Lateral Leaflet Suppression 1 (LLS1), encoding the MtYUCCA1 protein, regulates lateral leaflet development in Medicago truncatula

Abstract

Summary In species with compound leaves, the positions of leaflet primordium initiation are associated with local peaks of auxin accumulation. However, the role of auxin during the late developmental stages and outgrowth of compound leaves remains largely unknown. Using genome resequencing approaches, we identified insertion sites at four alleles of the LATERAL LEAFLET SUPPRESSION1 (LLS1) gene, encoding the auxin biosynthetic enzyme YUCCA1 in Medicago truncatula. Linkage analysis and complementation tests showed that the lls1 mutant phenotypes were caused by the Tnt1 insertions that disrupted the LLS1 gene. The transcripts of LLS1 can be detected in primordia at early stages of leaf initiation and later in the basal regions of leaflets, and finally in vein tissues at late leaf developmental stages. Vein numbers and auxin content are reduced in the lls1‐1 mutant. Analysis of the lls1 sgl1 and lls1 palm1 double mutants revealed that SGL1 is epistatic to LLS1, and LLS1 works with PALM1 in an independent pathway to regulate the growth of lateral leaflets. Our work demonstrates that the YUCCA1/YUCCA4 subgroup plays very important roles in the outgrowth of lateral leaflets during compound leaf development of M. truncatula, in addition to leaf venation.

Cloning and Functional Analysis of Dwarf Gene Mini Plant 1 (MNP1) in Medicago truncatula

“…The molecular cloning of the MNP1 gene referred to the method reported previously [ 62 ]. We screened the Tnt1 retrotransposon insertion mutant collection of M. truncatula (ecotype R108) and isolated two mnp1 alleles ( mnp1-1 , NF0500 and mnp1-2 , NF13564) with severely dwarfed phenotypes.…”

From genes to networks: The genetic control of leaf development

“…Auxin coordinates phyllotaxis and regulates the process of leaflet initiation (Bilsborough et al, 2011; Xiong and Jiao, 2019). In M. truncatula , the product of LATERAL LEAFLET SUPPRESSION 1 ( LLS1 ) participates in auxin synthesis (Zhao et al, 2020a). The lls1 mutant is compromised with respect to the outgrowth of LTs, an observation which has been taken to imply that LLS1 is required for the development of the lateral but not the terminal leaflets (TLs) (Zhao et al, 2020a).…”

The F-box protein MIO1/SLB1 regulates organ size and leaf movement in Medicago truncatula

“…The organ size of legume crops and forage is one of the most important agronomic traits because it is closely related to final yield and quality. Those previously reported genes in M. truncatula , such as SGL1 ( SINGLE LEAFLET1 ), PALM1 , LLS1 ( LATERAL LEAFLET SUPPRESSION1 ), and PINNA1 ( PENTAFOLIATA1 ), all provide important clues as to how the total leaf area and biomass might be promoted through manipulating the number and size of leaflets ( Wang et al , 2008 ; Chen et al , 2010 ; He et al , 2020 ; Zhao et al , 2020 ). From the present study, the predicted MIO1/SLB1-BS1 module would be a useful candidate for the genetic manipulation of crop yields, via increased seed size or total biomass.…”