Expanding the Benefits of Tnt1 for the Identification of Dominant Mutations in Polyploid Crops: A Single Allelic Mutation in the MsNAC39 Gene Produces Multifoliated Alfalfa.

Cintia Jozefkowicz,Anelia Iantcheva,Ariel Odorizzi,Nicolás Ayub,Gabriela Soto,Cristina Gómez,Pascal Ratet

doi:10.3389/fpls.2021.805032

Abstract

Most major crops are polyploid species and the production of genetically engineered cultivars normally requires the introgression of transgenic or gene-edited traits into elite germplasm. Thus, a main goal of plant research is the search of systems to identify dominant mutations. In this article, we show that the Tnt1 element can be used to identify dominant mutations in allogamous tetraploid cultivated alfalfa. Specifically, we show that a single allelic mutation in the MsNAC39 gene produces multifoliate leaves (mfl) alfalfa plants, a pivot trait of breeding programs of this forage species. Finally, we discuss the potential application of a combination of preliminary screening of beneficial dominant mutants using Tnt1 mutant libraries and genome editing via the CRISPR/Cas9 system to identify target genes and to rapidly improve both autogamous and allogamous polyploid crops.

Highlights

Legume crops fix nitrogen symbiotically by interacting with soil nitrogen-fixing rhizobia, producing high-protein foods and reducing the use of nitrogen fertilizers derived from fossil fuel
We explore the use of Tnt1 for the identification of beneficial dominant mutations in alfalfa
There is a legal framework for the deregulation of transgenic plants, including transgenic alfalfa cultivars (Samac and Temple, 2021), the deregulation of transgenic events are long-term and expensive procedures

Summary

INTRODUCTION

Legume crops fix nitrogen symbiotically by interacting with soil nitrogen-fixing rhizobia, producing high-protein foods and reducing the use of nitrogen fertilizers derived from fossil fuel. The high expression of this type of beneficial traits (e.g., multifoliated leaves) obtained by the full allelic knockout of an individual alfalfa gene (e.g., palm1) in elite germplasms is not impossible, it requires an adaptation of the current introgression processes, a fact that increases the cost and time of production of a genetically modified alfalfa cultivar (Bottero et al, 2021). Around 50% of the mlf flowers show an increased number of petals (Figure 1H), an extremely unusual (

A MUTATION IN THE MsNAC39 GENE PRODUCES MULTIFOLIATE LEAF ALFALFA

DISCUSSION

Findings

DATA AVAILABILITY STATEMENT