The DOI matches its Crossref record; 100 of the 100 references it cites were found in a registry or an index.
Root Architecture Responses: In Search of Phosphate
Open accessAbstract
Soil phosphate represents the only source of phosphorus for plants and, consequently, is its entry into the trophic chain. This major component of nucleic acids, phospholipids, and energy currency of the cell (ATP) can limit plant growth because of its low mobility in soil. As a result, root responses to low phosphate favor the exploration of the shallower part of the soil, where phosphate tends to be more abundant, a strategy described as topsoil foraging. We will review the diverse developmental strategies that can be observed among plants by detailing the effect of phosphate deficiency on primary and lateral roots. We also discuss the formation of cluster roots: an advanced adaptive strategy to cope with low phosphate availability observed in a limited number of species. Finally, we will put this work into perspective for future research directions.
Overview
The claims and statistics of this paper haven’t been checked yet.
Run the check — free, no account needed. It reads the open-access text and checks the sources it cites.
Integrity signals
Registry
Cites
Statistics
Verification
Claims the paper makes
The claims and statistics of this paper haven’t been checked yet.
Run the check — free, no account needed. It reads the open-access text and checks the sources it cites.
Self-check
Percentages, sums and reported differences re-computed from the paper’s own numbers.
The self-check needs the paper’s full text.
Citations
Cites
Arbuscular mycorrhiza: the mother of plant root endosymbioses
Parniske, M. (2008) · Nature Reviews Microbiology · doi:10.1038/nrmicro1987 · Cited by 2,286
The plastic plant: root responses to heterogeneous supplies of nutrients
Hodge, A. (2004) · New Phytologist · doi:10.1111/j.1469-8137.2004.01015.x · Cited by 1,692
Plant nutrient-acquisition strategies change with soil age
Lambers, H., RAVEN, J., Shaver, G. R., & SMITH, S. (2008) · Trends in Ecology & Evolution · doi:10.1016/j.tree.2007.10.008 · Cited by 1,453
Lambers, H., Shane, M. W., Cramer, M. D., Pearse, S. J., & Veneklaas, E. J. (2006) · Annals of Botany · doi:10.1093/aob/mcl114 · Cited by 1,321
Smith, S. E., Jakobsen, I., Grønlund, M., & SMITH, F. A. (2011) · PLANT PHYSIOLOGY · doi:10.1104/pp.111.174581 · Cited by 1,307
Root Phenes for Enhanced Soil Exploration and Phosphorus Acquisition: Tools for Future Crops
Lynch, J. P. (2011) · PLANT PHYSIOLOGY · doi:10.1104/pp.111.175414 · Cited by 1,071
Opportunities for improving phosphorus‐use efficiency in crop plants
Veneklaas, E. J., Lambers, H., Bragg, J. G., Finnegan, P. M., Lovelock, C. E., Plaxton, W. C., Price, C. A., Scheible, W., Shane, M. W., White, P. J., et al. (2012) · New Phytologist · doi:10.1111/j.1469-8137.2012.04190.x · Cited by 1,035
Plasticity of the Arabidopsis Root System under Nutrient Deficiencies
Gruber, B. D., Giehl, R. F. H., Friedel, S., & von Wirén, N. (2013) · PLANT PHYSIOLOGY · doi:10.1104/pp.113.218453 · Cited by 964
Topsoil foraging – an architectural adaptation of plants to low phosphorus availability
Lynch, J. P., & Brown, K. M. (2001) · Plant and Soil · doi:10.1023/a:1013324727040 · Cited by 871
Shin, H., Shin, H., Dewbre, G. R., & Harrison, M. (2004) · The Plant Journal · doi:10.1111/j.1365-313x.2004.02161.x · Cited by 812
Cited by
Sorted by citations
Items 201–292 of 292
Redistribution of soil phosphorus from grassland to cropland in an organic dairy farm
Ohm, M., Schüler, M., Fystro, G., & Paulsen, H. M. (2015) · OpenAgrar · doi:10.3220/lbf1452867403000 · Cited by 3
Zulfiqar, A., Azhar, B. J., Zeb, A., Zeenat, A., Aman, S., Heckerthorn, S. A., & Shakeel, S. N. (2021) · Sains Malaysiana · doi:10.17576/jsm-2021-5006-10 · Cited by 3
Jorfi, A., Alavifazel, M., Gilani, A., Ardakani, M. R., & Lak, S. (2022) · Gesunde Pflanzen · doi:10.1007/s10343-022-00740-0 · Cited by 3
Quantitative Trait Loci Mapping of Heading Date in Wheat under Phosphorus Stress Conditions
Yang, B., Qiao, L., Zheng, X., Zheng, J., Wu, B., Li, X., & Zhao, J. (2024) · Genes · doi:10.3390/genes15091150 · Cited by 3
The role of ASR (ABA, Stress, and Ripening) genes in responses to phosphate starvation in rice roots
Barros, N. L. F., Gonçalves, B. X., Trenz, T. S., Menguer, P. K., Ponte, L. R., Calixto, C. P. G., Ricachenevsky, F. K., & Margis-Pinheiro, M. M. A. N. (2025) · Plant Stress · doi:10.1016/j.stress.2025.100824 · Cited by 3
Younessi‐Hamzekhanlu, M., Izadi‐Darbandi, A., Malboobi, M. A., & Ebrahimi, M. (2016) · DOAJ (DOAJ: Directory of Open Access Journals) · doi:10.22058/jpmb.2016.19661 · Cited by 3
Shee, R., Shee, D., Saha, T., Sahid, S., Paul, S., & Datta, R. (2022) · bioRxiv (Cold Spring Harbor Laboratory) · doi:10.1101/2022.11.03.515049 · Cited by 3
Heriansyah, P., Aziz, S. A., Sukma, D., & Nurcholis, W. (2025) · Ornamental Horticulture · doi:10.1590/2447-536x.v31.e312839 · Cited by 2
Mumtahina, N., Matsuoka, A., Uga, Y., Shimono, H., & Matsunami, M. (2026) · Field Crops Research · doi:10.1016/j.fcr.2026.110351 · Cited by 2
Zhao, Z., Chen, L., Migliorini, D., Albornoz, F. E., Finnegan, P. M., Ranathunge, K., & Lambers, H. (2026) · Plant and Soil · doi:10.1007/s11104-026-08375-0 · Cited by 2
Liu, X., Brunner, I. L., Liu, Z., Dai, G., Xie, L., Leng, M., Wang, J., Xu, S., Zhou, Y., Wang, C., et al. (2026) · Plant and Soil · doi:10.1007/s11104-026-08389-8 · Cited by 2
Kim, T.-M., Jeong, S., Choi, B., Kim, Y., & Kim, E. (2026) · Scientific Reports · doi:10.1038/s41598-026-40933-5 · Cited by 2
Understanding the Regulation of Root Development Towards Environmental Stresses for Crop Improvement
Sarkar, A. K., & Roy, S. (2021) · Signaling and communication in plants · doi:10.1007/978-3-030-84985-6_23 · Cited by 2
Regulation of plants nutrient deficiency responses by phytohormones
Deepika, D., Sonkar, K., & Singh, A. (2023) · Elsevier eBooks · doi:10.1016/b978-0-323-91886-2.00001-x · Cited by 2
Ramos, J. F. K., Alves, B. J. R., Alonso, J. M., Teixeira, P. C., & Benites, V. D. M. (2025) · Revista Brasileira de Ciência do Solo · doi:10.36783/18069657rbcs20240099 · Cited by 2
Slocum, R. D., Wang, H., Cai, X., Tomasevich, A. A., Kubecka, K. L., Clark, G., & Roux, S. J. (2025) · International Journal of Molecular Sciences · doi:10.3390/ijms262411857 · Cited by 2
NUTCRACKER-overexpressing Arabidopsis thaliana grows better under phosphate starvation
Ling, J., Huang, X., Jia, Y., Li, W., & Zhang, X. (2023) · Plant Growth Regulation · doi:10.1007/s10725-023-01014-z · Cited by 2
Bacterial-type plant ferroxidases tune local phosphate sensing in root developmentPreprint
Naumann, C., Heisters, M., Brandt, W., Janitza, P., Alfs, C., Tang, N., Nienguesso, A. T., Ziegler, J., Imre, R., Mechtler, K., et al. (2021) · bioRxiv (Cold Spring Harbor Laboratory) · doi:10.1101/2021.03.19.436157 · Cited by 2
Lewin, S., Francioli, D., Ulrich, A., & Kolb, S. (2021) · Research Square · doi:10.21203/rs.3.rs-798883/v1 · Cited by 2
Li, J., Yang, Y., Huang, H., Yu, J. H., Zhou, Q., Jia, Z., & Chen, S. C. (2025) · Journal of Applied Genetics · doi:10.1007/s13353-025-00965-5 · Cited by 1
Kohli, P. S., Donde, R., Sirohi, U., Singh, B., Anantha, M. S., Bhadana, V. P., Sundaram, R. M., Mangrauthia, S. K., & Giri, J. (2025) · Journal of Experimental Botany · doi:10.1093/jxb/eraf331 · Cited by 1
Mallavarapu, M. D., Ribaya, M., Val‐Torregrosa, B., & Segundo, B. S. (2025) · Plants · doi:10.3390/plants14213334 · Cited by 1
Zhou, C., Liao, J., Pan, Z., Xin, S., Xu, J., Li, N., Yang, B., Cai, N., & Xu, Y. (2025) · Industrial Crops and Products · doi:10.1016/j.indcrop.2025.122413 · Cited by 1
The SPX protein family in plants: from phosphate sensors to multifunctional signaling hubs
Ge, S., Yuan, K., & Lei, M. (2026) · Stress Biology · doi:10.1007/s44154-026-00307-3 · Cited by 2
Benjamin Wee, Y., Berkowitz, O., Ng, S., Pegg, A., Whelan, J., & Jost, R. (2026) · Industrial Crops and Products · doi:10.1016/j.indcrop.2026.123385 · Cited by 1
Self-citationGreen microalga (Coelastrella sp.) cultivated in wastewater is an effective phosphorus biofertilizer
Akuku, V., Toren, N., Khozin‐Goldberg, I., & Erel, R. (2026) · Journal of Applied Phycology · doi:10.1007/s10811-026-03863-3 · Cited by 1
Shelf-invading low-oxygen waters control Cenozoic organic carbon burial rates
Rickaby, R. E. M., Wood, T. J., Lu, Z., & Bjerrum, C. J. (2026) · Proceedings of the National Academy of Sciences · doi:10.1073/pnas.2526409123 · Cited by 1
Zhang, G., Li, Z., Kang, S., Tian, C., Zeng, L., Huang, T., Tan, Y., Su, F., Wang, Q., & Wang, S. (2026) · The Crop Journal · doi:10.1016/j.cj.2026.06.003 · Cited by 1
Singla, P., & Kaur, S. (2018) · Soil biology · doi:10.1007/978-3-319-75910-4_1 · Cited by 1
Revalska, M., & Iantcheva, A. (2018) · Agriculture & Food · Cited by 1
Rajesh, N. L., Narayana Rao, K., Sathishkumar, U., Wali, V. B., Basavaraj, K., Rudramurthy, H. V., & Desai, B. K. (2021) · F1000Research · doi:10.12688/f1000research.53095.1 · Cited by 1
Progression in plant phosphate uptake studies
Munusamy, U., Khuzaimah, Z., Kong, S. L., & Abdullah, S. N. A. (2022) · Asia-Pacific Journal of Molecular Biology and Biotechnology · doi:10.35118/apjmbb.2022.030.2.07 · Cited by 1
Rajesh, N. L., Narayana Rao, K., Sathishkumar, U., Wali, V. B., Basavaraj, K., Rudramurthy, H. V., & Desai, B. K. (2023) · F1000Research · doi:10.12688/f1000research.53095.2 · Cited by 1
Maslard, C., Arkoun, M., Leroy, F., Girodet, S., Salon, C., & Prudent, M. (2024) · Plant Cell & Environment · doi:10.1111/pce.15268 · Cited by 1
Han, X., Guo, H., Xu, C., Zhang, Q., & Li, Z. (2024) · Ecological Frontiers · doi:10.1016/j.ecofro.2024.11.004 · Cited by 1
Toren, N., & Erel, R. (2025) · Plant Physiology and Biochemistry · doi:10.1016/j.plaphy.2025.110263 · Cited by 1
Assessing the Divergent Soil Phosphorus Recovery Strategies in Domesticated and Wild Crops
Dixon, M. M., & Vivanco, J. M. (2025) · Plants · doi:10.3390/plants14152296 · Cited by 1
Bonnot, C., Nussaume, L., & Desnos, T. (2018) · Methods in molecular biology · doi:10.1007/978-1-4939-7874-8_6 · Cited by 1
Self-citationKarakter Percabangan Malai Genotipe Padi Sawah pada Berbagai Level Dosis Fosfor
Hastini, T., Suwarno, W. B., Ghulamahdi, M., & Hajrial, D. A. (2019) · Jurnal Agronomi Indonesia (Indonesian Journal of Agronomy) · doi:10.24831/jai.v47i2.25243 · Cited by 1
Modulation of primary meristem activity by gibberellins through DELLA-TCP interaction in Arabidopsis
Felipo-Benavent, A. (2017) · doi:10.4995/thesis/10251/82237 · Cited by 1
Bora, S. S., Dey, K. K., Borah, M., Rahman, M., Gogoi, M., Modi, M. K., & Barooah, M. (2021) · Research Square · doi:10.21203/rs.3.rs-347764/v1 · Cited by 1
Benjamin Wee, Y., Berkowitz, O., Ng, S., Pegg, A., Whelan, J., & Jost, R. (2025) · bioRxiv (Cold Spring Harbor Laboratory) · doi:10.1101/2025.09.18.677093 · Cited by 1
Self-citationH.A.DRajendran, B.Malgija, N.S.Ebenezer, ., U. M., Roch, G. V., J.Priyakumari, & Savarimuthu Ignacimuthu, S. J. (2018) · International Journal of Scientific Research in Biological Sciences · doi:10.26438/ijsrbs/v5i4.119124
Sintomas de deficiência de macronutrientes em alface
Filho, A. B. C., Rodrigues, M. A., da Silva, M. L. P., & Mendoza-Cortez, J. W. (2020) · Científica · doi:10.15361/1984-5529.2020v48n3p271-290
Nutrient Reduction in the Initial Growth of Caatinga Tree Species
de Oliveira, F. S., Rocha, J. L. A., Alves, J. D. M., dos Santos, L. C., & de Mesquita, E. F. (2021) · Floresta e Ambiente · doi:10.1590/2179-8087-floram-2021-0044
Tian-zhi, G., & Zhang, D. (2021) · International Journal of Current Research in Biosciences and Plant Biology · doi:10.20546/ijcrbp.2021.809.002
Interaction of Cytokinin and Ethylene in the Regulation of Primary Root Growth and Development
Shakeel, S. N., Swain, S., Aman, S., & Schaller, G. E. (2021) · Signaling and communication in plants · doi:10.1007/978-3-030-84985-6_13
Sönmez, F. (2022) · Toprak Bilimi ve Bitki Besleme Dergisi · doi:10.33409/tbbbd.1127512
Ahmad, N., Ibrahim, S., Kuang, L., Tian, Z., Wang, X., Wang, H., & Dun, X. (2023) · Research Square · doi:10.21203/rs.3.rs-3094390/v1
Zhang, Q., Ren, J., Zhang, Y., Guo, M., Yi, K., & Ruan, W. (2023) · Scientia Sinica Vitae · doi:10.1360/ssv-2023-0048
Rajesh, N. L., Narayana Rao, K., Sathishkumar, U., Wali, V. B., Basavaraj, K., Rudramurthy, H. V., & Desai, B. K. (2023) · F1000Research · doi:10.12688/f1000research.53095.3
Strigolactone receptor DAD2 promotes lateral root formation in Petunia hybridaPreprint
Khuvung, K., Courty, P., & Reinhardt, D. (2024) · bioRxiv (Cold Spring Harbor Laboratory) · doi:10.1101/2024.08.28.609930
A plastidial lipoyl synthase LIP1p plays a crucial role in phosphate homeostasis in Arabidopsis
Ge, S., Xiao, X., Zhang, K., Yang, C., Dong, J., Chen, K., Lv, Q., Satheesh, V., & Lei, M. (2024) · The Plant Journal · doi:10.1111/tpj.17117
Toren, N., & Erel, R. (2025) · SSRN Electronic Journal · doi:10.2139/ssrn.5236483
Jin, Q., Gao, R., Yao, J., Huang, Z., Liu, K., Wei, G., Dong, W., & Wang, Z. (2025) · Plant Communications · doi:10.1016/j.xplc.2025.101680
Ma, C., Chen, Q., Wang, S., & Lers, A. (2021) · Figshare · doi:10.6084/m9.figshare.14532516
Ma, C., Chen, Q., Wang, S., & Lers, A. (2021) · Figshare · doi:10.6084/m9.figshare.14532522
Ma, C., Chen, Q., Wang, S., & Lers, A. (2021) · Figshare · doi:10.6084/m9.figshare.14532534
Cockerton, H. M., Li, B., Stavridou, E., Johnson, A. W., Karlström, A., Armitage, A. D., Martinez-Crucis, A., Arjona, L. G., Harrison, N., Barber-Pérez, N., et al. (2020) · Figshare · doi:10.6084/m9.figshare.12109770
Ma, C., Chen, Q., Wang, S., & Lers, A. (2021) · Figshare · doi:10.6084/m9.figshare.14532513
Cockerton, H. M., Li, B., Stavridou, E., Johnson, A. W., Karlström, A., Armitage, A. D., Martinez-Crucis, A., Arjona, L. G., Harrison, N., Barber-Pérez, N., et al. (2020) · Figshare · doi:10.6084/m9.figshare.12109764
Ma, C., Chen, Q., Wang, S., & Lers, A. (2021) · Figshare · doi:10.6084/m9.figshare.14532528
Ma, C., Chen, Q., Wang, S., & Lers, A. (2021) · Figshare · doi:10.6084/m9.figshare.14532504
Ma, C., Chen, Q., Wang, S., & Lers, A. (2021) · Figshare · doi:10.6084/m9.figshare.14532531
Ma, C., Chen, Q., Wang, S., & Lers, A. (2021) · Figshare · doi:10.6084/m9.figshare.14532519
Lewin, S., Francioli, D., Ulrich, A., & Kolb, S. (2021) · Figshare · doi:10.6084/m9.figshare.16800647
Wang, Z., Wang, Y., Du, Q., Yan, P., Yu, B., Li, W.-X., & Zou, C.-Q. (2023) · Figshare · doi:10.6084/m9.figshare.22600901
Ma, C., Chen, Q., Wang, S., & Lers, A. (2021) · Figshare · doi:10.6084/m9.figshare.14532510
Ma, C., Chen, Q., Wang, S., & Lers, A. (2021) · Figshare · doi:10.6084/m9.figshare.14532525
Ma, C., Chen, Q., Wang, S., & Lers, A. (2021) · Figshare · doi:10.6084/m9.figshare.14532507
Ma, C., Chen, Q., Wang, S., & Lers, A. (2021) · Figshare · doi:10.6084/m9.figshare.14532540
Ma, C., Chen, Q., Wang, S., & Lers, A. (2021) · Figshare · doi:10.6084/m9.figshare.14532537
Bonnin, M., Soriano, A., Lourkisti, R., Oustric, J., Calvez, L., Miranda, M., Leonhardt, N., Ollitrault, P., Berti, L., Santini, J., et al. (2026) · Plant Stress · doi:10.1016/j.stress.2026.101308
Real-time imaging of transcription to study phosphate sensing in plants
Hani, S. (2022) · theses.fr (ABES) · doi:10.70675/5461667cz5fd4z47f2zb3a4zd5d54c2ea194
Maslard, C. (2024) · theses.fr (ABES) · doi:10.70675/78900108z4663z41cdzbf26zafd5dc5f55cd
Benjamin Wee, Y., Jost, R., Whelan, J., & Berkowitz, O. (2026) · BMC Plant Biology · doi:10.1186/s12870-026-09379-9
Self-citationYuan, S., Zhang, Z., Zhang, Y., Li, J., Zuo, H., Wei, J., Chen, M., Huang, X., Zhang, S., Zhang, M., et al. (2026) · Industrial Crops and Products · doi:10.1016/j.indcrop.2026.123865
Regulation of root-to-shoot ratio in plant resource allocation by external and internal cues
Li, Q., Tong, Y., & Tong, H. (2026) · Journal of genetics and genomics/Journal of Genetics and Genomics · doi:10.1016/j.jgg.2026.07.010 · Cited by 2
Zhang, J., Pan, A., Song, Z., Liu, X., Zhang, J., & Zhang, G. (2026) · Frontiers in Plant Science · doi:10.3389/fpls.2026.1877859
Huang, X., Morales, A. O., Zou, W., He, X., Yu, B., von Tucher, S., Gu, L., Bienert, G. P., & Yu, P. (2026) · Plant and Soil · doi:10.1007/s11104-026-08935-4
Yurkov, A. P., Puzanskiy, R. K., Bogdanova, E. M., Kryukov, A. A., Vavulina, T. R., Belyaeva, A. I., Kosulnikova, A. I., Kosulnikov, Y. V., Laktionov, Y. V., Yemelyanov, V. V., et al. (2026) · International Journal of Molecular Sciences · doi:10.3390/ijms27177751
Chen, Y., Zhang, C., Cheng, F., Xu, Q., & Li, W. (2026) · Biology · doi:10.3390/biology15191676
Endophytes and Mineral Deficiency Stress
Khan, Z., Imran, A., Iftikhar, H., Khan, S., Ali, B., Saeed, F., Hussain, Z., & Latef, A. A. H. A. (2026) · IGI Global eBooks · doi:10.4018/979-8-2600-0036-6.ch015
Quintana, J., Delgado, M., Bascur, N., González-González, M., Curaqueo, G., Núñez-Montero, K., Vallejos, V., Cerda, Y., Banerjee, A., Peña, C., et al. (2026) · Horticulturae · doi:10.3390/horticulturae12101303
P., N. T., Huynh, L. T. P., Nguyen, V. P., Nghiem, L. H. T., Le, V. A., & Nguyen, O. T. K. (2026) · Theoretical and Experimental Plant Physiology · doi:10.1007/s40626-026-00413-7
Metadata
- Authors
- Péret, B., Desnos, T., Jost, R., Kanno, S., Berkowitz, O., & Nussaume, L.
- Affiliations
- Centre National de la Recherche Scientifique (FR)
- Venue
- Plant Physiology
- Publisher
- Oxford University Press (OUP)
- Published
- 2014-10-23
- Volume
- 166
- Issue
- 4
- Pages
- 1713-1723
- ISSN
- 0032-0889 (ISSN-L)
- 1532-2548
- PMC
- PMC4256877
- OpenAlex
- W2131102604
- Cited by
- 292
- References
- 100
- Citations by year
- 2026: 22 · 2025: 24 · 2024: 23 · 2023: 28 · 2022: 32 · 2021: 46 · 2020: 27 · 2019: 28 · 2018: 18 · 2017: 21 · 2016: 13 · 2015: 9 · 2014: 1
- FWCI
- 17.14
- Type
- journal article
- Language
- en
- Open access
- green
- www.ncbi.nlm.nih.gov
- Locations
- PLANT PHYSIOLOGY (publishedVersion)
- PubMed Central (publishedVersion)
- PubMed (publishedVersion)
- UWA Profiles and Research Repository (UWA) (submittedVersion, other-oa)
- HAL (submittedVersion)
- Funders
- Agence Nationale de la Recherche (ANR-11-PDOC-0003, ANR-09-BLAN-0118, ANR-11-RSNR-0005)
- Japan Society for the Promotion of Science (13J03284)
- Topics
- Life Sciences › Agricultural and Biological Sciences › Plant Science › Plant nutrient uptake and metabolism
- Life Sciences › Agricultural and Biological Sciences › Plant Science › Plant Parasitism and Resistance
- Life Sciences › Agricultural and Biological Sciences › Plant Science › Plant Molecular Biology Research
- Keywords
- root architecture, phosphate limitation, phosphorus acquisition, lateral roots, primary root, cluster roots, root development, nutrient limitation
- MeSH terms
- Phosphates, Phosphorus, Plants, Soil, Plant Roots, Plant Development
About these checks
Registry, retraction, Cites and statistics results are computed, not judged, with one exception: a printed reference that no index lists is read once by a model before it counts as a citation error. Claims are extracted by a model and kept only when their quote appears verbatim in the text; each cited source is then checked, with a model’s help, for whether it says what the claim relies on. Those verdicts can be wrong — read the claim’s quote and the cited source before relying on one.
Statistics and arithmetic are recomputed, not judged.
Confidence bands are shown only for fields calibrated on our annotated test set. None is calibrated yet, so no band is shown.
What counts as a claim ›How we measure confidence ›How we check this ›
Are you an author, or do you see a problem with this page? Request a review