A pair of homoeolog ClpP5 genes underlies a virescent yellow‐like mutant and its modifier in maize

Abstract

SUMMARYGene-background interaction is a commonly observed phenomenon in many species, but the molecular mechanisms of such an interaction is less well understood. Here we report the cloning of a maize mutant gene and its modifier. A recessive mutant with a virescent yellow-like (vyl) phenotype was identified in an ethyl methanesulfonate-mutagenized population derived from the maize inbred line B73. Homozygous mutant maize plants exhibited a yellow leaf phenotype after emergence but gradually recovered and became indistinguishable from wild-type plants after approximately 2 weeks. Taking the positional cloning approach, the Chr.9_ClpP5 gene, one of the proteolytic subunits of the chloroplast Clp protease complex, was identified and validated as the candidate gene for vyl. When introgressed by backcross into the maize inbred line PH09B, the mutant phenotype of vyl lasted much longer in the greenhouse and was lethal in the field, implying the presence of a modifier(s) for vyl. A major modifier locus was identified on chromosome 1, and a paralogous ClpP5 gene was isolated and confirmed as the candidate for the vyl-modifier. Expression of Chr.1_ClpP5 is induced significantly in B73 by the vyl mutation, while the expression of Chr.1_ClpP5 in PH09B is not responsive to the vyl mutation. Moreover, expression and sequence analysis suggests that the PH09B Chr.1_ClpP5 allele is functionally weaker than the B73 allele. We propose that functional redundancy between duplicated paralogous genes is the molecular mechanism for the interaction between vyl and its modifier.

Metabolic Flux Redirection and Transcriptomic Reprogramming in the Albino Tea Cultivar ‘Yu-Jin-Xiang’ with an Emphasis on Catechin Production

“…Natural high light shining upon pale leaves in spring led to a more extreme pale phenotype, whereas reduced light intensity through shading resulted in the rapid greening of leaf color of ‘YJX’. Similar light dependent leaf phenotypic changes have been reported previously in maize and Arabidopsis3435. Our data revealed that the non-shaded pale leaves of ‘YJX’ contained aberrant chloroplasts with undeveloped thylakoid membranes and significantly reduced chlorophylls and total carotenoids, both of which play crucial roles in photosystem assembly and, light-harvesting and the latter in photo-protection in chloroplasts3637, were found in PL compared to SL of ‘YJX’.…”

Fine Mapping of Virescent Leaf Gene v-1 in Cucumber (Cucumis sativus L.)

“…Chlorophyll a was reduced more than chlorophyll b (Table 1). The malfunctioning chloroplast and reduced chlorophyll biosynthesis in yellow young leaves seem to be a common feature for many temperature-dependent virescent mutants such as those found in Arabidopsis [20], cotton [32]; rice [7,18,26,33,34,35,36,37,38], maize [39], wheat [40], and apple [41]. Biswal et al [42] showed that the biosynthesis of chlorophyll a is closely linked to chloroplast development.…”

“…Most of these genes function in chlorophyll biosynthesis and catabolism, or in the developmental regulation of chloroplast, in the metabolism of carotenoids [26,33,34,35,36]. In Arabidopsis [44], rice [36], and maize [39], several virescent mutants were due to nucleotide changes in the chloroplast Clp protease complex which play important roles in plastid development.…”

Large-scale genetic analysis of chloroplast biogenesis in maize

“…The PML collection was assembled as a tool to deeply sample the 133 complement of nuclear genes required for the biogenesis of photosyn-134 thetically competent chloroplasts in plants. The collection consists of 135 2000 independently arising mutants that were selected from Mu- 136 active maize lines based on seedling chlorophyll deficiency (pale 137 green, albino, yellow, virescent, etc.) or an hcf phenotype.…”