Improvements of Fertility Restoration in Cytoplasmic Male Sterile Cotton by Enhanced Expression of Glutathione S-Transferase (GST) Gene

Abstract

The molecular and biochemical bases of fertility restoration were explored using cytoplasmic male sterile (CMS) Ji A, maintainer Ji B, and two cotton hybrids RF1 and QF1, developed by crossing CMS with DES-HAF277 (normal restorer) and Zheda strong restorer (transgenic restorer with GST gene), respectively. Transcript levels of both exogenous and endogenous GST genes were high in anther as compared to other plant tissues of the QF1 hybrid. Moreover, the expression of the GST gene during meiosis (stage 2) and microspore development (stage 3) was highest in the QF1 hybrid. The ratio of cyanide-resistant respiration to total respiration was also high in the QF1 hybrid during stage 2 and stage 3 as compared to the RF1 hybrid. O2 − and H2O2 contents increased more during stage 2 in the CMS line and stage 3 in the RF1 hybrid compared to the maintainer and QF1 hybrid. Similarly, MDA contents were at a maximum in CMS followed by the RF1, QF1, and the maintainer line during the whole course of anther development. In addition, the activities of antioxidant enzymes (SOD, POD, CAT, APX, GST, GR, and DHAR) and contents of non-enzymatic antioxidants (GSH and ASA) were elevated in the QF1 hybrid as compared to the RF1 hybrid, during the whole course of anther development. The present study suggests that the introgression of the GST gene into restorer lines could be a potential way to enhance restoration capability by maintaining the equilibrium between oxidative stress and scavenging enzymes, and might favor healthier development of microspores.