In the 21st century, global agriculture faces themajor challenge for supplying future sustainable food and vegetable production witha growing population under worsening anthropogenic climate change.
This changeresult in reducing available water and a rise in air temperatures. Mungbean (Vignaradiata (L.) Wilczek) is one of the most important leguminous staple crops becauseof its short life cycle (about 60 days) with wide adoptability, droughttolerance, fixing atmospheric nitrogen in its root nodules in association with soilrhizobium for thriving in N-deficient soils (Yaqub et al., 2010) as well as its valuablenutritional and health benefits. The global annual production is 3 million tonsof grain from more than 6 million hectares worldwide (Nair et al., 2013).
India is the world’s largestmungbean producers followed by China, Pakistan, Taiwan, Australia, Myanmar and Indonesia.Although Thailand is not among the major producers, mungbean is a strategiccrop for local and national agribusiness, being lower northern Thailandresponsible for about 0.14 million hectares. Nowadays about 4 thousand tons ofthe internal demand are consumed, however the Thailand government supplied only6 hundred tons of the total demand. (Office of Agricultural Economics, 2016).
The major constraints are inherently low yielding potential of the currentvarieties and susceptible to destructive diseases, a notable group of which arethe foliar diseases. Among them, Cercospora leaf spot (CLS) caused by Cercospora canescens Illis & Martin inflictsignificantly seed yield losses in mungbean. Under the rainy season couplingwith sufficient number of fungal spores, mungbean was severely and rapidlyinfected in the susceptible Uthong1 (UT1) and resistant (Pagasu) varieties to 68% and 35%, respectively (AVRDC, 1984). Powdery mildew (PM) causedby another fungus Sphaerotheca phaseoli is an important foliar diseaseof mungbean worldwide.
Its outbreak, mainly devastating in the winter season, canreduce seed yield more than 50% (Khajudparn et al., 2007) oreven 100% at the seedling stage (Reddy et al., 1994). Currently, these major yield losses wererecognized in all highly susceptible varieties of mungbean recommended tofarmers in Thailand i.e. UT1, Kampaeng Saen 1 (KPS1), KPS2, Chai Nat (CN36),CN60, CN72, CN84-1 and Suranaree University of Technology 1 (SUT1).
However, these recommended varieties,particularly KPS2, CN36, CN72 and CN84-1 have been still cultivated together with spraying chemicals as long as no new improvedvarieties were developed (Ngampongsai et al., 2015a). Chemical usage increases farmers’ production costs andhas adverse effects on human health including the environment. Moreover,regular spraying can cause the evolutionary change of chemical resistance inthe pathogen. In addition, some disease resistant varieties may be broken downby new virulent races according to the classic boom and bust cycles of majorgene resistance to plant pathogens.
Thus, usefulness of disease resistantvarieties pyramiding disease resistance genes is the most desirable strategy toprovide more durable and broad-spectrum resistance in an economical and eco-friendlyway.