PLANT PHYSIOLOGY , Vol 101, Issue 1 217-226, Copyright © 1993 by American Society of Plant Biologists
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ENVIRONMENTAL AND STRESS PHYSIOLOGY |
Constitutive and Inducible Aerobic and Anaerobic Stress Proteins in the Echinochloa Complex and Rice
C. V. Mujer, M. E. Rumpho, J. J. Lin and R. A. Kennedy
Department of Botany and Maryland Agricultural Experiment Station, University of Maryland, College Park, Maryland 20742
Anaerobic stress resulted in a change in the protein accumulation patterns
in shoots of several Echinochloa (barnyard grass) species and Oryza sativa
(L.) (rice) as resolved by two-dimensional gel electrophoresis. Of the six
Echinochloa species investigated, E. phyllopogon (Stev.) Koss, E. muricata
(Beauv.) Fern, E. oryzoides (Ard.) Fritsch Clayton, and E. crus-galli (L.)
Beauv. are tolerant of anaerobiosis and germinate in the absence of oxygen,
as does rice. In contrast, E. crus-pavonis (H.B.K.) Schult and E. colonum
(L.) Link are intolerant and do not germinate without oxygen. Computer
analysis of the protein patterns from the four tolerant species and rice
indicated that the anaerobic response is of five classes: class 1 proteins,
enhanced under anaerobiosis (9 to 13 polypeptides ranging from 16-68 kD);
class 2 proteins, unique to anaerobiosis (1 to 5 polypeptides ranging from
17-69 kD); class 3 proteins, remained constant under aerobiosis and
anaerobiosis; class 4 proteins, prominent only in air and repressed under
anoxia (3 to 7 polypeptides ranging from 19-45 kD); and class 5 proteins,
unique to aerobiosis (1 to 4 polypeptides ranging from 18-63 kD). In the
intolerant species, E. colonum and E. crus-pavonis, no polypeptides were
enhanced or repressed under anoxia (class 1 and class 4, respectively),
whereas in the tolerant Echinochloa species and rice, a total of at least 9
to 13 anaerobic stress proteins and 4 to 7 "aerobic" proteins were noted.
Immunoblotting identified two of the major anaerobic stress proteins as
fructose-1,6-bisphosphate aldolase and pyruvate decarboxylase. Based on the
differential response of the intolerant species to anaerobiosis, we suggest
that another set of genes, whose products may not necessarily be among the
major anaerobic stress polypeptides, might confer tolerance in Echinochloa
under prolonged anaerobic stress.
