Developmental atlas of white lupin cluster roots

Abstract

During the course of evolution, plants have developed various strategies to improve micronutrient acquisition, such as cluster roots. These spectacular structures are dedicated to efficient phosphate remobilization and acquisition. When exposed to Pi-limitation, white lupin forms cluster roots made of dense clusters of short specialized roots, called rootlets. Although the physiological activity of rootlets has been well studied, their development remains poorly described. Here, we provide a developmental atlas of white lupin early rootlet development, using molecular markers derived from the model plant Arabidopsis. We first focused on cell division patterns to determine which cells contribute to the rootlet primordium. Then, we identified homologs of previously described tissue specific genes based on protein sequence analysis and also using detailed transcriptomic data covering rootlet development. This study provides a comprehensive description of the developmental phases of rootlet formation, highlighting that rootlet primordium arises from divisions in pericycle, endodermis and cortex. We describe that rootlet primordium patterning follows eight stages during which tissue differentiation is established progressively.HighlightWhite lupin cluster roots consist in the formation of numerous rootlets whose development can be divided in 8 stages and involves divisions in the pericycle, endodermis and cortex.

Overexpression of LaGRAS enhances phosphorus acquisition via increased root growth of phosphorus‐deficient white lupin

“…The most prominent features of white lupin concerning P deficiency include the formation of specialized cluster roots (CRs, short and dense rootlets; Gallardo et al, 2020; Xu et al, 2020), synthesis of P‐scavenging enzymes (acid phosphatases) (Neumann et al, 2000), and exudation of organic acids (citrate and malate) (Johnson et al, 1996). These contribute to the release of P i (P inorganic) from organic P (P o ) sources, ultimately enhancing the available P acquisition and improving soil fertility (Gallardo et al, 2020; Liu et al, 2001). It has been well established that plants with CRs are more efficient (2 x − 13 x ) in P uptake and mobilization due to greater surface area (5 x ) than the non‐CRs (Maseko & Dakora, 2013).…”

“…White lupin ( Lupinus albus L.) is a promising legume crop with extreme tolerance to P deficiency (Aslam, Karanja, et al 2021) and high nitrogen fixation efficiency (Peix et al, 2015). The most prominent features of white lupin concerning P deficiency include the formation of specialized cluster roots (CRs, short and dense rootlets; Gallardo et al, 2020; Xu et al, 2020), synthesis of P‐scavenging enzymes (acid phosphatases) (Neumann et al, 2000), and exudation of organic acids (citrate and malate) (Johnson et al, 1996). These contribute to the release of P i (P inorganic) from organic P (P o ) sources, ultimately enhancing the available P acquisition and improving soil fertility (Gallardo et al, 2020; Liu et al, 2001).…”

Genome-wide association study reveals white lupin candidate gene involved in anthracnose resistance

“…In general, lupin species have long been considered valuable assets in crop rotations due to their unique symbiosis with Bradyrhizobium lupini, making them highly efficient nitrogen fixers (Fernández-Pascual et al 2007 ; Peix et al 2015 ). Specifically, white lupin is one of the few crops that form specialized cluster roots, which increase phosphorus availability by carboxylate secretion, significantly increasing soil fertility (Gallardo et al 2020 ; Lambers et al 2013 ). Since the development of sweet low alkaloid varieties (Kroc et al 2017 ), white lupin has become increasingly interesting for the food and feed industry (Lucas et al 2015 ).…”