title: Seed set, pollen morphology and pollen surface composition response to heat stress in field pea.
abstract: Pea (Pisum sativum L.) is a major legume crop grown in a semi-arid climate in Western Canada, where heat stress affects pollination, seed set and yield. Seed set and pod growth characteristics, along with in vitro percentage pollen germination, pollen tube growth and pollen surface composition, were measured in two pea cultivars (CDC Golden and CDC Sage) subjected to five maximum temperature regimes ranging from 24 to 36 °C. Heat stress reduced percentage pollen germination, pollen tube length, pod length, seed number per pod, and the seed-ovule ratio. Percentage pollen germination of CDC Sage was greater than CDC Golden at 36 °C. No visible morphological differences in pollen grains or the pollen surface were observed between the heat and control-treated pea. However, pollen wall (intine) thickness increased due to heat stress. Mid-infrared attenuated total reflectance (MIR-ATR) spectra revealed that the chemical composition (lipid, proteins and carbohydrates) of each cultivar's pollen grains responded differently to heat stress. The lipid region of the pollen coat and exine of CDC Sage was more stable compared with CDC Golden at 36 °C. Secondary derivatives of ATR spectra indicated the presence of two lipid types, with different amounts present in pollen grains from each cultivar.
authors.affiliation: Department of Plant Sciences, University of Saskatchewan, Saskatoon, Saskatchewan, Canada, S7N 5A8.
authors.forename: Yunfei
authors.initials: Y
authors.lastname: Jiang
authors.affiliation: Canadian Light Source Inc., Saskatoon, Saskatchewan, Canada, S7N 2V3.
authors.forename: Rachid
authors.initials: R
authors.lastname: Lahlali
authors.affiliation: Canadian Light Source Inc., Saskatoon, Saskatchewan, Canada, S7N 2V3.
authors.forename: Chithra
authors.initials: C
authors.lastname: Karunakaran
authors.affiliation: Canadian Light Source Inc., Saskatoon, Saskatchewan, Canada, S7N 2V3.
authors.forename: Saroj
authors.initials: S
authors.lastname: Kumar
authors.affiliation: Department of Biology, University of Saskatchewan, Saskatoon, Saskatchewan, Canada, S7N 5A8.
authors.forename: Arthur R
authors.initials: AR
authors.lastname: Davis
authors.affiliation: Department of Plant Sciences, University of Saskatchewan, Saskatoon, Saskatchewan, Canada, S7N 5A8.
authors.forename: Rosalind A
authors.initials: RA
authors.lastname: Bueckert
mesh_terms: D018525:Germination; D018869:Heat-Shock Response; D050356:Lipid Metabolism; D018532:Pisum sativum / Q000033:anatomy & histology / Q000254:growth & development / Q000502:physiology*; D011058:Pollen / Q000033:anatomy & histology / Q000254:growth & development / Q000502:physiology; D053205:Pollen Tube / Q000254:growth & development / Q000502:physiology; D012639:Seeds / Q000033:anatomy & histology / Q000254:growth & development / Q000502:physiology
keywords: ATR spectroscopy; Pisum sativum; SEM; TEm; high temperature; pollen wall structure