Evaluation and screening of low phosphorus stress tolerance of common bean (Phaseolus vulgaris L.)

A field experiment was carried out to screen low phosphorus tolerance indexes in common bean. Analysis and comparison of the coefficient of variation of the relative values of phosphorus efficiency-related indexes in 30 common bean varieties subjected to different phosphorus treatments were identified. Plant dry matter weight, phosphorus accumulation, and acid phosphatase activity are important indexes for determining low-phosphorus tolerance. A comprehensive evaluation system for low-phosphorus tolerance in common bean was established using the fuzzy membership function method. Varieties with a composite index ≥ 0.49 were identified as low phosphorus tolerant varieties, including “Longyun 13,” “Longyun 6,” and “Long17- 3525,” while varieties with a composite index ≤ 0.27 were identified as varieties sensitive to low phosphorus, including “Long12-2752,” “NR,” and “Long15-1554.” Bangladesh J. Bot. 50(3): 903-909, 2021 (September) Special

High-Throughput Root Network System Analysis for Low Phosphorus Tolerance in Maize at Seedling Stage

The root system is the important organ of a plant, helping to anchor the plant and take up nutrients from the soil. The purpose of this investigation was to determine the magnitude of the root network system (RNS) through phenotypic variability in a broad range of maize inbred lines. The GiA Root software was used to identify root attributes from images. After germination, the inbred lines were grown hydroponically for 15 days in a high-lux plant growth room with low phosphorus (LP) and normal phosphorus (NP) treatments. Variance analysis revealed a large range of variability present among the inbred lines, with intermediate to high heritabilities ranging from 0.59 to 0.95 for all RNS traits, demonstrating uniformity through the experiments. The proportions of genetic variance ranged from 0.01–0.60 in different maize RNS traits. A strong positive linear relationship between best linear unbiased predictors (BLUPs) with estimated means was found for all the RNS traits. The Euclidean genetic distances between the studied inbred lines ranged from 0.61 to 29.33, showing a higher amount of diversity. More than 79% of the overall genetic variation was explained by the first three principal components, with high loadings from the measurements of network length (NWL), network surface area (NWSA), network perimeter (NWP), network area (NWA), the maximum number of roots (MANR), median number of roots (MENR), network volume (NWV), network convex area (NWCA), specific root length (SRL), network depth (NWD), number of connected components (NCC), and network width (NWW). The biplot of genotype by trait interaction exposed superior genotypes with a relatively high expression of favorable trait combinations. Some outstanding genotypes with higher values of most RNS traits were identified through MGIDI analysis. These lines may be convenient for enhancing LP tolerance in maize.

Genome-Wide Analysis of Purple Acid Phosphatase Genes in Brassica rapa and Their Association with Pollen Development and Phosphorus Deprivation Stress

PAPs (purple acid phosphatases) belong to the metallo-phosphoesterase superfamily and play important roles in developmental processes, phosphorus foraging, and recycling. However, the specific functions of BrPAPs in Brassica rapa are poorly understood. In this study, 39 BrPAPs were identified and divided into three major clades and nine subgroups. In 8 of the 39 BrPAPs, some invariant amino acid residues were lost or shifted. Based on an expression profiling analysis, BrPAP11, 14, 20, 24, 29, and 34 were specifically expressed in fertile floral buds, indicating their critical roles during pollen development. A total of 21 BrPAPs responded to Pi deprivation in either shoots or roots. Of these, BrPAP4, 5, 19, and 21 were upregulated in roots under Pi depravation conditions, while BrPAP12 was upregulated in the roots in normal conditions. BrPAP28 was upregulated in shoots under Pi depravation conditions, indicating its function shifted compared with its Arabidopsis homolog, AtPAP26. The present work contributes to further investigation of BrPAPs as candidate genes for genetic improvement studies of low phosphorus tolerance as well as for creating male sterile lines based on gene editing methods in Brassica rapa.

Genetic diversity for drought and low-phosphorus tolerance in rice (Oryza sativa L.) varieties and donors adapted to rainfed drought-prone ecologies

Drought and phosphate availability are two major abiotic factors limiting productivity of rice in rainfed upland areas. There has been a constant need for new improved donor with tolerance to multiple abiotic stress conditions for rainfed rice breeding. In the present study, a set of 32 popular rice varieties and landraces were evaluated for drought and low-phosphorus (P) tolerance, and also characterized using grain yield under reproductive drought QTLs (DTY QTLs) and Pup1 linked/specific molecular markers. Twenty-seven genotypes were identified as tolerant to moderately tolerant to drought. The SSR markers linked to ten DTY QTLs classified the genotypes into two groups corresponding to aus and indica. The tolerant genotypes were distributed under both groups. Based on the core markers of Pup1 locus, complete tolerant haplotype was recorded in nine genotypes other than the tolerant check Dular. Nine more genotypes showed the incomplete tolerant haplotypes. The rice genotypes showed significantly high genetic variability for low-P tolerance in hydroponic study. A few genotypes revealed non-Pup1 type tolerance which needs further confirmation.