Genetic Dissection of Phosphorous Uptake and Utilization Efficiency Traits Using GWAS in Mungbean

Mungbean (Vignaradiata L. Wilczek) is an early maturing legume grown predominantly in Asia for its protein-rich seeds. P deficiency can lead to several physiological disorders which ultimately result in a low grain yield in mungbean. The genetic dissection of PUpE (Puptake efficiency) and PUtE (P utilization efficiency) traits are essential for breeding mungbean varieties with a high P uptake and utilization efficiency. The study involves an association mapping panel consisting of 120 mungbean genotypes which were phenotyped for total dry weight, P concentration, total P uptake, and P utilization efficiency under low P (LP) and normal P (NP) conditions in a hydroponic system. A genotyping-by-sequencing (GBS) based genome-wide association study (GWAS) approach was employed to dissect the complexity of PUpE and PUtE traits at the genetic level in mungbean. This has identified 116 SNPs in 61 protein-coding genes and of these, 16 have been found to enhance phosphorous uptake and utilization efficiency in mungbeans. We identified six genes with a high expression (VRADI01G04370, VRADI05G20860, VRADI06G12490, VRADI08G20910, VRADI08G00070 and VRADI09G09030) in root, shoot apical meristem and leaf, indicating their role in the regulation of P uptake and utilization efficiency in mungbean. The SNPs present in three genes have also been validated using a Sanger sequencing approach.

Identification of genetic factors controlling phosphorus utilization efficiency in wheat by genome-wide association study with principal component analysis

ABSTRACTDespite the economic importance of P utilization efficiency, information on genetic factors underlying this trait remains elusive. To address that, we performed a genome-wide association study in a spring wheat diversity panel ranging from landraces to elite varieties. We evaluated the phenotype variation for P utilization efficiency in controlled conditions and genotype variation using wheat 90K SNP array. Phenotype variables were transformed into a smaller set of uncorrelated principal components that captured the most important variation data. We identified two significant loci associated with both P utilization efficiency and the 1st principal component on chromosomes 3A and 4A: qPE1-3A and qPE2-4A. Annotation of genes at these loci revealed 53 wheat genes, among which 6 were identified in significantly enriched pathways. The expression pattern of these 6 genes indicated that TraesCS4A02G481800, involved in pyruvate metabolism and TCA cycle, had a significantly higher expression in the P efficient variety under limited P conditions. Further characterization of these loci and candidate genes can help stimulate P utilization efficiency in wheat.KEY MESSAGEWe report two new loci for P utilization efficiency on chromosomes 3A and 4A of wheat. The prioritized candidate genes at these loci can be investigated by molecular biology techniques to improve P efficiency in wheat and grass relatives.

Detection of QTL for phosphorus efficiency and biomass traits at the seedling stage in wheat

Phosphorus (P) is one of the most vital nutrient elements in crop output and quality formation. In this study, four biomass, four P uptake efficiency (PupE), and three P-utilization efficiency (PutE) traits were investigated using a set of recombinant inbred lines (RILs) derived from a cross of “SN0431 × LM21”, under hydroponic culture trials at low P (LP) and normal P (NP) levels in two different seasons, respectively. A total of 85 QTL were identified on 18 chromosomes except for 1D, 2A, and 3D. Among them, 36 and 42 QTL were detected under LP and NP, respectively, and seven QTL were simultaneously detected under LP and NP. Seventeen relatively high-frequency QTL (RHF-QTL) were detected. The average contributions of 13 major RHF-QTL were over 10.00%. Five important QTL clusters were detected on chromosomes 4D, 5A, and 5B. Among them, positive linkages were observed between PutE and biomass traits at four QTL clusters, C1, C2, C3, and C6, showing these loci may be hot spots for genetic control of both phosphorus utilization and biomass accumulation in wheat seedlings. In addition, correlation analysis indicated that three biomass traits (SDW, RDW, and TDW) should be used as primary selection indexes for PE at the seedling stage.

Strategic timing and rate of phosphorus fertilization improves phosphorus-use efficiency in two contrasting cultivars of subirrigated greenhouse-grown chrysanthemum

Greenhouse floriculture operations pose significant environmental risk due to extensive inputs of fertilizer, especially nitrogen and phosphorus (P). Recent evidence shows that the use efficiency for nitrogen or sulphur is markedly improved in subirrigated potted chrysanthemums (Chrysanthemum morifolium Ramat.) by supplying a moderate level of the nutrient during vegetative growth, and removing the entire nutrient suite at the onset of reproductive growth, without adverse effects on plant quality. Here, two split-plot experiments were conducted with subirrigated, potted, disbudded chrysanthemums grown in a peat:perlite mixture under greenhouse conditions (high- or low-ambient light) with inorganic orthophosphate (Pi) treatment (2.6 mmol L−1 Pi supplied during the vegetative and reproductive stages, and 2.6, 1.95, or 1.3 mmol L−1 Pi supplied during the vegetative stage only) as the main plot and cultivar (‘Olympia’ and ‘Covington’) as the subplot. Market quality plants with sufficient tissue P were produced even when Pi delivery was reduced by approximately 75% over the crop cycle, compared with industry standards. The primary mechanism for sustaining plant growth with decreasing Pi delivery was improved acquisition or uptake efficiency, although some changes in internal P-utilization efficiency were evident, including the remobilization of both organic P and Pi during inflorescence development. Differences in biomass yields, tissue P concentrations, content-based P-use efficiency (PUEC = mg shoot dry mass/mg shoot P content) with constant Pi acquisition, and uptake- versus remobilization-based P supply for inflorescence growth established that ‘Olympia’ has a greater P-utilization efficiency than ‘Covington’. This modified subirrigation practice could contribute significantly to low-input production of floricultural crops.

Mineralization of soluble P fertilizers and insoluble rock phosphate in response to phosphate-solubilizing bacteria and poultry manure and their effect on the growth and P utilization efficiency of chilli (<i>Capsicum annuum</i> L.)

The ability of soil microorganisms and organic manure to convert insoluble phosphorus (P) to an accessible form offers a biological rescue system for improving P utilization efficiency in soil–plant systems. Our objective was to examine the P mineralization potential of two soluble P fertilizers (SPF), i.e., single superphosphate (SSP) and diammonium phosphate (DAP), and of insoluble rock phosphate (RP) with and without phosphate-solubilizing bacteria (PSB) and poultry manure (PM) and their subsequent effect on the growth, yield and P utilization efficiency (PUE) of chilli (Capsicum annuum L.). An incubation study was carried out on a loam (slightly alkaline) soil with 12 treatments: T0 – control; T1 – RP; T2 – SSP; T3 – DAP; T4 – PM; T5 – 1/2 RP+1/2 SSP; T6 – 1/2 RP+1/2 DAP; T7 – 1/2 RP+1/2 PM; T8 – RP+PSB; T9 – 1/2 RP+1/2 SSP+PSB; T10 – 1/2 RP+1/2 DAP+PSB; and T11 – 1/2 RP+1/2 PM+PSB. Phosphorus mineralization was measured by analyzing extractable P from the amended soil incubated under controlled conditions at 25 °C for periods of 0, 5, 15, 25, 35 and 60 days. A complementary greenhouse experiment was conducted in pots with chilli (Capsicum annuum L.) as a test crop. Growth, yield, P uptake and PUE of the chilli was determined during the study. Results indicated that P mineralization in soil amended with RP was 6.0–11.5 mg kg−1, while both soluble P fertilizers resulted in 68–73 mg P kg−1 at day 0, which decreased by 79–82 % at the end of incubation. The integrated use of PSB and PM with RP in T11 stimulated P mineralization by releasing a maximum of 25 mg P kg−1 that was maintained at high levels without any loss. Use of PSB decreased soil pH. In the greenhouse experiment, RP alone or RP+PSB did not have a significant impact on plant growth. However, the combined use of RP, PM and PSB in T11 resulted in similar growth, yield and P uptake of chilli as DAP. The PUE of applied P varied from 4 to 29 % and was higher in the treatments that included PSB. We conclude that the use of PSB and PM with insoluble RP or with soluble P fertilizers could be a promising approach to enhance P availability from both low-grade RP and SPF for crop production in intensive cropping systems.