| Abstract Detail
Biotic and abiotic stress Kaur, Harleen [1], Ozga, Jocelyn A. [1], Reinecke, Dennis M. [1]. Heat stress affects reproductive growth and auxin response in pea (Pisum sativum L.). Exposure to heat stress conditions during flowering and fruit development inhibits flower/fruit/seed growth, and thereby reduces seed yield in many crops. We found that exposure of pea (var. ‘Carneval’; Pisum sativum L.) plants to moderate heat temperatures (33oC for 6 h) for 6 days during the early flowering stage reduced plant height, fruit number, seed number and total seed weight compared to plants under normal temperature (19oC) conditions. These data support that heat stress exposure at early flowering can adversely affect the reproductive phase of an agronomic cultivar of field pea at a temperature and duration usually observed during flowering time in the field on the Canadian prairies. Fruit set and fruit and seed development are complex processes that are regulated by plant hormones including auxins. The auxin 4-chloroindole-3-acetic acid (4-Cl-IAA, naturally occurring in pea) stimulates pea fruit (pericarp) growth, but the other naturally occurring auxin indole-3-acetic acid (IAA) does not (Ozga and Reinecke, 2003, J Plant Growth Regul, 22:73). In order to determine if part of the inhibitory effect of high temperature on fruit growth is through modulation of auxin response in this tissue, we performed pea split-pericarp growth assays (Ozga et al., 1992, Plant Physiol, 100:88) on ‘Carneval’ plants grown under non-stressed and heat stressed (as described above) conditions. Pericarps (2 days after anthesis) were split down the dorsal suture and seeds were either left intact or removed, and pericarps were treated with 0.1 % Tween 80 as controls. Deseeded pericarps were also treated with IAA or 4-Cl-IAA (50 µM in 0.1% Tween 80) directly to the inside surface of the pericarp wall. Under moderate heat stress conditions, pericarp growth was reduced in pericarps with seeds by approximately 44%. As seeds are required for pericarp growth, pericarps without seeds did not grow under non-stressed or heat-stressed conditions. Heat stress reduced 4-Cl-IAA-induced pericarp growth by approximately 50%. Application of IAA did not stimulate pericarp growth under non-stressed or heat-stressed conditions. These data support that heat stress reduces the stimulating effects of seeds and the auxin 4-Cl-IAA on pericarp growth similarly. Since developing seeds have high levels of auxins, these data also support that reduced auxin response may be a key factor leading to reduced fruit set and growth, resulting in decreased seed yield of crops exposed to heat stress conditions during flowering/fruit development.
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1 - University of Alberta, Plant BioSystems Group, Department of Agricultural, Food, and Nutritional Science, Edmonton, AB, T6G 2P5, Canada
Keywords:
Heat stress
fruit development
auxin
pea.
Presentation Type: Oral Paper:Papers for Topics
Session: 7
Location: Salon 13/14/The Shaw Conference Centre
Date: Monday, July 27th, 2015
Time: 11:00 AM
Number: 7012
Abstract ID:997
Candidate for Awards:None |
