Matching roots to their environment

Background

Plants form the base of the terrestrial food chain and provide medicines, fuel, fibre and industrial materials to humans. Vascular land plants rely on their roots to acquire the water and mineral elements necessary for their survival in nature or their yield and nutritional quality in agriculture. Major biogeochemical fluxes of all elements occur through plant roots, and the roots of agricultural crops have a significant role to play in soil sustainability, carbon sequestration, reducing emissions of greenhouse gasses, and in preventing the eutrophication of water bodies associated with the application of mineral fertilizers.

Scope

This article provides the context for a Special Issue of Annals of Botany on ‘Matching Roots to Their Environment’. It first examines how land plants and their roots evolved, describes how the ecology of roots and their rhizospheres contributes to the acquisition of soil resources, and discusses the influence of plant roots on biogeochemical cycles. It then describes the role of roots in overcoming the constraints to crop production imposed by hostile or infertile soils, illustrates root phenotypes that improve the acquisition of mineral elements and water, and discusses high-throughput methods to screen for these traits in the laboratory, glasshouse and field. Finally, it considers whether knowledge of adaptations improving the acquisition of resources in natural environments can be used to develop root systems for sustainable agriculture in the future.     

Luxury uptake of magnesium by peas,Pisum sativum

Increasing the magnesium (Mg) concentration of vegetables (biofortification) will often require ‘luxury’ uptake where the whole‐plant concentration of Mg (c_p) is greater than required for maximum yield. Our aim was to quantify some of the physiological factors influencing luxury uptake of Mg to aid subsequent development of agronomic techniques for biofortification. Peas, Pisum sativum, were used as a test species. A sand culture experiment related vegetative growth and c_p for plants grown with a range of Mg and potassium (K) supply rates. We developed a model of Mg uptake including feedback control exerted by c_p. The model was parameterised with results from a solution culture experiment and then used to explore ways to increase luxury uptake of Mg. Feedback control of Mg uptake by c_p was weak. Biomass did not increase if the Mg concentration exceeded 0.11% in the whole plant or 0.13% in the shoots. Values obtained in the field are often larger than this. Our results indicate that luxury uptake of Mg by peas is readily achieved, provided that there is ample supply of Mg²⁺ to the root surfaces. In field soils though, transport of Mg²⁺ to the roots may limit uptake and cation exchange processes restrict the ability of Mg fertilisers to substantially increase Mg uptake. Increasing root growth will usually increase Mg uptake, but c_p may not rise if biomass is also increased.     

铬对中国林蛙蝌蚪生长发育的毒性效应

为评价水域环境中铬元素对两栖动物幼体的急性毒性,将中国林蛙(Rana chensinensis)28～29期蝌蚪分别暴露于30～35 mg·L-1Cr(Ⅲ)6个不同浓度和10 ～ 45mg·L-1Cr(Ⅵ)6个不同浓度的水体中,分别在24、48、72和96 h统计蝌蚪的死亡率及半致死浓度(LC50).结果表明:暴露24、48、72和96 h,Cr(Ⅲ)对蝌蚪的LC50分别为34.09±1.06、33.47±0.65、32.58±0.11和(32.05±0.20) mg·L-1,安全浓度(SC)为(3.21±0.02)mg·L-1;Cr(Ⅵ)对蝌蚪的LC50分别为91.97±5.32、51.19±4.62、35.79±1.40和(28.81±1.87) mg·L-1,安全浓度(SC)为(2.88±0.19) rng·L-1.观察表明:Cr(Ⅲ)的急性毒性是通过与蝌蚪皮肤表面的分泌物结合后粘附在鳃部,导致呼吸障碍致死;而Cr(Ⅵ)的强氧化性可导致蝌蚪的表皮溃变,鳃部萎缩致死;另外,将28～29期蝌蚪暴露于安全浓度(SC)以下的含铬水体进行慢性实验,通过检测蝌蚪的体长、体重和完全变态时间显示,低浓度的Cr(Ⅲ)和Cr(Ⅵ)对蝌蚪的生长发育仍具有一定的抑制作用,并可导致畸型发生,其作用强度呈现剂量效应,但时间累积效应不规律.     

华西雨屏区香樟人工林土壤表层细根生物量和碳储量

2010年11月-2011年12月, 研究了华西雨屏区31年生香樟人工林土壤表层(0～30 cm)细根生物量及碳储量.结果表明: 香樟人工林土壤0～30 cm层细根总生物量(活根+死根)和碳储量的平均值分别为1592.29 kg·hm^-2和660.68 kg C·hm^-2,其中活细根贡献率分别为91.1%和91.8%.随着土壤深度的增加,香樟1～5级活细根和死细根的生物量及碳储量均显著减少;随着根序等级的升高,香樟活细根生物量及碳储量显著增加.香樟细根总生物量及碳储量均在秋季最高、冬季最低,死细根生物量及碳储量为冬季最高、夏季最低;1级根和2级根生物量及碳储量均在夏季最高、冬季最低,而3~5级根则为秋季最高、冬季最低.土壤养分和水分的空间异质性是导致细根生物量和碳储量变化的主要原因.     

Detection of medullary thyroid microcarcinoma using ultrasound‐guided fine needle aspiration cytology

G. C. H. Yang, K. Fried and P. H. Levine Detection of medullary thyroid microcarcinoma using ultrasound‐guided fine needle aspiration cytology Objective: Compared with incidental papillary thyroid microcarcinoma (microPTC), incidental medullary thyroid microcarcinoma (microMTC) is clinically more significant. The objective of the present study was to summarize our experience in detecting microMTCs. Methods: From 1995 to 2011, there were 10 825 thyroid fine needle aspirates (FNAs) guided using high‐resolution ultrasound with on‐site preparation and evaluation by a cytopathologist. Of the 140 microcarcinomas detected, 132 were microPTCs and eight were microMTCs, which are the subject of the present study. Results: All eight cases were incidentalomas and none of the five women and three men, age 37–70 years, had a family history of MTC. One patient had two FNAs at an interval of 10 months, two had a single lymph node metastasis and one had a 0.1‐cm tumour nodule near the main tumour. Four of five plasmacytoid cell microMCTs had irregular borders; two round cell and one rectangular cell tumours had smooth borders. In contrast, 17 larger MTCs diagnosed in the same period included seven plasmacytoid, four giant cell and six spindle cell types. All five plasmacytoid microMTCs were correctly diagnosed on FNA, but the round cell and rectangular cell tumours were undercalled as follicular lesions. Sampling of colloid from adjacent follicles was noted in microMTCs. Two were diagnosed on histology following recommended surgery and one was diagnosed on recommended repeat FNA. Conclusions: US‐guided FNA of thyroid lesions is a powerful tool in the detection of microMTCs, provided that cytopathologists are alerted to the pitfalls described in the present study.     

Follow‐up of atypia and follicular lesions of undetermined significance in thyroid fine needle aspiration cytology

N. Dincer, S. Balci, A. Yazgan, G. Guney, R. Ersoy, B. Cakir and G. Guler
Follow‐up of atypia and follicular lesions of undetermined significance in thyroid fine needle aspiration cytology Objective: To report our experience of atypia of undetermined significance (AUS)/follicular lesion of undetermined significance (FLUS) rate and outcome. Methods: Among 7658 patients with 19 569 nodules, 524 (2.7%) nodules were diagnosed as AUS/FLUS on fine needle aspiration (FNA). After exclusion of patients with simultaneous nodules that were suspicious for follicular neoplasm or malignancy or that were malignant, 368 (4.8%) patients were diagnosed as AUS/FLUS. The outcome of 146 patients who had undergone surgery or repeated fine needle aspirate at the time of preparation of this study was evaluated. The original FNAs were matched to repeated FNAs and thyroidectomy or diagnostic lobectomy specimens. Results: Seventy‐two (19.6%) of the 368 patients had directly undergone surgery, either a lobectomy or a thyroidectomy: of these, 27 (37.5%) had neoplastic nodules (21 were malignant). Seventy‐four (20.1%) of the 368 patients had repeat FNA. On second FNA, 47 of 74 (63.5%) were benign, three were suspicious for follicular neoplasm, one was malignant and 23 (31.1%) were non‐diagnostic. Four patients had a third FNA: two were AUS/FLUS, one was malignant and one non‐diagnostic. One patient had a fourth FNA, which was diagnosed as AUS/FLUS. Sixteen (21.6%) of 74 patients with repeat FNA had surgery: three of these had neoplastic nodules (two were malignant). Overall, 88 of the 368 (23.9%) patients had a thyroidectomy of which 30 (34.1%) were neoplastic and 23 (26.1%) malignant. The neoplastic rate for patients who were once diagnosed with AUS/FLUS was 8.2% and the malignancy rate 6.3%. The malignancy rate for patients on follow‐up at the time we prepared the study was 15.7% (23/146); 222 remained on follow‐up without surgery or repeat FNA or were managed elsewhere. Conclusions: Although in this category repeat FNA is expected rather than excision, we suggest evaluation of all AUS/FLUS patients in multidisciplinary meetings to decide management and recommend follow‐up of all patients with this diagnosis.     

Multinational study of oestrogen and progesterone receptor immunocytochemistry on breast carcinoma fine needle aspirates

?. P. Marin?ek, N. Nolde, I. Kardum‐Skelin, R. Nizzoli, B. Önal, T. Rezanko, E. Tani, K. T. Ostovi?, P. Vielh, F. Schmitt and G. Kocjan
Multinational study of oestrogen and progesterone receptor immunocytochemistry on breast carcinoma fine needle aspirates Objectives: To collect data on the variability of immunocytochemical (ICC) procedures used to detect oestrogen/progesterone receptors (ER/PR) on cytological material; to test the reproducibility of results; and to identify the crucial points in the ICC procedures that affect the result. Methods: Ten laboratories from eight countries participated in a two‐part study. In the first part, one of the participants (the coordinator) prepared and distributed cytospins from a fine needle aspirate of a primary breast carcinoma. Laboratories performed ICC staining for ER/PR according to their own methods on the test slides and in‐house positive controls. Slides were returned to the coordinator together with information on the preparation of positive control slides and the ICC methodology used. In the second part, obligatory methods of fixation and antigen retrieval were specified. Evaluation of results included grading the number of positive cells, staining intensity, background staining, cytoplasmic staining, sample condition and cellularity. Participants evaluated their own results, which were subsequently evaluated by the coordinator. Results: There was great variability in the preparation of slides for in‐house controls and ICC methodology. The outcome of ICC staining of in‐house control slides was excellent in two laboratories, adequate in three, sub‐optimal in four and inadequate in one. Only six obtained a positive reaction on the test slides and not all were of a high quality. Results of the second run were greatly improved in terms of cellularity of in‐house positive control slides, and scores for the percentage of stained cells and staining intensity of control and test slides. Cytospins and monolayer (ThinPrep^®) preparations were superior to direct smears; methods of fixation and antigen retrieval were the key points in the staining process. Conclusions: Our experience points to the need for guidelines for hormonal receptor determination and external quality control on cytological material, in order for cytological methods to be used in routine clinical practice with a suitable degree of confidence.     

Generation of the antioxidant yellow pigment derived from 4-methylthio-3-butenyl isothiocyanate in salted radish roots (takuan-zuke)

2-[3-(2-Thioxopyrrolidin-3-ylidene)methyl]-tryptophan (TPMT) is a yellow pigment of salted radish roots (takuan-zuke) derived from 4-methylthio-3-butenyl isothiocyanate (MTBITC), the pungent component of radish roots. Here, we prepared salted radish and analyzed the behavior of the yellow pigment and related substances in the dehydration process and long-term salting process. All salted radish samples turned yellow, and their b^* values increased with time and temperature. The salted radish that was sun-dried and pickled at room temperature turned the brightest yellow, and the generation of TPMT was clearly confirmed. These results indicate that tissue shrinkage due to dehydration, salting temperature, and pH play important roles in the yellowing of takuan-zuke.     

Hyphomycetes in the River Kelvin

Summary

The hyphomycete spora of the River Kelvin and its tributary, the Allander Water, was sampled during October 1986 to January 1987. Twenty spore types were found, the commonest being Flagellospora curvula and Lemonniera aquatica. Spore numbers were high in October and declined during the autumn to an undetectable level by the end of December, but leaves collected in December and January yielded spores on incubation in water.     

The growth characteristics and yield potential of rice (Oryza sativa) under non‐flooded irrigation in arid region

The objectives of this field experiment were to study the growth characteristics and yield potential of rice plants under non‐flooded irrigation in arid area. Non‐flooded treatments included drip irrigation with plastic mulching treatments (DIs), furrow irrigation with plastic mulching treatment (FIM) and furrow irrigation with non‐mulching treatment (FIN). Conventional flooded cultivation (F) was check treatment (CK). The four drip irrigation treatments differed in the amount of water applied before and after panicle initiation. Root length density, leaf dry weight, shoot dry weight and root activity were generally higher in the non‐flood‐irrigated treatments (especially the drip‐irrigated treatments) than in the flood‐irrigated treatment at mid‐tillering. However, the growth and development of rice plants were limited after jointing in the non‐flooded irrigation treatments. Increasing the root/shoot ratio and root length density in the 20–40 cm depth and decreasing specific root length at 0–20 cm soil layer were important mechanisms for helping the rice plants to adapt to the non‐flooded environmental stresses. Finally, the grain yield in the non‐flooded irrigation treatments was lower than that in the F treatment. These low yields were mainly attributed to the low root length density at 0–20 cm depth and root activity. Generally speaking, the restricted degrees in the DIs were smaller than that in the FIM and FIN treatments. Among the DIs, both the highest grain yield (8223–8900 kg ha^?1) and the highest water use efficiency (WUE) (0.63) were observed when the soil water content was kept at ?30 kPa before panicle initiation and at ?15 kPa after panicle initiation (referred to as the DI2 treatment). The yield in the DI2 treatment was not significantly different than that in the flood‐irrigated treatment. However, WUE was 2.5 times higher in the DI2 treatment than in the F treatment. These results suggest that drip irrigation technology can be considered as a better water‐saving cultivation of rice plants in arid region.