Madan Pal Singh

Marker Aided Incorporation of Saltol, a Major QTL Associated with Seedling Stage Salt Tolerance, into Oryza sativa ‘Pusa Basmati 1121’

Pusa Basmati 1121 (PB1121), an elite Basmati rice cultivar is vulnerable to salinity at seedling stage. A study was undertaken to impart seedling-stage salt tolerance into PB1121 by transferring a quantitative trait locus (QTL), Saltol, using FL478 as donor, through marker assisted backcrossing. Sequence tagged microsatellite site (STMS) marker RM 3412, tightly linked to Saltol was used for foreground selection. Background recovery was estimated using 90 genome-wide STMS markers. Systematic phenotypic selection helped in accelerated recovery of recurrent parent phenome (RPP). A set of 51 BC3F2 lines homozygous for Saltol were advanced to develop four improved near isogenic lines (NILs) of PB1121 with seedling stage salt tolerance. The background genome recovery in the NILs ranged from 93.3 to 99.4%. The improved NILs were either similar or better than the recurrent parent PB1121 for yield, grain and cooking quality and duration. Biochemical analyses revealed significant variation in shoot and root Na+ and K+ concentrations. Correlation between shoot and root Na+ concentration was stronger than that between root and shoot K+ concentration. The effect of QTL integration into the NILs was studied through expression profiling of OsHKT1;5, one of the genes present in the Saltol region. The NILs had significantly higher OsHKT1;5 expression than the recurrent parent PB1121, but lower than FL478 on salt exposure validating the successful introgression of Saltol in the NILs. This was also confirmed under agronomic evaluation, wherein the NILs showed greater salt tolerance at seedling stage. One of the NILs, Pusa1734-8-3-3 (NIL3) showed comparable yield and cooking quality to the recurrent parent PB1121, with high field level seedling stage salinity tolerance and shorter duration. This is the first report of successful introgression of Saltol into a Basmati rice cultivar.

Marker-Assisted Introgression of Saltol QTL Enhances Seedling Stage Salt Tolerance in the Rice Variety “Pusa Basmati 1”

Marker-assisted selection is an unequivocal translational research tool for crop improvement in the genomics era. Pusa Basmati 1 (PB1) is an elite Indian Basmati rice cultivar sensitive to salinity. Here, we report enhanced seedling stage salt tolerance in improved PB1 genotypes developed through marker-assisted transfer of a major QTL, Saltol. A highly salt tolerant line, FL478, was used as the Saltol donor. Parental polymorphism survey using 456 microsatellite (SSR)/QTL-linked markers revealed 14.3% polymorphism between PB1 and FL478. Foreground selection was carried out using three Saltol-linked polymorphic SSR markers RM8094, RM493, and RM10793 and background selection by 62 genome-wide polymorphic SSR markers. In every backcross generation, foreground selection was restricted to the triple heterozygotes of foreground markers, which was followed by phenotypic and background selections. Twenty-four near isogenic lines (NILs), with recurrent parent genome recovery of 96.0–98.4%, were selected after two backcrosses followed by three selfing generations. NILs exhibited agronomic traits similar to those of PB1 and additional improvement in the seedling stage salt tolerance. They are being tested for per se performance under salt-affected locations for release as commercial varieties. These NILs appear promising for enhancing rice production in salinity-affected pockets of Basmati Geographical Indication (GI) areas of India.

Impact of elevated CO2 on rice brown planthopper Nilaparvata lugens (Stal.)

Influence of elevated CO2 (570±25 ppm) on the rice brown plant hopper (BPH), Nilaparvata lugens (Stal.) was studied in the Free Air Carbon Enrichment (FACE) facility during rainy season 2013. The BPH appeared on the crop during last week of August (35th Standard Meteorological Week- SMW) that corresponded to 44 days after transplanting (DAT). From 35th to 38th SMW, total BPH population under both elevated and ambient conditions did not differ significantly; however, significantly higher BPH population was recorded from 39th to 44th SMW under elevated CO2. The peak incidence was recorded in the second week of October (42nd SMW) under both the conditions. Significantly higher canopy circumference under elevated condition provided better environmental condition for the BPH multiplication.

Physiological Response of Maize Under Rising Atmospheric CO2 and Temperature

The projections for future climate change may have a strong influence on agricultural productivity. Maize, being a C4 plant, has evolved to adapt to the atmospheric CO2 concentration with higher photosynthetic efficiency than C3 plants. It is believed that C3 plants would gain a competitive advantage under increasing CO2, but studies indicate that C4 plants sometimes perform better due to improved water use efficiency at the ecosystem level. C4 plant species have higher temperature optima for growth than C3 plants. Temperatures above this range can affect the photosynthetic machinery, thereby decreasing growth. Despite the indication about the improvement in growth of C4 plants under increasing CO2 levels, the contribution of other factors still remains unclear in maize. This compilation is an attempt to highlight the factors and processes affected by climate change in maize and the areas of research that need to be strengthened to understand the underlying mechanisms.

Monitoring of CO2 exchange and carbon pools in vegetation and soil

Global efforts to reduce the emissions require proper monitoring and understanding of the carbon inputs and outputs by the terrestrial ecosystems i.e. vegetation and soil. Photosynthesis and net primary productivity can be used as indicators of carbon exchange and their estimate can be made through traditional approaches as well as other approaches e.g. mechanistic photosynthesis models and the light use efficiency with satellite data. Advancements have taken place for monitoring the CO2 exchange at different scales viz. leaf, stand-, landscape levels, vertical carbon column- and satellite observations. There are methods to partition the fluxes based on discrimination of isotopes of carbon by terrestrial ecosystem processes. The soil is a vast reservoir of carbon and has a great potential for atmospheric carbon sequestration. Monitoring of carbon and fluxes in soil is therefore an essential aspect in the era of changing climate. The root systems are monitored mostly in a destructive manner but many non-destructive methods have also been devised. Similarly, soil carbon estimation with traditional chemical method can be replaced by reflectance spectroscopy for rapid and large area estimations. Measurement of soil respiration and its partitioning also helps in verifying the capacity of soil as a net source or net sink. Monitoring of the pools and fluxes therefore uses multi-technique and -disciplinary approaches. Uncertainties in the estimates occur due to the multi-factorial effects and have implications on carbon trading. Therefore more effective monitoring and reduction of the uncertainties is needed.