Genomics-assisted breeding in four major pulse crops of developing countries: present status and prospects

The global population is continuously increasing and is expected to reach nine billion by 2050. This huge population pressure will lead to severe shortage of food, natural resources and arable land. Such an alarming situation is most likely to arise in developing countries due to increase in the proportion of people suffering from protein and micronutrient malnutrition. Pulses being a primary and affordable source of proteins and minerals play a key role in alleviating the protein calorie malnutrition, micronutrient deficiencies and other undernourishment-related issues. Additionally, pulses are a vital source of livelihood generation for millions of resource-poor farmers practising agriculture in the semi-arid and sub-tropical regions. Limited success achieved through conventional breeding so far in most of the pulse crops will not be enough to feed the ever increasing population. In this context, genomics-assisted breeding (GAB) holds promise in enhancing the genetic gains. Though pulses have long been considered as orphan crops, recent advances in the area of pulse genomics are noteworthy, e.g. discovery of genome-wide genetic markers, high-throughput genotyping and sequencing platforms, high-density genetic linkage/QTL maps and, more importantly, the availability of whole-genome sequence. With genome sequence in hand, there is a great scope to apply genome-wide methods for trait mapping using association studies and to choose desirable genotypes via genomic selection. It is anticipated that GAB will speed up the progress of genetic improvement of pulses, leading to the rapid development of cultivars with higher yield, enhanced stress tolerance and wider adaptability

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Not AvailableRice is the most important food crop both in value and volume for the Asian population. Frequent drought, flood and salinity stresses exacerbated by global climate change adversely affect rice production in more than fifty percent of the rice growing areas. Green revolution high yielding varieties carrying sd1 dwarfing gene have almost fully replaced the traditional climate resilient landraces and varieties of rice. However, these were bred primarily for yield under high input conditions and therefore are sensitive to adverse climatic conditions. Hence, there is urgent need to combine the high productivity with climate resilience. Knowledge of rice genome and genes for tolerance to different abiotic stresses provided us an opportunity to transfer favorable alleles of these genes into high yielding varieties through genomics-assisted backcross breeding through multi-institutional networks. Six consistent genomic regions (QTLs) for grain yield under drought; namely qDTY1.1, qDTY2.1, qDTY2.2, qDTY3.1, qDTY3.2 and qDTY12.1 have been transferred to flood tolerant versions of mega varieties of rice, Swarna, Samba Mahsuri and IR 64. To address the problem of flash flooding qSUB1 QTL has been transferred to nine popular rice varieties, namely ADT 46, Bahadur, Ranjit, HUR 105, Sarjoo 52, Pooja, Pratikshya MTU 1075 and Rajendra Mahsuri. Further, qSALTOL1 QTL for seedling stage salt tolerance and qSSISFH8.1 for reproductive stage salt tolerance have been transferred to six popular rice varieties, ADT 45, Gayatri, MTU 1010, PR 114, Pusa 44 and Sarjoo 52. We used foreground selection markers for the presence of desired gene/QTL and recombinant selection markers for reduction of linkage drag around these genes. Genotypic background selection was done after BC3F3 stage using a 50K SNP chip on a set of 20 advance lines obtained by phenotypic selection for closeness to the recipient parents. Near-isogenic lines (NILs) with more than 95% similarity to the recipient parent genome have been released and notified for commercial cultivation and are gaining fast popularity. These climate smart rice varieties will provide production stability in the adverse ecologies and support farmer’s income and livelihood.Not Availabl

Plant-induced changes in the bioavailability of heavy metals in soil and biosolids assessed by DGT measurements

Purpose: This study investigated the effects of plants on the available pools of heavy metals and their re-supply potential in contaminated substrates in a short-term experiment using five metal-accumulating willow and poplar species/cultivars and in a longer-term experiment for Salix x reichardtii. Material and methods: Five species of willow and poplar were grown in either soil or biosolids for short-term experiment (4 months). Further investigations of longer-term effects of plant on metal availability were conducted with S. x reichardtii grown in biosolids in a column (100 cm height and 37.5 cm diameter) experiment over a period of 12 months. Samples collected before and after experiments were determined for pH and bioavailability of metals using diffusive gradients in thin films (DGT). Various pools of metals in biosolids were determined by sequential extraction. Concentrations of heavy metals in plant material were determined. Results and discussion: The concentration of metals determined by DGT (C) and concentration of metals in pore water (C) of Ni, Cu, Zn, and Cd in soil and biosolids generally decreased significantly compared to the initial measurements and were usually lower than those of the controls. However, C and C were higher in planted soil compared to those in the controls. There was a negative correlation between Ni, Zn, and Cd in plant shoots and C in both soil and biosolids. The R values, the ratio of C/C calculated for Ni, Cd and Zn of planted substrates, were significantly higher than the corresponding R values of initial substrates. By contrast, R values for Cu showed little change. R values for Ni, Zn, and Cd were higher in planted biosolids compared to the unplanted biosolids. While S. x reichardtii leaf Cd, Ni, and Zn concentrations increased significantly over time, leaf Cu concentration declined. The patterns of plant uptake for the metals reflected the patterns observed by DGT and soil solution measurements of R. Sequential extraction of heavy metals from biosolids after 12 month's experimentation confirmed that Cu was predominantly in the organic fraction. Conclusions: The short-term effects of plants on the bioavailability of metals in soils and biosolids were different. The R values of cultivated treatments varied between species but were not significantly different from the control in most of the cases. The longer-term experiment indicated that both C and C of Ni, Zn, and Cd decreased significantly over time in both planted and unplanted treatments. The results of this study demonstrated that R values measured by DGT may be useful in assessing the potential bioavailability of heavy metals in soil and biosolids