Figure 1.
A. Relative sizes and structures of the genes for abasic endonucleases Ape1L, Ape2, and Arp. Diagrams show intron/exon structures, the positions of primers used to assay the identities of alleles, the locations of T-DNA inserts and, for Arp, the mis-sense mutation (*). For Ape2, only the predicted coding regions of gene model At4g36050.1 are shown. B. Relative sizes and predicted domains of the APE1L, APE2, and ARP proteins. xth, Xth exodeoxyribonuclease III; sap, DNA binding; zfp, GRF-type zinc-finger protein.
Figure 2.
Expression of Ape1L (top), Ape2 (middle), and Arp (bottom) genes.
RT-PCR used template RNAs extracted from a selection of strains. Genotype of each strain, indicated by PCR analysis of extracted DNA, is shown at the top. In each strain with a T-DNA insertion, ape1L-1, ape2-1, and arp-2, accumulation of transcript of the corresponding gene was undetectable. RNA accumulation differed among the arp-1 base-substitution strains.
Table 1.
Genotypes of progeny from the self-cross of a plant triply heterozygous for ape1L-1, ape2-1, and arp-1 and their wild-type alleles.1
Table 2.
Genotypes of progeny resulting from self-crosses of strains with various combinations of mutations in Ape1L, Ape2, and Arp.
Figure 3.
Development of ape1L-1, ape-2-1 mutant seeds.
A. Immature silique produced by self-cross of a plant heterozygous for ape1L-1 and homozygous for ape2-1. B. Cleared pre-globular stage seeds showing one normally developing seed (left) and one aberrant (right) embryo proper and suspensor phenotype from the same silique; scale bar = 80 µm. A number of seeds continue to develop to the heart stage (C) while some seeds remain at the pre-globular stage of development (arrow); scale bar = 85 µm. D. Close-up of (C) showing a seed arrested at the pre-globular stage of development; scale bar = 15 µm. By the bent cotyledon stage (E) some seeds within the same silique show no visible embryo within the central vacuole (*); scale bar = 120 µm. E, embryo proper; S, suspensor.
Table 3.
Development of ape1L-1, ape2-1 embryos in siliques at different stages of development1.
Figure 4.
Correlations between genes related to DNA repair, growth and development, and photosynthesis.
Correlations between the expression levels of genes in different organs and stages of development were calculated from the Arabidopsis Genome Expression data set in TAIR. Abbreviations: BER, genes of the base excision repair pathway: OGG, oxoguanine glycosylase (At1g21710); Fen, flap endonuclease (At5g26680); Myh, MutY homologue (adenine-DNA glycosylase, At4g12740); Arp, abasic endonuclease-redox protein (At2g41460); Ape1L, abasic endonuclease-1-like (At3g48425); Fpg, formamidopyrimidine-DNA glycosylase (At1g52500); Udg, uracil-DNA glycosylase (At3g18630); XRCC-1, X-ray repair complementing defective repair in Chinese hamster cells-1 (At1g80850); Ape2, abasic endonuclease 2 (At4g36050). GD: growth and development genes: Prc3, proteasome subunit a2 (At1g16470); Tua4, tubulin A4 (At1g04820); H2B, histone 2B (At1g07790). Ps: photosynthetic genes: RboS, ribulosebisphosphate small subunit (At1g67090); Lhcp, light harvesting chloroplast protein (At1g29910). The data set contains entries for 80 organs/stages, although not all entries have data for all genes. The 95% confidence level is ±0.18.