Journal of Chemical Ecology 46(8):1-15 (Aug
2020)
The Influence of
Arbuscular Mycorrhizal Fungi on Plant Reproduction
Alison E Bennett, Heiler C.
Meek
Abstract
Arbuscular mycorrhizal (AM)
fungi can influence all components of plant reproduction including pollen
delivery, pollen germination, pollen tube growth, fertilization, and seed
germination. AM fungi associate with plant roots, uptake nutrients, and prime
plants for faster defense responses. Our literature review first identified
four testable hypotheses describing how AM fungi could alter pollen delivery:
(1) We hypothesize AM fungi promote floral display size. The influence of AM fungi
on flower size and number is supported by literature, however there are no
studies on floral color. (2) We hypothesize AM fungi promote pollen and nectar
quality and quantity, and, as reported before, AM fungi promote male fitness
over female fitness. (3) We hypothesize AM fungi promote both earlier and
longer flowering times, but we found no consistent trend in the data for
earlier or later or longer flowering times. (4) We hypothesize AM fungi alter
floral secondary chemistry and VOCs, and find there is clear evidence for the
alteration of floral chemistry but little data on VOCs. Second, we focus on how
AM fungi could alter pollen germination, pollen tube growth, and fertilization,
and present three testable hypotheses. We found evidence that AM fungi influence
pollen germination and pollen tube growth, production of seeds, and seed
germination. However, while most of these influences are positive they are not
conclusive, because studies have been conducted in small numbers of systems and
groups. Therefore, we conclude that the majority of research to date may not be
measuring the influence of AM fungi on the most important components of plant
reproduction: pollen germination, pollen tube growth, fertilization, and seed
germination.