|MCNELLIE, JAMES - Iowa State University|
|YU, JIANMING - Iowa State University|
Submitted to: Crop Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 8/31/2018
Publication Date: 10/18/2018
Citation: Mcnellie, J.P., Chen, J., Yu, J. 2018. Genetic mapping of foliar and tassel heat stress tolerance in maize. Crop Science. 58:2484-2493. https://doi.org/10.2135/cropsci2018.05.0291.
Interpretive Summary: High temperature is a major environmental stress negatively impacting corn (maize) yields world-wide. However, the genetic and molecular mechanisms controlling heat stress tolerance are not clear. An ARS scientist at Lubbock, Texas and scientists from Iowa State University evaluated heat stress responses of two maize mapping populations for two major foliar traits that contribute to grain yield under farm conditions. The research identified 22 quantitative trait loci that are significantly associated with heat tolerance/sensitivity in maize. The results represent a starting point for understanding heat stress tolerance in maize, and should help to facilitate breeding for enhanced heat tolerance maize hybrid.
Technical Abstract: Few studies have examined the genetic architecture of heat stress tolerance in field grown Zea Mays (maize). To meet the challenges of feeding a growing population, a better understanding of the genetic and molecular mechanisms controlling heat stress tolerance is required. To address this knowledge gap, we evaluated two bi-parental recombinant inbred line populations (B73 × NC350 and B73 × CML103) for leaf and tassel heat stress tolerant traits. Irrigation ensured well-watered conditions to remove confounding effects of drought stress. Two foliar traits were evaluated, leaf firing and leaf blotching, and when possible, were scored at three vegetative stages. Phenotyping occurred following a heat stress event, defined as three consecutive days with maximum air temperature greater than 36°C. We detected 22 significant QTL, 15 in B73 × NC350 and 7 in B73 × CML103. There was little difference in QTL number and position for traits measured at multiple vegetative stages. Leaf firing and leaf blotching QTL largely co-localized. The development of leaf firing (death of leaf tissue) was differentiable between parents. The parental forms of leaf firing were not significantly correlated, and QTL did not co-localize. Fourteen QTL explained less than 10% of variation. This study is a preliminary step in unraveling the genetic control of heat stress tolerance in maize. These results are relevant for the genetic improvement of maize due to the importance of B73 in forming the foundation of modern dent germplasm.