RESUMEN
Mungbean is an important but understudied food legume compared with other major grain crops. Genetic studies through development of high-through put markers, linkage map construction and QTL analysis can accelerate and improve the efficiency of mining for genes for breeding in this crop. This study used four mungbean F5 recombinant inbred lines (RILs) from crosses of two wild types (ACC 1, ACC 87) and two cultivars (Berken, Kiloga) and DArT markers to construct individual and consensus linkage maps and to identify QTLs associated with 54 traits in mungbean. The number of polymorphic DArT markers identified among the four RIL populations varied from 1062 to 2013. The individual maps covered the lengths of 629.7-883.5 cM, comprising 672-981 DArT markers and 15-19 linkage groups (LG) with average distance between markers of 0.9-1.2 cM. The consensus map had the total length of 795.3 cM, comprising 1539 DArT markers and resolved 11 LGs with an average inter-marker distance of 0.65 cM. Sixty-two QTLs were identified for 39 traits across 10 LGs of the consensus map. Major QTLs were identified for two special traits, late flowering inherited from ACC 1 (6 QTLs, PVE of 11.2-29.9%) and perenniality inherited from ACC 87 (3 QTLs, PVE of 17.4-22.6%) in separate population analysis. Number of congruent QTLs across four mungbean populations and the consensus map was 18 for 13 traits. These results illustrated the high efficiency of DArT marker application in mungbean genetic dissection and suggested the future potential employment of identified QTLs for mungbean improvement.
RESUMEN
Mungbean is an important pulse crop and is predominantly cultivated across Asia. However, its production is hampered by climate change-induced drought stress. Drought affects various morpho-physiological processes associated with growth and molecular functions. This study analyzed growth responses and VrDREB2A gene expression in two mungbean cultivars, DX208 and Tam Thanh Hoa under water deficit at vegetative and flowering stages. Water use and growth characters were evaluated at four time-points (8, 12, 15 and 20-day drought) and 7-day recovery while yield components and yield were recorded after harvesting. Differential expression of VrDREB2A gene was analyzed at four time-points for leaf and root. Plants used up water more quickly at the flowering stage than vegetative stage. The data for plant height, leaf number, above-ground plant biomass and root weight indicated that drought stress significantly repressed mungbean growth, with a reduction relative to the control by 4.0-85%. Yield components and individual yield reduced significantly by 50-60%, with more reduction in drought imposed under the vegetative stage. VrDREB2A expression began to increase on a 12-day drought and was significant in stressed roots on a 20-day drought at the vegetative stage. In contrast, an increase in VrDREB2A expression occurred from 8-day and lasted until a 20-day drought in stressed leave and root at the flowering stage. Overall, the vegetative stage was more sensitive to drought than the flowering stage. A cultivar with less relative reduction in growth and yield related traits and higher VrDREB2A expression was more tolerant to drought. VrDREB2A functioned as an important transcriptional activator and can increase the drought stress tolerance of the mungbean. SUPPLEMENTARY INFORMATION: The online version contains supplementary material available at 10.1007/s12298-021-01089-w.