Average expression stability values (M) of the candidate reference genes.

<p>Average expression stability values (M) of the reference genes were measured during stepwise exclusion of the least stable reference genes. A lower M value indicated more stable expression, as analyzed by the geNorm software in papaya sample sets under different experimental conditions, including different storage temperatures (a), hot water treatment (b), modified atmosphere packaging (c), hormone treatment (d), 1-MCP fumigation treatment (e), different developmental stages (f), different tissues (g), biotic stress (h), postharvest ripening: cultivar of ‘<i>Shuiyou 2′</i> (i), cultivar of ‘<i>Hongri 1′</i> (j), cultivar of ‘<i>Hongri 3′</i> (k). Different cultivars samples (l) and all papaya samples (m) were also given.