INFLORESCENCE DEFICIENT IN ABSCISSION-like is an abscission-associated and phytohormone-regulated gene in flower separation of Lupinus luteus

Abstract

Abscission is a natural process that occurs to facilitate shedding of no longer needed organs, but on the other hand, can be triggered by certain environmental conditions, e.g. biotic or abiotic stresses. Regardless of the stimuli, organ shedding takes place specifically at the abscission zone (AZ). A signaling pathway that controls this process in Arabidopsis thaliana from ligand to receptors has been proposed. However, knowledge concerning the influence of plant hormones on these molecular elements still remains enigmatic. Excessive and premature flower abscission in the crop species Lupinus luteus L. is a process of substantial interest to the agricultural industry, as it can affect yield. Our strategy combined molecular studies, comprehensive ultrastructural and histological analysis, as well as exogenous hormone treatment to describe the contribution of the Lupinus IDA-like gene in flower abscission. In the AZ of the naturally abscised flowers, the differentiation of morphologically distinct cells characterized by progressive degradation processes was accompanied by LlIDL mRNA accumulation. A similar effect was observed following early steps of AZ activation and after abscisic acid or ethylene treatments. These phytohormones, previously pointed out as key stimulators of flower separation, altered the temporal expression pattern of LlIDL. Exogenous EPIP peptide synthesized on the basis of LlIDL sequence, significantly increased flower abortion rate, which indicates that this motif governs protein activity. In conclusion, our data provide new evidence for LlIDA involvement in both the early and late events of flower abscission supported by detailed spatiotemporal characterization of AZ cell structure and ultrastructure.

Re-evaluation of the ethylene-dependent and -independent pathways in the regulation of floral and organ abscission

“…Ethylene also induced expression of the IDA gene in non-AZ tissues, such as petioles and leaf blades, in soybean (Tucker and Yang, 2012). In addition, a recent report demonstrated that ethylene induced the expression of EgHSL and EgIDA genes in the AZ of oil palm fruits (Stø et al, 2015), and that ethephon induced the expression of the IDA-like genes in the AZ cells of the fruitlet peduncle in litchi (Ying et al, 2016), as well as in the AZ of lupine flowers (Wilmowicz et al, 2018). In all the above studies, the increased expression of the IDA or HSL genes in the AZ was detected early, prior to the onset of abscission, indicating a direct effect of ethylene on IDA expression.…”

“…These observations led to the suggestion that the IDA-HAE-HSL2 complex contributes to an ethylene-independent abscission pathway (Jinn et al, 2000;Butenko et al, 2003;Butenko et al, 2006). The involvement of orthologs of IDA, HAE, and HSL2 in the abscission process has been demonstrated in other plant species (Tucker and Yang, 2012;Stø et al, 2015;Wilmowicz et al, 2018). Moreover, the IDA orthologs from citrus (CitIDA3) (Estornell et al, 2015) and litchi (LcIDL1) (Ying et al, 2016) were shown to be expressed during abscission, and their expression in Arabidopsis accelerated floral organ abscission.…”

Formation of the Secondary Abscission Zone Induced by the Interaction of Methyl Jasmonate and Auxin in Bryophyllum calycinum: Relevance to Auxin Status and Histology

“…For instance, cell divisions were involved in differentiation of the secondary abscission zone in the stem of excised gibberellin-treated cotyledonary nodes of cotton [47] and Phaseolus vulgaris [19]. Cell division is also associated with flower abscission induced by ABA and ethylene treatment of Lupinus luteus [48]. As shown in Figures 2 and 3, the abscission zone was characterized by the presence of newly synthesized cell plates that resulted from periclinal cell division within one layer of mother cells in the stems of B. calycinum.…”

Differential expression of IDA (INFLORESCENCE DEFICIENT IN ABSCISSION)-like genes in Nicotiana benthamiana during corolla abscission, stem growth and water stress

“…C). Furthermore, the representation of the EPIP motif of all IDA peptides that have been associated so far with abscission, this is Arabidopsis AtIDA and AtIDL1 [1], citrus CitIDA3 [16], soybean GmIDA2a and GmIDA2b [15], Litchi LcIDL1 [20], oil palm EgIDA5 [17], Lupinus LlIDA [19] and tomato SlycIDA1 [15] and its orthologs with very similar sequence detected in clade I of Figure 1, including StubIDA4, SmelIDA5, CaIDA4, NbenIDA1A and NbenIDA1B) suggests that the relevant positions of the EPIP motif are P11, S13A/G14P15S16 and R18H19N20 (Figure 2, D).…”

“…In addition to Arabidopsis, IDA-like genes have been identified in some crop species associated with organ abscission and the emergence of lateral roots [14] as well. Regarding organ abscission, particular members of the IDA-like gene family of tomato (SlIDA1), soybean (GmIDA2a), citrus (CitIDA3), litchi (LcIDL1), oil palm (EgIDA5) and yellow lupine (LlIDA) were highly expressed in leaf, flower or fruit abscission zones during abscission [15][16][17][18][19]. In addition, the AtIDA homologues of citrus (CitIDA3) and litchi (LcIDA1) were able to induce earlier floral organ abscission and to rescue the ida2 abscission deficiency when ectopically expressed in Arabidopsis [16,20].…”