SEQUENCING, EXPRESSION PATTERN AND RFLP-MAPPING OF A SENESCENCE-ENHANCED CDNA FROM ZEA-MAYS WITH HIGH HOMOLOGY TO ORYZAIN-GAMMA AND ALEURAIN

Sequence analysis of a 1.4 kb clone from a cDNA library of senescing Z ea mays leaves reveals an open reading frame for a 360 amino acid prot ein. Both the DNA and deduced amino acid sequences are highly homologo us to the cysteine proteinases oryzain gamma and aleurain. Northern an alysis demonstrates that the corresponding RNA level increases during natural leaf senescence, seedling germination and in chilling of toler ant maize lines, but decreases in a sensitive line. The mRNA level als o decreases in regreening leaves, in dark-induced senescence and in nu trient or water stress. Southern and RFLP analysis provide evidence th at the gene has two copies, on chromosomes 2 and 7.