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

The contribution of animal breeding to reducing the environmental impact of livestock production

Animal production is responsible for 14.5% of total anthropogenic greenhouse gas (GHG) emissions. Approximately half of these emissions originate directly from animal production, whereas the other half comes from feed production. Animal breeding aims at improving animal production and efficient use of resources, which results in a reduction of environmental impact. In this chapter we quantify the contribution of animal breeding to reducing the environmental impact of the four major livestock species in the Netherlands, namely laying hens, broilers and pigs (all monogastrics), and dairy cattle (ruminants). For eggs, and broiler and pig meat we focussed on GHG emissions and nitrogen and phosphorus efficiency, whereas for dairy we focussed on enteric methane emissions, an important contributor to GHG emissions. Results showed that current selection strategies on increased (feed) efficiency indirectly reduces environmental impact per unit of animal product by about 1% per year. If the aim is to directly select on environmental traits, recording of new traits is required; e.g., nitrogen and phosphorus contents of meat and eggs, and methane emission of individual dairy cows.

Evaluating Heritability and Relationships among Phosphorus Efficiency Traits in Maize under Low P Soils of Western Kenya

Low available phosphorus (P) remains a major limitation to maize (Zea mays L.) productivity across the world. Selection for P efficiency is key as part of strategies to achieving agricultural sustainability. The objectives of this study were to: (i) determine the phenotypic and genetic relationships among P-efficiency traits in maize under low P soils and (ii) determine the heritability of some of these traits under similar conditions. A total of 32 experimental maize hybrids were evaluated for tolerance to low P in a replicated trial at four locations for one season. The experiment was laid out in a split plot arrangement in RCBD replicated 3 times across two P levels (36 kgP/ha and 6 KgP/ha). Grain yield had the highest correlation (r= 0.44-0.95) with most P- efficiency traits at both P conditions. It also exhibited high positive and significant correlations with plant height (rg = 0.72**) ear height (rg = 0.54*), cob Length (rg =0.81**) and stover yield (rg = 0.61**) while it was negatively correlated with days to anthesis and silking. The correlation between grain and shoot P concentration and grain P content with majority of the P efficiency indices (P acquisition &Utilization efficiencies &P efficiency) at both P levels was low & tended to be negative and non-significant indicating that seed P reserve, and stover P concentration, had minimal contribution to differential P efficiency. However, the relationship between shoot P content with P-efficiency traits was significant (r= 0.51-0.95), suggesting that shoot P content is a useful parameter in selecting for P efficiency in maize. Moderate to high heritability (0.50-0.95) was observed for the various traits showing that a large proportion of the observed variations were due to genetic differences among the hybrids. This study has determined genetic and phenotypic associations among P selection parameters that can help in flexing the selection methodologies to suite unique circumstances and environments.

Population structure and genome-wide association studies in bread wheat for phosphorus efficiency traits using 35 K Wheat Breeder’s Affymetrix array

Soil bioavailability of phosphorus (P) is a major concern for crop productivity worldwide. As phosphatic fertilizers are a non-renewable resource associated with economic and environmental issues so, the sustainable option is to develop P use efficient crop varieties. We phenotyped 82 diverse wheat (Triticum aestivum L.) accessions in soil and hydroponics at low and sufficient P. To identify the genic regions for P efficiency traits, the accessions were genotyped using the 35 K-SNP array and genome-wide association study (GWAS) was performed. The high-quality SNPs across the genomes were evenly distributed with polymorphic information content values varying between 0.090 and 0.375. Structure analysis revealed three subpopulations (C1, C2, C3) and the phenotypic responses of these subpopulations were assessed for P efficiency traits. The C2 subpopulation showed the highest genetic variance and heritability values for numerous agronomically important traits as well as strong correlation under both P levels in soil and hydroponics. GWAS revealed 78 marker-trait associations (MTAs) but only 35 MTAs passed Bonferroni Correction. A total of 297 candidate genes were identified for these MTAs and their annotation suggested their involvement in several biological process. Out of 35, nine (9) MTAs were controlling polygenic trait (two controlling four traits, one controlling three traits and six controlling two traits). These multi-trait MTAs (each controlling two or more than two correlated traits) could be utilized for improving bread wheat to tolerate low P stress through marker-assisted selection (MAS).

Identification of loci and candidate gene GmSPX-RING1 responsible for phosphorus efficiency in soybean via genome-wide association analysis

Background Phosphorus (P) is an essential element in maintaining high biomass and yield in crops. Soybean [Glycine max (L.) Merr.] requires a large amount of P during growth and development. Improvement of P efficiency and identification of P efficiency genes are important strategies for increasing soybean yield. Results Genome-wide association analysis (GWAS) with NJAU 355 K SoySNP array was performed to identify single nucleotide polymorphisms (SNPs) significantly associated with three shoot P efficiency-related traits of a natural population of 211 cultivated soybeans and relative values of these traits under normal P (+P) condition and P deficiency (−P) condition. A total of 155 SNPs were identified significantly associated with P efficiency-related traits. SNPs that were significantly associated with shoot dry weight formed a SNP cluster on chromosome 11, while SNPs that were significantly associated with shoot P concentration formed a SNP cluster on chromosome 10. Thirteen haplotypes were identified based on 12 SNPs, and Hap9 was considered as the optimal haplotype. Four SNPs (AX-93636685, AX-93636692, AX-93932863, and AX-93932874) located on chromosome 10 were identified to be significantly associated with shoot P concentration under +P condition in two hydroponic experiments. Among these four SNPs, two of them (AX-93636685 and AX-93932874) were also significantly associated with the relative values of shoot P concentration under two P conditions. One SNP AX-93932874 was detected within 5′-untranslated region of Glyma.10 g018800, which contained SPX and RING domains and was named as GmSPX-RING1. Furthermore, the function research of GmSPX-RING1 was carried out in soybean hairy root transformation. Compared with their respective controls, P concentration in GmSPX-RING1 overexpressing transgenic hairy roots was significantly reduced by 32.75% under +P condition; In contrast, P concentration in RNA interference of GmSPX-RING1 transgenic hairy roots was increased by 38.90 and 14.51% under +P and -P conditions, respectively. Conclusions This study shows that the candidate gene GmSPX-RING1 affects soybean phosphorus efficiency by negatively regulating soybean phosphorus concentration in soybean hairy roots. The SNPs and candidate genes identified should be potential for improvement of P efficiency in future soybean breeding programs.