RETRACTED: Formation of Proto-Kranz in C3 Rice Induced by Spike-Stalk Injection Method

Abstract

Introduction of C4 photosynthetic traits into C3 crops is an important strategy for improving photosynthetic capacity and productivity. Here, we report the research results of a variant line of sorghum–rice (SR) plant with big panicle and high spikelet density by introducing sorghum genome DNA into rice by spike-stalk injection. The whole-genome resequencing showed that a few sorghum genes could be integrated into the rice genome. Gene expression was confirmed for two C4 photosynthetic enzymes containing pyruvate, orthophosphate dikinase and phosphoenolpyruvate carboxykinase. Exogenous sorghum DNA integration induced a series of key traits associated with the C4 pathway called “proto-Kranz” anatomy, including leaf thickness, bundle sheath number and size, and chloroplast size in bundle sheath cells. Significantly, transgenic plants exhibited enhanced photosynthetic capacity resulting from both photosynthetic CO2-concentrating effect and improved energy balance, which led to an increase in carbohydrate levels and productivity. Furthermore, such rice plant exhibited delayed leaf senescence. In summary, this study provides a proof for the feasibility of inducing the transition from C3 leaf anatomy to proto-Kranz by spike-stalk injection to achieve efficient photosynthesis and increase productivity.

Editorial: Introgression Breeding in Cultivated Plants

“…New lines of wheat with introgression from Aegilops caudata L. have been obtained by Grewal et al after crossing this species with the bread wheat cultivar Paragon, showing the ph1/ph1 mutant genotype, to obtain a set of recombinant introgression lines (ILs) with potential materials carrying the enhanced disease resistance from A. caudata. Apart from methods based on sexual crossings, the so-called Exogenous DNA Transfer (EDT) methods allow circumventing hybridization and introgression from CWRs that are not sexually compatible with the crop (Ali et al, 2015;Jiang et al, 2021). One of these methods, the spike-stalk injection method, consisting of the injection of exogenous DNA close to the inflorescence a few days after meiosis (De la Pena et al, 1987) Legumes are an important source of protein and oil and can make an effective contribution to sustainable agriculture due to their capacity of symbiotic associations with Rhizobium nitrogenfixing bacteria (Soumare et al, 2020).…”

RETRACTED: Jiang et al. Formation of Proto-Kranz in C3 Rice Induced by Spike-Stalk Injection Method. Int. J. Mol. Sci. 2021, 22, 4305

“…The journal and the authors retract the article “Formation of Proto-Kranz in C3 Rice Induced by Spike-Stalk Injection Method” [ 1 ] cited above.…”

“…Following publication, concerns were brought to the attention of the editors regarding experimental results from [ 1 ] that were found to be unreliable, namely: (1) Several sorghum genes were integrated into the rice genome; (2) Sorghum PPDK and PEPCK genes were expressed in the sorghum–rice (SR) plant; (3) Integration of sorghum DNA caused proto-Kranz anatomy. This has brought about uncertainty regarding the scientific conclusions.…”

“…The authors have not been able to provide a satisfactory explanation for these irregularities and the journal’s Editors-in-Chief no longer has confidence in the conclusions of the paper. Therefore, to ensure the addition of only high-quality scientific works to the field of scholarly publication, this paper [ 1 ] is retracted and shall be marked accordingly. The authors agree with this retraction.…”