Comparative physiology and cellular responses of different peanut cultivars under PEG-induced drought at seedling stage.

BACKGROUND

Tolerance to drought stress varies among peanut (Arachis hypogaea L.) cultivars, drought-tolerant cultivars maintained robust root volume coupled with intensified antioxidant enzyme activity and osmotic substance but drought-sensitive cultivars adversely. It is vital to identify the underlying mechanism to induce root volume decreased except for the reasons mention above or the possible physiology and cellular responses under drought. Therefore, two drought-tolerant cultivars, Nonghua 5 (NH5) and Huayu 22 (HY22), and two drought-sensitive cultivars, Nonghua 16 (NH16) and Fuhua 18 (FH18) were used, in which root morphology, physiology indices, antioxidant enzyme activity and osmotic substance, membrane system damage, root anatomical structures, programmed cell death (PCD) were determined under PEG-induced drought at seedling stage.

RESULTS

Compared with NH16 and FH18, NH5 and HY22 had higher levels of antioxidant enzyme activity, more substances related to osmotic adjustment, and lower levels of reactive oxygen species and cell membrane injury. And in NH5 and HY22 cultivars, relatively intact cell structures were observed and were sustained for 6 days under drought stress. Conversely, the physiology of NH16 and FH18 under the same conditions decreased for the first 3 days, and the cell structure collapsed. Obvious PCD was appeared in NH16 and FH18 cultivars. In addition, genes related to the inhibition of PCD, root hair growth, and drought resistance were upregulated in NH5 and HY22 cultivars.

CONCLUSIONS

The results of this study firstly investigates physiological, cellular response and PCD processing under drought, which sheds on novel insight on cultivar-specific PCD dynamics in peanut root hairs.