recently identified homozygous smallie mutant mice (BKS.HRS. Ddr2^slie/slie/J, Ddr2^slie/slie mutants), which lack a functional DDR2. Ddr2^slie/slie mutant mice are dwarfed and infertile due to peripheral dysregulation of the endocrine system. To understand the role of DDR2 signaling in spermatogenesis, we studied the expression of several receptors, enzymes, and proteins related to spermatogenesis in wild‐type and Ddr2^slie/slie mutant mice at 10 weeks and 5 months of age. DDR2 were expressed in adult wild‐type male mice in Leydig cells. The number of differentiated spermatozoa in the seminal fluid was significantly lower in the Ddr2^slie/slie mutant mice than in the wild‐type mice. The number of TUNEL‐positive cells was significantly greater in 5‐month‐old Ddr2^slie/slie mutants. Testosterone was significantly reduced at 5 months of age, but LH was similar in both types of mice at both 10 weeks and 5 months of age. The expression levels of LH receptors (Lhcgr), StAR, P450scc, and Hsd3β6 were not significantly different between the two types of mice at 10 weeks of age, but they were significantly reduced in 5‐month‐old Ddr2^slie/slie mutants compared to wild‐type mice of the same age. DDR2 was expressed in the Leydig cells of adult wild‐type male mice. In conclusion, our results indicated that DDR2 signaling plays a critical role in the maintenance of male spermatogenesis. Mol. Reprod. Dev. 77: 29–37, 2010. © 2009 Wiley‐Liss, Inc.     

Allometric relationship between body mass and aerobic metabolism in zebrafish Danio rerio

The relationship between body mass (M) and metabolic rate was investigated through the assessment of active (R_A) and standard (R_S) metabolic rate at different life stages in zebrafish Danio rerio (5 day‐old larvae, 2 month‐old juveniles and 6 month‐old adults). Scaling exponents and constants were assessed for standard (R_S = 0·273M^0·965 in mgO₂ g^?1 h^?1) and active metabolic rate (R_A = 0·799M^0·926 in mgO₂ g^?1 h^?1). These data provide the basis for further experiments regarding the effects of environmental factors on aerobic metabolism throughout the life cycle of this species.     

Differential survival among life stages contributes to co‐dominance of Abies mariesii and Abies veitchii in a sub‐alpine old‐growth forest

Questions: Are there interspecific differences in mortality and recruitment rates across life stages between two shade‐tolerant dominant trees in a sub‐alpine old‐growth forest? Do such differences in demography contribute to the coexistence and co‐dominance of the two species? Location: Sub‐alpine, old‐growth forest on Mt. Ontake, central Honshu, Japan. Methods: From 1980 to 2005, we recorded DBH and status (alive or dead) of all Abies mariesii and A. veitchii individuals (DBH ≥ 5 cm) in a 0.44‐ha plot. Based on this 25 year census, we quantified mortality and recruitment rates of the two species in three life stages (small tree, 5 cm ≤ DBH < 10 cm; subcanopy tree, 10 cm ≤ DBH < 20 cm; canopy tree, DBH ≥ 20 cm). Results: Significant interspecific differences in mortality and recruitment rates were observed in both the small tree and sub‐canopy tree stages. In this forest, saplings (< 5 cm DBH) are mostly buried by snow‐pack during winter. As a consequence, saplings of A. mariesii, which is snow and shade tolerant, show higher rates of recruitment into the small tree stage than do those of A. veitchii. Above the snow‐pack, trees must tolerate dry, cold temperatures. A. veitchii, which can more readily endure such climate conditions, showed lower mortality rate at the subcanopy stage and a higher recruitment rate into the canopy tree stage. This differential mortality and recruitment among life‐stages determines relative dominance of the two species in the canopy. Conclusion: Differential growth conditions along a vertical gradient in this old forest determine survival of the two species prior to reaching the canopy, and consequently allow co‐dominance at the canopy stage.     

Effects of delayed mating and male mating history on the reproductive potential of Leucoptera coffeella (Lepidoptera: Lyonetiidae)

Abstract 1 Despite the importance of Leucoptera coffeella (Guérin‐Mèneville) in coffee production worldwide, there is a lack of information on its reproduction. This knowledge will help in mass rearing, and support the development of behavioural control techniques for this insect. The present study determined the effects of delayed mating and previous matings of male L. coffeella on fecundity, egg viability and frequency of female remating. 2 The highest levels of fecundity and egg viability were obtained from matings of 1–3‐day‐old females. When females mated at 5 days of age, there were reductions of 40% in oviposition and of 43% in egg viability. 3 Females mated with 2‐day‐old virgin males were more fecund than those mated with older males; egg viability was also low (18%) from females mated with older males. 4 Virgin females that mated with virgin males laid a greater number of eggs than those mated with previously copulated males. Egg viability decreased with the increase in the number of previous male matings. 5 Five‐day‐old females remated in greater proportion than 2–3‐day‐old females. Females that copulated with males that had previously mated three times had higher rates of remating than those that copulated with virgin males. 6 The results obtained indicate that 1–3 days after emergence is the optimum age for mating. The implications of these findings for the control of L. coffeella by synthetic sex pheromone are discussed.     

Colonization of Tubú (Montanoa guatemalensis,Asteraceae) Windbreaks by Woody Species1

Tubú (Montanoa guatemalensis, Asteraceae) is a popular tree used in windbreaks in the San Luis valley near the Monteverde cloud forests of Costa Rica. Seventy‐eight woody taxa from 32 families were found in the understory of 19 tubú windbreaks (five 4‐yr‐old, eight 12‐yr‐old, and six 20‐yr‐old). Mean size of tubú increased with stand age, but tubú was neither replacing itself nor spreading from the windbreaks. Density of other trees and shrubs ≥1 m was higher in 4‐yr‐old plots than in 20‐yr‐old plots, but density of other trees <1 m tall did not vary with windbreak age. Whereas richness of species ≥1 m was higher for 12‐ and 20‐yr‐old plots than for 4‐yr‐old plots, species richness of trees <1 m tall did not vary with windbreak stand age. Higher proportions of the woody colonists in 12‐ and 20‐yr‐old plots were animal dispersed than in 4‐yr‐old plots. Tubú windbreaks may undergo major changes in woody species composition, with Daphnopsis americana, Inga punctata, and Trichilia havanensis likely to predominate in the future.     

Antennal and behavioural responses of Heortia vitessoides females to host plant volatiles of Aquilaria sinensis

This study investigated volatiles from Aquilaria sinensis (Lour.) Gilg (Thymelaeaceae) leaves that attracted Heortia vitessoides Moore (Lepidoptera: Crambidae). Volatiles from young and old A. sinensis leaves were identified and quantified by gas chromatography–mass spectrometry and gas chromatography‐electroantennogram detection. Both wind tunnel bioassays and field tests were conducted to measure the attraction of adults to synthetic blends of volatiles from leaves of different maturations. Consistent electroantennographic activity was obtained for nine and three compounds from headspace collections of young and old A. sinensis leaves, respectively. Qualitative and quantitative differences were found among two odour profiles. In wind tunnel experiments, the fresh young leaves proved to be more attractive to females than old leaves. A nine‐component mixture, including hexanal, limonene, 2‐hexanol, octanal, (Z)‐3‐hexenyl acetate, (Z)‐3‐hexen‐1‐ol, nonanal, decanal, and 2,6,10‐trimethyl‐dodecane (with a ratio of 2:16:9:4:63:100:13:10:5) from young leaves attracted moths significantly more than the three‐component mixture of nonanal, decanal, and 2,6,10‐trimethyl‐dodecane (with a ratio of 11:14:26) from old leaves. Further subtractive bioassays conducted in the wind tunnel showed that both the complete nine‐component mixture and a subtracted four‐component mixture of hexanal, (Z)‐3‐hexenyl acetate, nonanal, and decanal (with a ratio of 2:63:13:10) elicited equivalent responses in females. All components in the four‐component blend were essential for optimal attraction. In a field trial using the nine‐ and four‐component blends, more moths were captured using both blends than in traps baited with hexane only. Our study indicates that the odour blends of young leaves play an important role in H. vitessoides host plant recognition. The mechanisms behind host recognition and age‐dependent changes in leaf chemistry are discussed.     

Effects of age and size on critical swimming speed of juvenile Chinese sturgeon Acipenser sinensis at seasonal temperatures

Changes in the critical swimming speed (U_crit, cm s^?1) with ontogeny of 2·5–12·5 month‐old juvenile anadromous Chinese sturgeon Acipenser sinesis were measured in a modified Blazka‐type swimming tunnel. The absolute U_crit increased with length, mass and age; the relative U^′_crit (body lengths, s^?1), however, decreased. Juvenile A. sinesis did not display a parr–smolt transformation at the length or age threshold to tolerate full‐strength seawater.     

Roothairless5, which functions in maize (Zea mays L.) root hair initiation and elongation encodes a monocot‐specific NADPH oxidase

Root hairs are instrumental for nutrient uptake in monocot cereals. The maize (Zea mays L.) roothairless5 (rth5) mutant displays defects in root hair initiation and elongation manifested by a reduced density and length of root hairs. Map‐based cloning revealed that the rth5 gene encodes a monocot‐specific NADPH oxidase. RNA‐Seq, in situ hybridization and qRT‐PCR experiments demonstrated that the rth5 gene displays preferential expression in root hairs but also accumulates to low levels in other tissues. Immunolocalization detected RTH5 proteins in the epidermis of the elongation and differentiation zone of primary roots. Because superoxide and hydrogen peroxide levels are reduced in the tips of growing rth5 mutant root hairs as compared with wild‐type, and Reactive oxygen species (ROS) is known to be involved in tip growth, we hypothesize that the RTH5 protein is responsible for establishing the high levels of ROS in the tips of growing root hairs required for elongation. Consistent with this hypothesis, a comparative RNA‐Seq analysis of 6‐day‐old rth5 versus wild‐type primary roots revealed significant over‐representation of only two gene ontology (GO) classes related to the biological functions (i.e. oxidation/reduction and carbohydrate metabolism) among 893 differentially expressed genes (FDR <5%). Within these two classes the subgroups ‘response to oxidative stress’ and ‘cellulose biosynthesis’ were most prominently represented.