| 1. |
- Batte, Michael, et al.
(författare)
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Crossbreeding East African Highland Bananas: Lessons Learnt Relevant to the Botany of the Crop After 21 Years of Genetic Enhancement
- 2019
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Ingår i: Frontiers in Plant Science. - : Frontiers Media SA. - 1664-462X. ; 10
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Tidskriftsartikel (refereegranskat)abstract
- East African highland bananas (EAHB) were regarded as sterile. Their screening for female fertility with "Calcutta 4" as male parent revealed that 37 EAHB were fertile. This was the foundation for the establishment of the EAHB crossbreeding programs by the International Institute of Tropical Agriculture (IITA) and the National Agricultural Research Organization (NARO) in Uganda in the mid-1990s. The aim of this study was to assess the progress and efficiency of the EAHB breeding program at IITA, Sendusu in Uganda. Data on pollinations, seeds generated and germinated, plus hybrids selected between 1995 and 2015 were analyzed. Pollination success and seed germination percentages for different cross combinations were calculated. The month of pollination did not result in significantly different (P = 0.501) pollination success. Musa acuminata subsp. malaccensis accession 250 had the highest pollination success (66.8%), followed by the cultivar "Rose" (66.6%) among the diploid males. Twenty-five EAHB out of 41 studied for female fertility produced up to 305 seeds per pollinated bunch, and were therefore deemed fertile. The percentage of seed germination varied among crosses: 26% for 2x x 4x, 23% for 2x x 2x, 11% for 3x x 2x, and 7% for 4x x 2x. Twenty-seven NARITA hybrids (mostly secondary triploids ensuing from the 4x x 2x) were selected for further evaluation in the East African region. One so far -"NARITA 7"- was officially released to farmers in Uganda. Although pollination of EAHB can be conducted throughout the year, the seed set and germination is low. Thus, further research on pollination conditions and optimization of embryo culture protocols should be done to boost seed set and embryo germination, respectively. More research in floral biology and seed germination as well as other breeding strategies are required to increase the efficiency of the EAHB breeding program.
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| 2. |
- Batte, Michael, et al.
(författare)
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Heterobeltiosis in banana and genetic gains through crossbreeding
- 2020
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Ingår i: Proceedings. - Basel Switzerland : MDPI. ; 36
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Konferensbidrag (refereegranskat)abstract
- Heterosis, or hybrid vigour, is the superiority of the hybrid for a certain trait over the mean of its two parents. Heterobeltiosis is a form of heterosis where the hybrid is superior to its best parent. Banana breeding is a tedious, time-consuming process, taking up to two decades to develop a hybrid. Understanding heterosis in banana breeding will contribute to selecting right breeding materials for further crossing, thus increasing banana breeding efficiency. Here we document heterobeltiosis by using the recently bred NARITA ‘Matooke’ hybrids and their ancestors. NARITA hybrids, their parents (4x and 2x), grandparents (3x and 2x), and local 3x ‘Matooke’ cultivar checks were planted in a rectangular lattice design with two replications. Yield and other agronomic data were collected at flowering and harvest. The NARITAs were compared with their 3x ‘Matooke’ grandmothers. Heterobeltiosis on bunch weight was calculated with the data of 3 cycles. All the NARITAs showed heterobeltiosis for bunch weight. NARITA 17 had the highest grandparent heterobeltiosis (ca. 250%). Genetic gains due to crossbreeding were determined for fruit yield considering three generations: matooke cultigen (C0), primary tetraploid hybrids (C1) and secondary tetraploid hybrids (C2). The average genetic gain (from C0 to C2) rates for bunch weight (kg) and yield potential (t ha−1 year−1) were 1.4% and 1.3% per year, respectively.
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| 3. |
- Batte, Michael
(författare)
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Increasing efficiency of the breeding pipeline for East African highland bananas
- 2019
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Banana breeding is a technically challenging endeavor due to the low reproductive fertility, low seed germination, long selection cycle period and large space requirement for field evaluation, among others. Innovations in the current breeding program are required to increase the rate of genetic gain delivery to farmers. This study considers five approaches to tackle this challenge; 1) assessment of the available minimum descriptor list for suitability to characterize the East African highland banana (EAHB) germplasm, 2) analysis of crossbreeding data of EAHB for the first 21 years (from 1995 to 2015) at the International Institute of Tropical Agriculture as a basis for designing future interventions, 3) path analysis to determine a breeding ideotype for EAHB, 4) estimation of heterobeltiosis (hybrid vigour) for the NARITA hybrids (mostly secondary triploids ensuing from the 4x × 2x), and 5) phenotyping a diploid banana population (‘Calcutta 4’ × ‘Zebrina GF’ ) for resistance to Radopholus similis. Ten out of 31 descriptors studied were stable but had similar scores in EAHB cultivars and therefore are not suitable to distinguish between them. The month of pollination did not result in significantly different (P = 0.501) pollination success, implying that pollination of EAHB can be conducted throughout the year. However, the seed set, and rate of germination were still low. Thus, further research about seed production and germination is required. Twenty-seven NARITAs were selected for further evaluation in the East African region. Path analysis revealed that fruit length, circumference and number, number of hands and plant cycle number had a direct positive effect on the bunch weight (a proxy for edible yield). Significant progressive heterobeltiosis for bunch weight was found in all the NARITAs. Half of the NARITAs had negative heterobeltiosis for stature. The diploid population was found to segregate for resistance to R. similis. Results from Dunnett’s test grouped the population in three main phenotypic classes, with 75 susceptible, 17 intermediates and 19 resistant genotypes. Chi-square goodness of fit test revealed that this resembles a phenotypic ratio of 9:3:4 suggesting recessive epistasis.
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| 4. |
- Batte, Michael, et al.
(författare)
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Significant progressive heterobeltiosis in banana crossbreeding
- 2020
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Ingår i: BMC Plant Biology. - : Springer Science and Business Media LLC. - 1471-2229. ; 20
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Tidskriftsartikel (refereegranskat)abstract
- BackgroundHeterobeltiosis is the phenomenon when the hybrid's performance is superior to its best performing parent. Banana (Musa spp. AAA) breeding is a tedious, time-consuming process, taking up to two decades to develop a consumer acceptable hybrid. Exploiting heterobeltiosis in banana breeding will help to select breeding material with high complementarity, thus increasing banana breeding efficiency. The aim of this study was therefore to determine and document the level of heterobeltiosis of bunch weight and plant stature in the East African highland bananas, in order to identify potential parents that can be used to produce offspring with desired bunch weight and stature after a few crosses.ResultsThis research found significant progressive heterobeltiosis in cross-bred 'Matooke' (highland cooking) banana hybrids, also known as NARITAs, when grown together across years with their parents and grandparents in Uganda. Most (all except 4) NARITAs exhibited positive heterobeltiosis for bunch weight, whereas slightly more than half of them had negative heterobeltiosis for stature. The secondary triploid NARITA 17 had the highest heterobeltiosis for bunch weight: 249% versus its 'Matooke' grandparent and 136% against its primary tetraploid parent. Broad sense heritability (across three cropping cycles) for yield potential and bunch weight were high (0.84 and 0.76 respectively), while that of plant stature was very low (0.0035). There was a positive significant correlation (P < 0.05) between grandparent heterobeltiosis for bunch weight and genetic distance between parents (r=0.39, P=0.036), bunch weight (r=0.7, P<0.001), plant stature (r=0.38, P=0.033) and yield potential (r=0.59, P<0.001). Grandparent heterobeltiosis for plant stature was significantly, but negatively, correlated to the genetic distance between parents (r=-0.6, P<0.001).ConclusionsSuch significant heterobeltiosis exhibited for bunch weight is to our knowledge the largest among main food crops. Since bananas are vegetatively propagated, the effect of heterobeltiosis is easily fixed in the hybrids and will not be lost over time after the release and further commercialization of these hybrids.
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| 5. |
- Batte, Michael, et al.
(författare)
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Suitability of existing Musa morphological descriptors to characterize East African highland 'matooke' bananas
- 2018
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Ingår i: Genetic Resources and Crop Evolution. - : Springer Science and Business Media LLC. - 0925-9864 .- 1573-5109. ; 65, s. 645-657
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Tidskriftsartikel (refereegranskat)abstract
- Morphological traits are commonly used for characterizing plant genetic resources. Germplasm characterization should be based on distinctly identifiable, stable and heritable traits that are expressed consistently and are easy to distinguish by the human eye. Characterization and documentation of a representative sample of East African highland bananas (Lujugira-Mutika subgroup) was carried out following an internationally accepted standard protocol for bananas. Eleven cultivars were characterized using an existing set of minimum descriptors (31 qualitative and quantitative traits) with the aim of determining stable descriptors and the ability of these descriptors to distinguish among East African highland banana cultivars. There was variation in stability of these descriptors within cultivars and across the 11 cultivars. Only 10 (32%) out of 31 descriptors studied were stable in the 11 cultivars. However, they had similar scores and therefore are not suitable to distinguish between cultivars within this group. Nonetheless, these 10 descriptors may be useful for distinguishing the East African highland bananas as a group from other groups of bananas. A few descriptors were unique to the cultivar 'Tereza' and may be used to distinguish this cultivar from other 'matooke' cultivars. None of the quantitative descriptors were stable.
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| 6. |
- Batte, Michael, et al.
(författare)
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Traits that define yield and genetic gain in East African highland banana breeding
- 2021
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Ingår i: Euphytica. - : Springer Science and Business Media LLC. - 0014-2336 .- 1573-5060. ; 217
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Tidskriftsartikel (refereegranskat)abstract
- East African highland bananas (Musa spp. AAA group) are an important staple in the Great Lakes region of East Africa. Their production has declined due to pests and diseases. Breeding for host plant resistance is a sustainable option for addressing this challenge. Understanding the relationships between growth parameters and bunch weight (i.e., yield) is crucial to guide breeding efforts for this crop. We investigated cause-effect relationships, through path analysis, in bunch weight of East African highland banana derived hybrids, their parents and grandparents. These family structures were planted in a 7 × 8 rectangular lattice design, replicated twice. Genetic gains for bunch weight (kg plant−1) and yield potential (t ha−1 year−1) were estimated. Significant increases of bunch weight and yield potential were noted from the landrace triploid germplasm, their derived primary tetraploid hybrids and secondary triploid bred-germplasm. Path analysis revealed that fruit length, circumference and number, number of hands and plant cycle number had a direct positive effect on the bunch weight. Days to fruit filling, days to maturity and index of non-spotted leaves had indirect effects on bunch weight. The average genetic gains for bunch weight and yield potential were 1.4% and 1.3% per year, respectively. This is the first report about genetic gains in banana breeding. Our findings may be useful for assessing progress and directing future breeding efforts in banana breeding.
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| 7. |
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| 8. |
- Ortega, Pablo, et al.
(författare)
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Improving Arctic Weather and Seasonal Climate Prediction : Recommendations for Future Forecast Systems Evolution from the European Project APPLICATE
- 2022
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Ingår i: Bulletin of The American Meteorological Society - (BAMS). - 0003-0007 .- 1520-0477. ; 103:10, s. E2203-E2213
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Tidskriftsartikel (refereegranskat)abstract
- The Arctic environment is changing, increasing the vulnerability of local communities and ecosystems, and impacting its socio-economic landscape. In this context, weather and climate prediction systems can be powerful tools to support strategic planning and decision-making at different time horizons. This article presents several success stories from the H2020 project APPLICATE on how to advance Arctic weather and seasonal climate prediction, synthesizing the key lessons learned throughout the project and providing recommendations for future model and forecast system development.
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