Convergent Loss of Awn in Two Cultivated Rice Species Oryza sativa and Oryza glaberrima Is Caused by Mutations in Different Loci.
A long awn is one of the distinct morphological features of wild rice species. This organ is thought to aid in seed dispersal and prevent predation by animals. Most cultivated varieties of Oryza sativa and Oryza glaberrima, however, have lost the ability to form long awns. The causal genetic factors responsible for the loss of awn in these two rice species remain largely unknown. Here, we evaluated three sets of chromosome segment substitution lines (CSSLs) in a common O. sativa genetic background (cv. Koshihikari) that harbor genomic fragments from Oryza nivara, Oryza rufipogon, and Oryza glaberrima donors. Phenotypic analyses of these libraries revealed the existence of three genes, Regulator of Awn Elongation 1 (RAE1), RAE2, and RAE3, involved in the loss of long awns in cultivated rice. Donor segments at two of these genes, RAE1 and RAE2, induced long awn formation in the CSSLs whereas an O. sativa segment at RAE3 induced long awn formation in O. glaberrima. These results suggest that the two cultivated rice species, O. sativa and O. glaberrima, have taken independent paths to become awnless.
Bioscience and Biotechnology Center, Nagoya University, Furo-cho, Chikusa, Nagoya, Aichi 464-8601, Japan.
Tomoyuki
T
Furuta
Bioscience and Biotechnology Center, Nagoya University, Furo-cho, Chikusa, Nagoya, Aichi 464-8601, Japan.
Norio
N
Komeda
Bioscience and Biotechnology Center, Nagoya University, Furo-cho, Chikusa, Nagoya, Aichi 464-8601, Japan.
Kenji
K
Asano
Bioscience and Biotechnology Center, Nagoya University, Furo-cho, Chikusa, Nagoya, Aichi 464-8601, Japan.
Kanako
K
Uehara
Bioscience and Biotechnology Center, Nagoya University, Furo-cho, Chikusa, Nagoya, Aichi 464-8601, Japan.
Rico
R
Gamuyao
Bioscience and Biotechnology Center, Nagoya University, Furo-cho, Chikusa, Nagoya, Aichi 464-8601, Japan.
Rosalyn B
RB
Angeles-Shim
Bioscience and Biotechnology Center, Nagoya University, Furo-cho, Chikusa, Nagoya, Aichi 464-8601, Japan.
Keisuke
K
Nagai
Bioscience and Biotechnology Center, Nagoya University, Furo-cho, Chikusa, Nagoya, Aichi 464-8601, Japan.
Kazuyuki
K
Doi
Department of Plant Breeding and Genetics, Cornell University, Ithaca, New York 14853-1901.
Diane R
DR
Wang
Plant Breeding Laboratory, Kyushu University, Higashi-ku, Fukuoka 812-8581, Japan.
Hideshi
H
Yasui
Plant Breeding Laboratory, Kyushu University, Higashi-ku, Fukuoka 812-8581, Japan.
Atsushi
A
Yoshimura
National Institute of Agrobiological Sciences, Tsukuba, Ibaraki 305-8634, Japan.
Jianzhong
J
Wu
Department of Plant Breeding and Genetics, Cornell University, Ithaca, New York 14853-1901 srm4@cornell.edu ashi@agr.nagoya-u.ac.jp.
Susan R
SR
McCouch
Bioscience and Biotechnology Center, Nagoya University, Furo-cho, Chikusa, Nagoya, Aichi 464-8601, Japan srm4@cornell.edu ashi@agr.nagoya-u.ac.jp.
Motoyuki
M
Ashikari
D019143:Evolution, Molecular; D056426:Genetic Loci; D018745:Genome, Plant; D009154:Mutation; D012275:Oryza / Q000235:genetics*; D012639:Seeds / Q000235:genetics*
African rice; Asian rice; CSSLs; awn; domestication