Biotechnological Approaches to Evolve Sorghum (Sorghum bicolor (L.) Moench) for Drought Stress Tolerance and Shoot fly Resistance
Kiranmayee K N S Usha1,2, Hash C Tom3, Deshpande Santosh P1,*, Varaprasad K V G K, Kishor P B Kavi2
1International Crops Research Institute for the Semi-Arid Tropics, Hyderabad, 502324, India
2Department of Genetics, Osmania University, Hyderabad, 500007, India
3International Crop Research Institute for the Semi-Arid Tropics, BP12404, Niamey, Niger
Online published on 16 December, 2015.
Sorghum is a model tropical grass that uses C4 photosynthetic activity. But its yield is affected by many abiotic stresses likeheat, drought, cold, salt and also biotic stresses such as shoot fly, midges, and stem borerfromseedling stages to maturity. This article summarizes the terminal drought stress tolerance mechanism with staygreen phenotype expression during postflowering and also mechanisms of early shoot fly resistance during seedling stages of crop growth. The trait stay-green is extensively studied and its correlation to yield makes the stay-green trait more special for research and in marker assisted back cross programs. Under terminal drought stress conditions, stay-green trait is expressed with a complex mechanism involving many transcription factors, chlorophyll retention and nitrogen remobilization from leaves to maintain longer photosynthetic activity. Shoot fly resistance on the other hand, involves manyphysico-chemical, biologicaland morphological traits. Out of the many morphological traits, seedling leaf blade glossiness and trichome density are well characterized at genetic level and can assist as shoot fly resistance sources in marker-assisted breeding programs as they are highly negatively correlated with shoot fly dead heart formation. However, quantitative trait loci (QTL) mapping studies and candidate genes identified for the stay-green and shoot fly component traits need to be further validated with fine mapping, gene cloning and expression level studies. Pyramiding these two traits into a high yielding sorghum variety may lead to multiple stress resistance which could ultimately benefit the marginal farmers in India.
Sorghum, shoot fly resistance, staygreen, drought tolerance, QTL, marker-assisted selection.