New Insights into Desiccation-Associated Gene Regulation by Lilium longiflorum ASR during Pollen Maturation and in Transgenic Arabidopsis - International Review of Cell and Molecular Biology - page 45

plants, including potato ( Frankel et al., 2007 ; Silhavy et al., 1995 ), pomelo
( Canel et al., 1995 ), loblolly pine ( Chang et al., 1996 ), apricot ( Mbeguie-A-
Mbeguie et al., 1997 ), maize ( Riccardi et al., 1998 ), lily ( Huang et al., 2000 ;
Wang et al., 1998 ), rice ( Kim et al., 2009 ; Vaidyanathan et al., 1999 ; Yang
et al., 2004 ), Cucumis melo ( Hong et al., 2002 ), grape ( Cakir et al., 2003 ),
Ginkgo biloba ( Shen et al., 2005 ), plantain ( Liu et al., 2010 ), and strawberry
( Chen et al., 2011 ). However, these genes are not present in Arabidopsis .
Recently, an Asr gene, SbASR- 1, was identified in an extreme halophyte
Salicornia brachiata that has a unique genetic makeup with well-developed
adaptation mechanism to survive in a saline condition ( Jha et al., 2012 ).
Among various species, ASR genes are expressed in different organs,
such as the fruits of tomato, pomelo, apricot, melon, grape, and strawberry
( Canel et al., 1995 ; Chen et al., 2011 ; Iusem et al., 1993 ; Mbeguie-A-Mbe-
guie et al., 1997 ); the roots, leaves, and seedlings of tomato, rice, pine, Ginkgo
biloba , and maize ( Amitai-Zeigerson et al., 1994 ; Cakir et al., 2003 ; Chang
et al., 1996 ; Hong et al., 2002 ; Liu et al., 2010 ; Riccardi et al., 1998 ; Shen
et al., 2005 ; Vaidyanathan et al., 1999 ; Yang et al., 2004 ); the leaves, stems,
and tubers of potato ( Frankel et al., 2007 ; Silhavy et al., 1995 ); developing
tomato seeds ( Maskin et al., 2008 ); and pollen of lily ( Huang et al., 2000 ;
Wang et al., 1998 ). Although the Asr gene may be expressed in different
organs under different conditions, the lily Asr is pollen-specific and is only
expressed during the maturation drying stage of anther/pollen develop-
ment ( Huang et al., 2000 ; Wang et al., 1998 ).
3.1.2. Gene Polymorphism and Adaptation
The lily Asr gene structure consists of two exons separated by one intron
( Yang et al., 2008 ). The result is consistent with four mAsr genes and other
Asr sequences from various species ( Henry et al., 2011 ). All Asr genes typi-
cally have two exons, one intron structure, and their characteristic ABA/
water-deficit stress (WDS) domain. In most species, Asr genes belong to a
small gene family. The number of plant Asr genes available in plant genome
varies from one in grape ( Cakir et al., 2003 ), at least four in banana ( Henry
et al., 2011 ), six in rice ( Philippe et al., 2010 ), nine in maize ( Virlouvet et al.,
2011 ) and four in pine and tomato ( Chang et al., 1996 ; Frankel et al., 2007 ).
Recently, Fischer et al. (2011) discovered a new member of the gene fam-
ily, Asr5 , in tomato. The comparison of the sequences from different species
suggests that family members from a single species are more closely related
to each other than to Asr members from other species ( Carrari et al., 2004 ;
Philippe et al., 2010 ). This observation suggests that Asr genes may originate