Cytogenetic Analyses of PSL1 Mutant, a Novel Low‐Temperature‐Sensitive Purple‐Striped Leaf Color Mutant in Wheat

Abstract

Low‐temperature‐sensitive leaf color mutants are valuable materials for investigating the mechanisms related to chloroplast development and chlorophyll biosynthesis under low‐temperature conditions. PSL1 is a spontaneous low‐temperature‐sensitive purple‐striped leaf mutant of wheat (Triticum aestivum L.). The progeny of PSL1 exhibited three leaf color phenotypes under low‐temperature conditions (i.e., purple and albino leaf [pur], purple‐striped and albino‐striped leaf [pst], and normal green leaf [gre]). The leaf color of pur and pst displayed normal green under high temperature conditions. The leaf color of gre remained normal green under cold or high temperatures. The critical low temperature for leaf color variations in pur and pst was ∼5°C for >35 d. The shapes of chloroplasts in the purple and albino leaf sectors were irregular in pur and pst, where the thylakoid lamellar was undeveloped and no grana formed. The chlorophyll and carotenoid contents of pur and gre were remarkably reduced in the purple and albino periods, but the anthocyanin contents accumulated greatly in the same period. The photosynthetic capacities of the flag leaves in pur, pst, and gre were the same as that in the Xinong1125 during the heading stage. Genetic analysis showed that the leaf color mutations in PSL1 in response to temperature were controlled by cytoplasmic inheritance. Quantitative real‐time polymerase chain reaction showed that the psbA and psbC genes were downregulated most in the newly developed leaf tissues in pur and pst under low temperatures. This indicated that the psbA and psbC genes may be involved in chloroplast development under low‐temperature conditions in wheat.