Insect damage influences heat and water stress resistance gene expression in field grown popcorn: Implications in developing crop varieties adapted to climate change

Authors: Dowd, Patrick; Johnson, Eric

Submitted to: Mitigation and Adaptation Strategies for Global Change
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 11/22/2017
Publication Date: 12/6/2017
Citation: Dowd, P.F., Johnson, E.T. 2017. Insect damage influences heat and water stress resistance gene expression in field grown popcorn: Implications in developing crop varieties adapted to climate change. Mitigation and Adaptation Strategies for Global Change. 23(7):1063-1081. http://link.springer.com/article/10.1007/s11027-017-9772-x.
DOI: https://doi.org/10.1007/s11027-017-9772-x

Interpretive Summary: Sustainable production of agricultural commodities is threatened by climate change issues. Understanding the factors that can influence production under stress conditions is necessary so that appropriately tolerant crops can be produced by breeding. The expression of genes responsible for resistance to heat and drought stress was determined in years of low and high heat and drought stress in popcorn kernels that were from undamaged ears, and from ears damaged by insects. The expression of heat stress resistance genes increased in stress years, but the expression of drought resistance genes often decreased in stress years. The expression of a greater number of some classes of genes for drought tolerance decreased in kernels from insect damaged ears compared to undamaged ears during stress years. The results indicate that the effects of insect damage on expression of heat and drought stress genes needs to be considered in breeding for heat and drought stress resistance in crops, so that crops with better sustainable production can be developed.

Technical Abstract: Warming climatic conditions can pose potential problems for crop production, but detailed effects at the molecular level on potentially affected crop plants are lacking. Popcorn is a valuable snack food worldwide, and is difficult to improve by breeding due to multigenic influences on popping. It has been little studied at the molecular level under different climatic conditions. A maize gene microarray was used to investigate changes in expression of genes involved in resistance to heat and water stress in milk stage popcorn kernels at two sites over a three year period. As expected, in years of heat and water stress, expression of many heat shock and senescence related proteins increased compared to the year when weather was closer to average conditions. In contrast, the expression of many genes related to water stress resistance decreased in years of weather stress. Gene expression patterns from kernels of insect damaged ears were often different from those of kernels of undamaged ears, especially for those related to water stress resistance, notably aquaporins and late embryogenesis abundant proteins, which had more differences in expression in years of stress versus less stress compared to kernels from undamaged ears. These results are a cause for concern should climate conditions warm, as water stress genes are not being upregulated to promote resistance, which is likely to result in reduced yields and quality issues. The influence of insect damage on expression of abiotic stress resistance genes can further complicate predictions of how climate warming could affect crop production.