Molecular profiling of BADH2 locus reveals distinct functional allelic polymorphism associated with fragrance variation in Indian aromatic rice germplasm.

Allelic variability of the aroma gene, betaine aldehyde dehydrogenase 2 (BADH2) was studied in a random subset of indigenous aromatic rice germplasm along with a few exotic aromatic accessions. Use of functional markers of four badh2 alleles identified that the test panel possessed only two alleles, badh2-E7 and badh2-p-5'UTR. Two other alleles, badh2.2 and badh2-E4-5.2 were absent. Based on the alleles present, four functional polymorphisms (FP) were detected, namely FP1 to FP4. 188 genotypes possessed FP1 having both the badh2-p-5'UTR and badh2-E7 (71.8%) alleles. The badh2 allele with FP1 is named badh2-E7-p. 39 genotypes (14.9%) possessed only the badh2-p-5'UTR allele (FP3), while three genotypes were found to carry only the badh2-E7 allele (FP2). We also found that 32 genotypes (12.2%) did not have any of the target aroma alleles tested in this study (FP4). Interestingly, for badh2-p-5'UTR marker, the expected 198 bp amplicon for the non-aromatic allele could not be detected among any of the genotypes tested. Instead, an amplicon of 456 bp length appeared with 100% presence in the non-aromatic checks. Notwithstanding, the 456 bp allele also showed a 16% presence among the aromatic lines. This article forms the first report of this allele, named badh2-p1, among aromatic rice. Quantification of 2-Acetyl-1-Pyrroline (2AP) content and sensory evaluation among the test genotypes showed that those with FP1 are highly aromatic than the genotypes carrying other types of FPs. But, a few strongly aromatic lines showed lower 2AP content. The BADH2 characterization carried out in this study is suggestive of identifying the additional gene(s)/ allele(s) governing aroma among the Indian fragrant rice. Supplementary Information: The online version contains supplementary material available at 10.1007/s12298-022-01181-9.

A novel LOX3-null allele (lox3-b) originated in the aromatic Basmati rice cultivars imparts storage stability to rice bran.

Rapid deterioration of rice bran due to the LOX3 enzyme catalysed oxidation of PUFA is the major bottleneck for its utilization in various downstream applications. In the present study, we have identified a set of nine novel LOX3-null rice accessions carrying a deletion of C residue in the exon2 causing a frameshift mutation resulting in a truncated non-functional LOX3 protein. Our study, further manifested the predominance of C deletion based LOX3-null allele, named lox3-b, in the aromatic rice germplasm particularly in the Indian Basmati rice group. The LOX3-null genotypes exhibited significantly reduced rancidity, after six months of storage. They also showed significantly lower percentage reduction of linoleic acid (LA), higher γ-oryzanol content and lower hexanal content. A functional dCAPS marker designed based on the deletion polymorphism clearly differentiated LOX3 and lox3-b alleles, and has the potential application in marker assisted rice breeding programmes to develop cultivars with better bran storability.

Genome-Wide Association Mapping Reveals Novel Putative Gene Candidates Governing Reproductive Stage Heat Stress Tolerance in Rice.

Temperature rise predicted for the future will severely affect rice productivity because the crop is highly sensitive to heat stress at the reproductive stage. Breeding tolerant varieties is an economically viable option to combat heat stress, for which the knowledge of target genomic regions associated with the reproductive stage heat stress tolerance (RSHT) is essential. A set of 192 rice genotypes of diverse origins were evaluated under natural field conditions through staggered sowings for RSHT using two surrogate traits, spikelet fertility and grain yield, which showed significant reduction under heat stress. These genotypes were genotyped using a 50 k SNP array, and the association analysis identified 10 quantitative trait nucleotides (QTNs) for grain yield, of which one QTN (qHTGY8.1) was consistent across the different models used. Only two out of 10 MTAs coincided with the previously reported QTLs, making the remaing eight novel. A total of 22 QTNs were observed for spikelet fertility, among which qHTSF5.1 was consistently found across three models. Of the QTNs identified, seven coincided with previous reports, while the remaining QTNs were new. The genes near the QTNs were found associated with the protein-protein interaction, protein ubiquitination, stress signal transduction, and so forth, qualifying them to be putative for RSHT. An in silico expression analysis revealed the predominant expression of genes identified for spikelet fertility in reproductive organs. Further validation of the biological relevance of QTNs in conferring heat stress tolerance will enable their utilization in improving the reproductive stage heat stress tolerance in rice.

Molecular mapping of QTLs for grain dimension traits in Basmati rice.

Basmati rice is known for its extra-long slender grains, exceptional kernel dimensions after cooking, high volume expansion, and strong aroma. Developing high yielding Basmati rice varieties with good cooking quality is a gigantic task. Therefore, identifying the genomic regions governing the grain and cooked kernel dimension traits is of utmost importance for its use in marker-assisted breeding. Although several QTLs governing grain dimension traits have been reported, limited attempts have been made to map QTLs for grain and cooked kernel dimension traits of Basmati rice. In the current study, a population of recombinant inbred lines (RIL) was generated from a cross of Sonasal and Pusa Basmati 1121 (PB1121). In the RIL population, there was a significant positive correlation among the length (RRL: rough rice length, MRL: milled rice length, CKL: cooked kernel length) and breadth (RRB: rough rice breadth, MRB: milled rice breadth and CKB: cooked kernel breadth) of the related traits, while there was significant negative correlation between them. QTL mapping has led to the identification of four major genomic regions governing MRL and CKL. Two QTLs co-localize with the earlier reported major gene GS3 and a QTL qGRL7.1, while the remaining two QTLs viz., qCKL3.2 (qMRL3.2) and qCKL4.1 (qMRL4.1) were novel. The QTL qCKL3.2 has been bracketed to a genomic region of 0.78 Mb between the markers RM15247 and RM15281. Annotation of this region identified 18 gene models, of which the genes predicted to encode pentatricopeptides and brassinosteroid insensitive 1-associated receptor kinase 1 precursor may be the putative candidate genes. Furthermore, we identified a novel QTL qKER2.1 governing kernel elongation ratio (KER) in Basmati rice.

Kinetics of ß-carotene degradation under different storage conditions in transgenic Golden Rice® lines.

The effect of vacuum packing and ambient storage conditions on the stability of the ß-carotene in the transgenic Golden Rice® lines was studied. The ß-carotene was quantified using RP-HPLC at bimonthly intervals for a period of six months. The ß-carotene concentration in the genotypes analyzed ranged from 7.13 to 22.81 µg/g of endosperm. The transgene being the same in all the genotypes, variation in the ß-carotene concentration reflects on the genetic background of the rice variety and the transgene position that governed the differential accumulation of ß-carotene. It was observed that in the absence of light, oxidative degradation is higher followed by thermal degradation. Weibull model with higher R2 best explained the degradation kinetics of ß-carotene in Golden Rice® lines across all the storage conditions. The knowledge generated through this study can be utilized in devising an effective delivery system for Golden Rice® to the consumer.

Indoleacetic acid production by Rhizobium sp. from a leguminous tree, Erythrina indica.

Rhizobium sp. isolated from the root nodules of Erythrina indica Lamk., a leguminous tree, produced large amounts of indoleacetic acid (IAA) from tryptophan. L-Tryptophan (2 mg/ mL) was preferred to DL-tryptophan for IAA synthesis. Attempts were made to optimize the cultural requirements for an accelerated IAA production. An enrichment of the carbon-free incubation medium with maltose (1 %), MnSO4 x H2O (5 microg/mL), and Triton X-100 (100 ppm) promoted the synthesized IAA content of the medium by 480 %.

Resurgence of malaria in Calcutta in 1995: a hospital based study.

A total of 405 cases of fever who were either admitted to the Hospital or attended in paediatric out patient Department or Emergency of Medical College Hospital, Calcutta between January '95 and November '95 were included in the study. Majority of cases presented with usual features of malaria like fever with chill and rigor, hepatosplenomegaly, pallor. Apart from these, complicated manifestations like shock, convulsion D.I.C and jaundice were also observed. Some unusual presentations with severe diarrhoea, dehydration and features like that of acute viral respiratory tract infection were highly confusing in terms of clinical diagnosis. P. falciparum was observed in 35.5% of cases. Overall therapeutic response to chloroquin was good, However, two patients died of cerebral Malaria. Five cases of severe malaria were caused by P. vivax however, other etiological features could not be found to attribute the severe nature of these illnesses.