Evaluation of Proline Amount, Yield and Expression of Genes Involved in Drought Stress in Maize Cultivars

Drought stress is one of the most important environmental stress that affect maize grain yield worldwide. The event of drought stress in field is investable. In order to solve the problem some suggestions have been made, among those, it seems the best one is using tolerated cultivars.

Experiment was conducted in split plot format by using randomized complete block design with three replicates in field condition. The main factor was three level of drought treatments including 75+- 5 mm (control), 115+- 5 mm (mild stress) and 140+- 5 mm (severe stress) evaporation out of evaporation pan class A. The sub factor included three maize cultivars, 704 single cross, Karoon and Mobin. Sampling for gene expression including ZmAN13, ZmSOD3, CAT2 and ZmMET1 were conducted at three growth stages including four leaves, anthesis and 10 days after anthesis. Measuring of grain yield and proline were conducted at harvesting stage.

The amount of genes catalase and superoxide-dismutase increased by mild drought stress whereas for two genes metalothinonein and ZmAN13 increased by severe drought stress. The Karoon cultivar showed increases transcript for all genes at all sampling stages. The amount of proline was higher in mild drought stress rather than severe, also, Karoon cultivar had higher level of proline rather than other cultivars. Grain yield was decreased significantly by drought stress treatments. Single cross 704 has 3.90 ton/ha in overall and it showed no statistical difference to Mobin grain yield. Karoon cultivar had most grain yield amount (5.02 ton/ha) by severe drought stress.

Karoon cultivar showed the most amount of grain yield under drought stress treatments in compared to other cultivars. This was somehow expected base on gene expression trend as well as proline amount in Karoon cultivar.