title: Time-lapse imaging of self- and cross-pollinations in Brassica rapa.
abstract: OBJECTIVE
  Pollination is an important process in the life cycle of plants and is the first step in bringing together the male and female gametophytes for plant reproduction. While pollination has been studied for many years, accurate knowledge of the morphological aspects of this process is still far from complete. This study therefore focuses on a morphological characterization of pollination, using time-series image analysis of self- and cross-pollinations in Brassica rapa.
  
  
  METHODS
  Time-lapse imaging of pollen behaviour during self- and cross-pollinations was recorded for 90 min, at 1 min intervals, using a stereoscopic microscope. Using time-series digital images of pollination, characteristic features of pollen behaviours during self- and cross-pollinations were studied.
  
  
  RESULTS
  Pollen exhibited various behaviours in both self- and cross-pollinations, and these were classified into six representative patterns: germination, expansion, contraction, sudden contraction, pulsation and no change. It is noteworthy that in 'contraction' pollen grains shrunk within a short period of 30-50 min, and in 'pulsation' repeated expansion and contraction occurred with an interval of 10 min, suggesting that a dehydration system is operating in pollination. All of the six patterns were observed on an individual stigma with both self- and cross-pollinations, and the difference between self- and cross-pollinations was in the ratios of the different behaviours. With regard to water transport to and from pollen grains, this occurred in multiple steps, before, during and after hydration. Thus, pollination is regulated by a combination of multiple components of hydration, rehydration and dehydration systems.
  
  
  CONCLUSIONS
  Regulated hydration of pollen is a key process for both pollination and self-incompatibility, and this is achieved by a balanced complex of hydration, dehydration and nutrient supply to pollen grains from stigmatic papilla cells.
authors: Graduate School of Life Sciences, Tohoku University, 2-1-1, Katahira, Aoba-ku, Sendai 980-8577, Japan.
authors: Kenichiro
authors: K
authors: Hiroi
authors: Mikako
authors: M
authors: Sone
authors: Satomi
authors: S
authors: Sakazono
authors: Masaaki
authors: M
authors: Osaka
authors: Hiromi
authors: H
authors: Masuko-Suzuki
authors: Tomoki
authors: T
authors: Matsuda
authors: Go
authors: G
authors: Suzuki
authors: Keita
authors: K
authors: Suwabe
authors: Masao
authors: M
authors: Watanabe
mesh_terms: D029741:Brassica rapa / Q000502:physiology*; D011058:Pollen / Q000502:physiology*; D054817:Pollination; D057945:Self-Fertilization; D060436:Self-Incompatibility in Flowering Plants; D059008:Time-Lapse Imaging
keywords: Brassica rapa; Brassicaceae; live imaging; pollen hydration; pollen–stigma interaction; pollination; self-incompatibility; time-lapse imaging
references: Genetics. 1999 Sep;153(1):391-400
references: 10471721
references: J Cell Sci. 1986 Feb;80:141-57
references: 3522612
references: Mol Cell Proteomics. 2011 Dec;10(12):M111.011338
references: 21890472
references: Protoplasma. 2006 Aug;228(1-3):31-9
references: 16937052
references: J Exp Bot. 2010 Apr;61(7):1987-99
references: 20181663
references: Nature. 2000 Feb 24;403(6772):913-6
references: 10706292
references: Proc Natl Acad Sci U S A. 1998 Jan 6;95(1):382-7
references: 9419384
references: Development. 1999 Dec;126(23):5431-40
references: 10556067
references: J Cell Sci. 1985 Jun;76:321-36
references: 4066794
references: Proc Jpn Acad Ser B Phys Biol Sci. 2012;88(10):519-35
references: 23229748
references: Plant Physiol. 2007 May;144(1):72-81
references: 17337527
references: Science. 1999 Nov 26;286(5445):1729-31
references: 10576738
references: Plant Cell. 2009 Sep;21(9):2655-71
references: 19789280
references: Science. 2001 Sep 7;293(5536):1824-6
references: 11546871
references: Proc Natl Acad Sci U S A. 1991 Oct 1;88(19):8816-20
references: 1681543
references: Nature. 2001 Oct 4;413(6855):534-8
references: 11586363
references: Genes Genet Syst. 2010;85(5):297-310
references: 21317542
references: Plant Physiol. 2004 Nov;136(3):3562-71
references: 15489279
references: Proc Natl Acad Sci U S A. 2000 Feb 15;97(4):1920-5
references: 10677556
references: Science. 1999 Nov 26;286(5445):1697-700
references: 10576728
references: Plant Physiol. 2001 Apr;125(4):2095-103
references: 11299389
references: Plant Cell. 2003 Apr;15(4):885-98
references: 12671085
references: New Phytol. 1990 Mar;114(3):511-518
references: 33873981
references: New Phytol. 1992 Jul;121(3):413-424
references: 33874153
references: Science. 2004 Mar 5;303(5663):1516-9
references: 15001779
references: FEBS Lett. 2008 Dec 10;582(29):4077-82
references: 19022253