Plant growth regulators affecting corn (Zea mays L.) physiology and rab17 expression under drought conditions

Finding methods, which may improve corn (Zea mays L.) growth and physiology under drought stress, is of significance. Accordingly, the effects of different plant growth regulators (PGRs) including benzyl adenine (BA6), gibberellins (GA(3+7)), proline (Pr), and BA6 + GA(3+7) + Pr (sub plots), at different drought levels including control (S1), moderate (S2) and severe (S3) (main plots) on the physiology and genetic contents of corn (Single Cross 704) plants were investigated. A two-year field research, as a split plot on the basis of a randomized complete block design with four replications, was conducted in the Research Field of Islamic Azad University, Isfahan, Iran in 2015-2016. Corn physiological parameters including carotenoids (Car), total chlorophyll (Chlt), chlorophyll a (Chla), chlorophyll b (Chlb), plasma membrane resistance (PR), and rab17 expression were determined. Analysis of variance and comparison of means indicated the experimental treatments significantly (P <= 0.01) affected the measured parameters. The combination of PGRs and drought stress was not significant on PR, and just drought stress had a significant effect on rab17 expression at P <= 0.01. The year parameter significantly affected corn Car and PR. Although stress decreased plant Car, and Chl contents, it increased PR. The tested PGRs significantly improved corn physiology and rab17 expression, and interestingly their effectiveness enhanced with increasing the level of stress (significant interaction of PGRs and drought stress). The role of proline as an RNA binding protein affecting RNA activity and rab17 expression and subsequent corn tolerance under drought stress has been suggested.

Automated summary

This study investigated the effects of different plant growth regulators (PGRs) on the physiology and genetic contents of corn under drought stress. The results showed that these PGRs significantly improved corn growth and expression under drought stress. Additionally, proline was suggested to play a role in enhancing corn tolerance to drought stress by affecting RNA activity and rab17 expression.