Table 5.

Comparison of gene expression levels of DT and DS cassava genotypes after 10 days of stress. Quantitative RT-PCR was performed for each identified gene on three biological replicates for each genotype (MH96/0686 and Nyalanda) after 10 days of stress. Duplicate reactions were run for every biological replicate. The ΔΔCT method of relative gene quantification was used to make the various comparisons of relative gene expression from the qRT-PCR data, using REST. The DS is used as a calibrator, i.e. the relative expression level of each gene is shown as the relative times higher expression in DT (MH96/0686) than in DS (Nyalanda) under drought stress. The ‘Result’ column indicates whether each gene is significantly expressed at higher levels under drought in MH96/0686 versus Nyalanda. A gene is significantly up-regulated or down-regulated when its expression in a treatment is higher than or lower than in a calibrator (standard/baseline), respectively, and when the t-test statistic is lower than 0.05 (at 95 % significant level). The expression in a calibrator is taken as unity (one), expression of more than one is up-regulation and expression less than one is down-regulation. The t-statistic will show whether the up-regulation or down-regulation is significant or non-significant (NS).

Gene	Fold higher in MH96/0686 (compared with Nyalanda)	SE	95 % CI	Probability (P = 0.05)	Result
MeALDH	1.797	1.038–3.258	0.6444.879	0.040	Up-regulation
MeATTF	2.040	1.585–2.669	1.377–3.090	0.000	Up-regulation
MeGBF3	1.890	1.379–2.579	1.099–3.128	0.000	Up-regulation
MeGE3	3.033	1.762–5.233	1.122–8.913	0.000	Up-regulation
MeGF14	1.330	0.842–1.921	0.669–2.521	0.123	NS
MeMYC2	1.180	0.767–1.775	0.634–2.532	0.350	NS
MeMSD	1.221	0.800–1.664	0.589–3.109	0.326	NS
MeRD28	1.501	1.065–1.966	0.866–2.133	0.017	Up-regulation
MeP5CS	1.659	0.992–2.709	0.712–3.197	0.040	Up-regulation
MeZFP	2.197	1.115–3.590	0.815–3.900	0.017	Up-regulation