Male Sterile Version Research Articles

Rendimiento de híbridos androestériles y fértiles de maíz en dos localidades en Valles Altos de México


 
 
 En este trabajo se evaluaron cinco híbridos trilineales de maíz (H-53AE1, H-53AE2, H-47AER1, H-47AER2, H-48AE1), en sus versiones androestéril y fértil, en dos localidades de VallesAltos. El objetivo fue definir la capacidad productiva de cada uno. La investigación se llevó a cabo en el ciclo primavera verano 2010, en el Campo Experimental Valle de México (CEVAMEX) y en la Facultad de Estudios Superiores Cuautitlán (FESC). Los tratamientos en el estudio fueron: los híbridos trilineales, las versiones androestéril y fértil y las dos localidades. El análisis estadístico se efectuó en forma factorial considerando los factores híbridos, androesterilidad/ fertilidad, localidades y las interacciones. Para rendimiento se observaron diferencias significativas para localidades, así como para híbridos, pero no para el factor androesterilidad/ fertilidad. Se concluyó que la localidad FESC (9 340 kg ha-1), fue superior a la media del CEVAMEX (7 141 kg ha-1). El mayor rendimiento se obtuvo con el híbrido H-53AE1, con 9 226 y el menor fue H-48 AE1 (7 617 kg ha1). Se encontró que la media de la versión androesteril, considerando todos los genotipos y las dos localidades, exhibió un rendimiento de 8 498 kg ha-1, similar estadísticamente al rendimiento de la versión fértil (7 983 kg ha-1).
 
 

Productividad de grano de cuatro híbridos trilineales de maíz en versión androestéril y fértil.

The objective of this study was to evaluate the productivity of maize hybrids developed for The High Valleys of Mexico. Four hybrids in their versions of male-sterile and fertile were evaluated in four uniform experiments using a randomized complete block design, at the Experimental Station of Mexico (CEVAMEX) and the Faculty of Higher Studios Cuautitlan (FESC-UNAM). The statistical analysis was performed in a combined form with the factors: hybrids (4), locations (4), male sterility/fertility versions (2), and the interactions between these factors. Significant differences for genotypes (p≤0.01), for locations and for interaction hybrid x locations (p≤0.05) were detected. The coefficient of variation for seed yield was 21.5% and overall mean was of 6,998 kg/ha. The site CEVAMEX 2009, in its first planting date, produced 8829 kg/ha and surpassed the other three environments. The performance of the four hybrids was similar (p>0.05). The male sterile version had a yield of 7170 kg/ha, similar (p>0.05) to the fertile version (6826 kg/ha), which confirms that the versions of the fertile and male-sterile hybrids of this study are isogenic.

Registration of ATx3363 and BTx3363 Black Sorghum Germplasms

The sorghum [Sorghum bicolor (L.) Moench] germplasms ATx3363 (Reg. No. GP‐731, PI 668028) and BTx3363 (Reg. No. GP‐732, PI 668029) were developed and released by Texas AgriLife Research sorghum breeding program in 2012. Tx3363 is a grain sorghum seed parent designed to produce a very dark‐colored (i.e., black) grain hybrid in combination with Tx3362. BTx3363 was developed with pedigree selection methods and the male sterile version (ATx3363) was developed via backcrossing using ATx623 as a source of A1 cytoplasm. Grain produced from the combination of Tx3363/Tx3362 has potential use and application as a natural colorant and source of antioxidants. The color is associated with high levels of 3‐deoxyanthocyanins in the pericarp of the grain. Therefore, they have application as natural colorants in many processed food products. Because these compounds are present in the pericarp, they are easily concentrated by simply decorticating the grain and collecting the resulting bran. Tx3363 sorghum germplasm can be used as a seed parent to produce hybrids rich in 3‐deoxyanthocyanins or as a breeding parent to produce additional lines with this unique characteristic.

‘Mountain Majesty’: A Tomato Spotted Wilt Virus-resistant Fresh-market Hybrid Tomato and Its Parents NC 714 and NC 1CS

‘Mountain Majesty’, the F1 hybrid of NC 714·NC 1CS (Fig. 1), resulted from a tomato breeding effort to develop a superior largefruited hybrid tomato with improved fruit color based on the crimson (og) gene combined with fusarium wilt, verticillium wilt, and TSWV resistances adapted to vine-ripe production in North Carolina (NC). NC 714 resulted from selfing NC 03113, the F1 hybrid of Fla 8044 · NC 00318–15(x)-1 (Fig. 1). Fla 8044 is a large-fruited, hightemperature fruit set line with desirable horticultural traits and multiple disease resistance genes obtained from the University of Florida tomato breeding program. NC 00318–15(x)-1 is an F2 selection obtained by crossing a male sterile version of NC 84173 with an F3 generation line derived from selfing the North Carolina State University (NCSU)-released hybrid ‘Mountain Crest’ (NC 84173 · NC 1 rinEC) (Gardner, 2006). The crimson gene in NC 714 was derived from the NC 1rinEC parent of ‘Mountain Crest’ and Fla 8044. The objective of breeding NC 714 was to incorporate desirable fruit characteristics and superior combining ability from NC 84173 (Gardner, 1992) together with the crimson gene for increased red fruit color and lycopene content. Single plant selections were made for large fruit size, high yield, and other desirable horticultural traits in the F2 through F5 generations derived from selfing NC 03113. NC 1 CS resulted from selfing NC 056, the F1 hybrid of NC 123S ·NC 0255(x)-1 (Fig. 1). NC 123S, which combines single dominant gene resistances to TSWV, fusarium wilt race 3, and nematodes (Sw-5, I-3, Mi genes) and was released from the NC breeding program. ‘Amelia’ F1 hybrid, from which NC 123S was developed, is a codeveloped hybrid using NC 111F-2(98) as a source of the I-3 gene for fusarium wilt race 3 resistance crossed with a Clause Seed Company proprietary line having the Sw-5 and Mi genes. NC 0255(x)-1 is an outstanding large-fruited selection with the crimson gene that traces its pedigree back to breeding lines and cultivars developed in the NC tomato breeding program over a 25year period (Fig. 1). The source of the crimson gene in NC 0255(x)-1 is ‘Suncoast’, an inbred cultivar released from the University of Florida breeding program.

Registration of Tx2929 through Tx2934 Sorghum Germplasm

The sorghum [Sorghum bicolor (L.) Moench] germplasm lines A/BTx2929 through A/BTx2934 (Reg. No. GP‐662, PI 650859 to Reg. No. GP‐673, PI 650870) were developed and released by the Texas Agricultural Experiment Station—now Texas AgriLife Research—College Station, TX, in 2004. These germplasm lines were selected and developed to provide the sorghum industry with elite seed‐parent sorghum germplasm of diverse pedigree with good general combining ability and unique combinations of grain color, plant color, agronomic traits, and resistance to head smut [caused by Sporosorium relianum) (Kuhn) Langdon & Fullerton], rust [caused by Puccinia purpurea (Cooke)], and anthracnose [caused by Colletotrichum graminicola (Ces.) G.W. Wilson]. These lines were developed using the pedigree breeding approach, and selections were carried out in Texas and Puerto Rico. Male‐sterile versions of these seed parents were produced using backcross breeding approaches and ATx623 as the source of male‐sterile cytoplasm. Backcrossing was conducted at either the Texas or Puerto Rico locations. Each of these germplasms was then evaluated in testcross combinations (with common pollinator parents) in multiple environments in Texas. Each of these germplasms showed good general combining ability and adaption for Texas sorghum production environments. This germplasm is suitable for use as a seed parent for the production of grain or forage sorghum hybrids or as parental sources for the development of improved seed parent lines.

Enhanced kernel set promoted by synchronous pollination determines a tradeoff between kernel number and kernel weight in temperate maize hybrids

Maize ( Zea mays L.) grain yield is strongly related to the number of harvested kernels, where kernel number can be increased by synchronously pollinating silks rather than allowing them to be progressively pollinated as they naturally appear from the husks. However, there is scarce evidence on how this practice affects kernel weight (KW) and plant grain yield (PGY), and no report exists on its effects when combined with treatments aimed to reduce apical dominance, like male sterility and detasseling. Field experiments were conducted in two growing seasons (Exp 1 and Exp 2) using two hybrids, cropped at contrasting stand densities (3 and 9 plants per m 2) and including (i) male-fertile and male-sterile versions, (ii) tasseled and detasseled plants, and (iii) natural (NP) and synchronous pollination (SP; pollen added manually to ears bagged 5 days after initial silking) systems. Tassel growth of sterile and fertile versions was also evaluated in a separate experiment (Exp 3). Detasseling increased the number of ears per plant reaching silking ( P < 0.001) of NP plants, but this beneficial effect of reduced apical dominance did not improve kernel number per plant (KNP) or PGY. Similarly, the early arrest of anther growth in male-sterile plants had no clear benefit on KNP. In contrast, KNP was enhanced by synchronous pollination (range between −13% and +71%; average of +15.4% in Exp 1 and +3.9% in Exp 2). However, this pollination system promoted a decreased in KW (range between −30% and +4%; average of −11.8% in Exp 1 and −7.8 in Exp 2) such that the treatment had no effect on PGY (range between −19% and +37%; average of +1% in Exp 1 and −4% in Exp 2). Because plant growth rate around flowering was not different between pollination treatments, assimilate availability per kernel was reduced from ovary fertilization onwards in synchronously pollinated plants when compared to open pollinated plants. This explains the reduced KW when increasing KNP by synchronous pollination. In summary, none of the imposed treatments allowed grain yield to be increased at the plant level.

Dominant male sterility in sorghum: effect of nuclear background on inheritance of tissue-culture-induced mutation

Occurrence of genetic instability and formation of stable mutations are basic genetic processes. This study demonstrates that nuclear background may influence the formation of stable dominant nuclear gene of male sterility (MS) on the basis of unstable mutation, which was induced in tissue culture of the sorghum haploid (cv. Milo-145). The mutants with complete or partial MS segregated in variable ratios in the progenies of diploid regenerants were obtained from different experiments on cultivation of haploid tissues. In the Milo-145 genetic background the mutation demonstrated somatic instability and was gradually eliminated by self-pollination of partially sterile plants. Hybridization of the MS-plants with the sorghum line SK-723, a fertility-restorer of the cytoplasmic MS A1 (milo) type, maintained the induced mutation. By repeated backcrossing of MS-plants with SK-723, the male-sterile versions of this line (SK-723- Ms(tc)) have been created. In BC-generations, fertile, partially and completely sterile plants were observed. The MS-plants from BC-generations are proposed to contain a dominant gene Ms(tc) while fertile plants were ms(tc)/ms(tc) homozygotes. Crossing the original MS-plants with SK-723 was a key factor in stabilization of the Ms(tc) gene. Dominant expression of the Ms(tc) was observed in male-sterile versions of other sorghum lines created by backcrossing to SK-723- Ms(tc). The lines fertility-restorers for this mutation have been revealed. In the crosses of restored F1 hybrids with emasculated plants of the non-restoring line, the Ms(tc) has been transferred through the pollen and manifested in the F1 generation. The possibility of the Ms(tc) originating as a result of interaction of an unstable allele of the Milo-145 with the SK-723 genome is discussed.

Inheritance of reduced plant height in the sunflower line Dw 89

AbstractThe objective of the present research was to study the inheritance of reduced plant height in the sunflower line Dw 89. Plants of the cytoplasmic male sterile version of this line, cmsDw 89 (mean plant height of 47.4 cm) were crossed with plants of the restorer line RHA 271 (mean of 120.9 cm). F1 plants averaged 120.4 cm, which indicated dominance of standard over reduced plant height. F2 plants followed a segregation pattern of 1 : 15 (reduced : normal height), suggesting that reduced plant height in Dw 89 is controlled by alleles at two loci, designated Dw1 and Dw2. Class assignment in the F2 was confirmed through the evaluation of the F3 generation. Backcrosses to Dw 89 segregated with 1 : 3 (reduced : normal height) ratios, which confirmed the digenic inheritance of the trait. The evaluation of plant height distributions in F3 families suggested possible genetic interaction between the Dw1 and Dw2 loci.

STEM MORPHOLOGY AND ANATOMY IN ZEA MAYS AS INFLUENCED BY CYTOPLASMIC MALE STERDLITY AND RESTORER GENES

The stem morphology of three versions (normal, male-sterile, and restored) of five lines of corn (Zea mays L.) was examined. Corn stems in both the male-sterile (Texas cytoplasm) and restored versions of line Mp466 were shorter than the normal version. Stem diameters were less in the male-sterile version in two of the five lines examined. Histological examination of the three versions in line CI21 showed that vascular bundle radial diameters in cross sections were less in the male-sterile tassel culms than the normal. Reduction in the amount of phloem appeared to be the cause. Cells in longitudinal sections appeared to be about the same length in all versions, or shorter in the normal; therefore, shortening of the male-sterile stems apparently results from a reduction in cell number.