LsNRL4 enhances photosynthesis and decreases leaf angles in lettuce

Abstract

Lettuce (Lactuca sativa) is one of the most important vegetables worldwide and an ideal plant for producing protein drugs. Both well-functioning chloroplasts that perform robust photosynthesis and small leaf angles that enable dense planting are essential for high yields. In this study, we used an F 2 population derived from a cross between a lettuce cultivar with pale-green leaves and large leaf angles to a cultivar with dark-green leaves and small leaf angles to clone LsNRL4, which encodes an NPH3/RPT2-Like (NRL) protein. Unlike other NRL proteins in lettuce, the LsNRL4 lacks the BTB domain. Knockout mutants engineered using CRISPR/Cas9 and transgenic lines overexpressing LsNRL4 verified that LsNRL4 contributes to chloroplast development, photosynthesis and leaf angle. The LsNRL4 gene was not present in the parent with pale-green leaves and enlarged leaf angles. Loss of LsNRL4 results in the enlargement of chloroplasts, decreases in the amount of cellular space allocated to chloroplasts and defects in secondary cell wall biosynthesis in lamina joints. Overexpressing LsNRL4 significantly improved photosynthesis and decreased leaf angles. Indeed, the plant architecture of the overexpressing lines is ideal for dense planting. In summary, we identified a novel NRL gene that enhances photosynthesis and influences plant architecture. Our study provides new approaches for the breeding of lettuce that can be grown in dense planting in the open field or in modern plant factories. LsNRL4 homologues may also be used in other crops to increase photosynthesis and improve plant architecture.

DNA methylation variations underlie lettuce domestication and divergence

“…Although abundant genetic variations during lettuce domestication have been profiled by a large-scale whole genome resequencing study [ 6 ], there are few examples of genes that have been shown to be directly linked to lettuce domestication. Characterized lettuce genes that are possibly involved in lettuce domestication include lettuce APETALA2 regulating seed shape [ 56 ], LsKN1 controlling leafy head development [ 57 ], and LsNRL4 regulating photosynthesis and leaf angles [ 58 ]. Unfortunately, these genes do not contain domestication-induced DMRs.…”

Yellow-Green Leaf 19 Encoding a Specific and Conservative Protein for Photosynthetic Organisms Affects Tetrapyrrole Biosynthesis, Photosynthesis, and Reactive Oxygen Species Metabolism in Rice

“…Moreover, 14 plastid-encoded genes were detected, encoding the subunit of PSI (psaA, psaB, and psaC), core component of PSII (psbA, psbB, and psbC), NADH dehydrogenase subunit (ndhA and ndhB), cytochrome b 6 f complex subunit (petD), ATP synthase complex subunit (atpA and atpB), Rubisco large subunit (rbcL), and plastid-encoded RNA polymerase subunit (rpoA and rpoB). PSI is located primarily on the monolayer stromal thylakoid membrane, while PSII is mainly located on the stack of grana of the thylakoid membrane, both constituting important sites of bioluminescence [65]. The genes of PSI and PSII (psaA, psaB, psaC, psbA, psbB, and psbC) exhibited different degrees of lower gene expression in the ygl19 mutant (Figure 11B).…”