Additionally OsGly I overexpressing transgenic rice
Additionally, OsGly I-overexpressing transgenic rice plants had higher grain yields than WT (Table 2). Although there were no significant differences in the number of effective panicles per plant, panicle length, grain numbers per panicle, or 1000-grain weight between WT and transgenic plants, the seed setting rate was remarkably higher in the transgenic lines. This was likely the major factor contributing to the increase of yield in transgenic plants. Presumably, while rice crops were exposed to a wide range of multiple potential environmental stresses under natural field condition at various developmental times, especially at the times of flowering and double fertilization, overexpression of OsGly I provided transgenic rice plants with enhanced ability of tolerance against stresses as shown in salt, heavy metal, and drought tolerance assay presented here and thus increased field yield. Taken together, OsGly I might be a useful target for genetic engineering for cereals to withstand abiotic stresses.
In the process of growth and development, in addition to abiotic stresses, crop plants also suffer from the dangers of a variety of diseases, causing 20–30% of yield loss when seriously occurred at harvest time (Mew et al., 2004). Breeding of disease-resistant varieties is the most economic and effective method to prevent crops from diseases hazard by introducing resistant gene resources. In our study, this glyoxalase I has been confirmed to play a role in the abiotic stresses tolerance. Results of previous research indicated glyoxalase I Chlorhexidine digluconate mg also were induced by bacterial pathogen (Zimaro et al., 2011) and fungal pathogen (Yang et al., 2007, Lin et al., 2010). It was reported that MG levels increased after fungal infection, and MG could in turn induce toxic metabolites, such as aflatoxin, one of the major threats to crop productivity and highly carcinogenic material produced by A. flavus and A. parasiticus. Thus glyoxalases possibly play a significant role in protecting plants from pathogens by using their enzyme activities (Chen et al., 2004, Kaur et al., 2014). Whether the rice glyoxalase I is also involved in plant disease resistance might be worth for further investigation.
Acknowledgements We thank Dr. Dale Karlson for his valuable suggestions and critical reading of this manuscript. This work was supported by the National Basic Research Program of China (973 Program) (No. 2011CB100401) and the Youth Science Fund of Sichuan of Agricultural sciences (No. 2013QNJJ-20).
Introduction Reactive α-oxo aldehydes such as glyoxal (GO) or methylglyoxal (MGO) are side products of glycolysis and fatty acid metabolism . They can also derive from oxidative reactions such as the Wolf- and Namiki-pathways , which are acting on less reactive aldehydes and early Maillard reaction products. The presence of α-oxo aldehydes results in the accelerated production of Maillard reaction products and in the accumulation of stable compounds, the so-called advanced glycation end products (AGEs) . This AGE-accumulation is a biomarker for aging and hyperglycemic conditions as in diabetes and also occurs in cancer cells. Cancer cells exhibit a greatly increased glycolytic flow with increased production of MGO as a result of the Warburg effect , which describes the predominance of anaerobic glucose metabolism even in the presence of sufficient oxygen. The detoxification of reactive aldehydes depends on at least three different enzyme systems. The most abundant and most frequently analyzed enzymes are glyoxalase I (GLO1) and -II (hydroxyacylglutathione hydrolase, HAGH) which utilize glutathione as cofactor . Other glyoxalases are DJ-1, also known as PARK-7and the aldo-keto reductase AKR7A2 . These enzymes utilize different reaction principles than glyoxalase I. DJ-1 produces glycolate and D-lactate form glyoxal without the need for a cofactor . NADPH-dependent aldo-ketoreductases, especially AKR7A2 might also play a significant role in aldehyde defense . Cancer cells rely on the sufficient activity of these detoxification systems as the production of reactive aldehydes is significantly increased. As a consequence, many cancer entities exhibit high expression levels of glyoxalase I, including breast cancer . Additionally, glyoxalase expression is important for multi drug resistance and chemotherapy . Therefore, glyoxalase I has been proposed as a target for anticancer therapies . However, so far, no GLO1 inhibitor has been established that has the potential to be used in therapy, mainly due to unfavorable side effects , . The exogenous application of MGO to further increase aldehyde stress, however, has shown promising effects in a mouse model .