Abstract
The longitudinal pattern of root aerenchyma formation of its relationship with the function of adventitious roots in rice remains unclear. In this study, the percentage of the aerenchyma area to the cross-sectional area (i.e., aerenchyma percentage) was fit with four non-linear models, namely, W0-Gompertz, Ti-Gompertz, logistic, and von Bertalanffy. Goodness-of-fit criteria such as the R2, the Akaike information criterion (AIC), and the Bayesian information criterion (BIC) were used to select the model. The bias of the parameters was evaluated using the difference between the ordinary least squares-based parameter estimates and the mean of 1,000 bootstrap-based parameter estimates and the symmetry of the distributions of these parameters. The results showed that the Ti-Gompertz model, which had a high goodness-of-fit with an R2 close to 1, lower AIC and BIC values, parameter estimates close to being unbiased, and good linear approximation, provided the best fit for the longitude pattern of rice aerenchyma formation with different root lengths among the competing models. Using the second- and third-order derivatives according to the distance from the root apex, the critical points of Ti-Gompertz were calculated. The rapid stage for aerenchyma formation was from the maximum acceleration point (1.38–1.76 cm from the root apex) to the maximum deceleration point (3.13–4.19 cm from the root apex). In this stage, the aerenchyma percentage increased by 5.3–15.7% per cm, suggesting that the cortical cells tended to die rapidly for the aerenchyma formation rather than for the respiration cost during this stage. Meanwhile, the volume of the aerenchyma of the entire roots could be computed using the integral function of the Ti-Gompertz model. We proposed that the longitudinal pattern of root aerenchyma formation modeled by the Ti-Gompertz model helped to deeply understand the relationship between the anatomical traits and physiological function in rice adventitious roots.
Highlights
The cortical aerenchyma of adventitious roots is a fundamental anatomical trait across scales from root architecture to programmed cell death and physiological function (Drew et al, 2000; Lynch, 2011; Vanhees et al, 2020)
The aerenchyma percentage gradually increased as the distance from the root apex in roots that were 4–7 cm in length increased
To pinpoint the usefulness of the proposed model and the given results, we focused on some applications to the real data, and the volume of the entire aerenchyma could be calculated using the integral function of the Ti-Gompertz model (Figure 7)
Summary
The cortical aerenchyma of adventitious roots is a fundamental anatomical trait across scales from root architecture to programmed cell death and physiological function (Drew et al, 2000; Lynch, 2011; Vanhees et al, 2020). Roots with greater gas-filled volume (i.e., greater aerenchyma or porosity) can achieve longer lengths in waterlogged soil than roots with lower aerenchyma and porosity (Armstrong, 1979; Armstrong and Beckett, 1987). Aerenchyma formation begins at the apical part of the roots and gradually grows toward the basal part of the rice adventitious roots, forming a longitudinal path for gas diffusion in flooded paddies (Armstrong, 1979; Colmer, 2003; Yamauchi et al, 2021). As the root apex grows farther away from the shoot base, root growth into anoxic waterlogged soils depends on the distance to which adequate oxygen can reach to sustain the respiratory demands of the root apex (Armstrong, 1979; Armstrong and Beckett, 1987). It is difficult to determine the aerenchyma formation along the entire root as preparing the crosssections of roots and extracting regional data from root crosssectional images are labor-intensive and have a low throughput (Takahashi and Pradal, 2021)
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
