Genetic variation in pea (Pisum sativum L.) demonstrates the importance of root but not shoot C/N ratios in the control of plant morphology and reveals a unique relationship between shoot length and nodulation intensity

Abstract

Nodule numbers are regulated through systemic autoregulatory signals produced by shoots and roots. The relative effects of shoot and root genotype on nodule numbers together with relationships to organ biomass, carbon (C) and nitrogen (N) status, and related parameters were measured in pea (Pisum sativum) exploiting natural genetic variation in maturity and apparent nodulation intensity. Reciprocal grafting experiments between the early (Athos), intermediate (Phönix) and late (S00182) maturity phenotypes were performed and Pearson's correlation coefficients for the parameters were calculated. No significant correlations were found between shoot C/N ratios and plant morphology parameters, but the root C/N ratio showed a strong correlation with root fresh and dry weights as well as with shoot fresh weight with less significant interactions with leaf number. Hence, the root C/N ratio rather than shoot C/N had a predominant influence on plant morphology when pea plants are grown under conditions of symbiotic nitrogen supply. The only phenotypic characteristic that showed a statistically significant correlation with nodulation intensity was shoot length, which accounted for 68.5% of the variation. A strong linear relationship was demonstrated between shoot length and nodule numbers. Hence, pea nodule numbers are controlled by factors related to shoot extension, but not by shoot or root biomass accumulation, total C or total N. The relationship between shoot length and nodule numbers persisted under field conditions. These results suggest that stem height could be used as a breeding marker for the selection of pea cultivars with high nodule numbers and high seed N contents.

Genome‐Wide Association Analysis of Diverse Soybean Genotypes Reveals Novel Markers for Nitrogen Traits

“…The genetic variability in Ndfa, [N], and C/N ratio in soybean is not well defined (Ludidi et al, 2007; Yoneyama et al, 2000); however we were able to identify multiple genomic loci likely associated with each trait (Table 5; Fig. 7).…”

Interactions between drought, ABA application and supplemental UV‐B in Populus yunnanensis

“…However, it has been reported that the balance between C and N availability is important in determining the relationship between the allocation of biomass to roots and shoots (Ludidi et al 2007). Across all treatments, P. yunnanensis allocated their dry matter between shoots and roots largely in relation to its internal C/N status, as can be seen from the significant linear relationships between Rs and C/N ratios in stems and roots, suggesting that the root-to-shoot partitioning is controlled by some aspect of the plant's C and N balance (Ludidi et al 2007). While the C/N ratios in stems and roots were correlated with Rs across all treatments, interestingly, C/N in leaves was largely independent of Rs.…”

Rhizobium Impacts on Seed Productivity, Quality, and Protection of Pisum sativum upon Disease Stress Caused by Didymella pinodes: Phenotypic, Proteomic, and Metabolomic Traits

“…Then, seeds were pre-germinated in trays including sterile mixture of vermiculite and perlite. Then, 3 days old germinated seeds were transplanted into the pots (3 L) with 2 kg pot -1 sterile soil (pH 5.6, N 7 mg/L, P 13 mg/L, and K 2 O 120 mg/L) as described in our previous study ( Desalegn et al, 2016 ) and placed under controlled environmental conditions (14-h day/10-h night; 600 μmol m -2 s -1 light intensity; 22°C/16°C day/night temperature; 60–70% relative humidity) ( Ludidi et al, 2007 ; Larrainzar et al, 2014 ). All NR plants were fertilized once a week with 200 mL of Broughton and Dilworth nutrient solution ( Broughton and Dilworth, 1970 ; Laguerre et al, 2007 ) containing 10 mM KNO 3 .…”