WEG1, which encodes a cell wall hydroxyproline‐rich glycoprotein, is essential for parental root elongation controlling lateral root formation in rice

Abstract

Lateral roots (LRs) determine the overall root system architecture, thus enabling plants to efficiently explore their underground environment for water and nutrients. However, the mechanisms regulating LR development are poorly understood in monocotyledonous plants. We characterized a rice mutant, wavy root elongation growth 1 (weg1), that produced higher number of long and thick LRs (L‐type LRs) formed from the curvatures of its wavy parental roots caused by asymmetric cell growth in the elongation zone. Consistent with this phenotype, was the expression of the WEG1 gene, which encodes a putative member of the hydroxyproline‐rich glycoprotein family that regulates cell wall extensibility, in the root elongation zone. The asymmetric elongation growth in roots is well known to be regulated by auxin, but we found that the distribution of auxin at the apical region of the mutant and the wild‐type roots was symmetric suggesting that the wavy root phenotype in rice is independent of auxin. However, the accumulation of auxin at the convex side of the curvatures, the site of L‐type LR formation, suggested that auxin likely induced the formation of L‐type LRs. This was supported by the need of a high amount of exogenous auxin to induce the formation of L‐type LRs. These results suggest that the MNU‐induced weg1 mutated gene regulates the auxin‐independent parental root elongation that controls the number of likely auxin‐induced L‐type LRs, thus reflecting its importance in improving rice root architecture.

Meta-QTL and ortho-MQTL analyses identified genomic regions controlling rice yield, yield-related traits and root architecture under water deficit conditions

“…For RDW, we detected two co-located MQTLs including MQTL-RDW1 and RDW2 co-locating with OsMGT1 and OsAIR1 genes, respectively. Additionally, WEG1 at MQTL-RDW5 is a novel gene that regulates root related traits 85 and may keep the same role under water deficit conditions.…”

“…no. (genomic position in Mb) Maize MQTL reference Ortho-MQTL-PH7 MQTL-PH7 4 (30.86–31.61) mQTL_PEH_10 10 (142.39–143.64) 85 MQTL-YLD2 2 (26.47–27.59) mQTL_GY_5 5 (196.85–199.69) 84 Ortho-MQTL-YLD2 MQTL5.7 5 (199.95–200.82) 16 Ortho-MQTL-YLD3 MQTL-YLD3 3 (29.58–30.36) mQTL_GY_1b 1 (276.04–279.33) 84 Ortho-MQTL-YLD4 MQTL-YLD4 4 (29.15–30.82) mQTL_GY_10b 10 (135.81–142.38) 84 Ortho-MQTL-YLD6 MQTL-YLD6 8 (0.26–0.71) MQTL6.1 6 (1.58–3.65) 16

Figure 4 Comparative maps of ortho-MQTLs between rice and maize. ( A ) ortho-MQTL-PH7, ( B ) ortho-MQTL-YLD2, ( C ) ortho-MQTL-YLD3, ( D ) ortho-MQTL-YLD4 and ( E ) ortho-MQTL-YLD6.

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Morpho-physiological and molecular mechanisms of phenotypic root plasticity for rice adaptation to water stress conditions

“…Gravitropic curvature upregulates auxin signaling in rice and induces L-type lateral root formation on the convex side (Lucob-Agustin et al 2020b). Additionally, weg1 mutants that showed wavy parental roots, including in the seminal and crown roots, and exhibited L-type lateral roots arising from the curvatures of the parental roots, revealed that wavy parental roots are important in increasing the frequency of L-type lateral roots through the non-canonical pathway (Lucob-Agustin et al 2020b).…”

Improved clearing method contributes to deep imaging of plant organs

“…Vegetative and reproductive SAMs were isolated by hand dissection of the basal region of rice under a microscope 31 . Generation of the transgenic lines OsMADS15-mOragene and DR5rev:NLS-3xVenus was previously reported 22,32 .…”