title: Effects of virus infection on pollen production and pollen performance: Implications for the spread of resistance alleles.
abstract: OBJECTIVE
  Studies over the past 25 years have shown that environmental stresses adversely affect male function, including pollen production and pollen performance (germination and pollen tube growth rate). Consequently, genetic variation among plants in resistance to a stress has the potential to impact pollen donation to conspecifics and, if deposited onto a stigma, the ability of the pollen to achieve fertilization. We examined the effects of a nonlethal virus epidemic on pollen production and pollen performance in a population of susceptible and resistant (transgenic) wild squash (Cucurbita pepo subsp. texana).
  
  
  METHODS
  We grew 135 susceptible and 45 virus-resistant wild squash plants in each of two 0.4-ha fields, initiated a zucchini yellow mosaic virus (ZYMV) epidemic, and recorded staminate and pistillate flower production per plant over the field season and the total number of mature fruit. We also assessed pollen production per flower on ZYMV-infected and non-infected plants and the ability of pollen from flowers on infected and non-infected plants to achieve fertilization under competitive conditions.
  
  
  RESULTS
  ZYMV infection reduced flower and fruit production per plant and pollen production per flower. Pollen from infected plants was also less likely to sire a seed under competitive conditions.
  
  
  CONCLUSIONS
  ZYMV infection adversely impacts the amount of pollen that can be donated to conspecifics, and pollen competition within the styles increases the probability that the ovules are fertilized by pollen from plants that are thriving when challenged by a viral disease.
authors.affiliation: Department of Biology, Pennsylvania State University, University Park, Pennsylvania 16802 USA.
authors.forename: Jacquelyn E
authors.initials: JE
authors.lastname: Harth
authors.affiliation: Department of Biology, Pennsylvania State University, Altoona, Pennsylvania 16601 USA.
authors.forename: James A
authors.initials: JA
authors.lastname: Winsor
authors.affiliation: Department of Biology, Pennsylvania State University, University Park, Pennsylvania 16802 USA.
authors.forename: Danelle R
authors.initials: DR
authors.lastname: Weakland
authors.affiliation: Department of Biology, Pennsylvania State University, University Park, Pennsylvania 16802 USA.
authors.forename: Kayla J
authors.initials: KJ
authors.lastname: Nowak
authors.affiliation: Department of Biology, Pennsylvania State University, University Park, Pennsylvania 16802 USA.
authors.forename: Matthew J
authors.initials: MJ
authors.lastname: Ferrari
authors.affiliation: Department of Biology, Pennsylvania State University, University Park, Pennsylvania 16802 USA as4@psu.edu.
authors.forename: Andrew G
authors.initials: AG
authors.lastname: Stephenson
mesh_terms: D000483:Alleles; D028464:Cucurbita / Q000235:genetics* / Q000821:virology*; D060467:Disease Resistance / Q000235:genetics*; D005638:Fruit / Q000254:growth & development; D010935:Plant Diseases / Q000235:genetics / Q000821:virology*; D011058:Pollen / Q000235:genetics / Q000254:growth & development* / Q000821:virology; D017800:Potyvirus / Q000502:physiology*; D012044:Regression Analysis; D012098:Reproduction; D012639:Seeds / Q000254:growth & development
keywords: Cucurbita pepo subsp. texana; Cucurbitaceae; male function; pollen competition; pollen production; reproductive output; virus epidemic; zucchini yellow mosaic virus