A valine residue deletion in ZmSig2A, a sigma factor, accounts for a revertible leaf-color mutation in maize

A nuclear-encoded sigma(σ) factor is essential for the transcriptional regulation of plant chloroplastencoded genes. Five putative maize r factors have been identified by database searches, but their functions are unknown. We report a maize leaf color mutant etiolated/albino leaf 1(eal1) that was derived from space mutation breeding. The eal1 mutant displays etiolated or albino leaves that then gradually turn to normal green at the seedling stage. The changes in eal1 leaf color are associated with changes in photosynthetic pigment content and chloroplast development. Map-based cloning revealed that a single amino-acid deletion changing Val_(480)-Val_(481)-Val_(482) to Val_(480)-Val_(481), in the C-terminal domain σ_(4) of the putative σ factor ZmSig2A, is responsible for the eal1 mutation. In comparison with the expression level of the wild-type(WT) allele ZmSig2A^(+) in WT plants, much higher expression of the mutant allele ZmSig2A^(⊿V) in eal1 plants was detected before the eal1 plants turned to normal green. ZmSig2A shows the highest similarity to rice OsSig2A and Arabidopsis SIG2. Ectopic expression of ZmSig2A^(+) or ZmSig2A^(⊿V) driven by the cauliflower mosaic virus 35 S promoter rescued the pale green leaf of the sig2 mutant, but ectopic expression of ZmSig2A^(⊿V) driven by the SIG2 promoter did not. We propose that the Val deletion generated a new weak allele of ZmSig2A that cannot completely abolish the ZmSig2A function. Some genes involved in chloroplast development and photosynthesis-associated nuclear genes showed significant expression differences between eal1 and WT plants. We conclude that ZmSig2A encoding a r factor is essential for maize chloroplast development. The eal1 mutant with a weak allele of ZmSig2A represents a valuable genetic resource for investigating the regulation of ZmSig2A-mediated chloroplast development in maize.The eal1 mutation may be useful as a marker for early identification and elimination of false hybrids or transgene transmission in the application of genetic male sterility to commercial hybrid seed production.

1-DE/MS Analysis of Proteins Related to the Spathe Color Variation in an Anthurium andraeanum Mutant

[Objectives] This study was conducted to explore the color variation mechanism of Anthurium andraeanum spathe at the protein level. [Methods]The differential proteins of wild type and its white mutant were separated and identified by using one-dimensional gel electrophoresis and mass spectrometry( 1-DE/MS). [Results] Compared with leaves and spadices,the 1-DE patterns of two kinds of spathe proteins were significantly different,and two different bands were detected in wild type spathes and mutant spathes respectively. The four significantly differential bands were selected and analyzed by mass spectrometry,and 138,111,70 and 427 proteins were identified respectively. The results of GO functional annotation analysis showed that the molecular functions of the proteins were mainly catalytic activity and binding,and the main biological processes involved were cellular process and metabolic process. Many proteins involved in the synthesis of anthocyanins and flavonoids,sugar metabolism and some resistance proteins were screened,indicating that the spathe color difference of A. andraeanum‘Pink champion'is not only related to anthocyanin anabolism,but also regulated by various metabolic pathways. [Conclusions]The study provides a new experimental basis for elucidating the molecular mechanism of the regulation of A. andraeanum flower color.

Analysis of variation in temperature-responsive leaf color mutant lines induced from Gamma irradiation in rice(Oryza sativa L.)

Eight lines of temperature-responsive leaf colormutants induced by applying 300 Gy Gamma-ray irradiation to Thermo-sensitive genic malesterile line 2177s,were obtained through con-tinuous selection in seven generations..Theleaves of these lines started to become greenafter the fourth leaf extension,and except