Identification of MADS-Box Transcription Factors in Iris laevigata and Functional Assessment of IlSEP3 and IlSVP during Flowering

Abstract

Iris laevigata is ideal for gardening and landscaping in northeast China because of its beautiful flowers and strong cold resistance. However, the short length of flowering time (2 days for individual flowers) greatly limits its applications. Molecular breeding and engineering hold high potential for producing I. laevigata of desirable flowering properties. A prerequisite is to identify and characterize key flowering control genes, the identity of which remains largely unknown in I. laevigata due to the lack of genome information. To fill this knowledge gap, we used sequencing data of the I. laevigata transcriptome to identify MADS-box gene-encoding transcription factors that have been shown to play key roles in developmental processes, including flowering. Our data revealed 41 putative MADS-box genes, which consisted of 8 type I (5 Mα and 3 Mβ, respectively) and 33 type II members (2 MIKC* and 31 MIKCC, respectively). We then selected IlSEP3 and IlSVP for functional studies and found that both are localized to the nucleus and that they interact physically in vitro. Ectopic expression of IlSEP3 in Arabidopsis resulted in early flowering (32 days) compared to that of control plants (36 days), which could be mediated by modulating the expression of FT, SOC1, AP1, SVP, SPL3, VRN1, and GA20OX. By contrast, plants overexpressing IlSVP were phenotypically similar to that of wild type. Our functional validation of IlSEP3 was consistent with the notion that SEP3 promotes flowering in multiple plant species and indicated that IlSEP3 regulates flowering in I. laevigata. Taken together, this work provided a systematic identification of MADS-box genes in I. laevigata and demonstrated that the flowering time of I. laevigata can be genetically controlled by altering the expression of key MADS-box genes.

Genome-wide analysis of MADS-box gene family in kiwifruit (Actinidia chinensis var. chinensis) and their potential role in floral sex differentiation

“…The MADS-box genes are involved in regulating many biological processes, such as seed germination ( He et al, 2019 ), vegetative growth ( Cohen et al, 2012 ), floral organ specification ( Kong et al, 2022 ), flowering ( Liu et al, 2022 ), embryo and fruit development ( Colombo et al, 2008 ; Pi et al, 2021 ). At present, most of the floral organ development-related genes belong to the MADS-box family.…”

WRKY22 Transcription Factor from Iris laevigata Regulates Flowering Time and Resistance to Salt and Drought

“…I. laevigata is native to northeast China with strong cold resistance and beautiful flowers of unique shape and bright color [26]. Such desirable traits make I. laevigata a good candidate for both landscaping and industrial use as a cutting flower.…”

“…Such desirable traits make I. laevigata a good candidate for both landscaping and industrial use as a cutting flower. However, the potential is dampened because of the short flowering period with only 2 days for a single flower and 20 days for the population [26]. To stagger the flowering time and prolong the flowering period, it is necessary to find genes that can advance or delay the flowering.…”

“…However, molecular studies in I. laevigata are difficult due to the lack of genome information [26]. Our group pioneered the first transcriptomics studies in the tepals of I. laevigata.…”

Genome-Wide Identification of MADS-Box Family Genes in Safflower (Carthamus tinctorius L.) and Functional Analysis of CtMADS24 during Flowering

“…Recent studies suggested the role of type I MADS-box genes in the regulation of endosperm development in Arabidopsis and grasses [ 9 , 10 , 11 ]. Similarly, MIKC-type members of MADS-box have been widely studied for their ability to form transcription factor complexes and their vital role in the control of flowering development [ 12 , 13 , 14 ]. According to the widely used ABCDE model of flower organ development, class A genes participate in sepal development in the first whorl; then, class A, B (AP3 and PI), and E (AGL3 and SEP) genes collectively control the petal identity in the second whorl, while class B, C (AG), and E genes all together control the stamen identity in the third whorl.…”