High temperature induced fertility transition and anther carbohydrate metabolism modification in a canola recessive genic male sterile line

Abstract

High temperature stress is an important abiotic stress during plant growth and development that can damage canola male reproductive organ development. In this present study, we characterized a canola genic male sterile line that its fertility can be restored after high temperature induction with heterozygous but not homozygous condition. Anther length and weight was elongated and increased 2 and 5.7 times at 9 days after high temperature treatment in heterozygous line. Furthermore, viable pollen grain was produced in the anther. Anther carbohydrate content was assayed. The result showed that fructose and sucrose contents were much more stable under heat stress both in hetero- or homozygous lines. However, glucose and starch content was considerably increased after high temperature treatment in heterozygous line. In particular, anther glucose content was twice as much as that of starch content after 5 days high temperature treatment. Activity of neutral invertase, acid invertase, and sucrose synthase were increased in the anther of heterozygous line under heat stress. But activity of neutral invertase was the highest among these three sucrose cleavage enzymes. Both activity of sucrose phosphate synthase and starch phosphorylase were decreased under heat stress in the anther of heterozygous line. Activity of ADP glucose pyrophosphorylase was greatly increased in the heterozygous line, which was beneficial for starch accumulation. Transcription level of carbohydrate related genes was analyzed. 27 and 34 of the carbohydrate related genes were identified for down- and up-regulated in the anther of heterozygous line, respectively. Their function involved in the regulation of heat tolerance of heterozygous line was also discussed. Key words: Canola, carbohydrate, gene.