Resistance of DB1 Transgenic Rice Line and others against Nilaparvata lugens, Brown Planthopper

Nilaparvata lugens (Stål), brown planthopper (BPH) is as a major pest of rice crop. Developing rice resistant to BPH is an economically and environmentally friendly approach. A transgenic rice line with DB1 (Dioscorea batatas tuber lectin 1) transgene has been engineered to overcome the problem. The objective of the experiment was to obtain the level of resistance of a DB1 rice line (DB1-inserted cv. Taichung 65) and some rice genotypes against two colonies of BPH. Resistance study was performed in BPH’s preference, honeydew excretion, crop damage, and population development. The resistant test was carried out using two biotypes BPH i.e., biotype 2 (Sukamandi) and biotype 3 (North Sumatera). The result showed that DB1 transgenic rice was moderately resistant to biotype 2, while to be susceptible when invested to biotype 3, indicating that the DB1 gene increases the resistance level, from susceptible to moderately resistant. All tested genotypes were chosen by biotype 2 for laying eggs, while for biotype 3 preferred five genotypes (DB1 transgenic line, PTB-33, Babawee, IR-64 dan IR-42). Genotype significantly differed on number of BPH and was considerably lower on PTB-33 than the others. Honeydew excretion of genotypes showed equal on biotype 2 and 3, except on biotype 3 of IR 42 (susceptible to BPH) which showing high amount of feces. PTB 33 had lower BPH population as compared to others, indicating high resistance to BPH of biotype 2 and 3 from Indonesia. © 2021 Friends Science Publishers

Morpho-Physiology and Antioxidant Enzyme Activities of Transgenic Rice Plant Overexpressing ABP57 under Reproductive Stage Drought Condition

MR219 transgenic rice line which overexpressed an auxin-binding protein (ABP57) and its wild-type cultivar, MR219, were screened under well-watered (WW) and drought stress (DS) conditions at the early reproductive stage. This study was conducted with the standard planting distance and under a normal environment to assess the yield advantages based on the field conditions. The aim of this study was to understand the response of these rice genotypes towards DS at morpho-physiological, biochemical, and agronomical levels. It was found that the DS had affected all these levels of the genotypes studied; however, the transgenic plant showed a higher number of tillers, flag leaf area, biomass, relative water content, total chlorophyll content, and antioxidative defense mechanism than the MR219 under DS. Compared to its wild-type, the transgenic plant showed an increased leaf photosynthetic rate by 7% under WW and 11% under DS. The transgenic plant also showed higher yields than MR219 under the WW (10%) and DS (59%). The results propose that drought tolerance is significantly improved in the MR219 transgenic rice line. It may develop a new opportunity for the drought-tolerant rice breeding programme via overexpression of ABP57.

Seed Plumpness of Rice with Inhibition Expression of Starch Branching Enzymes and Starch Properties, Grain Position on Panicle

Cereal crops with inhibition expression of starch branching enzyme (SBE) contain highly resistant starch in the endosperm, and have potential health benefits for human. However, seed plumpness is significantly different, with different inhibition effects of SBE expression, resulting in differently shrunken seeds. In this study, a transgenic resistant starch rice line, which has highly resistant starch and is developed through inhibition expression of SBEs, had non-, slightly, and moderately shrunken seeds with plumpness from high to low. The differently shrunken seeds had significantly different seed weight and starch content. Different morphological starch granules were detected in the endosperm and had similar spatial distribution pattern among the non-, slightly, and moderately shrunken seeds. Starches from differently shrunken seeds had similar amylose content and amylopectin structure. The protein amount of amylose/amylopectin synthesis key enzymes in endosperm was no different between differently shrunken seeds. The primary branch of the panicle had a higher percentage of non-shrunken seeds than did the secondary branch at the same part of the panicle. From the upper part to the base of the panicle, non-shrunken seeds gradually decreased but slightly and moderately shrunken seeds gradually increased. The above results indicated that the differently shrunken seeds in transgenic rice line had the same SBE dosage, and the starch morphology and structure had no relationship with seed plumpness. The grain position on the panicle influenced seed plumpness, but had no effect on starch properties.