Selection and Validation of Reference Genes in Sudan Grass ( (Piper) Stapf) under Various Abiotic Stresses by qRT-PCR.

Quantitative reverse transcription PCR (qRT-PCR) can screen applicable reference genes of species, and reference genes can be used to reduce experimental errors. Sudan grass ( (Piper) Stapf) is a high-yield, abiotic-tolerant annual high-quality forage with a wide range of uses. However, no studies have reported reference genes suitable for Sudan grass. Therefore, we found eight candidate reference genes, including , , , , , , , and , under salt stress (NaCl), drought stress (DR), acid aluminum stress (AlCl), and methyl jasmonate treatment (MeJA). By using geNorm, NormFinder, BestKeeper, and RefFinder, we ranked eight reference genes on the basis of their expression stabilities. The results indicated that the best reference gene was under all treatments. can be used in CK, MeJA, NaCl, and DR. can serve as the best reference gene in AlCl. Two target genes ( and ) belong to drought-stress-response genes, and they are highly expressed in Sudan grass according to transcriptome data. They were used to verify eight candidate reference genes under drought stress. The expression trends of the two most stable reference genes were similar, but the trend in expression for showed a significant difference. The reference genes we screened provided valuable guidance for future research on Sudan grass.