AUTHOR=Abd El-Moneim Diaa , Contreras Roberto , Silva-Navas Javier , Gallego Francisco Javier , Figueiras Ana M. , Benito Cesar 

TITLE=Repression of Mitochondrial Citrate Synthase Genes by Aluminum Stress in Roots of Secale cereale and Brachypodium distachyon

JOURNAL=Frontiers in Plant Science

VOLUME=13

YEAR=2022

URL=https://www.frontiersin.org/journals/plant-science/articles/10.3389/fpls.2022.832981

DOI=10.3389/fpls.2022.832981

ISSN=1664-462X

ABSTRACT=<p>Aluminum (Al) toxicity in acid soils influences plant development and yield. Almost 50% of arable land is acidic. Plants have evolved a variety of tolerance mechanisms for Al. In response to the presence of Al, various species exudate citrate from their roots. Rye (<italic>Secale cereale</italic> L.) secretes both citrate and malate, making it one of the most Al-tolerant cereal crops. However, no research has been done on the role of the mitochondrial <italic>citrate synthase</italic> (<italic>mCS</italic>) gene in Al-induced stress in the rye. We have isolated an <italic>mCS</italic> gene, encoding a mitochondrial CS isozyme, in two <italic>S. cereale</italic> cultivars (Al-tolerant cv. Ailés and Al-sensitive inbred rye line Riodeva; <italic>ScCS4</italic> gene) and in two <italic>Brachypodium distachyon</italic> lines (Al-tolerant ABR8 line and Al-sensitive ABR1 line; <italic>BdCS4</italic> gene). Both <italic>mCS4</italic> genes have 19 exons and 18 introns. The <italic>ScCS4</italic> gene was located on the <italic>6R</italic>L rye chromosome arm. Phylogenetic studies using cDNA and protein sequences have shown that the <italic>ScCS4</italic> gene and their ScCS protein are orthologous to <italic>mCS</italic> genes and CS proteins of different Poaceae plants. Expression studies of the <italic>ScCS4</italic> and <italic>BdSC4</italic> genes show that the amount of their corresponding mRNAs in the roots is higher than that in the leaves and that the amounts of mRNAs in plants treated and not treated with Al were higher in the Al-tolerant lines than that in the Al-sensitive lines of both species. In addition, the levels of <italic>ScCS4</italic> and <italic>BdCS4</italic> mRNAs were reduced in response to Al (repressive behavior) in the roots of the tolerant and sensitive lines of <italic>S. cereale</italic> and <italic>B. distachyon</italic>.</p>