Bulk RNA-Seq analysis to dissect the regulation of stigma position in tomato.
Author(s)
Date Issued
2020
Type
article
Volume
105
Issue
3
Start Page
263
End Page
285
Journal
Abstract
Domestication of cultivated tomato (Solanum lycopersicum L.) included the transition from allogamy to autogamy
that occurred through the loss of self-incompatibilty and the retraction of the stigma within the antheridial cone. Although
the inserted stigma is an established phenotype in modern tomatoes, an exserted stigma is still present in several landraces
or vintage varieties. Moreover, exsertion of the stigma is a frequent response to high temperature stress and, being a cause
of reduced fertility, a trait of increasing importance. Few QTLs for stigma position have been described and only one of
the underlying genes identified. To gain insights on genes involved in stigma position in tomato, a bulk RNA sequencing
(RNA-Seq) approach was adopted, using two groups of contrasting genotypes. Phenotypic analysis confirmed the extent
and the stability of stigma position in the selected genotypes, whereas they were highly heterogeneous for other reproductive
and productive traits. The RNA-Seq analysis yielded 801 differentially expressed genes (DEGs), 566 up-regulated and
235 down-regulated in the genotypes with exserted stigma. Validation by quantitative PCR indicated a high reliability of
the RNA-Seq data. Up-regulated DEGs were enriched for genes involved in the cell wall metabolism, lipid transport, auxin
response and flavonoid biosynthesis. Down-regulated DEGs were enriched for genes involved in translation. Validation of
selected genes on pistil tissue of the 26 single genotypes revealed that differences between bulks could both be due to a
general trend of the bulk or to the behaviour of single genotypes. Novel candidate genes potentially involved in the control
of stigma position in tomato are discussed.
Subjects
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