Expression of proteinase inhibitor II proteins during floral development in Solanum americanum

Abstract

The heterologous expression of serine proteinase inhibitor II (PIN2) proteins confers insect resistance in transgenic plants, but little is known of their endogenous roles. We have cloned two cDNAs encoding Solanum americanum PIN2 proteins, SaPIN2a and SaPIN2b. SaPIN2a is highly expressed in stem, particularly in the phloem, suggesting it could possibly regulate proteolysis in the sieve elements. When SaPIN2a was expressed in transgenic lettuce, we observed an inhibition of endogenous trypsin- and chymotrypsin-like activities. Here, we demonstrate that both SaPIN2a and SaPIN2b are expressed in floral tissues that are destined to undergo developmental programmed cell death (PCD), suggesting possible endogenous roles in inhibiting trypsin- and chymotrypsin-like activities during flower development. Northern and western blot analyses revealed that SaPIN2a and SaPIN2b mRNAs and proteins show highest expression early in floral development. In situ hybridization analysis and immunolocalization on floral sections, localized SaPIN2a and SaPIN2b mRNAs and their proteins to tissues that would apparently undergo PCD: the ovules, the stylar transmitting tissue, the stigma and the vascular bundles. Detection of PCD in floral sections was achieved using terminal deoxynucleotidyltransferase-mediated dUTP nick end labeling (TUNEL) analysis. Examination of the mid-style before, and 1 day after, pollination revealed that high expression of SaPIN2a and SaPIN2b in the style was inversely correlated with PCD.

Diverse forms of Pin-II family proteinase inhibitors from Capsicum annuum adversely affect the growth and development of Helicoverpa armigera

“…Two IRD PIs, SaPin-IIa and b from Solanum americanum, having a 74% sequence similarity are strongly expressed during early floral developmental stages. These PIs accumulate differentially, in developing ovules, implying their overlapping but not necessarily identical roles (Sin and Chye, 2004). CanPI genes in the present study were isolated from developing green fruit tissues.…”

Characterization of a stress responsive proteinase inhibitor gene with positive effect in improving drought resistance in rice

“…Plant PI proteins have been shown to have functions in various physiological and developmental processes (Mosolov and Valueva 2005). Reports on proteinase inhibitor II (PIN2), a serine-proteinase inhibitor which occurs in Solanaceae plants, show that it could play endogenous roles in environmental responses and development (Hendriks et al 1991;Pena-Cortes et al 1991;Sin and Chye 2004;Sin et al 2006). A soybean cysteine PI has been designated a novel role in modulating the programmed cell death (Solomon et al 1999).…”

Spatial and temporal expression patterns of diverse Pin-II proteinase inhibitor genes in Capsicum annuum Linn

“…This Pin-II type PIs are characterized by the diversity of their forms, ability to regulate proteins and genes spatially and temporally, and their expression. Recent reports describing the endogenous and/or defense roles of PIs from various Solanaceous species highlight their involvement in the plant's complex processes (Johnson et al, 2007;Sin and Chye, 2004;Xu et al, 2004;Wu et al, 2006).…”