Overexpression of mitochondrial genes in alloplasmic common wheat with a cytoplasm of wheatgrass (Agropyron trichophorum) showing depressed vigor and male sterility

Abstract

An alloplasmic hybrid (nucleus-cytoplasm hybrid) of common wheat (Triticum aestivum) with a cytoplasm of wheatgrass (Agropyron trichophorum) shows highly depressed vigor and complete male sterility. The presence of one short-arm telocentric homeologous group 1 chromosome (telosome) of the cytoplasm donor, however, restores normal vigor and male fertility of the hybrid. To study role(s) of the telosome on vigor/fertility restoration, mitochondrial genome organization and gene expression were compared among seedlings of the alloplasmic line showing depressed vigor, the corresponding restored line having a pair of the telosomes, and a euplasmic nuclear donor as control. No differences were detected in the mitochondrial genome structure between the depressed line and the restored line. Northern blot analysis using ten mitochondrial genes as probes showed no differences in transcript size and number between the depressed and restored lines, although clear differences were found in size of the major transcripts of two genes (cob and orf25) between the alloplasmic lines and the euplasmic control. Steady-state transcript levels were higher in the depressed line than in the other lines for all the mitochondrial genes analyzed including rrn18&5 when the same amount of mitochondrial RNA was loaded. The amount of rrn18&5 transcript in the total cellular RNA, however, did not differ among the lines. Run-on transcription analysis demonstrated markedly elevated transcriptional activities of all the mitochondrial genes analyzed in the depressed line based on unit amount of mitochondrial DNA, RNA and protein. The presence of Agropyron telosomes apparently normalized the level of mitochondrial transcription. These observations suggest either direct or indirect association of the observed mitochondrial gene overexpression with the depressed vigor and male sterility of the alloplasmic hybrid.

Overexpression of mitochondrial genes is caused by interactions between the nucleus of Brassica rapa and the cytoplasm of Diplotaxis muralis in the leaves of alloplasmic lines of B. rapa

“…Therefore, it is possible that the abnormal expression of mitochondrial genes could lead to a significant consumption of energy or unbalanced energy account, thus causing CMS. The greater accumulation of mitochondrial mRNA in alloplasmic CMS lines reported in Suzuki et al (1995) is consistent with the results obtained in the present study. On the other hand, the young buds of three alloplasmic lines of Brassica rapa had reduced mRNA accumulation of the nad3 gene compared to Diplotaxis muralis (Yamasaki et al 1998).…”

“…The expression of atpA, coxI, coxII, coxIII, and nad5 mRNA is greater in alloplasmic CMS wheat that carries the cytoplasm of Agropyron trichophorum than in euplasmic wheat or plants with restored fertility (Suzuki et al 1995). This alloplasmic CMS wheat also shows higher respiratory activity and higher cytochrome c oxidase activity compared to euplasmic wheat and plants with restored fertility (Nakamura et al 1991a(Nakamura et al , 1991b.…”

Study of mitochondrial genomes of allopllasmic recombinant wheat lines constructed on the basis of barley-wheat hybrids

“…In the work cited above [10], we analyzed sterile and self-fertile plants of alloplasmic lines with nuclear genomes that did not contain fragments of the barley (5,6,7,8,9), lines L-29, L-31, L-26, L-27, and L-36, respectively.…”

“…The best studied type of the phenotypic expression of heteroplasmy in plants is cytoplasmic male sterility (CMS), which is often associated with the presence and expression of novel gene variants generated by structural rearrangements in mitochondrial DNA [7]. Nuclear fertility-restoring genes may be involved in the regulation of the relative number of mitochondrial DNA (mtDNA) molecules connected with plant fertility or sterility [7,8]. In addition, the possible reason for the appearance of heterogeneity of the mitochondrial genome in distant hybrids and their backcross progeny may be a disturbance in inheritance of maternal type typical for the majority of higher plants and the possibility of mtDNA transmission from both parents [9].…”

Interspecific incompatibility in wide hybridization of plants and ways to overcome

“…В зависи-мости от ядерно-цитоплазматических комбинаций у ал-лоплазматических линий могут происходить нарушения клеточного развития, связанные с высокой частотой хро-мосомных аномалий в соматических клетках, приводящих к гибели клеток, подавлению роста и развития растений (Бадаева и др., 2006). Кроме того, у аллоплазматических линий отмечают задержку сроков созревания, проявление ЦМС, а также формирование беззародышевых или мор-щинистых семян, изменения в морфологии семядолей и листьев (Jiang et al, 1993;Suzuki et al, 1995), в структуре и окраске цветков (Farbos et al, 2001).…”