What is the Molecular Basis of Aroma in Biriyanicheera - A Tropical Aromatic Rice Genotype

The aromatic rice cultivars possess excellent aroma generally when grown in their favourable and specific environments. An early maturing selection from a Kerala aromatic local landrace with short grains, named ‘Biriyanicheera’, when grown in normal tropical conditions was sufficiently fragrant. The present study focused on the analysis of aroma in ‘Biriyanicheera’ rice genotype through molecular methods. The seeds of two aromatic rice varieties viz., Biriyanicheera and Gandhakasala (from Palakkad, Thrissur and Ernakulam districts) along with one non-aromatic rice variety Triveni (control) were used for the study. The BADH2 gene was amplified in all the three rice varieties. Upon sequencing the amplified PCR products of genomic DNA, the mutation in BADH2 gene was detected. The sequencing results of aromatic varieties revealed the presence of 8 base pair mutation in exon 7 in Biriyanicheera and Gandhakasala, whereas this mutation was absent in the non-aromatic variety Triveni. This indicated that aroma production in Biriyanicheera variety is due to similar mutation in BADH2 gene as that of the popular scented rice Basmati.

Alteration in expression level of some growth and stress-related genes after rhizobacteria inoculation to alleviate drought tolerance in sensitive rice genotype

Background Drought stress is one of the major abiotic stresses that adversely affect rice production. Four rice genotypes, Giza177, IR64 (as sensitive genotypes) and Vandana, Orabi3 (as tolerant genotypes) were used to screen and characterize the soil microbes associated with each genotype under drought stress. Results The soil microbes associated with the tolerant genotypes showed high drought tolerance and high levels of enzyme activity. The most drought-tolerant isolates were inoculated with the sensitive genotype Giza177 under drought conditions. Some morphological, biochemical and molecular responses of inoculated plants were estimated. Inoculated plants showed regulation of some growth and stress-related genes (COX1, AP2-EREBP, GRAM, NRAMP6, NAM, GST, DHN and three genes of expansin (EXP1, EXP2 and EXP3) under drought conditions. Expression profiling of these genes were highly induced in plants inoculated with 4E11 and were correlated with improved growth status under drought stress. Conclusion Based on this, drought-tolerant plant growth-promoting rhizobacteria (PGPRs) were associated with the drought-tolerant genotype (Orabi 3). They were related to the significant increase in soil enzymes activities (dehydrogenase, nitrogenase, urease and alkaline phosphatase) in the rhizosphere of tolerant genotype. Inoculation the drought-sensitive genotype (Giza 177) with the most drought-tolerant isolates improved the tolerance status of the sensitive rice genotype and induced the expression of some growth and stress-responsive genes. AP2-EREBP, NRAMP6, DHN and all expansin genes (EXP1, EXP2 and EXP3) were the highly induced genes in inoculated plants with 4E11 strain and the consortium of three selected strains under drought condition. Graphic abstract

Evaluation of rice genotypes for growth, yield and yield components

Twelve rice genotypes were evaluated under irrigated lowland and upland rainfed conditions in a randomized complete block design with three replications at Khumaltar, Lalitpur, Nepal in 2019. Data on plant height, panicle length, effective tillers per plant, fertile grain number per panicle and grain yield were taken. The variation was observed for plant height, panicle length, effective tillers per plant, fertile grain number per panicle among the evaluated rice genotypes. The rice genotype NR 11375-B-B-21 produced the highest grain yield (3974.75 kg/ha) followed by NR 11374-B-B-23 (3615.26 kg/ha) and NR 11145-B-B-B-6 (3597.56 kg/ha) under irrigated low land condition. Similarly, the rice genotypes, NR 11375-B-B-21 produced the highest grain yield (3837.15 kg/ha) followed by NR 11321-B-B-7-3 (3588.71 kg/ha) and NR 11305-B-B-1-3 (3292.36 kg/ha) under upland rainfed condition. The combined analysis showed that rice genotype NR 11375-B-B-21 produced the highest grain yield (3905.95 kg/ha) followed by NR 11374-B-B-23 (3494.63 kg/ha), and NR 11321-B-B-7-3 (3409.89 kg/ha) respectively. Thus, after evaluation of yield, two genotypes namely NR 11375-B-B-21, NR 11374-B-B-23, were selected as outstanding genotypes, which can be used as potential breeding materials for upland and low land environments of mid hills of Nepal.

EVALUATION OF RICE GENOTYPE AGAINST LEAF FOLDER, CASE WORM AND GRASSHOPPER DESECRATION UNDER FIELD CONDITION

The research on varietal screening of rice against leaf folder, caseworm and grasshopper damage was conducted during 2019 in Rampur, Chitwan to study the host plant resistant of different varieties of rice under field condition. The experiment was laid out in RCBD with three replications and seven treatments namely i) Makawanpur -1 ii) Mansuli iii) Radha-4 iv) Ramdhan v) Sabitri vi) Sama Mansuli sub-1 and vii) sukkha-3. The experiment revealed that lowest population of leaf folder, caseworm and grasshopper was recorded in variety Radha-4 followed by Ramdhan. The experiment showed the yield loss was significantly lower in Radha-4 followed by Sabitri and Ramdhan due to leaf folder, caseworm and grasshopper. So Radha-4 and sabitri would be good option in rice production for reducing insect pest damage.