QTL mapping of seedling tolerance to exposure to low temperature in the maize IBM RIL population.

Raeann Goering,James Whelan,Siri Larsen,Irina Makarevitch,Jia Tan,Ajay Kumar

doi:10.1371/journal.pone.0254437

Abstract

Maize is a cold sensitive crop that exhibits severe retardation of growth and development when exposed to cold spells during and right after germination, including the slowdown in development of new leaves and in formation of the photosynthetic apparatus. Improving cold tolerance in maize would allow early sowing to improve crop yield by prolonging a growing season and by decreasing the negative effects of summer drought, diseases, and pests. Two maize inbreds widely incorporated into American maize germplasm, B73 and Mo17, exhibit different levels of tolerance to low temperature exposure at seedling stage. In addition, thirty seven diverse inbred maize lines showed large variation for seedling response to low temperature exposure with lines with extremely low tolerance to seedling exposure to low temperatures falling into stiff stalk, non-stiff stalk, and tropical clades. We employed the maize intermated B73×Mo17 (IBM) recombinant inbred line population (IBM Syn4 RIL) to investigate the genetic architecture of cold stress tolerance at a young seedling stage and to identify quantitative trait loci (QTLs) controlling this variation. A panel of 97 recombinant inbred lines of IBM Syn4 were used to measure, and score based on several traits related to chlorophyll concentration, leaf color, and tissue damage. Our analysis resulted in detection of two QTLs with high additive impact, one on chromosome 1 (bin 1.02) and second on chromosome 5 (bin 5.05). Further investigation of the QTL regions using gene expression data provided a list of the candidate genes likely contributing to the variation in cold stress response. Among the genes located within QTL regions identified in this study and differentially expressed in response to low temperature exposure are the genes with putative functions related to auxin and gibberellin response, as well as general abiotic stress response, and genes coding for proteins with broad regulatory functions.

Highlights

Maize (Zea mays L.) is the most widely distributed crop in the world with approximately 92 million acres planted in the United States every year [1, 2]
quantitative trait locus (QTL) mapping of seedling tolerance to exposure to low temperature in the maize intermated B73×Mo17 (IBM) recombinant inbred lines (RILs) population for food and livestock feed, as well as for producing ethanol fuels, in many developing countries, it is grown by farmers and is used primarily as a food source
A panel of 97 recombinant inbred lines of IBM Syn4 was used as a QTL mapping population to identify QTL regions controlling variation in tolerance to cold temperature exposure of maize seedlings as measured by the chlorophyll concentration, leaf color, and tissue damage

Summary

Introduction

Maize (Zea mays L.) is the most widely distributed crop in the world with approximately 92 million acres planted in the United States every year [1, 2]. A panel of 97 recombinant inbred lines of IBM Syn4 was used as a QTL mapping population to identify QTL regions controlling variation in tolerance to cold temperature exposure of maize seedlings as measured by the chlorophyll concentration, leaf color, and tissue damage.

Results

Conclusion