Chloroplast genome aberration in micropropagation-derived albino Bambusa edulis mutants, ab1 and ab2

Abstract

Two albino mutants (ab1 and ab2) have been derived from long-term shoot proliferation of Bambusa edulis. Based on transmission electronic microscopy data, the chloroplasts of these mutants were abnormal. To study the mutation of gene regulation in the aberrant chloroplasts, we designed 19 pairs of chloroplast-encoded gene primers for genomic and RT-PCR. Only putative NAD(P)H-quinone oxidoreductase chain 4L (ndhE; DQ908943) and ribosomal protein S7 (rps7; DQ908931) were conserved in both the mutant and wild-type plants. The deletions in the chloroplast genome of these two mutants were different: nine genes were deleted in the chloroplast genomic aberration in ab1 and 11 genes in ab2. The chloroplast genes, NAD(P)H-quinone oxidoreductase chain 4 (ndhD; DQ908944), chloroplast 50S ribosomal protein L14 (rpl14; DQ908934), and ATP synthase beta chain (atpB; DQ908948) were abnormal in both mutants. The gene expressions of 18 of these 20 genes were correlated with their DNA copy number. The two exceptions were: ATP synthase CF0 A chain (atpI; DQ908946), whose expression in both mutants was not reduced even though the copy number was reduced; ribosomal protein S19 (rps19; DQ908949), whose expression was reduced or it was not expressed at all even though there was no difference in genomic copy number between the wild-type and mutant plants. The genomic PCR results showed that chloroplast genome aberrations do occur in multiple shoot proliferation, and this phenomenon may be involved in the generation of albino mutants.

Somatic embryogenesis and organogenesis in apomictic and sexual Brachiaria brizantha

“…Kowata et al (1995) demonstrated that rice plantlets recovered from 1-month-old induced calluses were green while those obtained from 11-month-old calluses were 100% albino. Moreover, Artunduaga et al (1988) tested three common bermudagrass varieties and obtained 90% albino plants, while the characterization of two micropropagation-derived albino Bambusa edulis mutants demonstrated aberrations in their chloroplast genomes, causing reduction or absence of thylakoids, accumulating the lipids in plastoglobules (Liu et al 2007). B brizantha seems to be sensitive to long exposure to 2,4 D in culture, possibly responsible for the high frequency of albinism observed in this grass species in 4-month-old embryogenic callus culture.…”

Identification of genes involved in spontaneous leaf color variation in Pseudosasa japonica

“…To do so, they employed a combination of suppressive subtractive hybridization (SSH) and microarray hybridization analyses, which mainly involved the stress response and photaesthesia. Subsequent research further showed that three chloroplast genes, NAD(P)H-quinone oxidoreductase chain 4, chloroplast 50S ribosomal protein L14, and ATP synthase beta chain, were supposed candidate genes for the albino mutants (Liu et al, 2007). However, current bamboo leaf color variation mechanisms were mainly derived from research on bamboo albino mutants from tissue culture lines.…”

Establishment of a cDNA library from Bambusa edulis Murno in vitro-grown shoots

“…Based on this classification and protein sequence similarity, we identified those genes that were metabolism-related and specific to photosynthesis for further investigation. The selection of this group of genes was based on work of Liu et al (2007) and Lin et al (2008), who used a genomic PCR approach in their study of an albino mutant derived from tissue culture and determined that the albino mutant was the result of aberrations in the chloroplast DNA. Base on the protein sequence similarity, fourteen chloroplastencoded genes were identified in our cDNA library, including pyruvate dehydrogenase E1 component beta subunit (pdhB), NADH dehydrogenase subunit 5 (ndhF), photosystem I assembly protein (ycf3), DNA-directed RNA polymerase beta subunit (rpoC1), ribosomal protein S19 (rps19), ribosomal protein S3 (rps3), ribosomal protein L16 (rpl16), RNA polymerase beta subunit (rpoB), ribosomal protein S12 (rps12), ribosomal protein S11 (rps11), ATP synthase CF0 C chain (atpH), ATP synthase CF0 A chain (atpI), ribulose 1,5-bisphosphate carboxylase/oxygenase large subunit (rbcL), and photosystem II 43-kDa protein (psbC).…”

“…There are nearly 3000 chloroplast proteins synthesized in precursor form on cytosolic ribosomes and then targeted post-translationally to chloroplasts (Martin et al 1998). The chloroplast genome of the B. edulis albino mutant has been shown to be aberrated (Liu et al 2007;Lin et al 2008) and, consequently, the chloroplasts of the albino mutant were also abnormal. We therefore propose that the photosynthesis-related genes were down-regulated in the albino mutant.…”

“…Long-term bamboo tissue culture systems are also not without disadvantages, one of which is the appearance of anomalies, such as the production of albino mutants (Lin and Chang 1998). In our laboratory, the albino mutants that have appeared spontaneously during tissue culture have been demonstrated by an aberrant chloroplast genome (Liu et al 2007;Lin et al 2008). It is well known that many chloroplastic genes are located in the nuclear genome (Martin et al 1998).…”