Gene expression profiling by cDNA-AFLP reveals potential candidate genes for imazapyr-induced male sterility in sunflower

Abstract

Chemically induced male sterility (CIMS) is a valuable tool for hybrid breeding in crops. In this context, the acetohydroxyacid synthase (AHAS)-inhibiting imazapyr has been proposed to induce male sterility in Imisun sunflower (Helianthus annuus L.) when applied during early reproductive development in a two-fold higher than recommended field dose. This study aimed to perform a comparative transcriptomic analysis to find out the molecular bases of the gametocidal effect of imazapyr on two Imisun genotypes differing in their herbicide resistance level: completely resistant and intermediate resistant. The CIMS of treated plants was confirmed at physiological and anatomical levels. A total of 948 differentially expressed transcript-derived fragments (TDFs) were identified by complementary DNA amplified fragment-length polymorphism (cDNA-AFLP) analysis at the three most informative developmental stages of anther development. Several genes related to xenobiotic metabolism and stress, including cytochrome P450 monooxygenases and ATP-binding cassette transporters, were identified in the completely resistant genotype. Interestingly, a group of genes, including protein kinases, sulfonylurea receptor 1, aspartic signal peptide-peptidase, and specific membrane transporters, were recognized from the differential TDFs simultaneously detected in both genotypes. Some of these transcripts were validated by quantitative real-time polymerase chain reaction (qPCR) in both genotypes. Therefore, these transcripts could be exclusively related to the CIMS in sunflower. Based on the results, we suggest a probable model of action for the gametocidal effect of imazapyr. Our research provides new insights into the molecular mechanisms of male sterility induction in sunflower.