Chromosome 5 contains the psi2 locus and the gene responsible for the psi2 phenotype.

(A) Rough mapping has located the psi2 mutation between markers LFY3 and g2368 in the C24 ecotype. Transposition of a mapped Ds-element present in the line Ds-392-13 (No-0 ecotype) was induced to identify the PSI2/AtPP7 gene. The Ds sequences in psi2-DS1 and psi2-DS2 plants allelic to psi2-1 has reinserted in the region corresponding to P1 clone MGI19. (B) RNA gel blot analysis of total RNA extracted from WT and psi2 mutants. The expression of the MGI19.6 gene corresponding to the AtPP7 gene was absent in the DS1 and DS2-transposon-induced psi2 mutant. Each line contained 20 µg RNA.