Tendril-lessRegulates Tendril Formation in Pea Leaves  

Abstract

Tendrils are contact-sensitive, filamentous organs that permit climbing plants to tether to their taller neighbors. Tendrilled legume species are grown as field crops, where the tendrils contribute to the physical support of the crop prior to harvest. The homeotic tendril-less (tl) mutation in garden pea (Pisum sativum), identified almost a century ago, transforms tendrils into leaflets. In this study, we used a systematic marker screen of fast neutron-generated tl deletion mutants to identify Tl as a Class I homeodomain leucine zipper (HDZIP) transcription factor. We confirmed the tendril-less phenotype as loss of function by targeting induced local lesions in genomes (TILLING) in garden pea and by analysis of the tendril-less phenotype of the t mutant in sweet pea (Lathyrus odoratus). The conversion of tendrils into leaflets in both mutants demonstrates that the pea tendril is a modified leaflet, inhibited from completing laminar development by Tl. We provide evidence to show that lamina inhibition requires Unifoliata/LEAFY-mediated Tl expression in organs emerging in the distal region of the leaf primordium. Phylogenetic analyses show that Tl is an unusual Class I HDZIP protein and that tendrils evolved either once or twice in Papilionoid legumes. We suggest that tendrils arose in the Fabeae clade of Papilionoid legumes through acquisition of the Tl gene.

STENOFOLIARegulates Blade Outgrowth and Leaf Vascular Patterning inMedicago truncatulaandNicotiana sylvestris

“…In addition to STF, LAM1, MAW, NS1, and NS2, which are WOX genes, class I HD-ZIP genes have been reported to control tendril and bract morphogenesis without necessarily disrupting polarity. For example, the tendril-less (tl) mutation in pea revealed that tendrils are modified leaves where lamina outgrowth is inhibited by repressive function of TL (Hofer et al, 2009), and a related gene in Arabidopsis, LATE MERISTEM IDENTITY1 (LMI1), is required for suppression of bract formation (Saddic et al, 2006). It remains to be shown if class I HD-ZIP genes target or interact with WOX genes in leaf primordia.…”

The b Gene of Pea Encodes a Defective Flavonoid 3′,5′-Hydroxylase, and Confers Pink Flower Color

“…1 compost with 30% extra grit. DNA was prepared from leaves according to Vershinin et al (2003), and RNA was prepared from flowers according to Hofer et al (2009).…”

Three Sequenced Legume Genomes and Many Crop Species: Rich Opportunities for Translational Genomics

“…The garden pea is in some senses the founding model for genetics, through Mendel's work in 1866. Pea has been further developed as a model for development traits such as compound leaf form (Tattersall et al, 2005), tendril formation (Hofer et al, 2009), transposon evolution (Jing et al, 2005), defense responses (Gao et al, 2004), starch and sugar synthesis (Barratt et al, 2001), and hormonal control of shoot branching (Beveridge et al, 2009). Common bean has been used to characterize the molecular basis of photoperiod sensitivity and determinacy (Kwak et al, 2008).…”