Identification and characterization of novel senescence‐associated genes from barley (Hordeum vulgare) primary leaves

Abstract

Leaf senescence is the final developmental stage of a leaf. The progression of barley primary leaf senescence was followed by measuring the senescence-specific decrease in chlorophyll content and photosystem II efficiency. In order to isolate novel factors involved in leaf senescence, a differential display approach with mRNA populations from young and senescing primary barley leaves was applied. In this approach, 90 senescence up-regulated cDNAs were identified. Nine of these clones were, after sequence analyses, further characterized. The senescence-associated expression was confirmed by Northern analyses or quantitative RealTime-PCR. In addition, involvement of the phytohormones ethylene and abscisic acid in regulation of these nine novel senescence-induced cDNA fragments was investigated. Two cDNA clones showed homologies to genes with a putative regulatory function. Two clones possessed high homologies to barley retroelements, and five clones may be involved in degradation or transport processes. One of these genes was further analysed. It encodes an ADP ribosylation factor 1-like protein (HvARF1) and includes sequence motifs representing a myristoylation site and four typical and well conserved ARF-like protein domains. The localization of the protein was investigated by confocal laser scanning microscopy of onion epidermal cells after particle bombardment with chimeric HvARF1-GFP constructs. Possible physiological roles of these nine novel SAGs during barley leaf senescence are discussed.

Arabidopsis WRKY57 Functions as a Node of Convergence for Jasmonic Acid– and Auxin-Mediated Signaling in Jasmonic Acid–Induced Leaf Senescence

“…The ARF7 and ARF19 genes are also induced in senescing leaves (Lin and Wu, 2004). In barley, a novel senescence-induced gene, ARF1, plays an important role during senescence-associated transport processes (Ay et al, 2008). Although auxin levels and auxin signaling are related to leaf senescence, the underlying regulatory mechanism is still unclear.…”

INDOLE‐3‐ACETIC ACID INDUCIBLE 17 positively modulates natural leaf senescence through melatonin‐mediated pathway in Arabidopsis

“…In the presence of auxin, auxin signaling is perceived by the binding of auxin to its receptor protein TRANSPORT INHIBITOR RESPONSE 1 (TIR1)/AUXIN SIGNALING F BOX PROTEINs (AFBs), promoting the ubiquitin‐mediated degradation of auxin/indole‐3‐acetic acid (AUX/IAA) proteins, releasing the auxin response factors (ARFs), and further activating the downstream auxin response genes . Besides the relationship of auxin level to leaf senescence, some proteins involved in auxin signaling pathway have apparent in the process of leaf senescence, such as barley ARF1 , AtARF2 , and AtIAA29 . Although remarkable advances have been made in understanding the link between auxin and leaf senescence, the specific mechanism and molecular details need to be further addressed.…”

A maize ADP‐ribosylation factor ZmArf2 increases organ and seed size by promoting cell expansion in Arabidopsis

“…ARF proteins control membrane traffic and organelle structure, and are regulated by a cycle of activating GTP‐binding and inactivating GTP hydrolysis (D'Souza‐Schorey and Chavrier , Gillingham and Munro ). ARFs have been identified in several plant species, such as rubber tree (Qin et al ), carrot (Kiyosue and Shinozaki , Asakura et al ), tomato (Davies ), potato (Zopa and Müller‐Rober , Zuk et al , Liu et al ), tobacco (Coemans et al ), Arabidopsis (Regad et al ), barley (Ay et al ), wheat (Kobayashi‐Uehara et al ), rice (Higo et al ) and maize (Verwoert et al , Yuan et al ).…”