玉米雄性不育资源的发掘与利用

植物雄性不育是指植物雄性生殖器官不能产生正常有功能花粉的现象.玉米(Zea mays L.)是重要的粮食作物之一,也是较早利用杂种优势的作物之一.当前,生产上广泛种植的玉米品种类型主要是单交种.我国玉米杂交种的播种面积常年稳定在6.2亿亩左右,年用种量10亿公斤以上,常年制种面积高达250多万亩.利用传统的人工去雄或机...     

Genetics of fertility restoration in the C-group of cytoplasmic male sterility in maize

The genetics of fertility restoration of cms-C group cytoplasm of maize was studied using crosses involving stable maintainer lines and lines that restored full pollen fertility. Pollen fertility in the sources of cms-C sterile cytoplasms studied was restored by a single dominant restorer (Rf4) gene. The fertility restoration was sporophytic. Allelism tests among five restorer lines showed that they all apparently carried the same alleles (Rf4 Rf4). Similar tests also demonstrated that seven nonrestoring maintainer lines had apparently the same genotype (rf4 rf4), although a partial "late break" of fertility was observed at low levels in some maintainer crosses. Comparative studies among different cms-C sources (C, Bb, ES, PR and RB) indicated that similar inheritance of fertility restoration was involved. The data indicated that a single, dominant Rf gene is involved in the restoration of several C-group cytoplasms, at least in the lines studied here. This is the first single-gene, sporophytic restorer system described in maize to date.     

Molecular-genetic analysis of maize mitochondrion regions associated with cytoplasmic male sterility

Molecular-genetic polymorphism of 86 world and Ukrainian breeding maize lines with S-, C- and T-types of cytoplasmic male sterility (CMS) and with normal wild type mitochondrion has been researched via mitochondrion regions PCR-analysis. Molecular marker system allowed to detect and identify definite type of CMS within maize lines, as well as to differentiate lines with definite CMS type either from lines with another CMS type or from normal wild type cytoplasm lines.     

Alterations in mitochondria associated with cytoplasmic and nuclear genes concerned with male sterility in maize

Summary Mitochondria isolated from etiolated shoots of a range of maize genotypes with the Texas cytoplasm conferring cytoplasmically-inherited male sterility, are sensitive to a pathotoxin isolated from Helmintho-sporium maydis, race T. The pathotoxin inhibits oxidation of ketoglutarate and malate and stimulates NADH oxidation. The time taken for the pathotoxin to induce these changes is a measure of the sensitivity of the mitochondria to the pathotoxin. A range of nine different pairs of genotypes, each pair differing principally in the presence of nuclear male fertility restorer alleles has been compared in their sensitivity to pathotoxin. In every case the line carrying the restorer alleles is more resistant to the pathotoxin. The restored genotypes can be quantitatively arranged into groups which correspond to the four different sources of the restorer genes in these lines. It is suggested that the restorer genes cause changes in mitochondria, which modify the functional aberration introduced by the cytoplasmically-inherited mutation causing sterility.     

玉米CMS-C同质异核不育系育性恢复的遗传研究

玉米是最早利用细胞质雄性不育系生产杂交种的作物之一,C型细胞质雄性不育系（C-type cytoplasmic male sterile, CMS-C）在杂交种生产中具有重要的作用,育性恢复的稳定性直接影响其应用价值。然而,玉米CMS-C的育性恢复机理复杂,且至今仍不明确。为进一步探究玉米CMS-C育性恢复的影响因素,本研究以玉米CMS-C同质异核不育系C48-2、C黄早四和C478为母本,分别与测验系18白、自330、5022以及恢复系A619组配杂交获得F₁。其中育性恢复F₁通过自交获得F₂,并以育性恢复F₁为父本分别给育性保持F₁授粉,组配双交群体,共获得4个F₂群体,6个双交群体。同时以不育系C48-2、C黄早四和C478为母本,各自的保持系48-2、黄早四和478为父本杂交组配不完全双列杂交F₁。将所有杂交组合的F₁、F₂以及双交组合群体分别在不同年份不同地点种植观察,通过植株田间育性调查并结合室内花粉镜检鉴定育性表现。结果表明：1) 同一测验系对玉米CMS-C同质异核不育系的恢保关系不同,暗示不育系的核背景参与调控育性恢复表现;2) 在不同年份不同地点对(C48-2×A619) F₂群体进行种植观察,发现不同环境下F₂群体可育株与不育株的分离比均符合15∶1,但在云南种植的可育株的育性级别主要为Ⅲ和Ⅳ级,而在四川种植的可育株的育性级别主要为Ⅴ级,表明环境对恢复系A619恢复后代的育性表现有影响;3) 通过恢保关系测定发现18白不能恢复C478,48-2也不能恢复C478,但双交群体[(C478×18白) F_1S×(C48-2×18白) F_1F]后代却出现了可育株与不育株的分离;同理,双交群体[(C48-2×自330) F_1S×(C478×自330) F_1F]的后代也出现了可育株与不育株的分离。因此,本文推测C48-2、C478核背景中存在微效恢复基因,这些微效基因与18白、自330中的微效恢复基因通过杂交聚合后能使C478、C48-2的育性恢复,暗示玉米CMS-C的育性恢复呈现一定的剂量效应。这些结果为进一步认识玉米CMS-C育性恢复的复杂性和多样性奠定了基础,为深入研究玉米CMS-C育性恢复机理以及加快CMS-C在不育化制种中的应用提供重要参考。     

Possible mitochondrial involvement in mechanism of cytoplasmic male sterility in maize (Zea mays L.)

The mechanism of cytoplasmic male sterility was investigated in maize by isolating mitochondria from seedlings and various anther stages and analyzing cytochrome oxidase and succinic dehydrogenase biochemically and electrophoretically. Sterile anthers exhibited a lack of biochemical activity and fewer isozymatic bands for cytochrome oxidase. No apparent differences were detected biochemically or electrophoretically between fertile and sterile anthers for succinate dehydrogenase.     

QTL involved in the partial restoration of male fertility of C-type cytoplasmic male sterility in maize

Partial restoration of male fertility limits the use of C-type cytoplasmic male sterility (C-CMS) for the production of hybrid seeds in maize. Nevertheless, the genetic basis of the trait is still unknown. Therefore, the aim to this study was to identify genomic regions that govern partial restoration by means of a QTL analysis carried out in an F₂ population (n = 180). This population was derived from the Corn Belt inbred lines B37C and K55. F₂BC₁ progenies were phenotyped at three locations in Switzerland. Male fertility was rated according to the quality and number of anthers as well as the anthesis-silking interval. A weak effect of environment on the expression of partial restoration was reflected by high heritabilities of all fertility-related traits. Partial restoration was inherited like an oligogenic trait. Three major QTL regions were found consistently across environments in the chromosomal bins 2.09, 3.06 and 7.03. Therefore, a marker-assisted counter-selection of partial restoration is promising. Minor QTL regions were found on chromosomes 3, 4, 5, 6 and 8. A combination of partial restorer alleles at different QTL can lead to full restoration of fertility. The maternal parent was clearly involved in the partial restoration, because the restorer alleles at QTL in bins 2.09, 6.04 and 7.03 originated from B37. The three major QTL regions collocated with other restorer genes of maize, a phenomenon, which seems to be typical for restorer genes. Therefore, a study of the clusters of restorer genes in maize could lead to a better understanding of their evolution and function. In this respect, the long arm of chromosome 2 is particularly interesting, because it harbors restorer genes for the three major CMS systems (C, T and S) of maize.     

A new source of cytoplasmic male sterility in maize induced by the nuclear gene,iojap

Summary Cytoplasmic male sterility (cms) was found in plants derived from the F₂ progeny of fertile, normal cytoplasm plants of the inbred R181 pollinated with a genetic stock carrying the recessive nuclear gene, iojap. The male sterile plants were maintained by back-crossing with the inbred W182BN which maintains all known sources of cytoplasmic male sterility. The new male sterile progeny were found to exhibit stable male sterility under field conditions in two environments. However, they were partially fertile in the hot, dry summer of 1983 at Aurora, NY. It was found that these lines were restored by lines that characteristically restore cms S group cytoplasms. Pollen phenotype studies indicated that the restoration was gametophytic in nature, also characteristic of the cms S group. Agarose gel electrophoresis of undigested mitochondrial DNA (mtDNA) from these steriles indicated that these lines have the S-1 and S-2 episomes characteristic of the cms S group. Restriction endonuclease digest patterns of mtDNA from these sterile lines digested with BamH I indicated that these steriles fit into the CA subgroup of the cms S group. The new source of cms has been designated cms Ij-1.     

A single point mutation in Ms44 results in dominant male sterility and improves nitrogen use efficiency in maize

Application of nitrogen fertilizer in the past 50 years has resulted in significant increases in crop yields. However, loss of nitrogen from crop fields has been associated with negative impacts on the environment. Developing maize hybrids with improved nitrogen use efficiency is a cost‐effective strategy for increasing yield sustainably. We report that a dominant male‐sterile mutant Ms44 encodes a lipid transfer protein which is expressed specifically in the tapetum. A single amino acid change from alanine to threonine at the signal peptide cleavage site of the Ms44 protein abolished protein processing and impeded the secretion of protein from tapetal cells into the locule, resulting in dominant male sterility. While the total nitrogen (N) content in plants was not changed, Ms44 male‐sterile plants reduced tassel growth and improved ear growth by partitioning more nitrogen to the ear, resulting in a 9.6% increase in kernel number. Hybrids carrying the Ms44 allele demonstrated a 4%–8.5% yield advantage when N is limiting, 1.7% yield advantage under drought and 0.9% yield advantage under optimal growth conditions relative to the yield of wild type. Furthermore, we have developed an Ms44 maintainer line for fertility restoration, male‐sterile inbred seed increase and hybrid seed production. This study reveals that protein secretion from the tapetum into the locule is critical for pollen development and demonstrates that a reduction in competition between tassel and ear by male sterility improves grain yield under low‐nitrogen conditions in maize.     

Variable presence of the 1.94kb mitochondrial plasmid in maize S cytoplasm and its relationship to cytoplasmic male sterility

Mitochondrial DNA (mtDNA) was isolated from over 100 different maize nucleo-cytoplasmic combinations. DNA preparations were assayed for the presence of the 1.94kb mitochondrial plasmid by agarose gel electrophoresis and hybridization to a recombinant clone of the plasmid. The plasmid was present in all tested inbreds which carried N, male fertile, cytoplasm or the cytoplasmically male sterile (cms) groups,cms-T andcms-C. However, members of thecms-S group differed with respect to the presence of the plasmid. Cytoplasms I, J and S possessed the plasmid, whereas cytoplasms B, CA, D, G, H, IA, ME, ML, PS, RD and VG did not.Cms-S group lines which had spontaneously reverted to fertility (nuclear and cytoplasmic revertants) did not exhibit a concomitant change in 1.94kb plasmid levels, although all such lines showed the previously reported alteration in levels of the linear mtDNAs, S1 and S2. The presence or absence of the plasmid was not correlated with (i) frequency of reversion to fertility, (ii) the degree of male sterility expressed, (iii) the presence or absence of standard nuclear restorer to fertility genes and (iv) nuclear genotype. Latin American races carrying RU cytoplasm possessed the plasmid, as did sweet corn varieties. The relevance of the data tocms and evolution of thecms-S group is discussed.     

AFLP and PCR-based markers linked to Rf3, a fertility restorer gene for S cytoplasmic male sterility in maize

The Rf3 gene restores the pollen fertility disturbed by S male sterile cytoplasm. In order to develop molecular markers tightly linked to Rf3, we used amplified fragment length polymorphism (AFLP) technique with near isogenic lines (NILs) and bulk segregant analysis (BSA). A BC₁F₁ population from a pair of NILs with different Rf3 locus was constructed and 528 primer combinations was screened. A linkage map was constructed around the Rf3 locus, which was mapped on the distal region of chromosome 2 long arm with the help of SSR marker UMC2184. The closest marker E7P6 was 0.9 cM away from Rf3. Marker E3P1, 2.4 cM from Rf3, and E12M7, 1.8 cM from Rf3, were converted into a codominant CAPS and a dominant SCAR marker, and designated as CAPSE3P1 and SCARE12M7, respectively. These markers are useful for marker-assisted selection and map-based cloning of the Rf3 gene.     

Cytoplasmic male sterility in barley

The maternal male sterile barley msm1 with or without a dominant gene, Rfmla, which restores male fertility, was studied. Determined with SDS-PAGE, the polypeptide pattern in the anthers of unrestored msm1 plants remains juvenile in the middle of anther development, two major zones being absent or weak. At the stage when anther development stops in msm1 plants, the anther proteins appear to be hydrolyzed to short-chain peptides. Restored plants, heterozygous for the restorer gene, Rfmla, behaved like the near-isogenic normal barley, cv. Adorra. The total leaf protein pattern of young leaf tissue and the chloroplastidic membrane protein pattern are normal in msm1 cytoplasm when studied with this technique. Chlorophyll b is unnecessary for restoration by Rfmla, though the restored plants have a lower chlorophyll a/b ratio than an unrestored plant in the mature stem leaf. Mature stem leaf pieces of unrestored msm1 plants were induced to senesce with 20 mM NaCl solution. This senescence was inhibited by exogenous kinetin. Leaf pieces of restored msm1 plants or those of near-isogenic normal barley behaved in the same way in the NaCl solution as in distilled water. Many features of the physiology of restored plants can be explained as the functions of cytokinins. Kernels of male sterile plants have a more rapid root elongation at germination than near-isogenic normal barley.     

Cytoplasmic male sterility in barley

Summary Restoration in the msm1 cytoplasm of barley (Hordeum vulgare L. s.l.) was studied from the standpoint of population biology and physiological effects on kernel protein. Restorer genes of 82 accessions of wild barley (ssp. spontaneum) from Israel were determined. 38% of the accessions were maintainers of sterility, 48% were partial restorers, and 14% were restorers. Fourteen dominant restorer genes are described, and evidence for three cases of allelism to Rfm1a is presented. The restorer accessions and their designated gene symbols are: PI 282636 (Rfm,,e), PI 282637 (Rfm,f), PI 282646 (Rfm,,g), PI 284742 (Rfm,h), PI 284743 (Rfm,,i), PI 284753 (Rfm,,j), PI 284755 (Rfm1d), PI 296838 (Rfm,,k), PI 296850 isolate 16/7 (Rfm,,l), PI 296853 (Rfm,,m), PI 296856 (Rfm1b), PI 296899 (Rfm,,n), PI 296919 (Rfm1c), PI 296944 (Rfm,,o). PI 296850 was found to contain both a restorer and a non-restorer genotype. None of the PI accessions with a restorer gene is a carrier of an msm1-type male sterilizing cytoplasm. In the present sample, plants with restoration ability occurred with a higher frequency in the material from the Judean Foothills than that from the other regions of Israel. The greater adaptive value of plants with restoration ability on certain soil associations in semiarid and subhumic climate is suggested. The considerable frequency of restorers and partial restorers in male fertile cytoplasm suggests that the restoration system evolved before the msm1-type cytoplasm. In the nuclear genotype near-isogenic with either Adorra or Risø 1508, msm1 plants heterozygous for Rfm1a produced 98.6 or 98.5% of the protein content in the respective recurrent pollen parent varieties. The amino acid compositions of the derivatives differed little from those of the varieties. In the derivatives, a consistent decrease was found in tryptophan, and consistent increases in isoleucine, phenyalanine, lysine, histidine, and arginine. In relation to glucose consumption, the bioenergetic cost calculated for the amino acid patterns found in the restored msm1 derivatives was slightly higher than that for the near-isogenic pollen parent varieties. The results suggest that the restorer gene in the heterozygous state normalizes the physiology of msm1 cytoplasm to a great extent.     

Density-related sterility in Eretmocerus mundus

While studying the reproductive capacity of Eretmocerus mundus Mercet (Hymenoptera: Aphelinidae) we found that varying numbers of females were sterile. Investigations showed that sterility occurred also in field populations, but at a very low rate. Laboratory sterility was significantly correlated with crowding of the parental females during oviposition. Whitefly hosts from which fertile of sterile females emerged did not differ in size, neither did the hind tibiae of fertile females differ in dimensions from those of sterile ones. Behavior of sterile females differed from that of the fertile ones in several parameters. They exhibited less leg drumming, used the ovipositor more frequently and for shorter durations, and changed more readily from probing to host stinging, and from a number of activities to walking. Altogether, their behavior appeared more restless and caused them to contact more hosts than fertile females. The possibility that the sterility is caused by crowding alone, or by the activity of microorganisms acting under crowded conditions, and the merits of the phenomenon for biological pest control are discussed.     

ORF355 confers enhanced salinity stress adaptability to S-type cytoplasmic male sterility maize by modulating the mitochondrial metabolic homeostasis

Moderate stimuli in mitochondria improve wideranging stress adaptability in animals, but whether mitochondria play similar roles in plants is largely unknown. Here, we report the enhanced stress adaptability of S-type cytoplasmic male sterility(CMS-S) maize and its association with mild expression of sterilizing gene ORF355. A CMS-S maize line exhibited superior growth potential and higher yield than those of the near-isogenic N-type line in saline fields. Moderate expression of ORF355 induced t...     

Cytoplasmic male sterility in barley

Summary The effect of the msm1 cytoplasm of barley (Hordeum vulgare L.) on kernel protein and lysine was studied using the near-isogenic, unrestored derivatives of seven barley varieties. With normal lysine varieties, Adorra, Bomi, CI 4362, and Hankkija's Eero, the msm1 cytoplasm produced an average of one percentage point more protein than did the normal cytoplasm of the same varieties. There was no difference between the two cytoplasms with respect to their effect on the lysine content. With high lysine varieties, Bomi Risø mutant 13, Bomi Risø mutant 1508, and CI 3947, msm1 produced almost one percentage point more protein but protein with a somewhat decreased lysine content.Induced partial spike fertility in normal Adorra was found to be associated with lysine in meal (r=–0.999), with protein in meal (r=–0.984), and with lysine in protein (r=0.941). Removal of the spikes on the secondary tillers affected both the protein and its lysine content. It is suggested that good spike fertility is an important pre-requisite when selecting high lysine and/or high protein segregants or mutants.     

Cytoplasmic male sterility in barley

Summary The associations between seedling reactions to three fungal pathogens (Puccinia hordei, Pyrenophora teres, and Rhynchosporium secalis) or between adult plant reaction to Rh. secalis and the male fertility restoration ability of msml cytoplasm were studied in about 100 accessions of Hordeum spontaneum. Significant differences in the severity of infection between classes of restoration ability were observed with two cultures of P. hordei (751 and 7,649) and with Rh. secalis on adult plants in the field. The cultures 7,432, 751 and 7,649 of P. hordei showed significant positive correlations between infection severity and restoration percentage. The culture 7,620 of P. hordei displayed a significant negative correlation. Rh. secalis (cultures 492A and 531 combined) on seedlings and the natural field infection in the 1978 season showed significant positive correlations. The accession class with the partial restoration ability of 0.1 to 5.0% of the four arbitrary classes (0.0, 0.1–5.0, 5.1–55.0, and 90.1–100%), displayed the lowest mean severity of infection in six of the eleven tests. Some frequently appearing races of these pathogens may operate as selective agents in the maintenance of restoration ability in the original spontaneum populations.