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28 November 2017, Volume 24 Issue 6 Previous Issue    Next Issue
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Current Status of Conventional and Molecular Interventions for Blast Resistance in Rice Srivastava Deepti, Shamim Md, Kumar Mahesh, Mishra Anurag, Pandey Pramila, Kumar Deepak, Yadav Prashant, Harrish Siddiqui Mohammed, Narayan Singh Kapildeo 2017, 24(6): 299-321.  DOI: 10.1016/j.rsci.2017.08.001 Abstract ( )   HTML ( )   PDF (1435KB) ( )   Pyricularia oryzae anamorph of Magnaporthe oryzae is one of the most notorious fungal pathogens causing severe economic loss in rice production worldwide. Various methods, viz. cultural, biological and molecular approaches, are utilized to counteract this pathogen. Moreover, some tolerant or resistant rice varieties have been developed with the help of breeding programmes. Isolation and molecular characterization of different blast resistance genes now open the gate for new possibilities to elucidate the actual allelic variants of these genes via various molecular breeding and transgenic approaches. However, the behavioral pattern of this fungus breakups the resistance barriers in the resistant or tolerant rice varieties. This host-pathogen barrier will be possibly countered in future research by comparative genomics data from available genome sequence data of rice and M. oryzae for durable resistance. Present review emphasized fascinating recent updates, new molecular breeding approaches, transgenic and genomics approaches (i.e. miRNA and genome editing) for the management of blast disease in rice. The updated information will be helpful for the durable, resistance breeding programme in rice against blast pathogen.

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Screening of Rice Cultivars for Morpho-Physiological Responses to Early-Season Soil Moisture Stress Singh Bhupinder, Raja Reddy Kambham, Diaz Redoña Edilberto, Walker Timothy 2017, 24(6): 322-335.  DOI: 10.1016/j.rsci.2017.10.001 Abstract ( )   HTML ( )   PDF (1362KB) ( )   The majority of rice (Oryza sativa L.) produced in the southern USA is drill-seeded and grown under upland-like conditions because permanent flooding is established after the four-leaf stage. Therefore, rice during the seedling growth stage will be subjected to variable soil moisture content. A greenhouse experiment was conducted to evaluate the performance of 15 rice cultivars commonly grown in Mississippi of USA under early-season soil moisture stress. Twenty morpho-physiological parameters of rice seedlings subjected to three different levels (100%, 66% and 33% field capacity) of soil moisture, from 10 to 30 d after sowing, were measured. Significant moisture stress × treatment interaction (P < 0.001) was observed for most of the parameters. Further, the total drought response index (TDRI) was developed to score the cultivars for drought tolerance with the variation from 26.88 to 36.21. Accordingly, the cultivars were classified into different groups of tolerance. The cultivars CL152 and CL142-AR were classified as the least and the most tolerant to drought based on TDRI and standard deviation, respectively. Even though both total root (R2 = 0.98) or shoot (R2 = 0.76) drought responses indices were positively correlated with TDRI, root traits were important in deriving the indices. Therefore, TDRI could be used to select cultivars for drought tolerance in a given environment and develop rice varieties with early-season drought tolerance. However, further research is needed to identify and characterize tolerance at other stages to assist breeding programs in rice.

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Assessment of SNP and InDel Variations Among Rice Lines of Tulaipanji x Ranjit Chandra Roy Subhas, Bhasker Reddy Lachagari Vijaya 2017, 24(6): 336-348.  DOI: 10.1016/j.rsci.2017.01.003 Abstract ( )   HTML ( )   PDF (663KB) ( )   Genotyping by sequencing (GBS) is the recent approach of next-generation sequencing technique for discovering and genotyping single nucleotide polymorphisms (SNPs) in crop species. Genotypic variation studies (SNPs and insertion-deletions/InDels) were performed using four rice lines based on GBS data by aligning to the reference genome Nipponbare. Local aromatic rice landrace Tulaipanji was crossed with Ranjit, and two distinct lines were identified from the progenies: one line with awns and aroma traits and the other without awns and aroma. Total number of SNPs and InDels identified were 52 810 and 4 327 at read depth 10, respectively. Out of the total polymorphic SNPs/InDels, 16 490 were intergeneric, 7 812 were inside gene, and 4 435 were intronic. Phylogenetically, Tulaipanji was closer to the reference genome nipponbare. Based on recurrent parent genome analysis, out of 10 013 alleles, 92.52% was introgressed into progeny-awn from Tulaipanji and 7.48% from Ranjit, whereas progeny-awnless carried 89.19% alleles from Ranjit and only 10.81% alleles from Tulaipanji. In addition, progeny-awn was the highest heterozygous (83.88%) and progeny-awnless was the least (2.24%) at this fifth generation of recombinant inbred lines. These SNP variations may be linked to the phenotypic traits and can be utilized in crop improvement through linkage mapping. These results suggest that adding a high density of SNP markers to a mapping or breeding population through GBS has a great value for numerous applications in rice breeding and genetics research.

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Variation in Antioxidants, Bioactive Compounds and Antioxidant Capacity in Germinated and Ungerminated Grains of Ten Rice Cultivars Kaur Maninder, Asthir Bavita, Mahajan Gulshan 2017, 24(6): 349-359.  DOI: 10.1016/j.rsci.2017.08.002 Abstract ( )   HTML ( )   PDF (655KB) ( )   Present study was conducted to characterise ten rice (Oryza sativa L.) cultivars viz. IET-23466, Dhan-201, IET-23448, MAS-946, IET-23445, IET-23463, IET-23455, PR-123, PR-115 and IET-23449 based on antioxidants (total phenolics, flavonols and tannins), bioactive compounds (phytic acid, gamma amino butyric acid, tocopherol and reduced ascorbate) and antioxidant activity (1,1-diphenyl-2- picrylhydrazyl radical scavenging activity, hydroxyl radical scavenging activity, free radical antioxidant power and total reducing power) with an aim to identify cultivars containing higher health promoting components after germination. Three cultivars IET-23466, IET-23463 and PR-123 performed better as revealed by higher level of antioxidants, bioactive compounds and antioxidant activity before and after germination. Three cultivars MAS-946, IET-23445 and IET-23449 had moderate level of antioxidants, bioactive compounds and antioxidant activity. Four cultivars Dhan-201, IET-23448, IET-23455 and PR-115 performed intermediately. Strong positive correlation was observed among total phenolics and the antioxidant activity. Phytic acid was found to be negatively correlated to the antioxidant activity. Our results highlighted that cultivars IET-23466, IET-23463 and PR-123 hold great potential after germination and would open up a useful opportunity for the functional food industry, and consumption of these cultivars after germination would afford health benefits to consumers since they contain higher level of antioxidants.

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Identification of Rice Accessions Associated with K+/Na+ Ratio and Salt Tolerance Based on Physiological and Molecular Responses Naga Bheema Lingeswara Reddy Inja, Kim Sung-Mi, Kim Beom-Ki, Yoon In-Sun, Kwon Taek-Ryoun 2017, 24(6): 360-364.  DOI: 10.1016/j.rsci.2017.10.002 Abstract ( )   HTML ( )   PDF (529KB) ( )   The key for rice plant survival under NaCl salt stress is maintaining a high K+/Na+ ratio in its cells. Selection for salt tolerance rice genotypes based on phenotypic performance alone will delay in progress in breeding. Use of molecular markers in tandem with physiological studies will help in better identification of salt tolerant rice accessions. Eight rice accessions along with the check Dongjin were screened using 1/2 Yoshida solution with 50 mmol/L NaCl at the seedling stage. The accessions IT001158, IT246674, IT260533 and IT291341 were classified as salt tolerant based on their K+/Na+ ratios. Seventeen SSR markers reported to be associated with K+/Na+ ratio were used to screen the accessions. Five SSR markers (RM8053, RM345, RM318, RM253 and RM7075) could differentiate accessions classified based on their K+/Na+ ratios. Banding pattern of the accessions was scored compared to the banding pattern of Dongjin. The study differentiated accessions based on their association of K+/Na+ ratio with molecular markers which are very reliable. These markers can play a significant role in screening large set of rice germplasms for salt tolerance and also help in identification of high-yielding varieties with better salt tolerance. The salt tolerant accessions can be taken forward into developing better varieties by conventional breeding and exploring genes for salt tolerance.