Characterization of a fertilization-induced and developmentally regulated plasma-membrane aquaporin expressed in reproductive tissues, in the wild potato Solanum chacoense Bitt.

Abstract

Fertilization triggers a unique and complex developmental program leading to embryogenesis and seed set. Growth and differentiation are accompanied by rapid metabolic changes as well as massive cellular reorganization inside the fertilized ovule. Using differential display to isolate genes involved in pollen-pistil interactions and early fertilization events, we isolated from Solanum chacoense Bitt. a fertilization-induced plasma-membrane intrinsic protein of the PIP2 family that is predominantly expressed in pistil and anthers tissues. Major intrinsic proteins (MIPs) consist of a large family of highly conserved membrane-spanning proteins that are mainly represented in plants by the aquaporins. Aquaporins, mainly of the PIP and TIP type, have been shown in many species to serve as water channels. In S. chacoense the ScPIP2a mRNA is developmentally regulated during anthesis, with mRNA levels gradually decreasing as the pistil reaches maturity. In flowers, strongest expression was observed in elongating styles, in stamens, and transiently in ovules following fertilization. In styles, maximal expression levels correlated with phases of rapid style elongation and with the formation of epidermal papillae. ScPIP2a mRNA was also strongly expressed in developing fruit, consistent with a role in cell expansion during maturation and development.

Pistil Factors Controlling Pollination

“…Recently, many water channel proteins, collectively named aquaporins, were described in plants; these indicate the existence of a very rapid and regulated water transport across biological membranes (Johanson et al, 2001). Some of these aquaporins or aquaporin-like genes are expressed in the pistil, among other plant tissues, of Solanum chacoense (O'Brien et al, 2002) and Brassica (Marin-Olivier et al, 2000;Dixit et al, 2001). Although it is attractive to speculate that they play a role in pollen hydration by the stigma, 35 putative aquaporin genes, classified on the basis of sequence identity, were found in the genome of Arabidopsis.…”

Expression and functional analysis of the rice plasma-membrane intrinsic protein gene family

“…The expression patterns of aquaporin genes in response to salt, drought, cold, submergence, light, and phytohormones have also been characterized in various plants [16][17][18][19][20][21][22][23][24]. Some aquaporins are tissue-specific, such as g-MIP in shoots of rice [21], g-TIP in seeds of Brassica napus [16] and ZmTIP2-3 in roots of maize [25].…”

Analysis of theNicotiana tabacumStigma/Style Transcriptome Reveals Gene Expression Differences between Wet and Dry Stigma Species

“…TTS is an arabinogalactan protein of the pistil extracellular matrix, which has been shown to attract pollen tubes and stimulates their growth (Cheung et al, 1995). Concerning the aquaporin, LTP, and PMEI similar sequences, there are reports about the importance of proteins with equivalent functions in the reproductive process (O'Brien et al, 2002;Park and Lord, 2003;Wolf et al, 2003, respectively). In Solanum chacoense, a fertilization-induced and developmentally regulated plasma membrane aquaporin (ScPIP2a) expressed in reproductive tissues has been identified (O'Brien et al, 2002).…”

“…Concerning the aquaporin, LTP, and PMEI similar sequences, there are reports about the importance of proteins with equivalent functions in the reproductive process (O'Brien et al, 2002;Park and Lord, 2003;Wolf et al, 2003, respectively). In Solanum chacoense, a fertilization-induced and developmentally regulated plasma membrane aquaporin (ScPIP2a) expressed in reproductive tissues has been identified (O'Brien et al, 2002). The maximal expression levels of ScPIP2a correlated with phases of rapid style elongation and papilla formation on stylar cortical cells, which is consistent with a role in cell elongation and expansion during pistil development.…”