Auxin Polar Transport and Automorphosis in Plants

Gravitational force on Earth is one of the major environmental factors affecting plant growth and development. Spacecraft and the International Space Station (ISS), and a three-dimensional (3-D) clinostat have been available to clarify the effects of gravistimulation on plant growth and development in space and on ground conditions, respectively. Under a stimulus-free environment such as space conditions, plants show a growth and developmental habit designated as 'automorphosis' or 'automorphogenesis'. Recent studies in hormonal physiology, together with space and molecular biology, have demonstrated the close relationships between automorphosis and polar auxin transport. Reduced polar auxin transport in space conditions, or induced by the application of polar auxin transport inhibitors, substantially induced automorphosis or automorphosis-like growth and development, indicating that polar auxin transport is responsible for graviresponse in plants. This concise review covers graviresponse in plants and automorphosis observed in space conditions, and polar auxin transport related to graviresponse in etiolated Alaska and ageotropum pea seedlings. Molecular aspects of polar auxin transport clarified in recent studies are also described.

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“…The relationship between PIN proteins and graviresponse in plants has recently been reviewed (Miyamoto et al . ; Ueda et al . ).…”

Section: Polar Auxin Transport Related To Automorphosis In Plantsmentioning

confidence: 98%

Close relationships between polar auxin transport and graviresponse in plants

et al. 2013

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“…A STS-95 space experiment clearly showed that microgravity conditions in space substantially affected the growth and development of etiolated Alaska pea seedlings, especially the growth of stems, roots and hook formation, and suppressed auxin polar transport in epicotyls (Ueda et al, 1999(Ueda et al, , 2000. Growth and development of plants observed under microgravity conditions has been recognized as automorphosis (Hoson et al, 1992;Stanković et al, 1998;Miyamoto et al, 2011). Automorphosis of pea seedlings observed in space was well simulated by clinorotation using a 3-dimensional (3-D) clinostat (Shimazu et al, 2001), and also phenocopied by the application of auxin polar transport inhibitors (Miyamoto et al, 2005, Hoshino et al, 2006.…”

Section: Introductionmentioning

confidence: 99%

Isolation of PsPINs and PsAUX1 cDNAs Encoding Putative Auxin Efflux and Influx Carriers and/or Facilitators, Respectively, from Etiolated Epicotyls of an Agravitropic Pea (Pisum sativum L.) Mutant, ageotropum

et al. 2012

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cDNAs containing the open reading frames of a putative auxin influx carrier and/or facilitator, PsAUX1 (Accession No. AB488680), and putative auxin efflux carriers and/or facilitators, PsPIN1, PsPIN2 and PsPIN3 (Accession No. AB488679, AB488681 and AB488678, respectively) from etiolated epicotyls of an agravitropic pea mutant, ageotropum, have been isolated. In PsPIN1 and PsPIN2, a few deduced amino acids were different between ageotropum and Alaska showing a normal gravitropic response. No insertion and deletion were observed in PsPIN1 and PsPIN2 of ageotropum compared with those of Alaska. However, PsAUX1 of ageotropum had additional amino acids at the C-terminus compared to that of Alaska. Phylogenetic analyses based on deduced amino acid sequences revealed that PsPIN1 of ageotropum and Alaska belonged to the same clade as MtPIN4, while PsPIN2 of ageotropum and Alaska belonged to a subclade including MtPIN3, BjPIN2, BjPIN3, SlPIN3 and SlPIN4. PsAUX1 of ageotropum with additional amino acids at C-terminus belonged to the same subclade as MiAUX1 and PtAUX1. PsPIN1, PsPIN2, PsPIN3 mRNAs in 3.5-day-old etiolated ageotropum pea seedlings were significantly expressed in the proximal and the distal sides of the first internode of epicotyls to cotyledon. Judging from the results of the structure and the expression of genes related to auxin polar transport, an abnormal gravitropic response of etiolated ageotropum pea seedlings might be related to post transcriptional regulation and translocation of PsAUX1, PsPIN1, PsPIN2 and PsPIN3 as well as the perturbation of auxin transport due to additional amino acids at C-terminus of PsAUX1. ©2012 Jpn. Soc. Biol. Sci.

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“…These facts described above indicate there is a specific system consisting with an asymmetric distribution of these proteins in plant cells to regulate auxin polar transport. The relationships between PIN proteins and a graviresponse in plants have recently been reviewed in this journal (Miyamoto et al, 2011).…”

Section: Introductionmentioning

confidence: 99%