Detection of the time of occurrence of nondisjunction induced by the r-X1 deficiency in Zea mays L.

Genome ◽  
1987 ◽  
Vol 29 (5) ◽  
pp. 782-785 ◽  
Author(s):  
Kevin D. Simcox ◽  
Jeffery D. Shadley ◽  
David F. Weber
Keyword(s):  
Zea Mays ◽  
Key Words ◽  
Zea Mays L ◽  
Embryo Sac ◽  
Mitotic Division ◽  
Polar Nucleus ◽  
Chromosome 6 ◽  
High Frequencies ◽  
The Third ◽  
Β Carotene

The r-X1 deficiency in maize produces high frequencies of aneuploid progeny by inducing nondisjunction during embryo sac development. The purpose of this investigation was to determine the embryo sac division at which the nondisjunctive event takes place. Monosomic-6 individuals were generated by crossing r-X1 containing plants by those carrying the y-pastel-8549 allele of the Y locus on chromosome 6. A strict dosage relationship exists between the number of dominant alleles of the Y locus and the level of β-carotene in the endosperm. We found that the level of β-carotene in the endosperm of kernels containing monosomic-6 embryos was comparable with that found in endosperms with one Y allele. This indicated that they contained only one maternally contributed chromosome 6. Only nondisjunction at the second postmeiotic division could have produced such an endosperm; thus, the nondisjunctive event occurs at this division. Another endosperm type expected from nondisjunction at this same division, with three dominant Y alleles, was not found. The absence of this endosperm type suggests that the egg nucleus and the polar nucleus originating at the micropylar pole are sister nuclei that arose from the same cell at the third embryo sac mitotic division. Key words: aneuploidy, embryo sac, nondisjunction, r-X1 deficiency, Zea.

Analysis of Nondisjunction Induced by the R-X1 Deficiency during Microsporogenesis in Zea Mays L.

Genetics ◽  
1988 ◽  
Vol 119 (4) ◽  
pp. 975-980
Author(s):  
Z Y Zhao ◽  
D F Weber
Keyword(s):  
Zea Mays L ◽  
Embryo Sac ◽  
Mitotic Division ◽  
The Other ◽  
Chromosome 6 ◽  
Nucleolar Organizing Region ◽  
Sperm Nuclei ◽  
Embryo Sac Formation ◽  
And Control ◽  
Generative Nuclei

Abstract The r-X1 deficiency in maize induces nondisjunction at the second mitotic division during embryo sac formation. However, it was not known if this deficiency also induces nondisjunction during the microspore divisions. Microsporogenesis in plants lacking or containing this deficiency was compared using two approaches. First, chromosome numbers were determined in generative nuclei. Many (8.3%) of the generative nuclei in r-X1-containing plants were aneuploid; however, those from control plants were all haploid. Thus, this deficiency induces nondisjunction during the first microspore division. Second, nucleoli were analyzed in microspores. The only nucleolar organizing region in maize is on chromosome 6. If chromosome 6 underwent nondisjunction during the first microspore division, one nucleus in binucleate microspores would contain no nucleolus and the other would contain two nucleoli (or one nucleolus if the nucleoli fused). Only one (0.03%) microspore of this type was observed in control plants while 1.12% were found in r-X1-containing plants. Thus, the r-X1 deficiency induces nondisjunction of chromosome 6 during the first microspore division. However, both of the sperm nuclei in trinucleate microspores contained one nucleolus in r-X1-containing and control plants; thus, this deficiency does not induce nondisjunction of chromosome 6 (and presumably other chromosomes) during the second microspore division.

scholarly journals Biologi Stenocranus pacificus Kirkaldy (Hemiptera: Delphacidae) pada tanaman jagung (Zea mays L.) di rumah kasa

2020 ◽  
Vol 17 (2) ◽  
pp. 104
Author(s):  
Dosma Ulina Simbolon ◽  
Maryani Cyccu Tobing ◽  
Darma Bakti
Keyword(s):  
Zea Mays ◽  
Life Cycle ◽  
Sex Ratio ◽  
Zea Mays L ◽  
Instar Nymph ◽  
Fourth Instar ◽  
The Third ◽  
First Instar ◽  
Corn Plants ◽  
North Sumatra

<p><em>Stenocranus pacificus </em>Kirkaldy (Hemiptera: Delphacidae) is destructive pest on corn plants in South Lampung and it has been reported to cause corn damages in North Sumatra. The  objective of this research was to study some aspects biology of <em>S. pacificus</em> on corn plants in screenhouse. The research was conducted by observing the biology of <em>S. pacificus</em> that was reared on corn plants in screenhouse.<em> </em>The results showed that life cycle of <em>S. pacificus </em>was 38–47 (41,60 ± 3,19) days: egg was 9–11 (10,20 ± 0,79) days, the first instar nymph was 3–4 (3,70 ± 0,48) days, the second instar nymph was 3–4 (3,90 ± 0,32) days, the third instar nymph was 3–4 (3,70 ± 0,48) days, the fourth instar nymph was 3–4 (3,80 ± 0,42) days, and the fifth instar nymph was 3–4 (3,60 ± 0,52) days. Age of female was 13–17 (15,30 ± 1,34) days. It was longer than age of male which was 8–12 (10,10 ± 1,20) days. Female could produce 181–214 (197,60 ± 11,64) eggs during its life. The sex ratio was 1:1,98.</p>

MEASUREMENT OF EVAPORATION FROM SOIL BENEATH CROP CANOPIES

1983 ◽  
Vol 63 (1) ◽  
pp. 137-141 ◽  
Author(s):  
G. K. WALKER
Keyword(s):  
Zea Mays ◽  
Key Words ◽  
Leaf Area ◽  
Energy Supply ◽  
Zea Mays L ◽  
Growing Season ◽  
Soil Core ◽  
Crop Cover ◽  
Intact Soil Core ◽  
Intact Soil

Evaporation rates beneath maize canopies were measured using an intact soil core technique. Early in the growing season evaporation rates were periodically high (4.0 mm∙day−1) following rain, but declined rapidly. At full crop cover, when energy supply normally limits evaporation, significant differences in evaporation were detected between canopies with leaf area indices of 3.0 and 4.0. Key words: Evaporation measurement, energy supply, Zea mays L., leaf area, soil evaporimeter, lysimeter

NULLISOMIC ANALYSIS OF NUCLEOLAR FORMATION IN ZEA MAYS

1978 ◽  
Vol 20 (1) ◽  
pp. 97-100 ◽  
Author(s):  
David F. Weber
Keyword(s):  
Zea Mays ◽  
Chromosome Number ◽  
Zea Mays L ◽  
Diploid Species ◽  
5S Rrna ◽  
Chromosome 6 ◽  
Chromosome 2 ◽  
Nucleolar Organizing Region

When a monosomic plant of a diploid species undergoes meiosis, two haploid and two nullisomic cells are produced. Zea mays L. microspore quartet cells nullisomic for chromosome number 1, 2, 4, 6, 7, 8, 9, or 10 produced by monosomics were analyzed. Cells nullisomic for chromosome 6, as expected, do not contain a nucleolus because chromosome 6 bears the nucleolar organizing region. Cells nullisomic for chromosome 2 contain nucleoli; therefore, the 5S rRNA template on chromosome 2 is not necessary for nucleolar formation. Cells nullisomic for chromosomes 1, 4, 7, 8, 9, or 10 also contain nucleoli; thus, no factors located on these chromosomes are necessary for nulceolar formation at the quartet stage.

Postemergence control of quackgrass [Elytrigia repens (L) Nevski] with DPX-79406 in corn (Zea mays L)

1994 ◽  
Vol 74 (2) ◽  
pp. 375-381 ◽  
Author(s):  
M. E. Reidy ◽  
C. J. Swanton
Keyword(s):  
Zea Mays ◽  
Key Words ◽  
Significant Interaction ◽  
Growth Stage ◽  
Field Experiments ◽  
Zea Mays L ◽  
Optimum Dose ◽  
Corn Yield ◽  
Leaf Stage ◽  
Elytrigia Repens

Laboratory and field experiments were established to determine the optimum dose and timing of postemergence applications of DPX-79406 for quackgrass control. Four node quackgrass rhizome fragments from each biotype were grown under controlled conditions. At the three-to-four-leaf stage, quackgrass plants were sprayed with DPX-79406 and evaluated for control. A significant response of quackgrass biotypes to DPX-79406 was evident only at lower doses. In the field, quackgrass was effectively controlled by all doses of DPX-79406. Significant growth-stage effects were observed for quackgrass shoot and rhizome dry weights in the year of application and in the year following application. There was a significant interaction between year and growth stage. In 1990, quackgrass biomass was greater when DPX-79406 was applied at the two-to-three-leaf stage of quackgrass than at the four-to-five-leaf stage. In 1991, however, the opposite occurred. Within a growth stage, the 6.25 g ha−1 dose was as effective for controlling quackgrass as 18.5 g ha−1, in both years of the study. In 1991, significant decreases in corn yield were observed for DPX-79406 doses of > 12.5 g ha−1 applied at the four-to-five-leaf stage of quackgrass. For all the variables studied, DPX-79406 doses of 6.25–12.5 g ha−1 resulted in consistent control of quackgrass. Key words: DPX-79406, nicosulfuron, rimsulfuron, quackgrass, Elytrigia repens, corn, Zea mays

scholarly journals Induction of Diploid Eggs With Colchicine During Embryo Sac Development in Populus

2010 ◽  
Vol 59 (1-6) ◽  
pp. 40-48 ◽  
Author(s):  
J. Wang ◽  
X. Y. Kang ◽  
D. L. Li ◽  
H. W. Chen ◽  
P. D. Zhang
Keyword(s):  
Generative Cell ◽  
Embryo Sac ◽  
Mitotic Division ◽  
Chromosome Counting ◽  
Paraffin Sections ◽  
Stigma Receptivity ◽  
The Third ◽  
Embryo Sac Development ◽  
2N Eggs ◽  
Colchicine Solution

Abstract Diploid (2n) eggs were induced by treating developing embryo sacs of Populus with colchicine solution, in order to produce triploid plants. The optimal pollinated time of female catkins was confirmed as timing point for each treatment. When female catkins of P. pseudo-simonii x P. nigra ‘Zheyin3#’ had become 5.62 ± 0.13 cm long 84 h after they emerged from their bract scales and all stigmas were exposed, pistils all over the entire catkin had optimal stigma receptivity. Observation of paraffin sections showed that embryo sac development of ‘Zheyin3#’, which initiated 12 h before pollination and finished 132 h after pollination, was a successive and asynchronous process. Generative cell division of pollen of the male parent P. x beijingensis took place 3-16 h after pollination. Catkins of 18-96 h after pollination of ‘Zheyin3#’ were treated with colchicine solution. In the progeny, twenty three triploids were detected by chromosome counting and the highest rate of triploids was 66.7% in one treatment. The rate of triploid yield was positively correlated with the frequency of four-nucleate embryo sacs (r = 0.6721, p = 0.0981) and was not significantly correlated with the percentages of uni-, twoand eight-nucleate embryo sac (r = -0.1667, p = 0.7210, r = -0.3069, p = 0.5031 and r = 0.0189, p = 0.9679, respectively), suggesting that the third mitotic division of embryo sac may be the effective stage to induce 2n eggs. Through this approach, completely homozygous 2n eggs can be produced. Its significance for plant breeding is discussed.

Hypostase development in Ornithogalum caudatum (Liliaceae) and notes on other types of modifications in the chalaza of angiosperm ovules

1980 ◽  
Vol 58 (19) ◽  
pp. 2059-2066 ◽  
Author(s):  
Varien R. Tilton
Keyword(s):  
Embryo Sac ◽  
Mitotic Division ◽  
Integral Function ◽  
Developmental Changes ◽  
Storage Tissue ◽  
Storage Product ◽  
The Third ◽  
Carbohydrate Storage ◽  
Mature Ovule ◽  
Ornithogalum Caudatum

Seven types of chalazal modifications have been reported to occur as normal developmental changes in angiosperm ovules. Among them is the hypostase, a group of usually lignified cells. In Ornithogalum, hypostase differentiation becomes evident during the meiotic–mitotic interphase. Differentiation proceeds toward the micropylar end of the ovule at first but later becomes bidirectional. Differentiation is usually completed after the third mitotic division of the megagametophyte has occurred. One to three hypostase cells per ovule have what appears to be a nonstarch carbohydrate storage product. The greatest proportion of starch reserves in the mature ovule occurs in the chalazal end of the nucellus and, although the hypostase does not seem to be an important storage tissue, it probably has an integral function in the translocation of nutrients into the megagametophyte and, after fertilization, into the embryo sac.

Adjacent II segregation products in B–A translocations of maize

Genome ◽  
1991 ◽  
Vol 34 (4) ◽  
pp. 595-602 ◽  
Author(s):  
B. Kindiger ◽  
C. Curtis ◽  
J. B. Beckett
Keyword(s):  
Zea Mays ◽  
Key Words ◽  
Zea Mays L ◽  
Genetic Data ◽  
B Chromosomes ◽  
Cytological Data ◽  
Opposite Pole

In maize (Zea mays L.), meiotic events in B–A translocations that cause the A chromosome to move to one pole and the A–B and B–A chromosomes to move to the opposite pole result in the production of balanced, functional microspores and megaspores. Meiotic events that allow other combinations of chromosomes to proceed to the two poles (A A–B and A B–A) lead to the production of both duplicate (A A–B) and deficient (B–A) spores. Microspores and often megaspores that are deficient for a segment of the A chromosome are expected to abort. Duplication-bearing gametes usually function through the egg but are less able to compete with the normal gametes in the pollen. Cytological data, and genetic data from pollen, kernel, and seedling counts, were used to identify the production of A A–B gametes by B–A translocation heterozygotes and hyperploids. Adjacent II segregation of the A and A–B chromosomes of B–A heterozygotes and hyperploids has been detected in stocks of several different B–A translocations. Some B–A translocations exhibited a frequency of adjacent II segregation as high as 23%.Key words: Zea mays, adjacent segregation, B chromosomes, translocation.

CO446 corn inbred line

2010 ◽  
Vol 90 (5) ◽  
pp. 703-706
Author(s):  
L. M. Reid ◽  
X. Zhu
Keyword(s):  
Zea Mays ◽  
Key Words ◽  
Inbred Line ◽  
Combining Ability ◽  
Zea Mays L ◽  
Lodging Resistance ◽  
Cultivar Description ◽  
Short Season ◽  
Corn Inbred

CO446 is a short-season corn (Zea mays L.) inbred line with excellent combining ability and lodging resistance in hybrids. This inbred performed well as a parent with both stiff and non-stiff stalk inbreds. Excellent yields were achieved with the non-stiff stalk commercial inbred LH295 and the stiff-stalk commercial tester inbred TR2040. Key words: Corn, maize, Zea mays, cultivar description

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