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41.
Canopy cover (CC) is a good predictor variable for plant growth parameters such as leaf area index and aboveground biomass.
A nondestructive, low-cost, and convenient method is presented for estimating CC using digital camera image analysis. CC was
estimated by the ratio of plant pixels to total pixels of digital camera image of rice field. To determine the criteria for
segmenting the rice plant from variable soil background, three mosaic images for rice plant, flooded/bare soil, and algae-infested
background were prepared from digital camera images that were taken in various field conditions. An image analysis program
was developed in Visual Basic to extract red, green, and blue (RGB) features from the mosaic images, calculate RGB-based color
indices, and compute the minimum segmentation error for separating rice plant from background. When judged by the segmentation
error, modified excessive green index (MEGI) showed the highest potential for segmenting rice plant from flooded/bare soil
background, followed by normalized green (g) and excessive green index (EGI). At the threshold MEGI value of 0.03, the segmentation
error was the lowest as 0.13%. Any single index considered was not satisfactory in segmenting rice plant from algae-infested
background. However, a discriminant function of 1.2553EGI + 0.01735G − 0.01474B was successful in segmenting rice plant from
flooded/bare soil and algaeinfested background with segmentation errors of 0.34 and 1.17%, respectively. CC for four rice
varieties from tillering to booting stage was estimated based on the threshold value of MEGI and discriminant function and
also manually using commercial software. Both estimates of CC showed good relationship of r2 = 0.94, suggesting that a digital camera could be used efficiently for measuring the CC of rice field. 相似文献
42.
43.
Oda E Ohki R Murasawa H Nemoto J Shibue T Yamashita T Tokino T Taniguchi T Tanaka N 《Science (New York, N.Y.)》2000,288(5468):1053-1058
A critical function of tumor suppressor p53 is the induction of apoptosis in cells exposed to noxious stresses. We report a previously unidentified pro-apoptotic gene, Noxa. Expression of Noxa induction in primary mouse cells exposed to x-ray irradiation was dependent on p53. Noxa encodes a Bcl-2 homology 3 (BH3)-only member of the Bcl-2 family of proteins; this member contains the BH3 region but not other BH domains. When ectopically expressed, Noxa underwent BH3 motif-dependent localization to mitochondria and interacted with anti-apoptotic Bcl-2 family members, resulting in the activation of caspase-9. We also demonstrate that blocking the endogenous Noxa induction results in the suppression of apoptosis. Noxa may thus represent a mediator of p53-dependent apoptosis. 相似文献
44.
Moytri RoyChowdhury Yulin Jia Aaron Jackson Melissa H. Jia Robert Fjellstrom Richard D. Cartwright 《Euphytica》2012,184(1):35-46
The Pi-z gene in rice confers resistance to a wide range of races of the rice blast fungus, Magnaporthe oryzae. The objective of this study was to characterize Pi-z in 111 rice germplasm accessions using DNA markers and pathogenicity assays. The existence of Pi-z in rice germplasm was detected by using four simple sequence repeat (SSR) markers (RM527, AP4791, AP5659-1, AP5659-5) closely
linked to Pi-z, and was verified using pathogenicity assays with an avirulent strain (IE1k) and two virulent races (IB33 and IB49). Among
111 germplasm accessions evaluated, 73 were found to contain the Pi-z gene using both SSR markers and pathogenicity assays. The remaining 38 germplasm accessions were found to be inconsistent
in their responses to the blast races IB33, IEIk and IB49 with expected SSR marker alleles, suggesting the presence of unexpected
SSR alleles and additional R gene(s). These characterized germplasm can be used for genetic studies and marker-assisted breeding for improving blast resistance
in rice. 相似文献
45.
Zhi-Wei Wang Lei Gao Hai Zhou Liu Shi Yong Mei Yuan Zhou Chang Ping Xiang Ting Wang 《Euphytica》2012,186(2):313-320
A male sterile plant appeared in the radish breeding program at the Hubei Academy of Agricultural Sciences, Hubei, China.
In its progeny, a two-type (half of plants male sterile, the other half male fertile) line 01GAB was established. An F2 population of 260 plants from a cross of male-sterile 01GAB and a male fertile line 9802H segregated for male fertility in
a 3:1 ratio indicating that fertility was restored by a single dominant gene, here designated RsMs. A PCR-based DNA marker specific to the male fertility Rfob gene in 9802H was absent in 01GAB. Linkage analysis placed the RsMs locus 10.7 cM away from the Rfo locus. In an F2 population of hybrids between 01GAB and male fertile 9802B, a co-dominant DNA marker for the RSultr3.2A (a radish sulfate transporter gene) locus was linked to the RsMs locus at 1.5 cM suggesting that fertility restoration in 01GAB was located in the region with known male sterility restorers
in radish. However, no maintainer for the 01GAB source of male sterility has been identified so far. Cytological observations
have shown that the abnormalities in male sterile anthers first appeared in tapetum at the tetrad stage, followed by a hypertrophy
of the tapetal cells at the vacuolate microspore period. These results suggest that male sterility in 01GAB is likely to be
genetic in nature, or it may represent a new type of the cytoplasmic male sterility. 相似文献
46.
Aneeta Pradhan Julie A. Plummer Matthew N. Nelson Wallace A. Cowling Guijun Yan 《Euphytica》2010,176(1):87-98
A triploid hybrid with an ABC genome constitution, produced from an interspecific cross between Brassica napus (AACC genome) and B. nigra (BB genome), was used as source material for chromosome doubling. Two approaches were undertaken for the production of hexaploids:
firstly, by self-pollination and open-pollination of the triploid hybrid; and secondly, by application of colchicine to axillary
meristems of triploid plants. Sixteen seeds were harvested from triploid plants and two seedlings were confirmed to be hexaploids
with 54 chromosomes. Pollen viability increased from 13% in triploids to a maximum of 49% in hexaploids. Petal length increased
from 1.3 cm (triploid) to 1.9 cm and 1.8 cm in the two hexaploids and longest stamen length increased from 0.9 cm (triploid)
to 1.1 cm in the hexaploids. Pollen grains were longer in hexaploids (43.7 and 46.3 μm) compared to the triploid (25.4 μm).
A few aneuploid offsprings were also observed, with chromosome number ranging from 34 to 48. This study shows that trigenomic
hexaploids can be produced in Brassica through interspecific hybridisation of B. napus and B. nigra followed by colchicine treatment. 相似文献
47.
Jundae Lee Jae Bok Yoon Jung-Heon Han Won Phil Lee Sang Hoon Kim Hyo Guen Park 《Euphytica》2010,173(1):55-61
Genic male sterility (GMS) has long been used as a tool for hybrid seed production in chili pepper (Capsicum annuum L.). We developed DNA markers linked to the GMS ms
3
gene in a segregating population using bulked segregant analysis (BSA) and amplified fragment length polymorphism (AFLP)
techniques. The segregating population was subjected to BSA-AFLP with 512 primer combinations. Three AFLP markers (Eagg/Mccc276, Eagc/Mctt178, and Ecag/Mtgc204) were identified as tightly linked to the ms
3
locus. Among them, we converted the AFLP marker Ecag/Mtgc204 to the cleavage amplified polymorphic sequence (CAPS) marker, named GMS3-CAPS, based on sequencing analysis of internal and
flanking regions for the markers between male-fertile and sterile plants. This marker will be useful for pepper breeding using
the GMS system. 相似文献
48.
The objective of this study was to identify molecular markers linked to fruit-related traits in the tomato subjected to high
temperatures. In total, 160 F2 plants derived from a cross between a heat-tolerant breeding line, CL5915-93D4-1-0-3 (Solanum esculentum), and a heat-sensitive wild accession, L4422 (S. pimpinellifolium), were grown in a greenhouse. Six traits including fruit number, fruit weight, brix, seed number, fruit setting, and flower
number were scored. The distributions of fruit number, fruit set, flower number, and seed number were skewed towards heat
susceptibility which is known to be characteristic of L4422. Polymorphic bands were generated by PCR-derived methods of RAPD,
ISSR and AFLP Polymorphism, the segregation ratio, and distribution over the genome of the above 3 markers were compared.
Ten linkage groups, ranging 20.6–151.6 cM in size, were constructed with 62 informative markers spanning a total of 776.3 cM.
Fruit-related quantitative trait loci (QTLs) were non-randomly distributed in the tomato genome. For the 6 traits investigated,
21 QTLs were dispersed on linkage groups 2–5. The genetic effects of the various QTLs were differently exhibited, in our study
we have respectively found from 10.5% to 30.2% of the variation explained by the QTL for flower number (FRN4) and brix (BX2).
Thirteen QTL-mapped markers were unique to 1 trait, and 4 markers were linked to more than 1 trait. Among them, QTLs linked
to the I868-470 marker had effects on fruit weight and brix, and a significant positive correlation between these 2 traits
was noted (r = 0.35, P < 0.05). Thus, the I868-470 marker may have the potential for simultaneous selection of high fruit weight and brix. These
markers also allowed us to align genome linkage maps across distantly related species and to reveal the co-localization between
these QTLs and major genes. 相似文献
49.
Plants of white clover (Trifolium repens L.) cultivar Crau, a self-fertile Crau genotype, and nine generations of inbred progeny were raised in sand culture in a
glasshouse experiment. Digital images of the root systems were made and root morphological characteristics were determined
on all the plants. Root architectural parameters were measured on the Crau parent and the S1, S4, S6, and S9 inbred lines. The clover roots became shorter and thicker with inbreeding but the number of root tips per plant was unchanged.
Root architecture (branching pattern) was largely unaffected by inbreeding. It is concluded that inbreeding white clover will
lead to shorter, thicker roots, and reduced nutrient uptake efficiency compared with the parent clover. The degree to which
these deleterious traits are overcome during the development of F1 hybrids needs to be determined. 相似文献
50.
The height-reducing gene Rht8 was introduced into Italian wheats by breeder Nazareno Strampelli from the Japanese landrace Akakomugi, and has been widely
used in wheats adapted to southern and eastern European conditions. Following identification of a close linkage to Rht8, microsatellite marker Gwm261 has been used extensively to screen large numbers of diverse international germplasm. A 192bp allele at this locus has been
taken as “diagnostic” for Rht8 and used to infer the international distribution of Rht8. In this paper, we report several instances of cultivars and mapping populations that vary for the presence of the 192bp
allele at the Xgwm261 locus (Xgwm261
192
), but with no associated reduction in height, suggesting a lack of association with Rht8. For instance, in the population derived from a cross between Sunco (Rht-B1b, Xgwm261
165
) and Tasman (Rht-D1b, Xgwm261
192
), there were significant height differences associated with the segregation of Rht-B1b and Rht-D1b, but no height differences between Xgwm261 genotypes. Similar results were obtained in a population derived from the cross between Molineux (Rht-B1b, Xgwm261
192
) and Trident (Rht-D1b Xgwm261
208
). In contrast, the cross between Trident and Chuanmai 18 (Xgwm261
192
) gave significant height effects at both the Rht-D1 and Xgwm261 loci, with no epistatic interaction between loci. Chuanmai 18 is closely related to the Strampelli wheat Mara (ancestrally
derived from Akakomugi) and is therefore likely to carry Rht8. The old Japanese cultivar Norin 10, used by Norman Borlaug to introduce Rht-B1b and Rht-D1b into Mexican wheats, also has a 192bp allele at the Xgwm261 locus, and the sequence of the amplified product is identical to that of Akakomugi. We suggest that the widespread use of
Norin 10-derived germplasm during and after the Green Revolution introduced a second haplotype into international germplasm,
in which Xgwm261
192
has no association with Rht8. Therefore, the presence of Xgwm261
192
is only indicative of Rht8 in wheat cultivars that have inherited this allele from Akakomugi or a Strampelli wheat ancestor. 相似文献