http://reply.papertrans.cn/2/168/16737/16737-31.png
http://reply.papertrans.cn/2/168/16737/16737-32.png
http://reply.papertrans.cn/2/168/16737/16737-33.png
http://reply.papertrans.cn/2/168/16737/16737-34.png
Submitted on: 17 February 1998.
Revised on: 21 April 1998.
Accepted on: 05 June 1998.
___________________JOURNAL OF EXPERIMENTAL BOTANY
http://reply.papertrans.cn/2/168/16737/16737-36.png